Abstract
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.
Highlights
Tropospheric ozone is one of the most important greenhouse gases and one of the most important components of photochemical smog
The enhancement of Tropospheric Ozone Column (TOC) is similar in magnitude as TOC enhancements observed during the follow events: (1) the wellknown biomass burning plume in the Southern Hemisphere that was transported over the South Atlantic, the coast of South Africa, along the Indian Ocean and towards Australia (e.g., Fishman et al, 1986, 1991); (2) TOC attributed to anthropogenic sources in the Northern Hemisphere, for instance northern India; and (3) the Mediterranean summer ozone pool attributed to the stratospheric–tropospheric exchange (STE) (Zanis et al, 2014)
This study focuses on the analysis of the regional contribution to longrange transport (LRT), the influence of the meteorological conditions, the local chemistry and STE, and the inter-annual variability in the spring ozone maxima in order to better understand the climate interact with the distribution of tropospheric ozone through temperature, humidity and dynamics
Summary
Tropospheric ozone is one of the most important greenhouse gases and one of the most important components of photochemical smog. In a remote region like AS, an intuitive hypothesis is that longrange transport (LRT) of ozone from more polluted regions or from STE may be the drivers This is because of the longer ozone lifetime in spring and the weak local production over remote areas (Wang et al, 1998). This study focuses on the analysis of the regional contribution to LRT, the influence of the meteorological conditions, the local chemistry and STE, and the inter-annual variability in the spring ozone maxima in order to better understand the climate interact with the distribution of tropospheric ozone through temperature, humidity and dynamics.
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