TY - JOUR
T1 - Planetary Boundary Layer Height Modulates Aerosol—Water Vapor Interactions During Winter in the Megacity of Delhi
AU - S. Raj, Subha
AU - Krüger, Ovid O.
AU - Sharma, Amit
AU - Panda, Upasana
AU - Pöhlker, Christopher
AU - Walter, David
AU - Förster, Jan David
AU - Singh, Rishi Pal
AU - Swetha, S.
AU - Klimach, Thomas
AU - Darbyshire, Eoghan
AU - Martin, Scot T.
AU - McFiggans, Gordon
AU - Coe, Hugh
AU - Allan, James
AU - Ravikrishna, R.
AU - Soni, Vijay Kumar
AU - Su, Hang
AU - Andreae, Meinrat O.
AU - Pöschl, Ulrich
AU - Pöhlker, Mira L.
AU - Gunthe, Sachin S.
N1 - Funding Information:
SSG gratefully acknowledges funding from Ministry of Earth Sciences (MoES; sanction number MoES/16/20/12-RDEAS, dated March 31, 2014), Government of India, for the purchase of the Cloud Condensation Nuclei Counter (CCNC). This work was supported by partial funding from the Ministry of Earth Sciences (MoES; sanction number MoES/16/04/2 017-APHH (PROMOTE)), Government of India. This work was also partially supported by the UK Natural Environment Research Council and the Newton Fund through the PROMOTE project of the APHH-Delhi programme, grant ref. NE/P016480/1 and NE/P016472/1. All the authors are grateful to the APHH-PROMOTE team for providing logistic and experimental support during the campaign. We thank Alfatech Services, New Delhi, for their generous technical support during the campaign. We thank the Max Planck super computing facility (COBRA) for the support in WRF modeling. SSR was the recipient of a scholarship from the Indo-German Centre for Sustainability through the German Academic Exchange Service under the initiative “A New Passage to India” funded through the Federal Ministry for Education and Research in 2019 and 2020. SSR, MLP and SSG acknowledge this support for conducting in-person and virtual discussions. SSR acknowledges the team at Max Planck Institute for Chemistry for facilitating the research stay and discussions. SSR also acknowledges the Ministry of Human Resources Development, Government of India for a fellowship. We thank three anonymous reviewers for their valuable suggestions, which has further helped to improve our manuscript. The article processing charges for this open-access publication were covered by the Max Planck Society.
Funding Information:
SSG gratefully acknowledges funding from Ministry of Earth Sciences (MoES; sanction number MoES/16/20/12‐RDEAS, dated March 31, 2014), Government of India, for the purchase of the Cloud Condensation Nuclei Counter (CCNC). This work was supported by partial funding from the Ministry of Earth Sciences (MoES; sanction number MoES/16/04/2 017‐APHH (PROMOTE)), Government of India. This work was also partially supported by the UK Natural Environment Research Council and the Newton Fund through the PROMOTE project of the APHH‐Delhi programme, grant ref. NE/P016480/1 and NE/P016472/1. All the authors are grateful to the APHH‐PROMOTE team for providing logistic and experimental support during the campaign. We thank Alfatech Services, New Delhi, for their generous technical support during the campaign. We thank the Max Planck super computing facility (COBRA) for the support in WRF modeling. SSR was the recipient of a scholarship from the Indo‐German Centre for Sustainability through the German Academic Exchange Service under the initiative “A New Passage to India” funded through the Federal Ministry for Education and Research in 2019 and 2020. SSR, MLP and SSG acknowledge this support for conducting in‐person and virtual discussions. SSR acknowledges the team at Max Planck Institute for Chemistry for facilitating the research stay and discussions. SSR also acknowledges the Ministry of Human Resources Development, Government of India for a fellowship. We thank three anonymous reviewers for their valuable suggestions, which has further helped to improve our manuscript. The article processing charges for this open‐access publication were covered by the Max Planck Society. −3 D a D m f org 1 f inorg 1 H BL M BC,e μ −3 MAF S S N CCN S S −3 N CN,10 −3 RH S T S,D a D a S
Publisher Copyright:
© 2021. The Authors.
PY - 2021/12/27
Y1 - 2021/12/27
N2 - The Indo-Gangetic Plain (IGP) is one of the dominant sources of air pollution worldwide. During winter, the variations in planetary boundary layer (PBL) height, driven by a strong radiative thermal inversion, affect the regional air pollution dispersion. To date, measurements of aerosol-water vapor interactions, especially cloud condensation nuclei (CCN) activity, are limited in the Indian subcontinent, causing large uncertainties in radiative forcing estimates of aerosol-cloud interactions. We present the results of a one-month field campaign (February-March 2018) in the megacity, Delhi, a significant polluter in the IGP. We measured the composition of fine particulate matter (PM1) and size-resolved CCN properties over a wide range of water vapor supersaturations. The analysis includes PBL modeling, backward trajectories, receptor models and fire spots to elucidate the influence of PBL and air mass origins on aerosols. The aerosol properties depended strongly on PBL height and a simple power-law fit could parameterize the observed correlations of PM1 mass, aerosol particle number and CCN number with PBL height, indicating PBL induced changes in aerosol accumulation. The low inorganic mass fractions, low aerosol hygroscopicity and high externally mixed weakly CCN-active particles under low PBL height ((Formula presented.) 100 m) indicated the influence of PBL on aerosol aging processes. In contrast, aerosol properties did not depend strongly on air mass origins or wind direction, implying that the observed aerosol and CCN are from local emissions. An error function could parameterize the relationship between CCN number and supersaturation throughout the campaign.
AB - The Indo-Gangetic Plain (IGP) is one of the dominant sources of air pollution worldwide. During winter, the variations in planetary boundary layer (PBL) height, driven by a strong radiative thermal inversion, affect the regional air pollution dispersion. To date, measurements of aerosol-water vapor interactions, especially cloud condensation nuclei (CCN) activity, are limited in the Indian subcontinent, causing large uncertainties in radiative forcing estimates of aerosol-cloud interactions. We present the results of a one-month field campaign (February-March 2018) in the megacity, Delhi, a significant polluter in the IGP. We measured the composition of fine particulate matter (PM1) and size-resolved CCN properties over a wide range of water vapor supersaturations. The analysis includes PBL modeling, backward trajectories, receptor models and fire spots to elucidate the influence of PBL and air mass origins on aerosols. The aerosol properties depended strongly on PBL height and a simple power-law fit could parameterize the observed correlations of PM1 mass, aerosol particle number and CCN number with PBL height, indicating PBL induced changes in aerosol accumulation. The low inorganic mass fractions, low aerosol hygroscopicity and high externally mixed weakly CCN-active particles under low PBL height ((Formula presented.) 100 m) indicated the influence of PBL on aerosol aging processes. In contrast, aerosol properties did not depend strongly on air mass origins or wind direction, implying that the observed aerosol and CCN are from local emissions. An error function could parameterize the relationship between CCN number and supersaturation throughout the campaign.
KW - aerosol
KW - cloud condensation nuclei
KW - megacity
KW - meteorology
KW - New Delhi
KW - planetary boundary layer
UR - http://www.scopus.com/inward/record.url?scp=85121745134&partnerID=8YFLogxK
U2 - 10.1029/2021JD035681
DO - 10.1029/2021JD035681
M3 - Article
AN - SCOPUS:85121745134
SN - 2169-897X
VL - 126
JO - Journal of Geophysical Research: Atmospheres
JF - Journal of Geophysical Research: Atmospheres
IS - 24
M1 - e2021JD035681
ER -