Test of Microphysics Treatment in Convection Parameterization Using TWP-ICE Data and NCAR SCAM and CAM3

Guang Zhang University of California, San Diego
Xiaoliang Song Scripps Institution of Oceanography

Category: Modeling

Working Group: Cloud Life Cycle

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Vertical profiles of cloud ice content inside convective cells from (top) NCAR SCAM control run, (middle) NCAR SCAM with new microphysics for convection, and (bottom) TWP-ICE observations.

As part of an effort to improve the convection parameterization scheme for the NCAR CAM3 using ARM/ASR observations, we incorporated a cloud microphysics parameterization into the Zhang-McFarlane convection scheme. The scheme is then evaluated against observations of cloud ice and water during the TWP-ICE experiment using the NCAR SCAM. It is found that this physically based treatment of convective microphysics yields more realistic vertical profiles of convective cloud ice and liquid water contents. Cloud water and ice budgets are calculated to estimate the role of cloud water and ice detrainment from convection as water source for large-scale clouds. The new microphysics treatment is further implemented into CAM3 to test its effect on GCM simulations of clouds. Results indicate that increase in ice and water contents in convective clouds leads to a moderate increase in tropical cloud amount and ice/liquid water path.

This poster will be displayed at ASR Science Team Meeting.