Improved simulation of El Ni\~no and its influence on the climate anomalies of the East Asia-western North Pacific in the ICM Version 2

TL;DR

This paper presents the second version of the ICM, which enhances short-term climate prediction accuracy for the East Asia-western North Pacific region by increasing atmospheric model resolution and better simulating El Niño impacts.

Contribution

The main novelty is the improved horizontal resolution of the ICM, leading to more accurate simulation of climate factors and El Niño effects in the EA-WNP region.

Findings

Enhanced simulation of El Niño impacts with more realistic anomalies.

Improved representation of the Indian Ocean capacitor effect.

Better reproduction of WNP air-sea interaction feedbacks.

Abstract

This study introduces the second version of the Integrated Climate Model (ICM). ICM is developed by the Center for Monsoon System Research, Institute of Atmospheric Physics to improve the short-term climate prediction of the East Asia-western North Pacific (EA-WNP). The main update of the second version of ICM (ICM.V2) relative to the first version (ICM.V1) is the improvement of the horizontal resolution of the atmospheric model from T31 spectral resolution (3.75{\deg}*3.75{\deg}) to T63 (1.875{\deg}*1.875{\deg}). As a result, some important factors for the short-term climate prediction of the EA-WNP is apparently improved from ICM.V1 to ICM.V2, including the climatological SST, the rainfall and circulation of the East Asian summer monsoon, and the variability and spatial pattern of ENSO. The impact of El Ni\~no on the EA-WNP climate simulated in ICM.V2 is also improved with more realistic anticyclonic anomalies and precipitation pattern over the EA-WNP. The tropical Indian ocean capacitor effect and the WNP local air-sea interaction feedback, two popular mechanisms to explain the impact of El Ni\~no on the EA-WNP climate is also realistically reproduced in ICM.V2, much improved relative to that in ICM.V1.