Elevated mixing ratios of surface ozone over the Arabian Sea

Lal, Shyam; Lawrence, M. G.

doi:10.1029/2000gl011828

Cited by 49 publications

(57 citation statements)

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“…Due to this, O 3 was measured from nearly all platforms during the INDOEX IFP and pre-INDOEX campaigns, including at ground stations, onboard the ships, by balloon sondes, and on the aircraft (e.g., Rhoads et al, 1997;Mandal et al, 1999;Naja et al, 1999Naja et al, , 2004Chand et al, 2001Chand et al, , 2003Rao et al, 2001;Peshin et al, 2001;Lal and Lawrence, 2001;de Gouw et al, 2001;Williams et al, 2002;Stehr et al, 2002;Burkert et al, 2003;Ladstätter-Weissenmayer et al, 2007). Since then, data from satellite retrievals (e.g., Fishman et al, 2003;Ladstätter-Weissenmayer et al, 2007) and model simulations (de Laat et al, 2001a;Saraf et al, 2003) focused on analyzing ozone in this region, as well as other cruises in the Indian Ocean (e.g., Lal et al, 2006Lal et al, , 2007, have added to this information base.…”

Section: Gasesmentioning

confidence: 99%

Atmospheric pollutant outflow from southern Asia: a review

2010

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Abstract. Southern Asia, extending from Pakistan and Afghanistan to Indonesia and Papua New Guinea, is one of the most heavily populated regions of the world. Biofuel and biomass burning play a disproportionately large role in the emissions of most key pollutant gases and aerosols there, in contrast to much of the rest of the Northern Hemisphere, where fossil fuel burning and industrial processes tend to dominate. This results in polluted air masses which are enriched in carbon-containing aerosols, carbon monoxide, and hydrocarbons. The outflow and long-distance transport of these polluted air masses is characterized by three distinct seasonal circulation patterns: the winter monsoon, the summer monsoon, and the monsoon transition periods. During winter, the near-surface flow is mostly northeasterly, and the regional pollution forms a thick haze layer in the lower troposphere which spreads out over millions of square km between southern Asia and the Intertropical Convergence Zone (ITCZ), located several degrees south of the equator over the Indian Ocean during this period. During summer, the heavy monsoon rains effectively remove soluble gases and aerosols. Less soluble species, on the other hand, are lifted to the upper troposphere in deep convective clouds, and are then transported away from the region by strong upper tropospheric winds, particularly towards northern Africa and the Mediterranean in the tropical easterly jet. Part of the pollution can reach the tropical tropopause layer, the gateway to the stratosphere. During the monsoon transition periods, the flow across the Indian Ocean is primarily zonal, and strong pollution plumes originating from both southeastern Asia and from Africa spread across the central Indian Ocean. This paper provides a review of the current state of knowledge based on the many observational and modeling studies over the last decades that have examined the southern AsianCorrespondence to: M. G. Lawrence (mark.lawrence@mpic.de) atmospheric pollutant outflow and its large scale effects. An outlook is provided as a guideline for future research, pointing out particularly critical issues such as: resolving discrepancies between top down and bottom up emissions estimates; assessing the processing and aging of the pollutant outflow; developing a better understanding of the observed elevated pollutant layers and their relationship to local sea breeze and large scale monsoon circulations; and determining the impacts of the pollutant outflow on the Asian monsoon meteorology and the regional hydrological cycle, in particular the mountain cryospheric reservoirs and the fresh water supply, which in turn directly impact the lives of over a billion inhabitants of southern Asia.

