Abstract— Snow is a very important component of the climate system which controls surface energy and water balances. Its high albedo, low thermal conductivity and properties of surface water storage impact regional to global climate. The various properties characterizing snow are highly variable and so have to be determined as dynamically active components of climate. However, on large spatial scales the properties of snow are not easily quantified either from numerical modelling or observations. Since neither observations (ground measurements or satellite retrievals) nor models alone are capable of providing enough adequate information about the time space variability of snow properties, it becomes necessary to combine their information. In the presented study the obtained with the regional climate model RegCM snow water equivalent (SWE) on monthly basis over Southeast Europe for a time window of 14 consecutive winters is compared with the Globsnow satellite product. The concordance between both datasets is evaluated with number of statistical scores. The result reveals the principal agreement between the two products, but however, with very significant discrepancies, mainly overestimations, for some years and gridcells.
Monitoring Changes in Antarctic Sea Ice Phenology: 1990-2015priscillaahn
This study analyzed changes in Antarctic sea ice phenology from 1990-2015 using satellite microwave data. The results show a trend of later melt seasons, with more sea ice persisting longer into the summer. Specifically, there was a 2.2% annual increase in the number of pixels classified as non-seasonal sea ice, indicating longer melt seasons. However, the classification scheme may not fully capture Antarctic sea ice behavior, which melts almost completely each summer due to less confinement than Arctic sea ice. Overall, the analysis found tentative evidence of delayed melt, but uncertainties remain regarding optimal classification of Antarctic sea ice types.
Modification and Climate Change Analysis of surrounding Environment using Rem...iosrjce
This document discusses the application of remote sensing (RS) and geographic information systems (GIS) in analyzing climate change and the surrounding environment. It begins by defining key terms related to climate, climate change, and RS and GIS. It then highlights several areas where RS and GIS have been applied, including glacier monitoring, vegetation change monitoring, and carbon trace/accounting. Studies are discussed that use RS and GIS to monitor glacier retreat, snow depth, land cover change, and above-ground carbon stocks. The document concludes that RS and GIS play a crucial role in understanding and managing climate change by providing important spatial data and enabling the monitoring of environmental changes over time.
CLIMATE CHANGE IMPACT ASSESSMENT ON MELTING GLACIERS USING RS & GISAbhiram Kanigolla
Remote sensing and GIS techniques are effective methods for mapping and monitoring glaciers and the impacts of climate change. Two case studies are summarized in the document. The first case study monitors the Gangotri glacier in India using satellite imagery and finds a 6% reduction in glacier area between 1962 and 2006. The second case study analyzes satellite images of Mount Suphan glacier in Turkey and determines that the glacier area decreased from 1.2 km2 to 0.33 km2 between 1977 and 2000, with climatic factors like increasing minimum temperatures contributing to the recession.
The discovery of year-round subsurface meltwater in Greenland's ice sheet in 2011 changed understanding of its hydrology. Satellite remote sensing could potentially monitor these perennial firn aquifers (PFAs) across time and throughout the year, extending data records. This study explores using microwave brightness temperature data from satellites to identify PFAs, addressing limitations of current monitoring methods. Preliminary results found locations with subsurface melting not explained by surface melt and regions of melt persisting into winter, consistent with known PFAs. Further work could improve identification methods and compare to established datasets.
- Abiotic controls, like precipitation and evaporation, dominate soil moisture spatiotemporal variability in wet climates, while biotic controls from vegetation become more important in Mediterranean climates.
- The relationship between the coefficient of variation (Cv) and mean soil moisture (Θ) was found to be unique and well described by an exponential or linear function for locations in Switzerland, but strong hysteretic cycles were observed for Mediterranean locations.
- Heterogeneity in soil properties increases Cv and tends to obscure any hysteresis, masking climatic and biotic controls on soil moisture variability. Heterogeneity can therefore hide the influences of climate and vegetation on soil moisture spatiotemporal patterns.
On 17/10/2013 TU Delft Climate Institute organised the symposium The Greenland and Antarctic ice sheets: present, future, and unknowns. This is one of the four presentations given there.
http://www.tudelft.nl/nl/actueel/agenda/event/detail/symposium-tu-delft-climate-institute-17th-october-2013/
On 17/10/2013 TU Delft Climate Institute organised the symposium The Greenland and Antarctic ice sheets: present, future, and unknowns. This is one of the four presentations given there.
http://www.tudelft.nl/nl/actueel/agenda/event/detail/symposium-tu-delft-climate-institute-17th-october-2013/
1) Recent advances allow global climate models to realistically simulate surface mass balance of ice sheets, through explicit representation of snow processes, sub-grid elevation effects, and coupling with ice sheet models.
2) When forced by a high emissions scenario, the model projects a doubling of surface melt and a negative surface mass balance over Greenland by 2100, contributing 0.55 meters to sea level rise.
3) This is due to a 4-5°C warming over Greenland, increased cloudiness reducing sunlight while enhancing downwelling longwave radiation, and a 500m average rise in the equilibrium line altitude.
Monitoring Changes in Antarctic Sea Ice Phenology: 1990-2015priscillaahn
This study analyzed changes in Antarctic sea ice phenology from 1990-2015 using satellite microwave data. The results show a trend of later melt seasons, with more sea ice persisting longer into the summer. Specifically, there was a 2.2% annual increase in the number of pixels classified as non-seasonal sea ice, indicating longer melt seasons. However, the classification scheme may not fully capture Antarctic sea ice behavior, which melts almost completely each summer due to less confinement than Arctic sea ice. Overall, the analysis found tentative evidence of delayed melt, but uncertainties remain regarding optimal classification of Antarctic sea ice types.
Modification and Climate Change Analysis of surrounding Environment using Rem...iosrjce
This document discusses the application of remote sensing (RS) and geographic information systems (GIS) in analyzing climate change and the surrounding environment. It begins by defining key terms related to climate, climate change, and RS and GIS. It then highlights several areas where RS and GIS have been applied, including glacier monitoring, vegetation change monitoring, and carbon trace/accounting. Studies are discussed that use RS and GIS to monitor glacier retreat, snow depth, land cover change, and above-ground carbon stocks. The document concludes that RS and GIS play a crucial role in understanding and managing climate change by providing important spatial data and enabling the monitoring of environmental changes over time.
CLIMATE CHANGE IMPACT ASSESSMENT ON MELTING GLACIERS USING RS & GISAbhiram Kanigolla
Remote sensing and GIS techniques are effective methods for mapping and monitoring glaciers and the impacts of climate change. Two case studies are summarized in the document. The first case study monitors the Gangotri glacier in India using satellite imagery and finds a 6% reduction in glacier area between 1962 and 2006. The second case study analyzes satellite images of Mount Suphan glacier in Turkey and determines that the glacier area decreased from 1.2 km2 to 0.33 km2 between 1977 and 2000, with climatic factors like increasing minimum temperatures contributing to the recession.
The discovery of year-round subsurface meltwater in Greenland's ice sheet in 2011 changed understanding of its hydrology. Satellite remote sensing could potentially monitor these perennial firn aquifers (PFAs) across time and throughout the year, extending data records. This study explores using microwave brightness temperature data from satellites to identify PFAs, addressing limitations of current monitoring methods. Preliminary results found locations with subsurface melting not explained by surface melt and regions of melt persisting into winter, consistent with known PFAs. Further work could improve identification methods and compare to established datasets.
- Abiotic controls, like precipitation and evaporation, dominate soil moisture spatiotemporal variability in wet climates, while biotic controls from vegetation become more important in Mediterranean climates.
- The relationship between the coefficient of variation (Cv) and mean soil moisture (Θ) was found to be unique and well described by an exponential or linear function for locations in Switzerland, but strong hysteretic cycles were observed for Mediterranean locations.
