High-resolution modelling of regional climate change scenario over South Asia R. Krishnan

1. Seminar on Socio Economic Implications of Climate Change Initiatives: Priorities and Implications for India Geospatial World Forum Hyderabad 18 – 21 January, 2011 High-resolution modelling of regional climate change scenario over South Asia R. Krishnan Centre for Climate Change Research Indian Institute of Tropical Meteorology, Pune

2. An Elegant Science Question: Are increases in greenhouse gases responsible for increase in global mean temperature (global warming)? 14.6 Global Temperature & Carbon Dioxide 1860-2008 395 0.76°C (1.4°F) since 1900 14.4 365 0.55°C (1.0°F) since 1979 14.2 335 14.0 13.8 305 13.6 275 13.4

3. Hypothesis • Greenhouse gases increase due to human activities. • Global warming is due to increases in greenhouse gases. • Global warming is due to human activities. Alternative Hypothesis • Global warming is due to natural variations of climate. How do you test such hypotheses? Climate Models; IPCC

4. What is a Climate Model? • Equations of motions and laws of thermodynamics to predict rate of change of: • T, P, V, q, etc. (A, O, L, CO2, etc.) • 10 Million Equations: • 100,000 Points × 100 Levels × 10 Variables • With Time Steps of:~ 10 Minutes • Use Supercomputers

5. Increase in Surface Temperature Observations Predictions with Anthropogenic/Natural forcings Predictions with Natrual forcings 1.0º C IPCC 2007

6. Challenges in assessment of future changes in South Asian monsoon rainfall • Wide variations and uncertainties among the IPCC AR4 models in capturing the mean monsoon rainfall over South Asia (eg., Kripalani et al. 2007, Annamalai et al. 2007). • Systematic biases in simulating the spatial pattern of present-day mean monsoon rainfall (eg., Gadgil and Sajani, 1998; Kripalani et al. 2007) • Realism of present-day climate simulation is an essential requirement for reliable assessment of future changes in monsoon

7. South Asia (5-35N, 65-95E)) Source: Kripalani et al. 2010

8. Summer monsoon precipitation IPCC models: 20C3M 1979-1998 Observed rainfall (JJAS) The 20c3m simulations attempt to replicate the overall climate variations during the period ~1850-present by imposing each modeling groups best estimates of natural (eg., solar irradiance and volcanic aerosols) and anthropogenic (eg. GHG, sulfate aerosols and ozone) during this period. Seven 20C3M models (GFDL CM2.0, GFDL-CM2.1, MPI-ECHAM5, MRI, MIROC3-HIRES, HadCM3, NCAR-PCM – Source: J. Shukla)

9. JJAS cumulative rainfall (1951-2009) Area average (90E – 97E ; 20N – 30N) IMD gridded rainfall dataset http://www.tropmet.res.in Long-term mean of JJAS rainfall (mm) Interannual variability of monsoon rainfall over Northeast India 2004 1999 2000 2001 2002 2003 2005 2006 2007 2008 2009 2010

10. Questions : On Attribution? How much of the observed variability of the mean Indian Summer Monsoon rainfall due to Climate Change? How much of the observed increase in temperature over India been decreased by increasing presence of aerosols? Questions : On Projections of Monsoon • What will happen to the monsoon hydrological cycle 50-100 years from now under different scenarios? In particular, will the quantum of seasonal mean rainfall increase or decrease and if so by how much? • What is the uncertainty in these projections? Can we quantify this uncertainty? • How can we reduce this uncertainty?

11. Some indicators of regional monsoon climate • Observed changes in frequency of monsoon depressions during the last century • Changes in the observed extreme rainfall events during the 20th century • Question: • Attribution: How much of the observed regional monsoon variability is due to global warming?

