Decadal to multi-decadal scale variability of Indian summer monsoon rainfall in the coupled ocean-atmosphere-chemistry climate model SOCOL-MPIOM

Abdul Malik,Eugene Rozanov,Stefan Muthers,Julien Anet,Alexander Stickler,Werner Schmutz,Stefan Brönnimann,Christoph C Raible

doi:10.1007/s00382-017-3529-9

Abstract

The present study is an effort to deepen the understanding of Indian summer monsoon rainfall (ISMR) on decadal to multi-decadal timescales. We use ensemble simulations for the period AD 1600–2000 carried out by the coupled Atmosphere-Ocean-Chemistry-Climate Model (AOCCM) SOCOL-MPIOM. Firstly, the SOCOL-MPIOM is evaluated using observational and reanalyses datasets. The model is able to realistically simulate the ISMR as well as relevant patterns of sea surface temperature and atmospheric circulation. Further, the influence of Atlantic Multi-decadal Oscillation (AMO), Pacific Decadal Oscillation (PDO), and El Niño Southern Oscillation (ENSO) variability on ISMR is realistically simulated. Secondly, we investigate the impact of internal climate variability and external climate forcings on ISMR on decadal to multi-decadal timescales over the past 400 years. The results show that AMO, PDO, and Total Solar Irradiance (TSI) play a considerable role in controlling the wet and dry decades of ISMR. Resembling observational findings most of the dry decades of ISMR occur during a negative phase of AMO and a simultaneous positive phase of PDO. The observational and simulated datasets reveal that on decadal to multi-decadal timescales the ISMR has consistent negative correlation with PDO whereas its correlation with AMO and TSI is not stationary over time.

Highlights

The Indian summer monsoon rainfall (ISMR) has a vital impact on the agrarian economy of this region
The spatial pattern of ISMR in L1 resembles with that of ERA-20C, 20CR, Global Precipitation Climatology Centre (GPCC), and ERA-Interim over most parts of the Indian monsoon region except over the Western Ghats where the model fails to capture the spatial pattern of relatively higher rainfall
The difference of the L1 mean precipitation with ERA-20C, 20CR, GPCC, and ERA-Interim shows that the model underestimates the precipitation over Hilly regions, the Western Ghats, the Himalayan Region, Northeast India, and over the west coast of Myanmar, which may be due to the lower spatial resolution and topographical differences of the model (Fig. 1f)

Summary

Introduction

The Indian summer monsoon rainfall (ISMR) has a vital impact on the agrarian economy of this region. In contrast to the AMO, the PDO, the leading mode of SSTs in the North Pacific Ocean with periodicities of 15–25 years and 50–70 years (e.g., Mantua and Hare 2002), is suggested having an opposite effect on ISMR (see, Krishnan et al 2003; Roy et al 2003; Krishnamurthy and Krishnamurthy 2013). These studies found that dry (wet) events are more likely over India when the positive (negative) phase of El Niño Southern Oscillation (ENSO) coincides with the positive (negative) phase of PDO. The above-mentioned studies indicate the influence of decadal to multi-decadal scale ocean modes on ISMR they do not show the stability of their relationship (sign of correlation and magnitude) with the ISMR

Objectives

Methods

Results

Conclusion