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Section: Gasesmentioning

confidence: 99%

Atmospheric pollutant outflow from southern Asia: a review

2010

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“…It is established in the previous studies that LRT plays an important role in the AS pre-monsoon ozone pool (Lal and Lawrence, 2001;Chand et al, 2003;Srivastava et al, 2011Srivastava et al, , 2012Lal et al, 2013Lal et al, , 2014. Trajectory models are used to investigate the LRT pathways of the air parcels.…”

Section: Long-range Transport Mechanism and Pollutant Accumulationmentioning

confidence: 99%

“…In previous studies using the ozonesonde measurements above the west coast of India and the data from two campaigns 1999 INDian Ocean EXperiment (INDOEX) campaigns and the Integrated Campaign for Aerosols, Gases and Radiation Budget (ICARB) campaign, which was conducted during March-May 2006), the higher AS TOC during pre-monsoon season was confirmed to be significantly influenced by LRT of the continental anthropogenically influenced outflows from the Middle East, western India, Africa, North America and Europe (Lal and Lawrence, 2001;Chand et al, 2003;Srivastava et al, 2011Srivastava et al, , 2012Lal et al, 2013Lal et al, , 2014. In addition, by comparing the INDOEX ozone measurements from both sides (northern and southern) of the ITCZ (Intertropical Convergence Zone), the influence of the ITCZ functioning as a sink for ozone was determined by the observed 4 times higher TOC values on the northern side of AS compared to the southern side (Chand et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Tropospheric ozone maxima observed over the Arabian Sea during the pre-monsoon

Jia¹,

Ladstätter-Weißenmayer²,

Hou

et al. 2017

Atmos. Chem. Phys.

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Abstract. An enhancement of the tropospheric ozone column (TOC) over Arabian Sea (AS) during the pre-monsoon season is reported in this study. The potential sources of the AS spring ozone pool are investigated by use of multiple data sets (e.g., SCIAMACHY Limb-Nadir-Matching TOC, OMI/MLS TOC, TES TOC, MACC reanalysis data, MOZART-4 model and HYSPLIT model). Three-quarters of the enhanced ozone concentrations are attributed to the 0-8 km height range. The main source of the ozone enhancement is considered to be caused by long-range transport of ozone pollutants from India ( ∼ 50 % contributions to the lowest 4 km, ∼ 20 % contributions to the 4-8 km height range), the Middle East, Africa and Europe (∼ 30 % in total). In addition, the vertical pollution accumulation in the lower troposphere, especially at 4-8 km, was found to be important for the AS spring ozone pool formation. Local photochemistry, on the other hand, plays a negligible role in producing ozone at the 4-8 km height range. In the 0-4 km height range, ozone is quickly removed by wet deposition. The AS spring TOC maxima are influenced by the dynamical variations caused by the sea surface temperature (SST) anomaly during the El Niño period in 2005 and 2010 with a ∼ 5 DU decrease.

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“…Surface level O 3 measurements were made using a Dasibi analyzer, which is based on the absorption of UV radiation at 253.7 nm by O 3 . The details of this analyzer and its calibration are given by Lal and Lawrence [2001]. During the cruise, southwesterly (SW) winds were predominantly transporting cleaner marine air from the southern Indian Ocean over the BOB.…”

Section: Introductionmentioning

confidence: 99%

Changes in surface ozone levels due to convective downdrafts over the Bay of Bengal

Sahu

Lal

2006

Geophysical Research Letters

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[1] Simultaneous measurements of surface level ozone (O 3 ) and meteorological parameters were made over the Bay of Bengal (BOB) during a cruise between 14 September and 12 October 2002. Variations in surface O 3 , equivalent potential temperature (q E ) and associated meteorological parameters clearly show evidence of convective downdrafts during 18-19 September and 25-26 September. Sharp increase in O 3 mixing ratio is coupled with decrease in q E value in the detrained air. The vertical wind velocity and satellite images also indicate significant convective activities during these periods. The maximum changes in O 3 and q E were 26 ppbv and 12 K, respectively. These events comprise of both short and long time scale downdrafts. Citation: Sahu, L. K., and S. Lal (2006), Changes in surface ozone levels due to convective downdrafts over the Bay of Bengal, Geophys. Res. Lett., 33, L10807,

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Elevated mixing ratios of surface ozone over the Arabian Sea

Abstract: Implications of these observations are discussed.

Cited by 49 publications

References 13 publications

Atmospheric pollutant outflow from southern Asia: a review

Atmospheric pollutant outflow from southern Asia: a review

Tropospheric ozone maxima observed over the Arabian Sea during the pre-monsoon

Changes in surface ozone levels due to convective downdrafts over the Bay of Bengal

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