12. All India summer monsoon rainfall variability Climatological Mean (JJAS) Interannual Variability Goswami et al., Science, 2006

13. Time series of count over CI Low & Moderate events Heavy events (>10cm) V. Heavy events (>15cm)

14. Increase in intensity of extreme events Goswami et al 2006 • Frequency as well as intensity of heavy & very-heavy rainfall events have significantly increased over Central India • Low and moderate events have significant decreasing trend over Central India • The seasonal mean does not have a trend because decreasing contribution from low and moderate events are compensated by increasing contribution from heavy events

15. Possible causes for the decreasing trend in the moderate rainfall events ? • Long-term trends in the large-scale monsoon circulation ? • Indications of weakening of the low-level monsoon flow (Joseph and Simon 2005) • Increasing frequency of “breaks” in monsoon rainfall (Ramesh Kumar et al. 2009) Zonal wind averaged over (12.5N – 17.5N; 70 E – 85 E) 1950-2002

16. Time series of frequency of monsoon depressions • Decreasing frequency of monsoon depressions during last 2-3 decades (eg., Rajeevan et al., 2000; Amin and Bhide, 2003; Dash et al., 2004) • Recovery in the activity of monsoon depressions during the recent years (2005 – 2007) • Activity of monsoon depressions modulated by low-frequency variability of atmospheric large-scale circulation on inter-decadal time-scales

17. Strategy on Regional Climate Change Research at IITMCentre for Climate Change Research (CCCR)Ministry of Earth Sciences, Govt. of India • To build capacity in the country in high resolution coupled ocean-atmosphere modelling to address issues on Attribution and Projection of regional Climate Change • Earth System Model (ESM) • To provide reliable input for Impact Assessment studies • Dynamic downscaling of regional monsoon climate using high resolution models; quantification of uncertainties • Observational monitoring: Network with other Institutions

18. Modelling Program Observational Program Objectives • To build a Global High-resolutionEarthSystem Model to address the Attribution & Projection of regional climate change – (Long-term) • To generate regional climate change scenarios for South Asia using Ultra High-resolution Regional Climate Models and quantify uncertainties. Provide reliable inputs for impact assessments. Contribute to IPCC AR5 – (Short-term) • To establish a High Altitude Cloud Physics Observatory for monitoring cloud-aerosol interactions – (Long-term) • To understand Past Changes in Monsoon Climate using Multiple Proxy Records. Reconstruction of an iconic monsoon index going back to a few thousand years – (Long-term) • To promote Outreach and Training for Capacity Building in Climate Change Research and Dissemination of Information – Long-term cont

19. High resolution regional climate change scenarios and quantification of uncertaintiesProvide reliable inputs for impact assessments and contribute to IPCC AR5 • High resolution dynamic downscaling of monsoon: Baseline climate runs using WRF, RegCM and LMDZ partially completed. Future climate scenario runs to be initiated in January 2011. • Two member 19 year (1989 : 2007) run of WRF (50 km) model completed. ERA Interim LBC • One member 19 year (1989 : 2007) run of RegCM (50 km) model completed. ERA Interim LBC • One member 10 year (1979 : 1988) run of LMDZ (50 km) model completed

20. CRU ERAIM WRF – KF2 CRU ERAIM WRF – BM CRU ERAIM RegCM - EML CRU ERAIM RegCM - GRL CRU ERAIM PRECIS CRU ERAIM LMDZ Jan Apr Jul Oct Jan Apr Jul Oct Monthly mean annual cycle of surface air temperature over Indian land region

21. IMD CMAP WRF – BM IMD CMAP WRF – KF2 IMD CMAP RegCM - EML IMD CMAP RegCM - GRL IMD CMAP PRECIS IMD CMAP LMDZ Jan Apr Jul Oct Jan Apr Jul Oct Monthly mean annual cycle of precipitation (mm/day) over Indian land region

22. High resolution monsoon simulations: Global model with zoom over monsoon domain JJAS rainfall JJAS SLP and winds 850 hPa LMD model 1 degree (Global) LMDZ model 1/3 degree zoom for Monsoon Domain (40-110E; 15S-30N) & 1 degree outside Initial runs made at CCCR on PRITHVI, IITM

23. Mean SLP and 850 hPa winds (JJAS) Mean rainfall (JJAS) LMDZ monsoon simulation at 50 km zoomed resolution – 10 year mean • Large scale structure of winds and SLP is well captured • Monsoon Trough has strong southward dip over eastern India and Bay of Bengal – Bias • Precipitation along West Coast and Central - Eastern India is reasonably well simulated • Rainfall over north Bay of Bengal is underestimated. Excessive rain over central Bay of Bengal • Rainfall over Equatorial Eastern Indian Ocean is underestimated

