Journal Article

PreJuSER-13170

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Seasonality of tropospheric ozone and water vapor over Delhi, India: a study based on MOZAIC measurement data

Sahu, L. K. ; Lal, S. ; Thouret, V. ; Smit, H. G.FZJ*

2009
Springer Science + Business Media B.V Dordrecht [u.a.]

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Please use a persistent id in citations: doi:10.1007/s10874-010-9146-1

Abstract: Tropospheric distributions of ozone (O-3) and water vapor (H2O) have been presented based on the Measurements of OZone and water vapor by Airbus In-Service AirCraft (MOZAIC) data over the metro and capital city of Delhi, India during 1996-2001. The vertical mixing ratios of both O-3 and H2O show strong seasonal variations. The mixing ratios of O-3 were often below 40 ppbv near the surface and higher values were observed in the free troposphere during the seasons of winter and spring. In the free troposphere, the high mixing ratio of O-3 during the seasons of winter and spring are mainly due to the long-range transport of O-3 and its precursors associated with the westerly-northwesterly circulation. In the lower and middle troposphere, the low mixing ratios of similar to 20-30 ppbv observed during the months of July-September are mainly due to prevailing summer monsoon circulation over Indian subcontinent. The summer monsoon circulation, southwest (SW) wind flow, transports the O-3-poor marine air from the Arabian Sea and Indian Ocean. The monthly averages of rainfall and mixing ratio of H2O show opposite seasonal cycles to that of O-3 mixing ratio in the lower and middle troposphere. The change in the transport pattern also causes substantial seasonal variation in the mixing ratio of H2O of 3-27 g/kg in the lower troposphere over Delhi. Except for some small-scale anomalies, the similar annual patterns in the mixing ratios of O-3 and H2O are repeated during the different years of 1996-2001. The case studies based on the profiles of O-3, relative humidity (RH) and temperature show distinct features of vertical distribution over Delhi. The impacts of long range transport of air mass from Africa, the Middle East, Indian Ocean and intrusions of stratospheric O-3 have also been demonstrated using the back trajectory model and remote sensing data for biomass burning and forest fire activities.

Keyword(s): J ; Rain (auto) ; Delhi (auto) ; Transport (auto) ; Marine (auto) ; Troposphere (auto) ; Tropical (auto) ; Ozone (auto) ; Fire (auto)

Note: The authors acknowledge for their strong support the European Commission, Airbus, CNRS-France, FZJ-Germany and the airlines (Lufthansa, Air France, Austrian and former Sabena who carry free of charge the MOZAIC instrumentation since 1994). We are thankful to the Indian Meteorological Department (IMD), Government of India for providing us the rainfall data. We are thankful to Dr. M. Kajino and Japan Meteorological Agency (JMA) for providing potential vorticity data. The ATSR World Fire Atlas data has been taken from Ionia products of European Space Agency.

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Contributing Institute(s):

1. Troposphäre (IEK-8)

Research Program(s):

1. Atmosphäre und Klima (P23)

Appears in the scientific report 2010

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