- Heterogeneity in soil properties increases Cv and tends to obscure any hysteresis, masking climatic and biotic controls on soil moisture variability. Heterogeneity can therefore hide the influences of climate and vegetation on soil moisture spatiotemporal patterns.
On 17/10/2013 TU Delft Climate Institute organised the symposium The Greenland and Antarctic ice sheets: present, future, and unknowns. This is one of the four presentations given there.
http://www.tudelft.nl/nl/actueel/agenda/event/detail/symposium-tu-delft-climate-institute-17th-october-2013/
On 17/10/2013 TU Delft Climate Institute organised the symposium The Greenland and Antarctic ice sheets: present, future, and unknowns. This is one of the four presentations given there.
http://www.tudelft.nl/nl/actueel/agenda/event/detail/symposium-tu-delft-climate-institute-17th-october-2013/
1) Recent advances allow global climate models to realistically simulate surface mass balance of ice sheets, through explicit representation of snow processes, sub-grid elevation effects, and coupling with ice sheet models.
2) When forced by a high emissions scenario, the model projects a doubling of surface melt and a negative surface mass balance over Greenland by 2100, contributing 0.55 meters to sea level rise.
3) This is due to a 4-5°C warming over Greenland, increased cloudiness reducing sunlight while enhancing downwelling longwave radiation, and a 500m average rise in the equilibrium line altitude.
The document analyzes data from NASA's GRACE program to estimate ice loss in Greenland between 2002-2016. It finds the average rate of ice loss across 30 basins was 34-38 cm per year. Extrapolating this rate to the entire ice sheet, it estimates it would take 5,200-8,900 years for all of Greenland's ice to melt. This ice loss is contributing to sea level rise, with potential future impacts.
Two concurring hydrological models (M1 and M2) that performed equally well when calibrated using only streamflow data showed important differences when microgravity data was added. The shape of the Pareto fronts obtained from multi-objective calibration using both streamflow and microgravity data provided useful insights to identify model limitations and indicated the value of including geophysical data to better constrain the inversion procedure. Time-lapse, relative microgravity surveys conducted over multiple field campaigns in the Vermigliana catchment in the Italian Alps allowed obtaining spatially distributed estimates of subsurface water storage changes to inform hydrological modeling.
StreamFlow Variability of 21 Watersheds, OregonDonnych Diaz
This study analyzed the relationship between streamflow runoff and physical attributes in 21 Oregon watersheds. Monthly streamflow data from 1958-2008 was collected and watershed characteristics like elevation, slope, aspect and land cover were determined. A multiple regression model found land cover, elevation and aspect significantly correlated with winter streamflow, but not summer flow. This suggests precipitation is important and the model needs additional variables like soil and snowpack to better predict streamflow runoff.
This document summarizes a study that used multisensor fusion of altimetry data to monitor changes in ice sheets from 2003 to 2009. The study reconstructed spatial and temporal elevation changes across Greenland by combining satellite laser altimetry from ICESat with airborne laser data. Results showed complex patterns of thickening and thinning, with average rates of 257 km3/yr of ice sheet loss, equivalent to 232 Gt/yr of mass loss.
This document discusses various geodetic remote sensing methods for estimating glacial mass balance, including altimetry, photogrammetry, and interferometric synthetic aperture radar (InSAR). It focuses on applications using the Geoscience Laser Altimeter System (GLAS) on ICESat, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), and compares the advantages and limitations of different techniques. Satellite and airborne altimetry have proven most successful for monitoring elevation changes over time to estimate mass balance, though challenges remain regarding spatial and temporal resolution of data.
Spatial-temporal Characterization of Hurricane Path using GNSS-derived Precip...CSCJournals
Global Navigation Satellite System (GNSS) precise point positioning (PPP) technique is capable of monitoring Precipitable Water Vapor (PWV) in high accuracy with low cost. As PWV is related to the initiation and development of a severe weather convective system, this study analyzed the characteristics of PWV variations over time and space to monitor and predict the path and the intensity of a severe rainfall during a hurricane. The PWV measurements are obtained by processing ground based GNSS data. The spatial and temporal variation of PWV and other meteorological variables are characterized for the time frames of before, during, and after the severe precipitation. The correlation effect between meteorological variables were mitigated by adapting a principle component analysis (PCA) and multivariate regression analysis. The method allows determining the expected movement of the rainfall up to 24 hours in advance. The proposed method was validated by analyzing the distribution pattern of the predicted PWV residual, its magnitude, and the actual observed PWV in the region. As a case study, we adopted one of the destructive and long-lived hurricane along the Florida, Georgia, North Carolina and South Carolina coast, namely, Hurricane Matthew, occurred in October 2016. From the experiment, we identified the areas closely fitting the prediction model by computing the residuals between the GNSS derived PWV measurements at each station in the test site. The residual of the predicted model is used for determining the track of extreme hurricane precipitation and potentially applied to evaluate its intensity. This study proved the effectiveness of the statistical model for forecasting the hurricane rainfall path that is potentially applied to a hazard early warning system.
River ice jams : risk evaluation, driving conditions and geomorphological imp...etbou24
This ppt describes my scientific activities over the last few years. It is of interest for scientists and engineers how want to know more about long-term ice jams dynamics and physical impacts. Please contact me for more info:
boucher@cerege.fr
This document discusses using the fully-integrated GSFLOW model to analyze the impact of low impact development (LID) strategies on surface water and groundwater flow. It presents a case study of a proposed urban development and evaluates the ability of LID strategies like green roofs, bioswales, infiltration galleries and permeable pavement to mitigate impacts to groundwater levels and discharge. The results show that with LID implementation, groundwater drawdowns were reduced by 86%, groundwater discharge to streams increased by 42%, and urban runoff generation was reduced by 80% compared to development without LIDs.
Differential interferometry of ALOS PALSAR data was used to monitor thickness changes of the Kangwure Glacier in the Himalayas between January 21 and March 8, 2010. The method provided high-accuracy measurement of thickness changes over a wide area, avoiding costly and labor-intensive in situ measurements. Results showed thinning of the glacier that agreed with historical data, demonstrating the potential of this InSAR method for long-term glacier monitoring. However, more data is still needed to fully validate the approach.
This document describes SiteFX and VIEWLOG software systems for environmental data management, hydrogeologic modeling, and integrated groundwater/surface water modeling using GSFLOW. The key capabilities mentioned include database management, data analysis and visualization tools, borehole logging, contour mapping, time series analysis, and integrated groundwater/surface water modeling to simulate processes like recharge, discharge, streamflow, and water table fluctuations.
This report analyzed oceanographic patterns of sea surface temperature (SST) and chlorophyll concentration using remotely sensed data at global and regional scales. At the global scale, SST and chlorophyll distributions followed expected patterns driven by ocean currents and upwelling/downwelling zones. Regionally along the Australian East Coast, SST and chlorophyll patterns revealed the influence of the East Australian Current, with seasonal and interannual variability observed. Comparison of remote sensing and in situ data showed good agreement for SST near the surface but limitations for subsurface measurements, highlighting the need for calibration and depth profiling through field work.
The document discusses monitoring of Himalayan glaciers and snow cover using satellite remote sensing. It summarizes that the Himalayas have over 33,000 sq km of glacial area, which is important for geomorphology and as an indicator of climate change. Satellite observations allow analysis of glacier features, distribution, fragmentation and retreat over time which has accelerated in recent decades.
This study used GRACE satellite data and GLDAS variables to quantify total water storage change (TWSC) and groundwater storage change (GWSC) in the North-Western Sahara Aquifer System (NWSAS) from 2003 to 2010. Preliminary results from 4 GRACE processing centers (JPL, CSR, GFZ, GRGS) showed annual GWSC ranging from +0.5 billion cubic meters (JPL) to -0.92 billion cubic meters (GRGS). After factoring in estimated groundwater withdrawals, the CSR estimate of -0.56 billion cubic meters annually was deemed most representative of actual conditions in the NWSAS.
