English: In late January 2022, a substantial dust storm enveloped the Arabian Sea. Plumes of desert dust affected populated areas around the basin, as winds carried the particles over Karachi, Mumbai, and numerous other cities and degraded air quality.

The Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA’s Aqua satellite acquired a true-color image of the storm on January 22, just as plumes of dust streamed from Oman, Pakistan, and Iran to create an extremely thick wall of dust over the Arabian Sea off the coast of Pakistan. Visibility in Karachi—the largest city in Pakistan—fell to about 500 meters (1600 feet) on that day.

Dust arose from three different countries but merged into a large plume that cast a pall over much of the Arabian Sea. NASA’s Earth Observatory quoted Hiren Jethva, a Morgan State University scientist based at NASA’s Goddard Space Flight Center, who stated the size of the plume was “quite remarkable,” as was its unusual path.

Initially on January 21, high winds associated with a low-pressure system whipped up dust and carried it toward the southeast. On January 22, the dust blew over the sea and then hooked toward the east. By January 23, dust blanketed western India, shrouding the states of Maharashtra, Gujarat, and Rajasthan.

According to Jethva, winter winds usually blow out from India toward the Arabian Sea, carrying various aerosols from local pollution and biomass burning. “However, the reversal of wind direction has likely occurred, bringing dust from the ocean to the Indian subcontinent,” Jethva said.

The dust hung in the air for days. In Mumbai, the air quality index on January 24 was “severe,” the highest of six categories in the country’s index. According to news reports, an air quality index that high in Mumbai is “unprecedented.” Toward the southeast, the city of Pune saw air quality in the “very poor” category, ranking worse that day than Delhi, where winter air quality is often affected by temperature inversions.n

The dust storm was accompanied by chilly weather. According to news reports, the dust in Mumbai contributed to the lowest daytime January temperature recorded in the city in a decade, reaching just 23.8°C (74.8°F) on January 23. On average, daytime temperatures in January reach 31°C (88°F).