Deep convective influence on the Asian summer monsoon and associated tracer variability observed with AIRS

The Asian summer monsoon anticyclone is fundamentally linked to climatological deep convection over south Asia, and the coupling of circulation and convection strongly influences constituent behavior in the upper troposphere – lower stratosphere (UTLS). This work explores variability of the monsoon circulation and trace constituents linked to transient deep convection, based on dynamical fields and outgoing longwave radiation (OLR) data, plus water vapor and ozone retrievals from the Atmospheric Infrared Sounder (AIRS) instrument. Within the monsoon region, transient deep convection varies with a time scale of ~10-20 days, linked to ‘breaks' in the monsoon circulation. We show that these convective events trigger variations of anticyclone itself, with strong correlations between OLR and the area of low potential vorticity (PV) defining the anticyclone. Relatively high PV (stratospheric air) is also advected to low latitudes to the east of the anticyclone following enhanced convection. AIRS data show that the transient convective events are associated with the vertical transport of low (high) ozone (water vapor) into the UTLS region, with largest effects over theta levels 340-360 K. These ozone and water vapor anomalies are subsequently advected with the monsoon circulation, with substantial influence on stratosphere-troposphere exchange.