Master's course defense presentation in Water Resource Management and GIS Tooryalay Ayoubi
1) The document summarizes a master's thesis that used the SWAT hydrological model within a GIS to simulate surface runoff in the Panjshir watershed in Afghanistan.
2) Key results included monthly and daily surface runoff predictions that matched observed discharge data with R2 values of 0.815 for calibration and 0.817 for validation.
3) The study also found that land use changes between 1993-2010 increased total water yield in the watershed, with average annual changes ranging from 1.2-4.5% between scenarios.
The document discusses the application of kriging in groundwater studies. Kriging is a geostatistical technique used to interpolate the value of a random field between known data points. It provides the best linear unbiased prediction and honors the observed spatial structure of the data. Two case studies are summarized that demonstrate how kriging can be used to generate groundwater level contour maps and correlate declining water levels with land cover changes detected from satellite images. The studies show that kriging produces more accurate representations of spatial variability in groundwater compared to other methods.
Measuring water from Sky: Basin-wide ET monitoring and applicationIwl Pcu
This document discusses using remote sensing to measure evapotranspiration (ET) at the basin scale. It introduces ETWatch, an operational remote sensing model for estimating ET. ETWatch uses inputs like net radiation, soil heat flux, aerodynamic roughness, and atmospheric boundary layer parameters derived from remote sensing data. The document outlines validation of ETWatch estimates against field measurements. It also describes applications of ETWatch for water balance studies and identifying target ET for sustainable water consumption in basins like the Hai Basin in China.
This document discusses coupling land surface models (LSM) with radiative transfer models (RTM) for assimilating microwave brightness temperature observations over India. It explains that the community microwave emission model is used as the forward operator to relate LSM states like soil moisture to brightness temperatures. An ensemble Kalman filter is used to update LSM states by combining forecasts with observations. Results show assimilating brightness temperatures improves Noah LSM soil moisture simulations compared to open-loop runs. Issues regarding biases and parameter estimation for the RTM are discussed.
This curriculum vitae outlines the personal details, education, skills, work experience and activities of Shareef Hamed Obaid Al shukari. It details his Bachelor's degree in Mechanical Engineering, work as an Insight Camera Engineer and Application Engineer, and skills in languages, computer programs, leadership and design.
The document analyzes data from NASA's GRACE program to estimate ice loss in Greenland between 2002-2016. It finds the average rate of ice loss across 30 basins was 34-38 cm per year. Extrapolating this rate to the entire ice sheet, it estimates it would take 5,200-8,900 years for all of Greenland's ice to melt. This ice loss is contributing to sea level rise, with potential future impacts.
Two concurring hydrological models (M1 and M2) that performed equally well when calibrated using only streamflow data showed important differences when microgravity data was added. The shape of the Pareto fronts obtained from multi-objective calibration using both streamflow and microgravity data provided useful insights to identify model limitations and indicated the value of including geophysical data to better constrain the inversion procedure. Time-lapse, relative microgravity surveys conducted over multiple field campaigns in the Vermigliana catchment in the Italian Alps allowed obtaining spatially distributed estimates of subsurface water storage changes to inform hydrological modeling.
StreamFlow Variability of 21 Watersheds, OregonDonnych Diaz
This study analyzed the relationship between streamflow runoff and physical attributes in 21 Oregon watersheds. Monthly streamflow data from 1958-2008 was collected and watershed characteristics like elevation, slope, aspect and land cover were determined. A multiple regression model found land cover, elevation and aspect significantly correlated with winter streamflow, but not summer flow. This suggests precipitation is important and the model needs additional variables like soil and snowpack to better predict streamflow runoff.
This document summarizes a study that used multisensor fusion of altimetry data to monitor changes in ice sheets from 2003 to 2009. The study reconstructed spatial and temporal elevation changes across Greenland by combining satellite laser altimetry from ICESat with airborne laser data. Results showed complex patterns of thickening and thinning, with average rates of 257 km3/yr of ice sheet loss, equivalent to 232 Gt/yr of mass loss.
This document discusses various geodetic remote sensing methods for estimating glacial mass balance, including altimetry, photogrammetry, and interferometric synthetic aperture radar (InSAR). It focuses on applications using the Geoscience Laser Altimeter System (GLAS) on ICESat, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), and compares the advantages and limitations of different techniques. Satellite and airborne altimetry have proven most successful for monitoring elevation changes over time to estimate mass balance, though challenges remain regarding spatial and temporal resolution of data.
Spatial-temporal Characterization of Hurricane Path using GNSS-derived Precip...CSCJournals
Global Navigation Satellite System (GNSS) precise point positioning (PPP) technique is capable of monitoring Precipitable Water Vapor (PWV) in high accuracy with low cost. As PWV is related to the initiation and development of a severe weather convective system, this study analyzed the characteristics of PWV variations over time and space to monitor and predict the path and the intensity of a severe rainfall during a hurricane. The PWV measurements are obtained by processing ground based GNSS data. The spatial and temporal variation of PWV and other meteorological variables are characterized for the time frames of before, during, and after the severe precipitation. The correlation effect between meteorological variables were mitigated by adapting a principle component analysis (PCA) and multivariate regression analysis. The method allows determining the expected movement of the rainfall up to 24 hours in advance. The proposed method was validated by analyzing the distribution pattern of the predicted PWV residual, its magnitude, and the actual observed PWV in the region. As a case study, we adopted one of the destructive and long-lived hurricane along the Florida, Georgia, North Carolina and South Carolina coast, namely, Hurricane Matthew, occurred in October 2016. From the experiment, we identified the areas closely fitting the prediction model by computing the residuals between the GNSS derived PWV measurements at each station in the test site. The residual of the predicted model is used for determining the track of extreme hurricane precipitation and potentially applied to evaluate its intensity. This study proved the effectiveness of the statistical model for forecasting the hurricane rainfall path that is potentially applied to a hazard early warning system.
River ice jams : risk evaluation, driving conditions and geomorphological imp...etbou24
This ppt describes my scientific activities over the last few years. It is of interest for scientists and engineers how want to know more about long-term ice jams dynamics and physical impacts. Please contact me for more info:
boucher@cerege.fr
This document discusses using the fully-integrated GSFLOW model to analyze the impact of low impact development (LID) strategies on surface water and groundwater flow. It presents a case study of a proposed urban development and evaluates the ability of LID strategies like green roofs, bioswales, infiltration galleries and permeable pavement to mitigate impacts to groundwater levels and discharge. The results show that with LID implementation, groundwater drawdowns were reduced by 86%, groundwater discharge to streams increased by 42%, and urban runoff generation was reduced by 80% compared to development without LIDs.
Differential interferometry of ALOS PALSAR data was used to monitor thickness changes of the Kangwure Glacier in the Himalayas between January 21 and March 8, 2010. The method provided high-accuracy measurement of thickness changes over a wide area, avoiding costly and labor-intensive in situ measurements. Results showed thinning of the glacier that agreed with historical data, demonstrating the potential of this InSAR method for long-term glacier monitoring. However, more data is still needed to fully validate the approach.
This document describes SiteFX and VIEWLOG software systems for environmental data management, hydrogeologic modeling, and integrated groundwater/surface water modeling using GSFLOW. The key capabilities mentioned include database management, data analysis and visualization tools, borehole logging, contour mapping, time series analysis, and integrated groundwater/surface water modeling to simulate processes like recharge, discharge, streamflow, and water table fluctuations.
