On the role of cloud adjustment time scale in simulating precipitation with Relaxed Arakawa-Schubert convection scheme

Jain, Deepesh Kumar and Chakraborty, Arindam and Nanjundiah, Ravi S (2012) On the role of cloud adjustment time scale in simulating precipitation with Relaxed Arakawa-Schubert convection scheme. In: Meteorology and Atmospheric Physics, 115 (1-2). pp. 1-13.

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Abstract

The precipitation by Relaxed Arakawa-Schubert cumulus parameterization in a General Circulation Model (GCM) is sensitive to the choice of relaxation parameter or specified cloud adjustment time scale. In the present study, we examine sensitivity of simulated precipitation to the choice of cloud adjustment time scale (tau(adj)) over different parts of the tropics using National Center for Environmental Prediction (NCEP) Seasonal Forecast Model (SFM) during June-September. The results show that a single specified value of tau(adj) performs best only over a particular region and different values are preferred over different parts of the world. To find a relation between tau(adj) and cloud depth (convective activity) we choose six regions over the tropics. Based on the observed relation between outgoing long-wave radiation and tau(adj), we propose a linear cloud-type dependent relaxation parameter to be used in the model. The simulations over most parts of the tropics show improved results due to this newly formulated cloud-type dependent relaxation parameter.

Item Type:	Journal Article
Publication:	Meteorology and Atmospheric Physics
Publisher:	Springer
Additional Information:	Copyright of this article belongs to Springer.
Keywords:	RAS convection scheme;General Circulation Model;Cloud adjustment time scale;Monsoon precipitation
Department/Centre:	Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences
Date Deposited:	09 Mar 2012 10:24
Last Modified:	09 Mar 2012 10:24
URI:	http://eprints.iisc.ac.in/id/eprint/43865

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