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IUKWC Workshop Nov16: Developing Hydro-climatic Services for Water Security – Session 4 – Item 5 edited S_Ghosh


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IUKWC Workshop November 2016: Developing Hydro-climatic Services for Water Security
Session 4.5 Subimal Ghosh

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IUKWC Workshop Nov16: Developing Hydro-climatic Services for Water Security – Session 4 – Item 5 edited S_Ghosh

  1. 1. Land Atmosphere Interactions during Summer Monsoon Subimal Ghosh Department of Civil Engineering IDP in Climate Studies IIT Bombay 1
  2. 2. Key Challenges in Hydro-meteorological Simulations Uncertainty across models Bias in the models 2
  3. 3. Climate Change Projections of Indian Monsoon and Uncertainty: More Confusion, Less Consensus  Ashfaq et al. (2009):  Suppression  Lee and wang (2014):  Increase  Chaturvedi et al. (2012):  Increase  Krishna Kumar et al. (2011):  Increase  Salvi et al. (2013):  Non-uniform Changes with slight increase for few scenarios 3
  4. 4. Uncertainty: Not only in Future Projections but also in present day Reanalysis4
  5. 5. But with an Improved Understanding this can be Reduced Sebastian et al. (2016), Scientific Reports (Nature Publishing Group) 5
  6. 6. Problems lie in the regional/ local scale simulations of Rainfall, Evaporation Needs improved understanding about regional processes 6
  7. 7. And the Same is true at Seasonal Scale: Dry Bias in Operational Model CFS V2 mm/day 7
  8. 8. Easy Solution  Bias Correction: is it correct 8 Atmospheric Model Bias Correction Hydrologic Model Bias corrections of the model output - a process I liken to transforming elephants into mice. - Upmanu Lall (AGU meet 2010) We have bias correction methods for any sorts of bias  We need physics based understanding of bias and physics guided model to correct them  Can we explain a fraction of bias with understanding of land surface feedback?
  9. 9. Land Surface Feedback Monsoon: Traditionally believed to be governed by large scale moisture transport from ocean • What are their contributions? • Can we quantify them? 9
  10. 10. 12/7/2016 10 Schematic representation Precipitation Recycling (Source: Dominguez, et al. 2006). Evapotranspiration Precipitable water Time step Local Recycling Ratio (R or ρ) Regional Recycling Ratio Recycled and Total Precipitation 3 2 1 [(Change in atmospheric moisture storage) + (zonal moisture fraction) + (meridional moisture fraction) ]= [ (evaporation)- (precipitation) ] Conservation of atm. Water vapor mass Dynamic Recycling Model The contribution of the locally evaporated water to the precipitation in the same region is known as ‘Precipitation Recycling’. ‘Precipitation Recycling’ is characterized by Recycling Ratio. 10
  11. 11. Recycling Ratio Recycled Precipitation Recycling Ratio Total Precipitation Pathak et al., (2015), JHM 11
  12. 12. Understanding Different Land and Oceanic Sources
  13. 13. Contributions from Different Sources Pathak et al. (2016), Jl of Climate
  14. 14. Good and Bad Monsoon Years
  15. 15. Intra-Seasonal Variations 15
  16. 16. Contributions 16 Pathak et al. (2016), Under Prep.
  17. 17. Impacts of Changes in LULC 17
  18. 18. LULC Changes in India 18
  19. 19. Impacts of LULC: Simulated Changes (WRF-CLM) Partially Consistent with Observed Changes19 Paul et al. (2016) Scientific Reports, Nature Publishing Group
  20. 20. Acknowledgement  Ministry of Earth Science (Hydrology) for funding the work  Students  Amey Pathak  Supantha Paul  Sahana A S  Anjana Devanand  Collaborators  Roxy Mathew Koll (IITM)  A K Sahai (IITM)  Surya Chandra Rao (IITM)  Praveen Kumar (UIUC)  Raghu Murtugudde (UMD)  Robert Oglesby (UNL) 20 Thank You