This report analyzed oceanographic patterns of sea surface temperature (SST) and chlorophyll concentration using remotely sensed data at global and regional scales. At the global scale, SST and chlorophyll distributions followed expected patterns driven by ocean currents and upwelling/downwelling zones. Regionally along the Australian East Coast, SST and chlorophyll patterns revealed the influence of the East Australian Current, with seasonal and interannual variability observed. Comparison of remote sensing and in situ data showed good agreement for SST near the surface but limitations for subsurface measurements, highlighting the need for calibration and depth profiling through field work.
The document discusses monitoring of Himalayan glaciers and snow cover using satellite remote sensing. It summarizes that the Himalayas have over 33,000 sq km of glacial area, which is important for geomorphology and as an indicator of climate change. Satellite observations allow analysis of glacier features, distribution, fragmentation and retreat over time which has accelerated in recent decades.
This study used GRACE satellite data and GLDAS variables to quantify total water storage change (TWSC) and groundwater storage change (GWSC) in the North-Western Sahara Aquifer System (NWSAS) from 2003 to 2010. Preliminary results from 4 GRACE processing centers (JPL, CSR, GFZ, GRGS) showed annual GWSC ranging from +0.5 billion cubic meters (JPL) to -0.92 billion cubic meters (GRGS). After factoring in estimated groundwater withdrawals, the CSR estimate of -0.56 billion cubic meters annually was deemed most representative of actual conditions in the NWSAS.
Master's course defense presentation in Water Resource Management and GIS Tooryalay Ayoubi
1) The document summarizes a master's thesis that used the SWAT hydrological model within a GIS to simulate surface runoff in the Panjshir watershed in Afghanistan.
2) Key results included monthly and daily surface runoff predictions that matched observed discharge data with R2 values of 0.815 for calibration and 0.817 for validation.
3) The study also found that land use changes between 1993-2010 increased total water yield in the watershed, with average annual changes ranging from 1.2-4.5% between scenarios.
The document discusses the application of kriging in groundwater studies. Kriging is a geostatistical technique used to interpolate the value of a random field between known data points. It provides the best linear unbiased prediction and honors the observed spatial structure of the data. Two case studies are summarized that demonstrate how kriging can be used to generate groundwater level contour maps and correlate declining water levels with land cover changes detected from satellite images. The studies show that kriging produces more accurate representations of spatial variability in groundwater compared to other methods.
Measuring water from Sky: Basin-wide ET monitoring and applicationIwl Pcu
This document discusses using remote sensing to measure evapotranspiration (ET) at the basin scale. It introduces ETWatch, an operational remote sensing model for estimating ET. ETWatch uses inputs like net radiation, soil heat flux, aerodynamic roughness, and atmospheric boundary layer parameters derived from remote sensing data. The document outlines validation of ETWatch estimates against field measurements. It also describes applications of ETWatch for water balance studies and identifying target ET for sustainable water consumption in basins like the Hai Basin in China.
This document discusses coupling land surface models (LSM) with radiative transfer models (RTM) for assimilating microwave brightness temperature observations over India. It explains that the community microwave emission model is used as the forward operator to relate LSM states like soil moisture to brightness temperatures. An ensemble Kalman filter is used to update LSM states by combining forecasts with observations. Results show assimilating brightness temperatures improves Noah LSM soil moisture simulations compared to open-loop runs. Issues regarding biases and parameter estimation for the RTM are discussed.
This curriculum vitae outlines the personal details, education, skills, work experience and activities of Shareef Hamed Obaid Al shukari. It details his Bachelor's degree in Mechanical Engineering, work as an Insight Camera Engineer and Application Engineer, and skills in languages, computer programs, leadership and design.
Este documento contiene varios chistes cortos. Los chistes tratan temas como un borracho que va a un bar, infidelidad conyugal, paternidad incierta, y la muerte de un pez a manos de un gato. Los chistes utilizan lenguaje coloquial y situaciones cómicas exageradas para provocar la risa.
Este documento descreve uma norma técnica brasileira para o registro e classificação de acidentes de trabalho. A norma fornece definições para termos como acidente, agente causador e tipos de causas. Ela também estabelece critérios para investigar acidentes, coletar estatísticas e analisar causas e consequências com o objetivo de prevenir acidentes futuros.
La Unión Europea ha acordado un paquete de sanciones contra Rusia por su invasión de Ucrania. Las sanciones incluyen restricciones a las importaciones de productos rusos de alta tecnología y a las exportaciones de bienes de lujo a Rusia. Además, se congelarán los activos de varios oligarcas rusos y se prohibirá el acceso de los bancos rusos a los mercados financieros de la UE.
The document discusses the communication of main products and ancillary texts for a movie teaser trailer called "The Haunting". It produced a poster, magazine cover, and teaser trailer to promote the horror genre. The colors red and black were used to indicate the horror genre. The unique selling points featured in the products were the actor Alden and a doll from the trailer. The products were designed to have a consistent brand identity with the horror genre like the movie "Insidious". The target audience was identified as 15-25 years old, as horrors generally appeal to teenagers. All three products connect the "The Haunting" brand cohesively.
Prepositions indicate direction, location and time. A preposition is a word that shows these relationships, such as "in," "on," "at," "from," and "to." Prepositions are used to connect nouns, pronouns, and phrases to other words in a sentence.
Jenny Pearce, Professor of Young People and Public Policy at the University of Bedfordshire, UK, and John Coleman, Senior Research Fellow in the Department of Education at Oxford University, Parenting teenage victims and perpetrators of violence: lessons rom research on prevention and support, Expert Consultation on Family and Parenting Support, UNICEF Office of Research – Innocenti Florence 26-27 May 2014
Content marketing 2015: Where Industry Minds Predict Where Content Marketing ...Danny Denhard
I hand picked a number of content marketing industry minds a number of Content Marketing questions.
The industry minds included range from founders of agencies, freelance consultants, publishers and directors of departments so this ensures the best answers possible to make it as relevant to you as possible.
The questions are aimed to help you develop your content marketing strategy for 2015 and is aimed for any marketer, SEO execs or anyone planning to market in 2015.
El documento discute si la crisis económica en España es historia. Aunque la economía está creciendo de nuevo y saliendo de la recesión, la crisis no se considera completamente superada ya que se espera que los niveles de PIB y empleo previos a la crisis no se alcancen hasta 2017 y 2025 respectivamente. La recuperación sigue siendo frágil y vulnerable a amenazas políticas como la corrupción y la incertidumbre electoral que podrían afectar negativamente las expectativas económicas.
The main character finds himself surrounded by demons in the woods and his locket breaks. He begins to transform into a demon himself. After entering an underground bunker to escape, the demons follow and circle around the now transformed main character, causing him to fully give in to his demonic nature and drop the locket, leaving it behind.
Marketing is a critical function for any business that wants to grow and thrive. While marketing can seem like an "intangible" area compared to other business functions, it is actually one of the most important ways for a company to connect with potential customers and turn them into loyal fans of the brand. By focusing on delivering value to the people they want to reach, companies can gain visibility, trust, and ultimately more revenue through an effective marketing strategy and execution.
The document describes an 18-year-old student named H'Bien Siu who was born in Vietnam and speaks Jarai, Vietnamese, and English. It discusses a school garden project at Garinger High School where students designed and built garden beds to plant a variety of vegetables and herbs, including tomatoes, beans, and peppers. The students participated in mixing soil and fertilizer, planting, maintaining, and harvesting the vegetables. They were able to take some of the fresh produce home.
This week the majority of planning and research was completed for the joint production between KSN Productions and Ranvir Films, allowing more time to focus on post production coursework and editing due to a change in location. Next week the team plans to finish remaining post production work and begin editing their final production after the teacher checks footage.
