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Water Vapor Assimilation, Preliminary Results of Correcting for Supersaturation. James Jung Cooperative Institute for Meteorological Satellite Studies University of Wisconsin - Madison 7 June 2013. Experiment Design. Investigate removal of supersaturation in the analysis - PowerPoint PPT Presentation
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Water Vapor Assimilation, Preliminary Results of
Correcting for Supersaturation
James Jung
Cooperative Institute for Meteorological Satellite Studies
University of Wisconsin - Madison
7 June 2013
Experiment Design
• 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
7 June 201311th JCSDA Workshop 2
Background
• 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
7 June 201311th JCSDA Workshop 3
48 hPa Specific Humidity
7 June 201311th JCSDA Workshop 8
Sp Hu
Re Hu
Experiment analysis Experiment - Control
107 hPa Humidity
7 June 201311th JCSDA Workshop 9
Sp Hu
Re Hu
Experiment analysis Experiment - Control
107 hPa Wind U and V component
1011th JCSDA Workshop 7 June 2013
U com
V com
Experiment analysis Experiment - Control
498 hPa Humidity
1111th JCSDA Workshop 7 June 2013
Sp Hu
Re Hu
Experiment analysis Experiment - Control
925 hPa Temperature
1211th JCSDA Workshop 7 June 2013
Sen T
Vir T
Experiment analysis Experiment - Control
48 hPa Specific Humidity
1411th JCSDA Workshop 7 June 2013
yellow/red = increasedblue/purple = decreased
11 July 2012 1 September 2012
107 hPa Specific Humidity
1511th JCSDA Workshop 7 June 2013
yellow/red = increasedblue/purple = decreased
11 July 2012 1 September 2012
196 hPa Specific Humidity
1611th JCSDA Workshop 7 June 2013
yellow/red = increasedblue/purple = decreased
11 July 2012 1 September 2012
Near Surface Temperature
1711th JCSDA Workshop 7 June 2013
yellow/red = increasedblue/purple = decreased
11 July 2012 1 September 2012
Temperature Time Series
1811th JCSDA Workshop 7 June 2013
•Lighter colors (near zero) are better•At almost all levels, the experiment is better in the Northern and Southern Hemispheres.
control exp
control exp
Temperature Bias
1911th JCSDA Workshop 7 June 2013
•Global average time series of temperature bias.•Temperature drifts colder that analysis at both (50 & 850 hPa) levels.•Water vapor adjustments reduce temperature drift
control exp
control exp
BetterWorse
BetterWorse
500 mb Anomaly Correlations
2011th JCSDA Workshop 7 June 2013
•exp (red) has the supersaturation removed.•Just removing supersaturation has a positive impact on anomaly correlations
controlexp
controlexp
BetterWorse
BetterWorse
Concerns
• 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.
7 June 201311th JCSDA Workshop 21
Summary
• 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
7 June 201311th JCSDA Workshop 22