On the connection between remote dust aerosol and Indian summer monsoon

Understanding of interaction between remote dust aerosol and Indian summer monsoon (ISM) remains dubious in literature because of wide disagreement among previous studies. This problem is revisited using version-2 of Modern-Era Retrospective Analysis for Research and Applications (MERRA-2) datasets. ISM variability at intraseasonal timescale is not constrained by the changes in dust aerosols over the most parts of West Asia and North Africa. A new hypothesis is proposed to explain covariability of dust over the Arabian Sea and ISM circulation. Large-scale forcing modulates monsoon intraseasonal oscillations (ISOs) and creates active-like condition over the Indian landmass extending up to the Arabian Sea and the Arabian Peninsula. Organized convection induces anomalous southwesterly and northwesterly circulation as a response to enhanced latent heating. Enhanced northwesterly winds strengthen transport of dust over the Arabian Sea. Augmented dust forcing and associated warming over the Arabian Sea is unlikely to create a positive feedback because of its limited spatial extent. Findings of the present study provide a new insight into remote dust-ISM connection problem and the hypothesis proposed differs considerably from the previously proposed hypotheses.