This document summarizes ground temperature analysis from sites located across different ecotypes (vegetation classes) in western Alaska. Key findings include:
- The absence of near-surface permafrost corresponds to ecotypes lacking a moss layer.
- Factors like thawing and freezing N-Factors help explain differences in permafrost temperatures between ecotypes. For example, one white spruce site receives less heat in summer but loses less heat in winter than another.
- A preliminary map was created predicting mean annual ground temperature ranges based on translating the ecotype classifications. This map could help understand how permafrost may change under climate change.
An optimized snowmelt lysimeter system for monitoring melt rates and collecti...NOMADPOWER
The contribution of snow meltwater to catchment streamflow can be quantified through hydrograph separation analyses for which stable water isotopes (18 O, 2 H) are used as environmental tracers. For this, the spatial and temporal variability of the isotopic composition of meltwater needs to be captured by the sampling method. This study compares an optimized snowmelt lysimeter system and an unheated precipitation collector with focus on their ability to capture snowmelt rates and the isotopic composition of snowmelt.
Glacier changes and climate trends derived from multiple sources in the data ...InfoAndina CONDESAN
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The document discusses sensitivity studies conducted for the CoReH2O mission to analyze how snowpack parameters like grain size, layering, and melting state affect X-band and Ku-band radar backscatter. It summarizes modeling and experimental results showing grain size has a critical effect on backscatter and SWE retrieval, while density has little effect. Layering within the snowpack, including refrozen layers, can impact the relationship between backscatter and SWE.
The RASCALS campaign measured snow albedo and related characteristics on the Greenland ice sheet to validate snow albedo parameterizations and satellite retrievals. Broadband and spectrally resolved surface albedo and reflectance were observed, along with snow physical properties. The Gardner-Sharp snow albedo parameterization was found to perform well using the campaign data. Comparison of reflectance measurements to the CM SAF SAL satellite product showed room for improvement in the retrievals. Future work will evaluate additional satellite datasets and make the campaign observations publicly available.
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The document provides background information on the COPE field campaign and the goals and instrumentation of the COPE-MED research project. The COPE campaign studied convective storms in southwest England through aircraft and ground-based radar observations. COPE-MED aims to investigate microphysical pathways and entrainment effects on precipitation formation. Key goals are to analyze cloud liquid water content and droplet number concentration measurements from the campaign and examine droplet spectral characteristics during non-precipitating cloud penetrations.
Arctic sea ice - use of observational datatracyrogers84
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Time Series Analysis of Rainfall in North Bangalore Metropolitan Region using...Dr Ramesh Dikpal
Rainfall studies are of utmost utility for understanding nature & hence the behaviour of climate changes. Time series is a set of observations taken at specified times usually at equal interval. The inherent variability displayed by many hydrological time series usually mask trends and periodic patterns. This situation has often led to “something” the original time series so that the effects of random variations are reduced and trends or cyclical patterns enhanced. Thus a set of data depending on time is called a Time series. Here, Rainfall series represent the time series. The time series analysis is helpful to compare the actual performance and analyse the cause of variations. By comparing different time series we can draw important conclusion. Graphical method implies in increasing trend for pre-monsoon, south-west monsoon, north-east monsoon and annually.Geo- informatics module consists of GIS mapping for Location map, Geomorphology map and Season wise Rainfall maps are generated. Autocorrelation indicates the periodicity observed as 37,16 & 6 years (PM), 12, 37 & 16 years (SWM), 8, 18 & 6 years (NEM) and 16, 22 & 8 years (Annual) respectively. Power spectral depicts the cyclicity of 37, 4 & 3 years (PM), 2, 4& 2 years (SWM), 3, 7 & 2 years (NEM) and 2, 4 & 2 years (Annual) respectively. Moving average displays prominent positive correlation coefficients at lags of 18 to 42 years in PM & SWM and 12 to 24 years in NEM & Annual. The southwest and southeast parts of the study area experience the heavy rainfall whereas the least rainfall areas are the northern parts of the study area.The short term and long term cyclicity observed in Autocorrelation, power spectrum and Moving Average. Spatial variation of rainfall for the three seasons and annual has been studied
1. The document analyzes changes in land surface albedo over the Qinghai-Tibetan Plateau from 2000 to 2009 using satellite data on albedo, snow cover, and vegetation indices.
2. Results show albedo is strongly correlated with snow cover, with higher albedo corresponding to more frequent snow cover. Summer albedo is correlated with vegetation indices.
3. Interannual trends found albedo changes were driven by changes in snow cover and vegetation in different regions of the plateau, with snow cover dominating in some areas and vegetation in others.
This study analyzed observed sea ice trends from 1980-2008 to evaluate regional variations and identify optimal climate models. Key findings:
1) Winter sea ice extent in the Atlantic region declined significantly faster than other regions, at a rate of 8.6% per decade.
2) A lead-lag analysis found warmer Atlantic Ocean temperatures were associated with reduced winter sea ice extent in that region.
3) Thirteen climate models were evaluated based on their ability to hindcast observed pan-Arctic and regional sea ice trends. The best performing models were selected to project future sea ice changes.
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Greetings all,
Nowadays, several datasets are -or will be- available in a near future to improve operational forecasting in most aspects, like the
ocean dynamics modeling, and the assimilation efficiency, that aims now to optimize the combination of temperature/salinity in
situ profiles, drifter's velocities, and sea surface height deduce from altimeter's data and GRACE or future Goce geoid. But also
strengthen forecasting system's applications, like the climate monitoring. For all these issues, an optimal use of ocean data,
always too sparse and not enough numerous, is mandatory.
Such studies are at the heart of this Newsletter issue. It begins with a Rio M.H. and Hernandez F. review of the Goce Mission,
dedicated to focus and document the shortest scales of the Earth's gravity field. Goce satellite is due to fly in December 2007.
With the next article Guinéhut S. and Larnicol G. investigate the influence of the in situ temperature profiles sampling on the
thermosteric sea level estimation. They show that the impact is not negligible, and can introduce large errors in the estimation. In
the second article, Benkiran M. and Greiner E. are evaluating the benefits of the drifter's velocities assimilation in the Mercator
Océan 1/3° Tropical and North Atlantic operational system. A description of the assimilation scheme upgrade to take into account
velocity control is given. Castruccio F. & al. describe in the third article the performance of an improved MDT reference for
altimetric data assimilation. They concentrate their study on the Tropical Pacific Ocean. Finally, the Newsletter comes to an end
with the Benkiran M. article. In his study, based on the 1/3° Mercator system, the impact of several altimeters data on the
assimilation performance is assessed
Have a good read
Glaciers are large, dense accumulations of snow and ice that form on land where snowfall exceeds melting over many years. They are distinct from sea ice and lake ice. Glaciers cover 10% of the world's land area and store the largest reservoir of fresh water on Earth. The scientific study of glaciers is called glaciology and involves understanding their relationships with climate, sea levels, and impacts on humans and the environment. Remote sensing techniques such as aerial photography, satellite imagery, and radar are powerful tools for monitoring and mapping glaciers, which are often located in remote areas. Different sensors can detect glacial features, measure glacier flow velocities, and help determine mass balances and snowmelt runoff.
Glacier area evolution of Nevados Caullaraju/Pastoruri in the last decadesInfoAndina CONDESAN
This document describes a study analyzing glacier area changes in the Nevados Caullaraju and Pastoruri regions of Peru between 1984-2011 using Landsat imagery and ancillary data. Historical Landsat 5 TM images from the dry season were processed to estimate clean and debris-covered glacier areas over time. Normalized difference snow index (NDSI) thresholding was used to delineate clean glaciers, but debris-covered areas were difficult to identify. The results found a significant decrease in glaciated area of 3.3 km2 per decade, consistent with ground-based data. However, errors in estimating total area were around 30% due to challenges in identifying debris-covered glaciers with optical remote sensing alone.
