1. Application Of KF-Convection Scheme In 3-D Chemical Transport Model
EAS6410
Chun Zhao

2. GA TECH - EAS6410 - Atmosphere Chemistry
Outline
Introduction
Application
Results and Discussion
4/20/2006
GA TECH - EAS Atmosphere Chemistry

3. GA TECH - EAS6410 - Atmosphere Chemistry
Introduction
3-D Chemistry Transport Model ( CTM)
Structure:
Transport:
Advection
Diffusion
Convection
Chemistry:
Emission
Dry Deposition
Chemistry
Setup and Initial
Chemistry
Transport
4/20/2006
GA TECH - EAS Atmosphere Chemistry

4. Grell-Convection Scheme
Structure:
Cloud top
Downdraft original layer
Downdraft flux
Updraft flux
Cloud bottom
Ground surface
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GA TECH - EAS Atmosphere Chemistry

5. GA TECH - EAS6410 - Atmosphere Chemistry
KF-Convection Scheme
Structure:
Cloud top
Downdraft Original layer
entrainment
detrainment
Downdraft flux
Cloud bottom
entrainment
detrainment
Downdraft End layer
Updraft flux
Ground surface
4/20/2006
GA TECH - EAS Atmosphere Chemistry

6. Convection Scheme Comparison
KF-Scheme
Including the effects of detrainment & entrainment;
Shallow (non precipitating) convection is allowed for any updraft that does not reach minimum cloud depth for precipitating clouds; 
The downdraft end layer is dependent.
Grell-Scheme
Without effects of detrainment & entrainment;
Without shallow convection, using a separate shallow convection;
The downdraft end layer is surface.
4/20/2006
GA TECH - EAS Atmosphere Chemistry

7. GA TECH - EAS6410 - Atmosphere Chemistry
Application
Convection variables
Simulate the KF-Convection variables using WRF model.
Determine necessary variables for chemical transport model.
Develop an interface to output these necessary variables at the pacific time. In my case, I choose the first week in March.
4/20/2006
GA TECH - EAS Atmosphere Chemistry

8. GA TECH - EAS6410 - Atmosphere Chemistry
Convection Parameterization
Determine whether convection process occurs at a particular time (deep convection or shallow convection).
Do parameterization (deep and shallow)
4/20/2006
GA TECH - EAS Atmosphere Chemistry

9. GA TECH - EAS6410 - Atmosphere Chemistry
Mass Balance Control
Doing subsiding and uplifting compensation to make mass balance during convection;
Set a maximum relative mass variance during convection , due to computation error.
Time Step Control
Check negative concentration value after transport;
Decrease time step, if there is any negative concentration value after transport.
4/20/2006
GA TECH - EAS Atmosphere Chemistry

10. GA TECH - EAS6410 - Atmosphere Chemistry
Result
KF-Convection effect
The convection effect comparison between the two different schemes
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GA TECH - EAS Atmosphere Chemistry

11. KF-Convection Effect Trend
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GA TECH - EAS Atmosphere Chemistry

12. GA TECH - EAS6410 - Atmosphere Chemistry
4/20/2006
GA TECH - EAS Atmosphere Chemistry

13. GA TECH - EAS6410 - Atmosphere Chemistry
500hpa
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GA TECH - EAS Atmosphere Chemistry

14. GA TECH - EAS6410 - Atmosphere Chemistry
500hpa
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GA TECH - EAS Atmosphere Chemistry

15. GA TECH - EAS6410 - Atmosphere Chemistry
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GA TECH - EAS Atmosphere Chemistry

16. Convection Effect Comparison
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GA TECH - EAS Atmosphere Chemistry

17. GA TECH - EAS6410 - Atmosphere Chemistry
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GA TECH - EAS Atmosphere Chemistry

18. GA TECH - EAS6410 - Atmosphere Chemistry
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GA TECH - EAS Atmosphere Chemistry

19. GA TECH - EAS6410 - Atmosphere Chemistry
4/20/2006
GA TECH - EAS Atmosphere Chemistry

20. GA TECH - EAS6410 - Atmosphere Chemistry
Summary
Convection effect in chemical transport process is very important;
Different convection schemes have different effect in transport;
There are still some problems to parameterize the convection very well in transport model. (i.e. time step control, mass balance)
4/20/2006
GA TECH - EAS Atmosphere Chemistry

21. GA TECH - EAS6410 - Atmosphere Chemistry
Question?
4/20/2006
GA TECH - EAS Atmosphere Chemistry