The Unusual Severe Dust Storm of May 2018 Over Northern India: Genesis, Propagation, and Associated Conditions

Abstract

AbstractOn the evening of May 02, 2018, an unusually severe dust storm (DS) from a convective system, which developed over the Thar Desert, struck northwest India resulting in more than 100 casualties. Analysis of its genesis from surface measurements and reanalysis data indicates that this DS was “Haboob” type which are formed when strong downdrafts from a convective system reaches the surface in arid regions. Surface observations show that this DS was accompanied by a sharp drop in temperature and visibility and increase in relative humidity. Model simulation at convective‐permitting scale reveals the complex structure of dust transport in space and time. In contrast to the generally observed dust storms over the Indo‐Gangetic Plain being mostly associated with westerly wind bringing dust from Southwest Asia and Eastern Africa, this particular DS was triggered by strong easterly wind. The moisture‐laden easterly wind at the surface level colliding against the dry westerlies from the desert region along a steep front resulted in strong convection over northwest India leading to the formation of strong downdrafts. This, in turn, was largely due to the positioning of the upper level jet stream, which modulated the location and the strengths of surface lows and highs. The importance of this study is that while recent studies indicate that dust aerosol over India is on the decline partly due to reduction in westerly wind strength, the present work shows that anomalous easterlies can provide an alternate pathway to intense dust storms over the region.