Comparison of satellite imagery based ice drift with wind model for the Caspi...Sergey Vernyayev
Many factors influencing the movement of ice such as wind, ice concentration, ice thickness,
roughness, water currents, Coriolis force, bathymetry, artificial and natural obstacles in the area. Current speeds in the Caspian Sea are relatively small and so the main driving force for ice movements is wind. Therefore, main goal of this work was to study wind-ice movement velocities dependence in the region and check how ice concentration and thickness influence on the movement of ice. A high number of measurements and observations was made to describe ice drift in the region, although the data was collected areas and usually not publicly available. In our work, we have used timely consequent optical and SAR satellite images to observe ice movements and its displacement over the area. Wind data for the same period and area was taken from wind models. Ice charts were prepared using visual interpretation of satellite imagery. Ice information (concentration, stage of development, floe size) were stored as vector data in SIGRID3 format. The described data has been correlated and analyzed. The analysis provided in the work can be used for the forecast of short term ice drift on the operational basis and can be the first step for creation of ice drift forecast model for the region of North Caspian Sea. The used data, methods and results of the study are described in this paper.
The document discusses satellite radar altimeter measurements of elevation changes in the Larsen Ice Shelf between 1992 and 2001. It finds that the ice shelf lowered by up to 0.27 meters per year on average. This thinning is explained by increased summer meltwater and loss of basal ice through melting. Enhanced ocean-driven melting may provide a link between regional climate warming and the successive breakup of sections of the Larsen Ice Shelf. Testing rules out other potential causes of thinning like changes in sea level, ocean density, or surface accumulation. The long-term thinning observed suggests meltwater production alone does not account for the lowering, indicating additional thinning mechanisms are also involved.
The document describes a new algorithm for producing hemispherical snow water equivalent (SWE) products that assimilates weather station snow depth observations and spaceborne microwave data. The algorithm integrates snow clearance data and auxiliary forest coverage data to improve upon traditional methods. Over a 30-year time series, the assimilation of different data sources provides more accurate SWE estimates than interpolation alone, especially in areas with sparse weather station data. Validation shows the new product typically increases SWE accuracy compared to background kriging interpolation fields. The resulting 30-year SWE dataset for the Northern Hemisphere is available online.
First results from_the_hubble_opal_program_jupiter_in_2015Sérgio Sacani
Os cientistas usando o Telescópio Espacial Hubble da NASA/ESA produziram novos mapas de Júpiter, que mostram as contínuas mudanças que ocorrem com a famosa Grande Mancha Vermelha. As imagens também revelam uma rara estrutura em forma de onda na atmosfera do planeta que não tinha sido vista por décadas. A nova imagem é a primeira de uma série de retratos anuais dos planetas externos do Sistema Solar, que nos darão um novo olhar desses mundos remotos, e ajudarão os cientistas a estudarem como eles mudam com o passar do tempo.
Nessa nova imagem de Júpiter, uma grande quantidade de feições foi capturada incluindo ventos, nuvens e tempestades. Os cientistas por trás dessas novas imagens, as obtiveram usando a Wide Field Camera 3 do Hubble, num período de observação de mais de 10 horas e produziram assim dois mapas completos do planeta, a partir das suas observações. Esses mapas fizeram com que fosse possível determinar a velocidade dos ventos em Júpiter, com a finalidade de identificar diferentes fenômenos na sua atmosfera além de traquear as suas feições mais famosas.
As novas imagens confirmam que a grande tempestade que tem existido na superfície de nuvens de Júpiter por no mínimo 300 anos, continua a encolher, mas mesmo que desapareça, ela irá morrer lutando. A tempestade, conhecida como Grande Mancha Vermelha, é vista aqui fazendo seus movimentos em espiral no centro da imagem do planeta. Ela tem diminuído de tamanho de maneira muito rápida de ano em ano. Mas agora, a taxa de encolhimento parece ter reduzido novamente, mesmo apesar da mancha ser cerca de 240 quilômetros menor do que era em 2014.
TU1.L10 - Arctic Sea Ice dynamics for Global Climate Models: Results from the...grssieee
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Simulated versus Satellite Retrieval Distribution Patterns of the Snow Water Equivalent over Southeast Europe
1. International Journal of Environmental & Agriculture Research (IJOEAR) ISSN:[2454-1850] [Vol-2, Issue-3, March- 2016]
Page | 115
Simulated versus Satellite Retrieval Distribution Patterns of the
Snow Water Equivalent over Southeast Europe
Hristo Chervenkov1
, Kiril Slavov2
1,2
National Institute of Meteorology and Hydrology – Bulgarian Academy of Sciences
Abstract— Snow is a very important component of the climate system which controls surface energy and water balances. Its
high albedo, low thermal conductivity and properties of surface water storage impact regional to global climate. The various
properties characterizing snow are highly variable and so have to be determined as dynamically active components of
climate. However, on large spatial scales the properties of snow are not easily quantified either from numerical modelling or
observations. Since neither observations (ground measurements or satellite retrievals) nor models alone are capable of
providing enough adequate information about the time space variability of snow properties, it becomes necessary to combine
their information. In the presented study the obtained with the regional climate model RegCM snow water equivalent (SWE)
on monthly basis over Southeast Europe for a time window of 14 consecutive winters is compared with the Globsnow
satellite product. The concordance between both datasets is evaluated with number of statistical scores. The result reveals
the principal agreement between the two products, but however, with very significant discrepancies, mainly overestimations,
for some years and gridcells.
Keywords— Snow water equivalent, Satellite observation, RegCM simulation, Globsnow product, Datasets comparison.
I. INTRODUCTION
The snow is a very important component of the climate system which controls surface energy and water balances and is the
largest transient feature of the land surface Yang et al., 2001). It has an effect on atmospheric circulation through changes to
the surface albedo, thermal conductivity, heat capacity and aerodynamic roughness as has been documented in numerous
observational and modelling studies (e.g., Barnet et al., 1989 Gong et al., 2003). According Cliford et al., (2010), the snow
properties of surface water storage control the availability of water in many ecosystems and to a sixth of the world’s
population. Therefore it is vital that snow is properly represented in geophysical models if we want to understand and make
predictions of weather, climate, the carbon cycle, flooding and drought.
The various properties characterizing snow are highly variable and so have to be determined as dynamically active
components of climate. These include the snow depth (hs), SWE, density, and snow cover area (SCA). The SWE is a
measure of the amount of water contained in snow pack and is the product of snow depth and snow density. Unfortunately,
from the four snow metrics listed above, only extent (i.e., SCA) is easily monitored using satellites. SCA, however, is only an
indirect measure of the world’s snow water resources (e.g., Brown, 2000 Brown et al. 2000). To understand global snow
water trends in the necessary depth, the most fundamental metric to assess is SWE, with hs a close second. However, on
large spatial scales the properties of snow are not easily quantified either from modelling or observations. For example,
station based snow measurements often lack spatial representativeness, especially in regions where the topography,
vegetation and overlaying atmosphere produce considerable heterogeneity of the snow-pack distribution (Liston, 2004).
