Abstract:
The genesis, dynamics, and impacts of a severe dust storm over the central Himalaya during June
13–17, 2018 have been investigated using in situ measurements, satellite data, and model reanalysis. A low pressure system over northern India and prevalence of strong winds (∼20 ms−1) triggered the dust storm leading
to poor visibility conditions and five-fold enhancement in the fine particulate matter (PM2.5) over the central
Himalaya. Enhancements in Aerosol Optical Depth (AOD) were observed to be stronger over the Himalayan
foothills site (Lumbini) than that over the Indo-Gangetic Plain (IGP) site-Gandhi College. The sharp reductions
in Angstrom exponent (α) from about 1.2 to 0.3 indicated the dominance of coarse-mode aerosols during the
dust episode. Model results show an enhancement in the dust from 1.5 to 2.5 Tg (∼70%) over the northern
Indian subcontinent, with about half of the contribution from the regional source (Thar Desert). Interestingly,
dust storm also had significant impacts on turbulent kinetic energy (2.9–9.6 m2
s−2), vertical momentum flux
(0.9–3.3 Nm−2), and sensible heat flux (34.8 to −33.9 Wm−2), suggesting turbulent mixing of aerosols and
cooling near the surface over the Himalayas. Our study highlights that the large-scale dust storms exposed
to additional dust and pollution from regional sources can profoundly impact the air quality, heat fluxes, and
radiative balance over the northern Indian subcontinent. The study would also help in evaluating the results of
climate models and to assess the impacts of dust on the hydrological processes and melting Himalayan glaciers.