24. Example of a monsoon depression in a typical synoptic chart

25. LMDZ simulation: Rainfall and 850 hPa streamlines during a typical monsoon low / depression Day 01 Day 02 Day 03 Day 04 Day 05 Day 06 Day 07 Day 08 Day 09 Day 10 Day 11 Day 12 Day 13 Day 14 Day 15 Day 16

26. LMDZ simulation: Evolution of SLP anomalies during a typical monsoon depression Day 01 Day 02 Day 03 Day 04 Day 05 Day 06 Day 07 Day 08 Day 09 Day 11 Day 10 Day 12 Day 13 Day 14 Day 15 Day 16

27. Earth System Model (ESM) development • Start with an atmosphere-ocean coupled model which has a realistic mean climate – eg. NCEP CFS • Fidelity in capturing the global and monsoon climate • Realistic representation of monsoon interannual variability • Features of ocean-atmosphere coupled interactions • … • Include components of the ESM • Aerosol and Chemistry Transport Module • Biogeochemistry Module (Terrestrial and Marine) • Sea-ice module • … • .

28. Climatological (JJAS) mean monsoon rainfall from CFS model – 100 year free run Climatological (JJAS) mean SST from CFS model – 100 year free run

29. Taylor diagram of spatial pattern of climatological seasonal mean (JJAS) rainfall CFS Model High pattern correlation with observed rainfall over India (IMD gridded Dataset) Source: Seasonal Prediction Group, IITM

30. Interannual variability of summer monsoon rainfall in the CFS model – 100 year free run Domain: 70E-90E; 10N-30N Time in years CFS model JJAS climatological mean rain rate = 5.80 mm / day (red line) Standard Deviation of JJAS rain rate = 0.82 mm / day Observed rainfall (IMD) JJAS climatological mean rain rate = 7.5 mm /day Standard Deviation = 0.85 mm / day

31. CMAP precip JJAS (1980-2009) CFSv2 precip JJAS 10 yr mean CFSv1 precip JJAS 100 yr mean CFSv2 runs on PRITHVI by CCCR

33. Plan to include ESM components in the CFS-2 coupled ocean-atmosphere model • CFS-2 coupled ocean-atmosphere model simulations on HPC initiated • Ocean Biogeochemistry Module coupled to MOM4. Runs are ongoing on HPC • Aerosol Transport Module coupled to AGCM. Runs are ongoing on HPC Ongoing efforts towards development of Earth System Model (ESM) to address the Scientific Challenges of Global Climate Change and the Asian Monsoon System Basic structure of ESM

34. Features of Dynamic Climate Data Portal CCCR Climate Data Web Portal http://www.cccr.res.in CCCR Visualize data with on-the-fly graphic Easy and user friendly analysis of climate data through graphical display on the browser with one click Example : IMD daily rainfall (1951 to 2009) URL: http://cccr.hpc:8080/CCCR Step 1: Click on the above URL Centre for Climate Change Research Indian Institute of Tropical Meteorology, Pashan , Pune – 411 008 Ministry of Earth Sciences, Govt. of India

35. Summary • Dynamic downscaling of regional monsoon climate using high resolution models. Efforts have been initiated at CCCR. • Downscaling simulations of present day and future monsoon climate scenarios will be completed by early 2012 (PRECIS, WRF, RegCM, LMDZ) • Contribute to IPCC AR5 report through its activity • Quantify uncertainties in regional monsoon projections using results from multiple models • Also employ bias correction techniques for reducing model errors • Share model data & conduct inter-disciplinary collaborative research towards impact assessment, vulnerability and adaptation. • Hydrological Modeling to be started at CCCR soon • Long term plans (~ 3-4 years) to develop an Earth System Model (ESM) • A global atmosphere-ocean coupled model (CFS) is operational. A century long simulation and several other runs have been performed • Aspects of global and regional monsoon climate are realistically captured by CFS model • Realistic features of monsoon interannual variability is seen from the CFS simulations (e.g., Atmosphere-ocean coupling over tropical Indo-Pacific, Monsoon and mid-latitude interactions, etc) • Plans to improve the simulation of present day monsoon climate in the CFS model. Need to reduce model systematic biases. • Ongoing efforts to include ESM components in CFS model (ie., Aerosol transport module, Marine and Terrestrial Ecosystem and Biogeochemistry module, Sea-Ice module, etc).

36. Thank you