Variability in air-pollutants, aerosols, and associated meteorology over peninsular India and neighboring ocean regions during COVID-19 lockdown to unlock phases

Comparing the atmospheric and ocean characteristics associated with two distinctly intensified pre‐monsoon tropical cyclones over the Bay of Bengal

“…The pre‐cyclone periods chosen for Amphan and Fani are March 25–May 15 and March 25–April 25, respectively. The date, March 25, is considered as the starting date of the pre‐cyclone period because the government of India and neighboring country Bangladesh imposed a nationwide lockdown from March 25 and March 26, 2020, respectively (Sarkar et al, 2021; Shammi et al, 2020). This can help in understanding more about the possible consequence of strict lockdown measures in 2020 on the intensification process of Amphan.…”

“…This can help in understanding more about the possible consequence of strict lockdown measures in 2020 on the intensification process of Amphan. Black dots are included in Figure 10 to represent the regions where the anomalies are beyond the interannual variation (i.e., the standard deviation of the climatological dataset), that is, the anomalies over these points can be considered significant (Sarkar et al, 2021).…”

“…In 2020, the strict measures imposed during the lockdown period (primarily during April–May) caused a significant decline in anthropogenic emissions over South Asia (Jain & Sharma, 2020; Kanniah et al, 2020; Lokhandwala & Gautam, 2020; Navinya et al, 2020; Sarkar et al, 2021; Tyagi et al, 2021). The decline in aerosol loading (∼ −0.1) is also reflected over the northern BOB (Figure 10a) since most of the nearby anthropogenic sources were completely shut down during the pandemic.…”

“…Due to emissions from industrial and transportation sectors, burning of agricultural waste, and coal‐fired power plants, anthropogenic aerosols mainly dominate in the eastern Indo‐Gangetic Plain (IGP) and nearby land areas (Gogoi et al, 2020; Sarkar et al, 2021). These pollutants can be further transported to the northern BOB by the prevailing winds during the pre‐monsoon season.…”

“…Besides, the northern BOB is heavily influenced by the continental outflow of fine‐mode anthropogenic aerosols transported from northeastern India, Bangladesh, and southeastern Myanmar (Babu et al, 2008; Kalapureddy & Devara, 2008; Nair et al, 2014; Tiwari et al, 2016). Values of the Aerosol Optical Depth (AOD) can reach as high as 0.8–1 near the head of the BOB (Sarin et al, 2021; Sarkar et al, 2021), indicating an extremely hazy condition. However, aerosol loading decreases (sometimes even up to above 50%) toward the southern BOB because of the lower contribution from anthropogenic sources there (Nair et al, 2009; Sarin et al, 2021).…”