Water Vapor Assimilation, Preliminary Results of Correcting for Supersaturation

1. Water Vapor Assimilation, Preliminary Results of Correcting for Supersaturation James Jung Cooperative Institute for Meteorological Satellite Studies University of Wisconsin - Madison 7 June 2013

2. Experiment Design 11th JCSDA Workshop • Investigate removal of supersaturation in the analysis • Clip supersaturation during each outer loop • Incorporate penalty for supersaturation during minimization • Review model background error • Look for potential to improve distribution • Review quality control and assimilation weights of existing water vapor channels (MW and IR) • Add IASI and CrIS water vapor channels

3. Background 11th JCSDA Workshop • Low resolution (T254) hybrid • Clip supersaturation at each outer loop • Most points come from model • Penalize supersaturation during minimization changed to 50 vice .05 • No changes to observations or observation weights

4. Time Series Analysis Differences

5. 200 hPa Temperature Analysis Differences Sen T Vir T 11th JCSDA Workshop

6. 200 hPa Humidity Analysis Differences Sp Hu Re Hu 11th JCSDA Workshop

7. Select levels 2012071100Zanalysis differences

8. 48 hPa Specific Humidity Experiment analysis Experiment - Control Sp Hu Re Hu 11th JCSDA Workshop

9. 107 hPa Humidity Experiment analysis Experiment - Control Sp Hu Re Hu 11th JCSDA Workshop

10. 107 hPa Wind U and V component Experiment analysis Experiment - Control U com V com 11th JCSDA Workshop

11. 498 hPa Humidity Experiment analysis Experiment - Control Sp Hu Re Hu 11th JCSDA Workshop

12. 925 hPa Temperature Experiment analysis Experiment - Control Sen T Vir T 11th JCSDA Workshop

13. Select levels 2012071100Z and 2012090100Zanalysis differences 11th JCSDA Workshop

14. 48 hPa Specific Humidity 11 July 2012 1 September 2012 yellow/red = increased blue/purple = decreased 11th JCSDA Workshop

15. 107 hPa Specific Humidity 11 July 2012 1 September 2012 yellow/red = increased blue/purple = decreased 11th JCSDA Workshop

16. 196 hPa Specific Humidity 11 July 2012 1 September 2012 yellow/red = increased blue/purple = decreased 11th JCSDA Workshop

17. Near Surface Temperature 11 July 2012 1 September 2012 yellow/red = increased blue/purple = decreased 11th JCSDA Workshop

18. Temperature Time Series control exp • Lighter colors (near zero) are better • At almost all levels, the experiment is better in the Northern and Southern Hemispheres. control exp 11th JCSDA Workshop

19. Temperature Bias control exp • Global average time series of temperature bias. • Temperature drifts colder that analysis at both (50 & 850 hPa) levels. • Water vapor adjustments reduce temperature drift Better Worse control exp Better Worse 11th JCSDA Workshop

20. 500 mb Anomaly Correlations control exp • exp (red) has the supersaturation removed. • Just removing supersaturation has a positive impact on anomaly correlations Better Worse Better Worse control exp 11th JCSDA Workshop

21. Concerns 11th JCSDA Workshop Poor vertical distribution of moisture increments. Moisture changes are large above 200mb and almost negligible at others (near surface). Large near surface temperature changes over Antarctica Supersaturation does not seem to be just random noise.

22. Summary 11th JCSDA Workshop • Removing supersaturation during the analysis changes the humidity field in the upper troposphere and stratosphere. • generally dryer • Forecast temperature drift with time is improved at most levels. • Warm and cold biases are reduced • Antarctica temperatures are colder in the analysis and forecasts. • Anomaly correlations are showing a small improvements

23. Questions 11th JCSDA Workshop