Testing a Warm Cloud Parameterization With Data From Field Campaigns Over Beijing
Abstract
We used a two-moment (mass and number) warm cloud scheme in conjunction with observations to study the effects of aerosol on cloud microphysics and precipitation. Regional model simulations were conducted over Beijing where intensive field experiments involving aircrafts, soundings and ground-based measurements were carried out during 2004-05. In the simulations, a tri-lognormal aerosol size distribution is used with the "accumulation" mode fitted to the aircraft measurements. Although the model simulated spatial and temporal evolution of cloud cover is in good agreement with observations, the cloud microphysics and precipitation show different characteristics. For example, for the case of June 25-26, 2005, the simulated mean (cloud and rain) water for a warm cloud system located 5-6 km is in good agreement with observed value of ~0.1 g/kg, but the partitioning between cloud and rain water is different, with cloud water dominates in the model while rainwater is much larger in the observations. Differences also exist in mean cloud/raindrop numbers and the mean effective cloud/raindrop radius between model simulations and observations. Preliminary assessments suggest that these features can be attributed partly to the uncertainty in the cloud and rainwater measurements, and partly to the many simplified treatments in model aerosol properties. Simulation results will also be presented to illustrate the sensitivity of cloud radiative heating/cooling and precipitation to aerosol size distribution; and to the radiative scheme and warm cloud scheme used in the model.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2006
- Bibcode:
- 2006AGUFM.A13C0938F
- Keywords:
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- 0305 Aerosols and particles (0345;
- 4801;
- 4906);
- 0320 Cloud physics and chemistry;
- 0321 Cloud/radiation interaction;
- 0429 Climate dynamics (1620);
- 1622 Earth system modeling (1225)