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Key Points: Satellite observations and Meso‐NH model simulations are used to investigate an intense dust storm over north India in June 2018Dust is mostly confined below 2 km in the monsoon flow over the Thar desert, northwest India and at ~3 km along the Ganges ValleyThe dust was accumulated in an arc‐shaped cloud in the convergence zone between the southwesterlies and the northwesterlies: the ITD A severe dust storm occurred over north India during 12–16 June 2018 is analyzed using satellite observations, reanalysis, ground‐based measurements, and model (Meso‐NH) simulations focusing on the dynamic processes that caused the dust‐storm generation, uplift, and propagation as well as its impacts on air quality. The initial dust emission was triggered by strong near‐surface southwesterlies (~15–20 m s−1) associated with the monsoon flow advancing northward, in response to the deepening of the thermal low over the Thar desert. The convergence between the northwesterlies and the monsoon flow along the Intertropical Discontinuity region caused high dust accumulation over northwest India in an area of weak winds. Convective mixing during daytime favors the vertical transport of dust to higher altitudes above the monsoon flow, but the towering Himalayas and the associated return northerly flow aloft play a blocking role leading to dust accumulation at heights between 1 and 3 km over northwest India. The prevailed northwesterlies in the middle troposphere favor the eastward transport of the dust plumes along the Ganges valley, helping to evacuate the dust toward east India. Based on Meso‐NH model simulations, the dust storm was associated with dust loads higher than 30 gm−2 and AODs higher than 3, in agreement with MODIS observations. The impact of the dust storm on the spatial‐temporal evolution of the PM10 and PM2.5 mass concentrations is studied using data from 23 air‐quality stations over northern India, indicating daily PM10 peaks reaching at ~900 μg m−3, implying a severe degradation of air quality. [ABSTRACT FROM AUTHOR]

The impact of long-range transported dust aerosols, originating from the Thar Desert region, to a high-altitude station in the central Himalayas was studied with the help of micro-pulse lidar (MPL) observations. A drastic change in lidar back-scatter profile was observed on a dust day as compared with that on a pre-dust day. The back-scatter coefficient on a dust day revealed that the dust layer peaked at an altitude ∼1300 m above ground level (AGL) and extended up to ∼3000 m AGL, with maximum value ∼3 × 10–5 m–1 sr–1. Aerosol Index (AI) and air mass back-trajectory analysis substantiate the transport of dust aerosols from the far-off Thar Desert region to the experimental site. A significant effect of dust aerosols was also observed over the station on the spectral aerosol optical depths (AODs), measured using a Microtops-II Sunphotometer. It showed significantly different spectral behaviour of AOD on a dust day as compared with that on a pre-dust day. The Ångström exponent (α) showed a marked decrease from 0.42 to 0.04 from the pre-dust day to the dust day. The aerosol radiative forcing estimated using the Santa Barbara DISORT (discrete ordinate radiative transfer) atmospheric radiative transfer (SBDART) model, in conjunction with the optical properties of aerosol and cloud (OPAC) model, showed values of about –30, –45 and +15 W m–2, respectively, at top-of-atmosphere (TOA), surface and in the atmosphere on the dust day. The positive atmosphere forcing caused an estimated heating of the lower atmosphere by ∼0.4 K day–1. [ABSTRACT FROM AUTHOR]