Preprints
https://doi.org/10.5194/egusphere-2023-88
https://doi.org/10.5194/egusphere-2023-88
14 Feb 2023
 | 14 Feb 2023
Status: this preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).

Transported aerosols regulate the pre-monsoon atmosphere over North-East India: a WRF-Chem modelling study

Neeldip Barman and Sharad Gokhale

Abstract. The study differentiates and quantifies the impacts of emissions emitted locally within North-East (NE) India region and those transported from outside this region to ascertain whether local or transported aerosols are more impactful in influencing this region’s atmosphere during the pre-monsoon season (March-April-May). Due to the existence of a declining pre-monsoon rainfall trend in NE India, the study also quantified the role of different aerosol effects w.r.t radiative forcing (RF) and rainfall. The study has been carried out using the WRF-Chem model by comparing simulation scenarios where emissions were turned on and off within and outside the NE region. The impact of all emissions as a whole and Black carbon (BC) specifically was studied. Results show that aerosols transported primarily from the Indo-Gangetic Plain (IGP) were responsible for 93.98 % of the PM10 mass over NE India’s atmosphere and 64.18 % of near-surface PM10 concentration. Transported aerosols contributed >50 % of BC, organic carbon, sulfate, nitrate, ammonium and dust aerosol concentration and hence a major contributor to air pollution. Hence, the aerosol effects were observed to be much greater with transported aerosols. Indirect aerosol effect was found to be the major effect and more impactful with transported aerosols that dominated both rainfall and RF, and suppressed rainfall significantly than the direct and semi-direct effect. However, the increase in direct radiative effects with an increase in transported BC counteracted the rainfall suppression caused by relevant processes of other aerosol effects. Thus, this study shows atmospheric transport to be an important process for this region as transported emissions, specifically from IGP were also found to have greater control over the region’s rainfall. Thus, emission control policies implemented in IGP will reduce air pollution as well as the climatic impacts of aerosols over the NE India region.

Neeldip Barman and Sharad Gokhale

Status: open (until 07 Apr 2023)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-88', Anonymous Referee #1, 19 Feb 2023 reply
    • AC1: 'Reply on RC1', Sharad Gokhale, 24 Feb 2023 reply

Neeldip Barman and Sharad Gokhale

Neeldip Barman and Sharad Gokhale

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Short summary
The study shows that during the pre-monsoon season transported aerosols, especially from Indo-Gangetic Plains (IGP) has a greater impact w.r.t air pollution, radiative forcing and rainfall over North-East (NE) India than emissions from within NE India itself. Hence, controlling emissions in the IGP will be significantly more fruitful in reducing pollution as well as climatic impacts over this region.