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Application Of KF-Convection Scheme In 3-D Chemical Transport Model. EAS6410 Chun Zhao. Outline. Introduction Application Results and Discussion. Introduction. 3-D Chemistry Transport Model ( CTM) Structure: Transport:
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Application Of KF-Convection Scheme In 3-D Chemical Transport Model EAS6410 Chun Zhao
Outline • Introduction • Application • Results and Discussion 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 GA TECH - EAS6410 - Atmosphere Chemistry
Grell-Convection Scheme • Structure: Cloud top Downdraft original layer Downdraft flux Updraft flux Cloud bottom Ground surface 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 GA TECH - EAS6410 - Atmosphere Chemistry
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. 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. 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) 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. GA TECH - EAS6410 - Atmosphere Chemistry
Result • KF-Convection effect • The convection effect comparison between the two different schemes GA TECH - EAS6410 - Atmosphere Chemistry
KF-Convection Effect Trend GA TECH - EAS6410 - Atmosphere Chemistry
500hpa GA TECH - EAS6410 - Atmosphere Chemistry
500hpa GA TECH - EAS6410 - Atmosphere Chemistry
Convection Effect Comparison 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) GA TECH - EAS6410 - Atmosphere Chemistry
Question? GA TECH - EAS6410 - Atmosphere Chemistry