The climate diagnostics of Asian summer monsoon

An endeavor is made to comprehend the diagnostic aspects of Asian summer monsoon in the climate scales using the forty-year (1958-97) reanalysis data of NCEP/NCAR. We bifurcated the time-mean circulation into the stable mean and transient eddy components and studied the mean circulation features, dynamics and energetics in terms of kinetic energy, vorticity, angular momentum heat and moisture budgets. The mean budgets delineate that the summer monsoon circulation is characterized as the source of kinetic energy and vorticity as well as sink of dry and moist static energy. While kinetic energy and vorticity are transported horizontally out of the domain, heat and moisture are transported into the domain. The generation of kinetic energy is manifested through available potential energy, and vorticity through sub-grid scale processes like cumulus convection. Further, the influx of heat and moisture is balanced by diabatic heating. The angular momentum is generated by pressure torque and balanced by influx of relative and omega momentum over the monsoon domain.