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  1. 1. Satellite imagingby Randall Bass and Laura JairamImprovIngresolutIonNew capabilities in satellite imagingA new imaging sensor promises huge improvements in meteorologicalsatellite-imaging information and products hen Explorer 7 was launched in The ABI will provide significant advancements polar orbiting sensors. Like previous GOES W 1959 by Verner Suomi and colleagues at the University of over the current fleet of GOES satellite instruments in several key areas, including the satellites, the ABI will image clouds and weather systems, monitor water vapor atWisconsin, it marked the first successful introduction of new spectral channels from three levels, and estimate sea-surfacemeteorological instrument on board an geostationary orbit and a remarkable temperatures, total column ozone, windorbiting spacecraft and the age of space- improvement in spatial and temporal resolution speed, and rainfall rates.based meteorology was born. Finally over current GOES imagery. With the addition of the 0.47 micronhumans were able to see weather from above The spectral characteristics of ABI visible channel, the 0.865-2.25 micron NIRthe atmosphere instead of from within it. combine visible, Near IR, and IR channels channels, and the 8.5 and 10.35 micron IRWhen TIROS-1 was launched in 1960, we spanning the range of 0.5-13.3 microns channels, ABI will greatly enhance thewere able to view the Earth and its weather (Table 1). The advantages of ABI’s channel monitoring of vegetative growth, thesystems as a whole for the first time, design are multifold. Heritage GOES identification of fire hot spots and volcanicchanging our perception of the Earth to an channels, highlighted in Table 1, will eruptions, the discrimination of snow andintegrated, inseparable system of land, continue long-standing data sets and ice, and the prediction of hurricaneocean, and atmosphere. The Applications support traditional GOES imagery products. intensities. The ABI will also be capable ofTechnology Satellite was launched into In addition, several new channels will onboard calibration, meaning more reliablegeostationary orbit in 1966, and time provide novel science benefits, as well as data and more accurate forecasting. Overall,domain images of weather patterns became measurements complimentary to current ABI’s channel characteristics represent thea reality. The Geostationary Operational combined knowledge of several decades ofSatellite (GOES) program began in 1975 and satellite research and engineering and willheralded the beginning of operational continue the GOES satellite programs’ moregeostationary satellite imagery that than 30 year trend of advancement in Earthcontinues to this day. monitoring and atmospheric remote sensing. Over time, satellite meteorology has ABI’s spectral advancements will bebecome routine. Images of storm systems further augmented by improvements in bothand hurricanes taken from space flash spatial and temporal resolution over theacross the local news broadcasts on a daily current GOES satellite capabilities. Thebasis. Today’s younger meteorologists have current GOES imager has a groundnever known a time without weather resolution of approximately 1km for visiblesatellite data to help prepare a forecast. But images, and 4km in all other bands. ABIreal-time pictures of weather systems and image resolution will be twice as fine atweekend forecasts are not the only use of 100% ground coverage with a 0.5km gridmeteorological satellite (METSAT) imagery. for visible images, a 1-2km grid for its NearThe demand for more and more information IR channels, and 2km for MWIR and LWIRon clouds, water vapor and other bands (Table 1).atmospheric constituents is increasing as the The current GOES Imager performs fullunderstanding of our complex atmosphere disk, CONUS, and mesoscale imaginggrows. This growing demand is driving the functions. However, the operational scantrend toward better, more elaborate weather system can only actively task one of thesatellites. Toward this end, ITT Corporation functions at a time, therefore each imageis building the newest imaging sensor, the must be scheduled for collection in a serialAdvanced Baseline Imager (ABI), for fashion. For example, the current GOESintegration on the next-generation GOES imager takes roughly 26 minutes to collect aseries, GOES-R and GOES-S. full Earth image, which are typically Simulation, derived from NASA MODIS data, scheduled once every three hours to collectABI characteristics showing how ABI clearly captures the over-shooting CONUS and regional images more regularly.The meteorological community awaits the (cold) cloud tops, while the GOES Imager does The rapid-scan mesoscale function can image not (Courtesy of CIMSS at the University ofupcoming launch of the GOES-R satellite with a regional area every minute, but at the Wisconsin-Madisonthe ABI on board, currently scheduled for 2015. expense of losing all METSAT coverage for112 • ME TEOROLOGICAL TEChnOLOGy InTERn ATIOn A L nOVEMBER 2010
