Sensitivity and uncertainty analysis of the different parameterization schemes in regional climate model RegCM4.5 for simulation of air temperature and precipitation over North and West of Iran

Document Type : Original Article

Authors

1 Department of Earth Science, Science and Research Branch, Islamic Azad University

2 Department of Earth Science, Science and Research Branch, Islamic Azad University, Tehran, Iran

3 Yazd Unversity, Yazd, IRAN

4 Division of space physics, Department of physics, physics faculty, Yazd university.

Abstract

In this study, the performance of the Regional Climate Model version 4 (RegCM4.5) with different parameterization schemes was evaluated to simulating the seasonal 2-m temperature and precipitation over the north and west of Iran in the period of 1986-2015.. For this purpose, the NNRP2 reanalysis data were used as initial and boundary conditions of the RegCM4.5 climate model as well as six different parameterization schemes for simulation. The results demonstrated that the RegCM4.5 model has good potential for simulating precipitation and surface temperature in the north and west of Iran. The model bias for 2- temperature in different regions of Iran using parameterization schemes is different. Magnitude of the model bias for land surface temperature over different regions of Iran varies by convection parameterization schemes. In most cases, the root mean square error between post-processed simulated seasonal average temperature and observation value was less than 1°C and their correlation coefficient was more than 0.9. In general, according to the surface temperature simulations, using the model data after post-processing with Holtslag-Grell and Holtslag-Kuo schemas, compared to other simulations, achieved better performance on the study area. So, for the average seasonal precipitation, the Emanuel scheme is suggested along with the two Holtslag and UW PBL schemas with a correlation between 0.55-0.75 and a standard deviation close to 1. Also, this research intends to investigate the performance of model in simulating 2-m temperature and precipitation by developing a multi-physics ensemble for RegCM4.5 model over north and west of Iran. The investigation on RegCM4.5 model uncertainty in the ensemble prediction of temperature and precipitation by combining physical schemas, shows that the amplitude of the model uncertainty can be reduced and more reliable predictions of temperature and precipitation can be achieved. So that UW PBL-Grell and Holtslag PBL-Emanuel schemes had a good performance for ensemble prediction of temperature and Holtslag PBL-Emanuel had a good performance for ensemble prediction of precipitation.

Keywords

Journal of Meteorology and Atmospheric Science
Volume 2, Issue 4 - Serial Number 4
March 2020
Pages 296-318

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