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Recent Climate Change Modeling Results

Recent Climate Change Modeling Results. Climate Impacts Group University of Washington With: Patrick Zahn, Cliff Mass, Rick Steed. Eric Salath é. Eric Slath é. IPCC Scenarios for Pacific Northwest Climate Change. 2-10°F. 1.5-4°F. 0.5-2°F. Changes in Pacific Storm Track.

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Recent Climate Change Modeling Results

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  1. Recent Climate Change Modeling Results Climate Impacts GroupUniversity of Washington With: Patrick Zahn, Cliff Mass, Rick Steed Eric Salathé Eric Slathé

  2. IPCC Scenarios for Pacific Northwest Climate Change 2-10°F 1.5-4°F 0.5-2°F

  3. Changes in Pacific Storm Track • Consensus of current Global Climate Models: • Intensification of Mid-latitude storms • Less frequent storms • Northward shift in storm track

  4. Shift in Pacific Storm Track J Yin, Geophys Res Lett, 2005 Temperature Change 1980-2000 to 2080-2100 Change in Eddy Growth S Pole EQ N Pole S Pole EQ N Pole

  5. Shift in Pacific Storm Track Observed 20th Century Model Composite 21st Century Model Composite Salathé, Geophys Res Lett, 2006

  6. Shift in Aleutian Low Observed 20th Century Model Composite Salathé, Geophys Res Lett, 2006

  7. Change in Orographic Enhancement Precip Change: Downscaling withoutwind effect Precip Change: Downscaling with wind effect Difference Salathé, Geophys Res Lett, 2006

  8. Downscaling

  9. Downscaling Methods Used in CIG Impacts studies Empirical Downscaling • Assumes climate model captures temperature and precipitation trends • Quick: Can do many scenarios • Shares uncertainties with global models • Regional Climate Model • Based on MM5 regional weather model • Represents regional weather processes • May produce local trends not depicted by global models • Additional modeling layer adds bias and uncertainty

  10. Mesoscale Climate Model • Based on MM5 Weather Model • Nested grids 135-45-15 km • Nudging on outermost grid by forcing global model • Advanced land-surface model (NOAH) with interactive deep soil temperature

  11. Potential Surprises • How does loss of snowpack feed back on the climate? • How do changes in the winds affect the local climate? • Are their changes in cloudiness that can affect the local rate of warming?

  12. MM5 Simulations • ECHAM5 global model to force the mesoscale system • 1990-2000 to see how well the system is working • 2020-2030, 2045-2055, 2090-2100Climate Change

  13. ECHAM5 20th Century Validation Temperature Bias 20th Century Temperature Trend RMS Error Precipitation Seasonal Cycle

  14. MM5-ECHAM 1990s Validation Max Temperature at SeaTac MM5-NNRP Obs Record High Obs Mean Tmax Temperature (°F) Obs Record Low MM5-ECHAM

  15. 1990s Validation Min Temperature at SeaTac MM5-NNRP Obs Record High Obs Mean Tmin Temperature (°F) Obs Record Low MM5-ECHAM

  16. 1990s Validation 1990-2000 Mean Surface temperature Gridded Observations MM5 - NCEP Reanalysis MM5 - ECHAM5 January July

  17. Winter Cold Bias • Cold episodes occurred 1-2 times per winter with temperature getting unrealistically cold (below 10F) in Puget Sound: • Also a general cold bias to minima, especially in Summer • Performance varies with global forcing model: • ECHAM5 better than PCM • NCEP Reanalysis performs quite well

  18. Why Cold Outbreaks? • Widespread surges of arctic air originate in Global Model, likely owing to poorly-resolved terrain (Cascades and Rockies). • Extreme cold air inherited by MM5. • Results from previous experiments with lower-resolution (T42) GCM indicate that higher resolution reduces frequency and severity of unrealistic cold events.

  19. Issues in downscaling Example of cold bias in PCM control simulation Due to poor resolution, model generates intermittentspuriously cold events over the Western US Surf Temp (K)

  20. Simulations of Future Climate Because there are some biases in the GCM runs, results for future decades (2020s, 2040s, and 2090s) will be evaluated against the ECHAM5-MM5 1990-2000 baseline

  21. Simulations of Future Climate Because there are some biases in the GCM runs, results for future decades (2020s, 2040s, and 2090s) will be evaluated against the ECHAM5-MM5 1990-2000 baseline

  22. Winter Warming 1990s to 2050s Temperature Change Difference betweenMM5 and ECHAM5 Change in Winter Temperature (degrees C) Change in Winter Temperature (degrees C)

  23. Surface Radiation Balance Increased Absorption ofSurface Solar Radiation

  24. Loss of Snow cover and Warming Snow Cover Change Temperature Change Change in fraction of days with snow cover Change in Winter Temperature (degrees C)

  25. Consistent trend over 21st Century 2020s 2050s 2090s Change in Winter Temperature (degrees C)

  26. MM5 Compared to raw Climate model 2020s 2050s 2090s Change in Winter Temperature (degrees C)

  27. Shift to Northerly Winds Change in Sea-level Pressure Change in Surface Winds

  28. Spring 1990s to 2050s Temperature Change Difference betweenMM5 and ECHAM5 Change in Spring Temperature (degrees C) Change in Spring Temperature (degrees C)

  29. Radiative Balance Reduced Incident Surface Solar Radiation Increased Absorption of Solar Radiation

  30. Pressure gradient and Cloud Pressure Change Cloud Change Percent Change in Low Cloud Change in 850-mb Height (m)

  31. Trend over 21st Century 2020s 2050s 2090s Change in Spring Temperature (degrees C)

  32. MM5 Compared to Raw Climate Model 2020s 2050s 2090s Change in Spring Temperature (degrees C)

  33. Winter Trends at Various Stations MM5 - ECHAM5 Temperature Change (°C)

  34. Winter Trends at Various Stations MM5 - ECHAM5 10 IPCC Models Temperature Change (°C) 1950 2000 2050 2100

  35. Applications: Air Quality

  36. Applications: Hydrology

  37. Summary Projected Pacific Northwest Climate Change warming: 1/4 to 1 ºF/decade Probably more warming in Summer than Winter Precipitation changes uncertain – Possibly wetter winters and drier summers Challenges Deficiencies in Global model propagate to regional model Biases from regional model Mesoscale model simulates different climate signal from global model Loss of snow amplifies warming in Winter and Spring Increased cloud cover in Spring -- reduces effect of snow loss

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