  2. 2. Satellite imaging Hurricane application Hurricanes have always been of interest to provide insight to better hurricane intensity maritime and coastal communities. Better estimation. The Hurricane Intensity hurricane track and intensity prediction are Estimate product has been developed to a priority for tropical meteorologists. generate hurricane central pressure data Hurricanes such as Andrew, Mitch and and maximum sustained winds in near real Katrina have demonstrated both the time. An intensity estimate analysis and an potential destruction of these storms and intensity trend of the storm will be created the difficulty in accurately predicting their using this product. strength and path. The National Hurricane Center will utilize Although hurricane detection products this information to make more accuratethe rest of the hemisphere. In normal mode, are well established using current GOES forecasts and advanced warnings. Datathe current GOES imager collects imagers, details about the eye of the storm from ABI not only helps forecasters warnapproximately four CONUS images per hour. are underdeveloped. Temporal and spatial the public of impending disasters, it will In contrast, the new ABI sensor will be able enhancements in the ABI will allow give meteorologists and climatologiststo take a full Earth image in just five minutes. scientists to monitor storm-eye insight into atmospheric conditions thatFurthermore, ABI has a flexible scan mode development in a similar way to watching cause these storms. Finally, ABI data maywhere one full Earth disk, three CONUS every frame of a movie in high definition help answer questions on whether climateimages, and 30 mesoscale (aka regional scale, rather than every 10th frame in standard change has an effect on the number andapproximately 1,000 x 1,000km) snapshots definition (below). This capability should intensity of hurricanes in the ocean basins.are collected every 15 minutes. ABI’s ability tofocus on regional atmospheric phenomenawith a 30-second refresh rate, while still Simulated images of themonitoring weather on a hemispheric scale, is 16 ABI bands for Hurricane Katrina. Thesetruly an exciting advancement for images were simulatedmeteorologists. This feature will greatly aid via a combination of highefforts to comprehensively track weather spatial-resolutionsystems affecting North America (see figures numerical model runsleft). It is estimated that ABI will provide 48 and advanced ‘forward’ radiative transfer modelstimes the amount of data available from the (Courtesy of CIMSS atcurrent GOES Imager. the University of Wisconsin-Madison)ABI productsABI will enable more accurate nowcastingand short-term forecasting than currentMETSAT data can provide, based solely onits finer spatial, spectral, and temporalresolution. The enhanced resolution andadditional channels on ABI will also offernew opportunities for remote sensing. The list of potential applications enticesmeteorologists, land-use planners and thecasual weather enthusiast. Supercelldetection, fire detection and characterization,upper-level sulfuric acid detection, air-qualityanalysis, vegetation monitoring, cloud-topphase/particle-size data, rainfall-ratedetection, and hurricane-intensity estimation,to name a few, are new and enhanced developed many new cloud products. ABI’s monitors convective developments, and alongproducts. They can be divided into three higher spatial- and temporal-resolution data with the cloud-top temperature and cloud-topcategories: weather and atmospheric allows forecasters to closely monitor the pressure products, will provide informationmonitoring products, climate monitoring, development of clouds in all weather for satellite-derived wind monitoring. Cloudand hazard detection. There are far too many situations. It will be used in conjunction with optical depth, cloud-particle size distribution,individual products to describe here, but a radiative transfer model to generate cloud- cloud liquid water and cloud-ice waterseveral of significance are highlighted. type and cloud top-phase products. These products round out the cloud-application The improved detection of clouds will products will classify the various types of suite. In addition to improving aircraft safety,benefit the weather community, as well as clouds. The phase (ice, water or mixed) of a these products will also provide vitalclimatologists and the aviation community. A cloud can impact aircraft icing conditions, and information for climate research.GOES-R Cloud Application Team has been therefore plays a key role in aviation routing Many people around the world arecreated and its members have already and planning. The cloud top-height product affected by flooding each year, particularly ME TEOROLOGICAL TEChnOLOGy InTER n ATIOn AL nOVEMBER 2010 • 113
