Unraveling the global teleconnections of Indian summer monsoon clouds: expedition from CMIP5 to CMIP6.

We have analyzed the teleconnection of total cloud fraction (TCF) with global sea surface temperature (SST) in multi-model ensembles (MME) of the fifth and sixth Coupled Model Intercomparison Projects (CMIP5 and CMIP6). CMIP6-MME has a more robust and realistic teleconnection (TCF and global SST) pattern over the extra-tropics (R ~ 0.43) and North Atlantic (R ~ 0.39) region, which in turn resulted in an improvement of rainfall bias over the Asian summer monsoon (ASM) region. CMIP6-MME can better reproduce mean TCF and have reduced dry (wet) rainfall bias on land (ocean) over the ASM region. Model bias with respect to seasonal mean rainfall, TCF, and outgoing longwave radiation (OLR) in CMIP6-MME are improved over the Indian Summer Monsoon (ISM) region by ~40%, ~45%, and ~ 31%, respectively, as compared to CMIP5-MME. Further, CMIP6-MME demonstrates a better spatial correlation with observation/reanalysis. The present study has also shown the lag correlations in the teleconnection analysis, i.e., the correlation of June–September (JJAS) mean of rainfall/TCF with October–December (OND) SST from observation/reanalysis, CMIP5-MME, and CMIP6-MME. The CMIP6-MME performs better than CMIP5-MME as compared to observation/reanalysis. The results establish the credibility of the CMIP6 models and provide a scientific basis for improving the seasonal prediction of ISM. • The total cloud fraction (TCF) over the ISM region is strongly associated with global predictors. • The seasonal mean biases of TCF and rainfall have seen improvement from CMIP5-MME to CMIP6-MME. • Improvement from CMIP5 to CMIP6 models may be attributed to the better depiction of the observed global teleconnections. [ABSTRACT FROM AUTHOR]