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IITM Earth System Model: Transformation of a Seasonal Prediction Model to a Long Term Climate Model

Swapna, P and Roxy, M and Aparna, K and Kulkarni, K and Prajeesh, AG and Ashok, K and Krishnan, R and Moorthi, S and Kumar, A and Goswami, BN (2014) IITM Earth System Model: Transformation of a Seasonal Prediction Model to a Long Term Climate Model. Bulletin of the American Meteorological Society, online. pp. 1-44.

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Abstract

With the goal of building an Earth System Model (ESM) appropriate for detection, attribution and projection of changes in the South Asian monsoon, a state-of-the-art seasonal prediction model, namely the Climate Forecast System version 2 (CFSv2) has been adapted to a climate model suitable for extended climate simulations at the Indian Institute of Tropical Meteorology (IITM), Pune, India. While the CFSv2 model has been skillful in predicting the Indian summer monsoon (ISM) on seasonal time scales, a century-long simulation with it shows biases in the ocean mixed-layer, resulting in a 1.5ºC cold bias in the global mean surface air temperature, a cold bias in the sea surface temperature (SST) and a cooler-than-observed troposphere. These biases limit the utility of CFSv2 to study climate change issues. To address biases, and to develop an Indian Earth System Model (IITM-ESMv1), the ocean component in CFSv2 was replaced at IITM with an improved version, having better physics and an interactive ocean biogeochemistry. A 100-year simulation with the new coupled model (with biogeochemistry switched off) shows substantial improvements, particularly in global mean surface temperature, tropical SST and mixed layer depth. The model demonstrates fidelity in capturing the dominant modes of climate variability such as the ENSO and Pacific Decadal Oscillation. The ENSO-ISM teleconnections and the seasonal lead-lags are also well simulated. The model, a successful result of the Indo-US collaboration, will contribute to the IPCC-AR6 simulations, a first from India.

Item Type: Article
Additional Information: Copyright of this article belongs to American Meteorological Society
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 10 Aug 2015 09:54
Last Modified: 10 Aug 2015 09:54
URI: http://moeseprints.incois.gov.in/id/eprint/2830

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