Of the two fundamental parameters, depth is quicker and easier to measure than SWE. No detailed estimates of the total
number of depth and SWE measurements made worldwide is available, but what is available suggests that considerably more
depths are collected than SWE measurements. So, for example, following the directives of the World Meteorological
Organization (WMO), hs is measured in every station of the network of the Bulgarian National Institute of Meteorology and
Hydrology at the Bulgarian Academy of Sciences (NIMH-BAS) every day, at 06 UTC and SWE - usually only five times
monthly. It is clear that data-sets with such time gaps are highly insufficient for any comprehensive snow climatology. This
fact is strengthened by the already mentioned spatial heterogeneity of the snow cover parameters. Satellite Earth observation
(SEO) and RCM provides spatially and temporally consistent data regularly; especially as many snow-affected areas are
covered with sparse ground-based measurement networks. Despite the weaknesses of both methods, data from these
2. International Journal of Environmental & Agriculture Research (IJOEAR) ISSN:[2454-1850] [Vol-2, Issue-3, March- 2016]
Page | 116
information sources should be combined with conventional data in optimal way in order to produce comprehensive
representation of the snow-pack distribution and its long-term dynamics. Hence, due to these weaknesses, which will be
adressed further, not RCM-, nor SEO-products can be treated solely as 'ultimate true', every evaluation of the model
performance (i.e. “model verification”), respectively the satellite data quality, based only upon the comparison with the other,
would be incorrect. It is possible and necessary, however, to asses the concordance between them over certain area for
climatologically long enough (i.e. more the decade) period.
The presented work is part of common effort in NIMH-BAS elaborate more reliable picture of snow- pack distribution and
its long-term dynamics over Bulgaria and the surrounding territories, involving all available information. Thus, subject of
previous paper of Chervenkov et al. (2015) was the comparison of RCM output for SWE with measurements and, therefore,
the presented study can be treated as possible continuation.
Main aim is to compare the gridded digital maps of SWE, resulting from the Globsnow SEO-product, which, as will be
shown further, are practically only one reasonable possibility, with the output of the well-known in the climatological
community regional climate model RegCM for 14 consecutive winters in the period 2000-2014 for the region of Southeast
Europe, searching, in particular, systematic disagreement.
The paper is organized as follows: The considered two information sources and the corresponding datasets are described
briefly in Section 1. Explanation of the methodology of the performed comparisons is placed in Section 2. Core of the paper
is Section 3, where the results are presented and commented. The conclusions and concise summary and the are briefly stated
in Section 4.
II. USED DATA
2.1 SEO SWE Product Globsnow
The SWE is measured by passive microwave (MW) radiometers carried by near-polar orbiting platforms on routinely basis
since 1988. All objects emit MWs, although the soil under the snow-pack emits stronger MW-signal and these microwaves
are scattered and attenuated by the snow as they travel upwards. The attenuation depend on the wavelength and the snow-
pack properties, in particular the amount of snow (SWE) grain size, snow density, presence of ice lenses and the amount of
liquid water. The shorter the wavelength the greater the scattering for a given set of snow-pack properties, thus the difference
between the signals at two wavelengths is related to the amount of snow and this is the basic of the measurement principle.
Although it has been theoretically derived and tested over certain areas this approach is known to suffer from a number of
issues, as dependence from the snow grain size, liquid water amount and vegetation cover as well as saturation in deeper
snow covers (SWE>120 mm). Not at least, shallow snow-packs cause little scattering and can be missed by microwave
sensors. These obstructive issues are inherent source of errors and biases and, strictly speaking, implemented techniques can
only minimize this effect. Additionally, satellite retrieval estimates require inversion algorithms to relate raw signals
recorded at the satellite to physical properties of the land surface and these inverted estimates can introduce further
deviations.
Several SEO SWE products for the Northern hemisphere are available nowadays. As far as their description is far beyond the
scope of the presented work, only the considered one will be discussed briefly here. The reader, however, can find in
Hancock et al. (2013) and in the references therein explanatory description of most of these products, as well as in depth
intercomparison between their performances.
SEO SWE product Globsnow, noted further as Globsnow, is main outcome of the European Space Agency (ESA) Data User
Element (DUE) GlobSnow-2 project (http://www.globsnow.info) with participants from 10 institutions.
The key objective of the project was the further development of methodologies for producing long-term records of snow
cover information at the global scale intended for climate research purposes. The efforts were focused on developing
methodologies for the retrieval of SCA and SWE information based on satellite data. The work involved acquisition of the
3. International Journal of Environmental & Agriculture Research (IJOEAR) ISSN:[2454-1850] [Vol-2, Issue-3, March- 2016]
Page | 117
long-term satellite data records and development of suitable algorithms and software for producing snow cover information
at the global scale spanning decades. Globsnow relays on considerable support from ancillary information from surface
observations, performed in network of established stations, located mainly over Fennoscandia (Metsämäki et al. 2015). The
sophisticated iterational Globsnow procedure includes emission inversion calculations used as first guess field, which are
corrected with ground measurements of the snow depth and grain size via original assimilation technique (see Takala et al.
2015 for detailed description).
Strong reasons has motivated the authors to choose Globsnow: First, the utilization of the state-of-the-art procedures for the
processing of the satellite retrieval ensures, at least theoretically, better final outcome in comparison with older counterparts.
Second, and most important, many studies (see, for instance, Hancock et al., 2013) demonstrate the overall better
performance of Globsnow. Not at at least is the unrestricted and unlimited access of validated SWE data-sets (daily, weekly
and monthly aggregated) and especially their time extend (more than 35 years), which is relevant for climatological
intercomparison studies as the presented here. As certain drawback of this informational source can be pointed the absence of
data for mountainous regions, which, at least from hydrological point of view, are important.
2.2 RCM simulations
RCMs have been developed and extensively applied in the recent decades for dynamically downscaling coarse resolution
information from different sources, such as global circulation models (GCMs) and reanalysis, for different purposes
including past climate simulations, as in the presented study and future climate projection. This widely used and productive
approach is applied here. The main simulation tool is the freely available version 4 of the Regional climate model RegCM of
the International Center of Theoretical Physics (ICTP) in Italy (www.ictp.it ). RegCM4 is a 3-dimensional, sigma-coordinate,
primitive equation RCM with dynamical core based (version 2 and later) on the hydrostatic version of the NCAR-PSU
Mesoscale Model 5 (MM5) (Grell et al. 1994). The radiative transfer package is taken from the Community Climate Model
v. 3 (CCM3) (Kiel et al.1996) The large-scale cloud and precipitation computations are performed by Subgrid Explicit
Moisture Scheme (SUBEX, Pal et al., 2000) and the land surface physics are according to the Biosphere-Atmosphere
Transfer Scheme (BATS, Dickinson et al., 1993). The adopted convective scheme for the RCM simulations in the present
study is the Grell scheme (Grell, 1993) with the Arakawa and Schubert (Arakawa and Schubert 1974) closure assumption.
The reanalysis datasets ERA-Interim of the European Centre for Medium-Range Weather Forecasts (ECMWF) (Dee et al.,
2011) are used for the initial and boundary conditions.
The model domain is centered over Bulgaria and consists of 72×77 20 km×20 km gridcells. The simulation period is from
1th November till 31th March (hereafter: winter) for 14 consecutive years between 2000 and 2014. Model output is the
gridded distribution of the SWE on 6-hourly basis (i.e. at 00, 06, 12 and 18 UTC), which are post-processed to the monthly
averages.
III. METHODOLOGY AND PERFORMED MODEL CALCULATIONS
Aim of the study, as already mentioned, is compare the gridded output of the considered data sources for the
target area and period, rather to perform long-term assessment of the snow cover. Thus and for sake of brevity a
detailed description of the snow climatology should be omitted. As usual in many climatological studies, January
is accepted as representative for the winter. Additionally, according Kjuchukova (1974), the climate mean snow
depth reaches maximum in the plains of Bulgaria at the end of January and due to this reasons all presented
comparisons are performed for this month.
The Globsnow SWE is presented on Fig. 1 and the simulated with the RegCM values on Fig. 2.
