In:
Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 21, No. 6 ( 2021-04-01), p. 5235-5251
Abstract:
Abstract. We have estimated the spatial changes in NO2 levels over different
regions of India during the COVID-19 lockdown (25 March–3 May 2020) using the satellite-based tropospheric column NO2 observed by
the Ozone Monitoring Instrument (OMI) and the Tropospheric Monitoring
Instrument (TROPOMI), as well as surface NO2 concentrations obtained
from the Central Pollution Control Board (CPCB) monitoring network. A
substantial reduction in NO2 levels was observed across India during
the lockdown compared to the same period during previous business-as-usual
years, except for some regions that were influenced by anomalous fires in
2020. The reduction (negative change) over the urban agglomerations was
substantial (∼ 20 %–40 %) and directly proportional to the
urban size and population density. Rural regions across India also
experienced lower NO2 values by ∼ 15 %–25 %. Localised
enhancements in NO2 associated with isolated emission increase
scattered across India were also detected. Observed percentage changes in
satellite and surface observations were consistent across most regions and
cities, but the surface observations were subject to larger variability
depending on their proximity to the local emission sources. Observations
also indicate NO2 enhancements of up to ∼ 25 % during
the lockdown associated with fire emissions over the north-east of India
and some parts of the central regions. In addition, the cities located near the
large fire emission sources show much smaller NO2 reduction than other
urban areas as the decrease at the surface was masked by enhancement in
NO2 due to the transport of the fire emissions.
Type of Medium:
Online Resource
ISSN:
1680-7324
DOI:
10.5194/acp-21-5235-2021
DOI:
10.5194/acp-21-5235-2021-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2021
detail.hit.zdb_id:
2092549-9
detail.hit.zdb_id:
2069847-1
