Comparison of seasonal and intraseasonal variation of tropical climate in NCAR CCM2 GCM with two different cumulus schemes |
| |
| Authors: | K Rajendran Ravi S Nanjundiah J Srinivasan |
| |
| Institution: | (1) Centre for Atmospheric and Oceanic Sciences, Bangalore, India, IN |
| |
| Abstract: | Summary
The seasonal and intraseasonal variation of tropical climate in National Center for Atmospheric Research (NCAR) Community
Climate Model Version 2 (CCM2) General Circulation Model (GCM) has been examined using two different cumulus parameterization
schemes, the moist convective adjustment scheme of Manabe et al. (1965) and the mass-flux scheme of Hack (1994). Ten-year
simulations have been undertaken with each of these schemes with SST prescribed according to the monthly mean climatology.
The seasonal mean rainfall in the tropics simulated by the moist convective adjustment scheme (MCA) scheme was found to be
more realistic than the mass-flux (Hack) scheme. The more realistic simulation by the MCA scheme was found to be on account
of the fact that the mean moist static energy of the lower troposphere in the MCA scheme was closer to the observations than
in the Hack scheme. In both the schemes, the precipitation in the tropics increases montonically with precipitable water vapour
when the precipitable water vapour is above 40 mm. This is consistent with relationship between precipitation and precipitable
water in the observations. The Hack scheme tends to simulate lower precipitation (for a given amount of precipitable water)
when compared to observations.
The MCA scheme simulates the eastward migration of convective systems along the equator quite well, although the speed of
propagation is somewhat low. The poleward migration of convective systems in the Indian region is more realistically simulated
by the MCA scheme than the Hack scheme. This is because the latitudinal gradient of the mean moist static energy in the MCA
scheme is more realistic than in the Hack scheme. Over most of the tropics, simulation by the MCA scheme is more realistic
on both seasonal and intraseasonal timescales.
Received November 1, 2000 Revised June 20, 2001 |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
