Numerical Simulation of a Monsoonal Link to the Rapid Arctic Ice Melt

In recent years, the South Asian summer monsoon has experienced increased rainfall over northwestern India and Pakistan. This study utilizes both observational analysis and numerical modeling to address the significance of atmospheric wave trains (excited from extreme rainfall) that provide a monsoonal link to the Arctic ice melt. These wave trains carry large values of heat content anomalies, heat transports and convergence of flux of heat. Most of these show slow increasing trends in the last 20 years. The monsoonal connection to the rapid Arctic ice melt is a new contribution of this study. This is shown from the passage of a vertical column of large positive values of the heat content anomaly that can be traced from the Asian monsoon belt to the Canadian Arctic. The heat flux along these episodic and intermittently active pathways is shown to be considerably larger than the atmospheric poleward flux across latitude circles and from the oceans. We compare model based simulation of many features such as precipitation, divergence and the divergent wind with those evaluated from the reanalysis fields. We have also examined the snow and ice cover data sets during and after these events. This numerical modeling suggests ways to interpret some recent episodes of rapid ice melts that may require a well-coordinated field experiment among atmosphere, ocean, ice and snow cover scientists. Such a well-coordinated study would sharpen our understanding of this one component of the ice melt, i.e. the monsoonal link, which appears to be fairly robust.