  3. 3. Satellite imaging Table 1: Channel Characteristics of the Advanced Baseline Imager ABI Channels Spectral Spatial Band Ch. Center Width IFOV Imagery Use Heritage Instruments Wavelength (µm) FWHM (µm) at nadir (km) VIS 1 0.47 0.04 1 Daytime aerosol over land, vegetative MODIS* health, coastal mapping 2 0.64 0.1 0.5 Daytime clouds, fog, insolation, winds Current GOES Imager and Sounder NIR 3 0.865 0.039 1 Daytime vegetation, burn scar, VIIRS**, AVHRR† aerosol over water, winds 4 1.378 0.015 2 Daytime cirrus clouds VIIRS, MODIS 5 1.61 0.06 1 Daytime cloud-top phase and particle size, VIIRS, AVHRR snow and cloud discrimination 6 2.25 0.05 2 Daytime land properties, cloud particle size, VIIRS, MODIS vegetation, snow, hot-spot identification MWIR 7 3.9 0.2 2 Surface, clouds, nighttime fog, winds, Current GOES Imager fire/hot-spot, volcanic eruption/ash, snow/ice detection, urban heat islands 8 6.185 0.83 2 High-level atmospheric water vapor, winds, rainfall Current GOES Imager 9 6.95 0.4 2 Mid-level atmospheric water vapor, winds, rainfall Current GOES Sounder 10 7.34 0.2 2 Lower-level water vapor, winds, upper-level Spectrally modified sulfuric acid (SO2 ) current GOES Sounder 11 8.5 0.4 2 Total water for stability, cloud phase, dust, MODIS Airborne SO2 aerosols Simulator (MAS) LWIR 12 9.61 0.38 2 Total ozone, turbulence, winds Spectrally modified current GOES Sounder 13 10.35 0.5 2 Hurricane intensity, surface moisture, cloud particle size MAS 14 11.2 0.8 2 Detection of hazardous weather conditions, Sea Surface Current GOES Sounder Temp (SST), clouds, rainfall rates 15 12.3 1 2 Total water, ash, dust, SST, cloud particle size Current GOES Sounder 16 13.3 0.6 2 Air temp, cloud heights and amounts, Current GOES Imager tropopause delineation and Sounder *MODerate Resolution Imaging Spectroradiometer (MODIS) ** Visible and Infrared Imager and Radiometer Suite (VIIRS) † Advanced Very High Resolution Radiometer (AVHRR)in low-lying regions like the Gulf of Mexico result, improved forecasts and advancedand the south-eastern coastlines of the USA. warning systems will allow forecasters andThree new products have been designed for the public to take more preventativeanticipated ABI data: rainfall rate, rainfall measures when faced with weatherpotential, and probability of rainfall. These phenomena. This short list of products isprecipitation-estimation products are only a small preview of the benefits that theexpected to reduce economic and human ABI suite will offer the weather communitycosts associated with flooding events. and the general public. A prototype model ofRainfall rate is designed to retrieve cloud the ABI is currently undergoing thermal-phases and particle sizes from the new vacuum testing at ITT’s Rochester, NYSWIR and MWIR bands on ABI. It will use a facility. This prototype model was built withstatistical model that will account for the specific design requirements of thenatural variation between, and within, actual flight model for GOES-R, which isregions rather than assuming one regional currently in production and on track for abase model. The improved 2km spatial Prototype model of ABI successful integration and, mostresolution will enable better accuracy in the importantly, a successful launch in 2015. zcalculation of rainfall rates. The rainfallpotential product will extrapolate Baseline Imager on the GOES series will be Randall Bass is a senior meteorologist with ITTinformation from the rainfall rate to aid in an excellent asset to meteorologists and Geospatial Systems, Herndon, Virginia and Lauraforecasting areas of heaviest rain and flood climatologists around the world. Its spectral, Jairam is a senior image scientist with ITT Geospatialpotential, with up to three hours of warning. spatial, and temporal advancements will Systems in Herndon. Cooperation came from RachelThe rainfall probability product is a three provide more accurate measurements of Fitzhugh, an image scientist with ITT Geospatialhour forecast, predicting the geographical cloud properties, convective development, Systems, Rochester, and Marie Knappenberger, aareas where rain is expected. The Advance rainfall rates and hurricane intensities. As a geoscientist in Rochester, New York114 • ME TEOROLOGICAL TEChnOLOGy InTERn ATIOn A L nOVEMBER 2010