Papers in 2021
Propagation of cloud base to higher levels during Covid-19-Lockdown
- Effect of polluted-to-clean conditions on cloud base height with synoptic conditions unaltered.
- Drop in pollutants continuing for a period resulted in upward shift of cloud base.
- Use of ceilometer for cloud base height and assessment of CCN.
- Significant negative correlation between cloud base height and CCN, precursor gases.
On modelling growing menace of household emissions under COVID-19 in Indian metros
- Two largest megacities in India Delhi and Mumbai during the COVID-19 lockdown showed short lived decrease in CO emissions
- The biofuel emissions from residential sector remained unabated and hence the CO concentrations jumped back to the original pre – lockdown levels.
- Elevated CO levels in Delhi are due to strong winds carrying polluted air from the hot spot in central India
- In spite of lockdown, the desired results are not achieved in some pollutants unless significant policy measures are taken on sectorial priority.
Papers in 2020
COVID-19 and environmental -weather markers: Unfolding baseline levels and veracity of linkages in tropical India
- The baseline levels of major criteria pollutants PM2.5 and NO2 have been experimentally achieved.
- This research concludes that people having exposure to higher baseline levels of particulate pollution are at greater risk of dying from COVID-19.
- The baseline levels of PM2.5 play a leading role in mortality whereas warmer temperatures show some sign in minimizing the infections.
Towards baseline air pollution under COVID-19: implication for chronic health and policy research for Delhi, India
- Due to the COVID-19 lockdown decline in emission sources of pollutants by ~85%–90% was observed in Delhi, resulting in sharp decline in the concentration of majority of pollutants.
- The baseline level that is defined as the minimum level reached after lockdown under consistent fair weather condition of major criteria pollutants is estimated.
Particulate Matter and Black Carbon in the Brahmaputra Valley of Northeast India: Observations and Model Simulation
- PM2.5, PM10 and BC was analyzed at Tezpur located in Brahmaputra valley and it indicated it has low local emissions, but susceptible to long range transport.
- High PM concentration is observed in winter season due to local atmospheric conditions and transport from west Asian deserts.
- Tezpur is comparatively cleaner than other north-east stations owing to its proximity to Kaziranga National Forest which aids in blocking the flow and deposition of aerosols.
- PM10 simulation by WRF-Chem is underestimated during pre-monsoon and winter season due to the low RH simulated by the model.
Impact of mixing layer height on air quality in winter
- The effect of MLH on PM2.5 and other gaseous pollutants was assessed during winter time at Delhi.
- PM2.5 and NOx varied inversely with MLH while Ozone showed positive correlation.
- Gases correlated better with MLH as compared to PM2.5 which might be indicating the ease of dispersion by the nature of respective components
- Delhi’s pollution is governed by meteorology to a large extent and hence the control measures will be more effective taking into account the meteorological conditions as well.
Characteristics and Variability of Carbonaceous Aerosols over a Semi Urban Location in Garhwal Himalayas
- The measurements of carbonaceous aerosols at a central Himalayan semi urban location have been carried out.
- Elemental carbon and Organic carbon concentration is found to be highest during post monsoon followed by premonsoon seasons attributed to biomass burning and local anthropogenic activities.
- OC/EC ratio indicates local production of pollutants dominates over long range transport over this region.
- Boundary layer dynamics plays significant role in trapping pollutants over the region
COVID-19 lockdown and air quality of SAFAR-India metro cities
- Ambient concentrations of PM2.5, PM10 and NO2 were examined in four megacities including Delhi, Ahmedabad, Mumbai and Pune of India during COVID-19 lockdown.
- Significant reductions (~60–66%) in NO2 were observed in all cities.
- Highest reduction in PM2.5 and PM10 were noticed in Delhi and Ahmedabad as against Mumbai and Pune.
- The low ratio of PM2.5/PM10 in Delhi and Ahmedabad suggests influence of wind-blown dust while relatively high ratio in Mumbai and Pune suggests dominance of secondary particles.