Indian Summer Monsoon and El Niño Southern Oscillation in CMIP5 Models: A Few Areas of Agreement and Disagreement

Abstract

Using the CMIP5 model outputs, a few characteristics of Indian Summer Monsoon (ISM) rainfall and Niño 3.4 temperature are analysed during June–July–August–September (JJAS). Focusing on specified regions around central-northeast India, some general characteristic features of ISM precipitation are studied, which are shown to be varying among models. The trend of decreasing rainfall in that region as noticed in observations suggests an inconsistency among models. The ENSO also shows variation, and its phasing indicates disagreement. Unlike other models, FGOALS-g2 is identified as not suggesting any trend in Niño 3.4 temperature and needs attention for model evaluation purposes. ISM and ENSO correlation in either historical or the RCP 8.5 scenario confirm a negative signature, agreeing with the usual ISM, ENSO connection. Precipitation over the globe shows a rising trend in an ensemble of CMIP5 model outputs for the RCP 8.5 scenario, though no consensus is reached for the Indian region. Precipitation time series around the Indian subcontinent vary widely among models. Analyses with various future scenarios indicate that the Indian subcontinent shows much larger uncertainty, in terms of precipitation, compared to that from the whole world. This study identifies a few areas where CMIP 5 models are in agreement or disagreement with each other. Such an analysis could be useful for understanding various processes in CMIP 5 models that involve ISM precipitation and can lead to improving the representation of processes in models.

Keywords

• Indian Summer Monsoon
• ENSO
• CMIP 5
• RCP 8.5