4. International Journal of Environmental & Agriculture Research (IJOEAR) ISSN:[2454-1850] [Vol-2, Issue-3, March- 2016]
Page | 118
FIGURE 1. MONTHLY AGGREGATED GLOBSNOW SWE (UNIT: KG.M-2) FOR JANUARY FOR THE PERIOD 2001 –
2014. JANUARY 2001 IS IN THE UL CORNER, THE ORDER IS IN ROWS.
FIGURE 2. SAME AS FIGURE 1, BUT FOR THE REGCM
5. International Journal of Environmental & Agriculture Research (IJOEAR) ISSN:[2454-1850] [Vol-2, Issue-3, March- 2016]
Page | 119
The comparison with the monthly aggregated Globsnow values is performed pixel-by-pixel using the inverse
distance weighted (IDW) interpolation method. The comparison is impossible if the SWE value in given
Globsnow pixel is below 0.001 mm (according the product description, -2, -1 and 0.001 are flags for mountains,
water basins and fractional snow cover correspondingly) or the Globhsnow value, respectively the Globsnow one
in some pixel are undefined. As far as the model domain is semi-mountainous, the exclusion of these pixels limits
significantly the number of the possible comparisons.
Traditionally the degree of agreement of the observed values Oi and their modelled correspondents Mi, is
estimated with set of frequently used statistical quantities, including the root mean square error (RMSE), the
correlation coefficient (also termed the Pearson correlation coefficient, r), the index of agreement (IA) and the
mean bias (BIAS). Explicit formulas for the first two will not be given due to their popularity, and the last two are
equal accordingly to:
N
=i
ii
N
=i
ii
OO+OM
MO
=IA
1
2
1
2
1
(1)
)OM(
N
=BIAS ii
N
=i
1
1
(2)
The summation is along the number of comparisons N and the overlines notes space-averaging. Additionally, the
pattern of the normalized mean bias (NMB), which is quantitative metrics of the departure of the modelled results
to the measurement in every pixel with geographical coordinates φ, λ is obtained, according to
%100
λ,
λ,λ,
λ,
O
MO
=NMB
(3)
IV. RESULTS
The values of the computed statistical indexes are shown in Table 1.
TABLE 1
VALUES OF THE STATISTICAL INDICES OF THE COMPARISON GLOBSNOW/REGCM YEAR-BY-YEAR. THE
SECOND COLUMN (―PAIRS NUMBER‖) CONTAINS THE LENGTH OF EACH DATASET (I.E. NUMBER OF POSSIBLE
GLOBSNOW/REGCM COMPARISON PAIRS). THE LAST ROW IS FOR THE UNITED DATASET.
year pairs number RMSE (kg.m-2) r (corr.coeff.) IA BIAS (kg.m-2)
2001 78 10.46 0.75 0.57 1.76
2002 1180 59.52 0.57 0.47 28.99
2003 636 51.76 0.06 0.15 24.80
2004 886 22.85 0.39 0.45 10.59
2005 279 5.48 0.45 0.58 -0.74
2006 750 38.74 0.48 0.43 17.71
2007 215 5.35 0.29 0.45 1.68
2008 700 20.94 0.25 0.46 2.93
2009 305 42.34 0.35 0.24 25.69
2010 332 54.76 0.64 0.48 34.96
2011 160 21.61 0.48 0.44 11.38
2012 161 40.31 0.01 0.17 26.68
2013 603 22.94 0.37 0.57 -6.20
2014 1219 9.26 0.52 0.36 0.62
TOTAL 7504 36.69 0.47 0.49 13.00
6. International Journal of Environmental & Agriculture Research (IJOEAR) ISSN:[2454-1850] [Vol-2, Issue-3, March- 2016]
Page | 120
As can be seen, depending from the winter, the number of the performed comparisons varies greatly – from up to
200 for years with overall thin snow cover, like 2001, 2011 and 2012 to more than 1100 in opposite case (the
years 2002 and 2014). The statistical scores vary also greatly, but, as general, no remarkable linkage between the
number of the comparisons and any pattern of the change of these indices can be determined.
The distribution of the NMB is presented on Figure 3.
FIGURE 3. DISTRIBUTION OF THE NMB (IN %) FOR THE SAME PERIOD IN THE SAME ORDER AS THE PREVIOUS
TWO FIGURES
The scatter plot diagrams for two winters, 2008 and 2014, when snow cover is relatively deep, are shown on
Figure 4. Additionally, the united (i.e. for all 14 months January) dataset is depicted on the same figure. Hence
the SWE varies naturally up to 3 orders, the log-log axes ensures more compact representation.
FIGURE 4. SCATTER PLOT DIAGRAMS FOR JANUARY 2008 (ON LEFT), JANUARY 2014 (IN THE MIDDLE) AND
FOR THE UNITED (I.E. FOR ALL 14 YEARS) DATASET. THE GLOBSNOW VALUES ARE ALONG THE ABSCISSA,
THE UNITS ARE kg.m-2.
The comparison can be extended further, in particular involving more advanced statistical methods, but the performed
7. International Journal of Environmental & Agriculture Research (IJOEAR) ISSN:[2454-1850] [Vol-2, Issue-3, March- 2016]
Page | 121
analysis, preliminary indeed, already reveals some basic features, which are summarized as follows:
In certain years and/or pixels of comparison the differences between the observed and the modelled values of the SWE are
significant and most drastic are the discrepancies in direction overestimation (NMB<<0), i.e. the model values are in orders
greater then the observed ones.
The analyzed information do not suggest the presence of sub domains, where these differences seems to be systematic.
Nevertheless however, over the central part of the domain (Bulgaria) NMB is most often in the interval -200% - 200%.
The scatter plot diagram for the united dataset shows best commensurability in the interval of values SWE 10-100 mm,
which is relevant, keeping in mind that the typical monthly average values over the plains in the domain is roughly around 50
mm. Hence these areas, which are with prevailing share in the domain’s topography, plays the most important role in the
regional agriculture and food supply, this fact is very relevant.
V. CONCLUSION
Providing spatially and temporally continuous distribution of the snow-pack pattern, the Globsnow SWE product is suitable
tool for quantitative assessment of the snow cover features. Despite its listed drawbacks, the Globsnow digital maps are
preferable for comparison with RCM output then the point wise ground measurements, which, at least in the domain are
scarce, irregular and delivers data with temporal gaps. So, in Bulgaria, only a couple of stations provides time series of
measurements on daily basis, with acceptable length in the period under consideration. Comparison with of these data with
RegCM4 model output, presented in Chervenkov et al., (2015), reveals that the biases over the whole time span are
acceptable, but, however, with large discrepancies in the day-by-day comparisons.
The overall judgment of the obtained results is hampered by the lack of information about the evaluation of the capabilities
of Globsnow in other regions of the hemisphere, where the snow-pack conditions and dynamics are different from those in
the northern part of Eurasia. The comparison of RCM RCA4 output with Globsnow for the territory of Sweden (see
Strandberg et al., 2014), although performed by other means and described concisely, reveals better concordance. This fact
suggest that the product's performance is not equal everywhere.
More generally, the efforts for synergistic treatment of the data from all available informational sources have to be continued
with increased activity. Thus, the COST action ES1404 (http://www.harmosnow.eu/index.php?page=Structure ) for
harmonization of the snow monitoring is significant step ahead in the right direction.
The model RegCM is constantly developed and, respectively, its simulation capabilities are steadily increasing. Further
numerical experiments have to performed, in particular comparisons with other data sources, among which the gridded
digital maps of assimilated data from objective analysis and/or reanalysis are most reliable hence it is impossible to obtain
meteorologically consistent snow cover patters without the means of the physical and mathematical simulation.
ACKNOWLEDGEMENTS
Deep gratitude to the organizations and institutes (ICTP, ECMWF, NCEP-NCAR, Unidata, MPI-M, Globsnow-consortium
and all others), which provides free of charge software and data. Without their innovative data services and tools this study
would be not possible.
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