Atmospheric Fine and Coarse Mode Aerosols at Different Environments of India and the Bay of Bengal During Winter-2014: Implications of a Coordinated Campaign

In this paper, we present mass concentrations of particulate matter [PM 2.5 , PM 10 size fractions and total suspended particulates (TSP)] measured simultaneously over land stations (Kullu, Patiala, Delhi, Ajmer, Agra, Lucknow, Varanasi, Giridih, Kolkata, Darjeeling, Jorhat, Itanagar, Imphal, Bhubaneswar, and Kadapa), mostly distributed across the Indo-Gangetic plain (IGP) of India as well as in the marine atmosphere over Bay of Bengal (BoB) in the period from 20 January to 3 February, 2014. The main objective of this study was to quantify the continental outflow of particulates (PM 2.5 , PM 10 and TSP) from IGP and associated regions into the BoB along with low level north-east wind flow during winter monsoon period. The present study provides a glimpse of the aerosol loading over the IGP region. During this campaign, the highest average PM 2.5 (187.8 ± 36.5 µg m −3 , range 125.6–256.2 µg m −3 ), PM 10 (272.6 ± 102.9 µg m −3 , range 147.6–520.1 µg m −3 ) and TSP (325.0 ± 71.5 µg m −3 , range 220.4–536.6 µg m −3 ) mass concentrations were recorded at Varanasi, Kolkata and Lucknow over middle and lower IGP regions. The PM 2.5 (average 41.3 ± 11.9 µg m −3 ; range 15.0–54.4 µg m −3 ), PM 10 (average 53.9 ± 18.9 µg m −3 ; range 30.1–82.1 µg m −3 ) and TSP (average 78.8 ± 29.7 µg m −3 ; range 49.1–184.5 µg m −3 ) loading over BoB were found to be comparable to land stations and suggests possible continental outflow. Over the continental region, the highest PM 2.5 /PM 10 ratio was recorded at Delhi (0.87). The PM 2.5 /PM 10 ratio over BoB (0.77) was found to be quite high and comparable to Varanasi (0.80) and Agra (0.79).