A comparative analysis of 14 5-year long climate simulations produced by the National Cen-

Abstract

14 A comparative analysis of 14 5-year long climate simulations produced by the National Cen15 tres for Environmental Predictions (NCEP) Climate Forecast System version 2 (CFSv2), in 16 which a stochastic multicloud (SMCM) cumulus parameterization is implemented, is pre17 sented here. These 5-year runs are made with different sets of parameters in order to figure 18 out the best model configuration based on a suite of state-of-the-art metrics. This analysis is 19 also a systematic attempt to understand the model sensitivity to the SMCM parameters. The 20 model is found to be resilient to minor changes in the parameters used implying robustness 21 of the SMCM formulation. The model is found to be most sensitive to the mid-tropospheric 22 dryness parameter (MTD) and to the stratiform cloud decay timescale (τ30). MTD is more 23 effective in controlling the global mean precipitation and its distribution while τ30 has more 24 effect on the organization of convection as noticed in the simulation of the Madden-Julian 25 oscillation (MJO). This is consistent with the fact that, in the SMCM formulation, mid26 tropospheric humidity controls the deepening of convection and stratiform clouds control 27 the backward tilt of tropospheric heating and the strength of unsaturated downdrafts which 28 cool and dry the boundary layer and trigger the propagation of organized convection. Many 29 other studies have also found mid-tropospheric humidity to be a key factor in the capacity of 30 a global climate model to simulate organized convection on the synoptic and intra-seasonal 31 scales. 32

11 Figures and Tables

Cite this paper

@inproceedings{Goswami2017ACA, title={A comparative analysis of 14 5-year long climate simulations produced by the National Cen-}, author={Bhaskar Goswami and Boualem Khouider and R. Phani and Pranab K Mukhopadhyay and Andrew J. Majda}, year={2017} }