Revisiting Andhi in northern India: A case study of severe dust-storm over the urban megacity of New Delhi

Abstract

Pre-monsoon dust storms also known as “Andhi” are one of the common phenomena occurring over the northern part of Indian sub-continent. Using the synergetic information from multiple platforms, the life cycle of an infamous dust storm event has been investigated, which impacted the urban megacity of New Delhi on May 30, 2014. The analysis from the radar revealed that the storm resulted from the merger of the outflow boundaries of two propagating thunderstorms in the mesoscale vicinity of New Delhi region. The leading edge of the outflow of downdraft cold air generated from the storm, ploughs the loose hot soil from the surface, thereby resulting to the severe dust storm over the region. Along with the heavy aerosol loading on that day as found from the satellite data, the evolution of the storm was also associated with sudden change in surface meteorological parameters which are manifested through the increase in near surface humidity (~ 70%) and pollution levels along with the decrease in surface temperature (−12%). Although the study is centered at one event, the inferences distilled from this study are beneficial for the improvement of the predictive capability of severe weather events particularly for the tropical countries.