Abstract
Abstract. Total column carbon monoxide (CO) concentration obtained from MOPITT (Measurement Of Pollution In The Troposphere) have been analyzed over the Indian subcontinent for a period of March, 2000 to December, 2010. Average monthly variation of columnar CO is investigated over the eastern and western coasts of India (latitude > 18°N). The columnar CO concentration is found to be larger over the east coast than the west coast. The higher columnar CO concentrations (2.3–2.8 x 1018 molec/cm2) occur during November to April months over both the coastal regions. The lower columnar CO concentrations (1.6–1.7 x 1018 molec/cm2) occur during July-August months over these coastal regions when air blows from the Bay of Bengal towards the east coast and from the Arabian Sea towards the west coast. The latitudinal variations of ten year averaged columnar CO are also investigated over the eastern and western coastlines of India (23.5°N to 8.5°N). The latitudinal gradient is stronger over the eastern coast (3.2 x 1016 molec/cm2/°N) with respect to the western coast (8.6 x 1015 molec/cm2/°N) due to injection of highly polluted air mass from the Indo-Gangetic Plain over the northern part of Bay of Bengal. In order to investigate the source of pollution, variation of columnar CO concentration over the 11 polluted cities situated in the Indo-Gangetic plain has been examined. Columnar CO concentrations are found to be significantly higher over the southeast Indo-Gangetic plain and show a linear decreasing tendency from southeast to northwest cities. The maximum columnar CO concentration is observed over Patna (~ 2.48 x 1018 molec/cm2) and minimum over Multan (~ 2.19 x 1018 molec/cm2). This indicates that south-eastern part of Indo-Gangetic plain is mainly contributing towards enhancement in columnar CO concentration over the eastern coast. Columnar CO concentration showed an increasing trend during 2000 to 2010 over all the 11 cities. This increasing tendency is stronger over the cities situated in the southeast part of Indo-Gangetic plain.
Highlights
Carbon monoxide (CO) is an important trace gas in the atmosphere as it plays a crucial role in atmospheric photochemistry through its reaction with highly reactive hydroxyl radicals (OH)
The maximum columnar carbon monoxide (CO) concentration is observed over Patna (~ 2.48 x 1018 molec/cm2) and minimum over Multan (~ 2.19 x 1018 molec/cm2)
Total column carbon monoxide (CO) concentration obtained from MOPITT instrument onboard the TERRA spacecraft have been analyzed over the east coast of India, west coast of India, and Indo-Gangetic plain for a period of March, 2000 to December, 2010
Summary
Carbon monoxide (CO) is an important trace gas in the atmosphere as it plays a crucial role in atmospheric photochemistry through its reaction with highly reactive hydroxyl radicals (OH). CO is one of the main precursors of secondary pollutant ozone (O3) in NOx rich environment and affects the ambient air quality (Crutzen and Zimmermann, 1991) Though it is not a direct greenhouse gas but it has a global warming potential because of its effects on the lifetimes of several greenhouse gases (Daniel and Solomon, 1998). IGP region is extended from Indus river system in Pakistan to Panjab, Hariyana, Delhi, Uttar Pradesh, Bihar, West Bengal and Bangladesh This is one of the most populated regions in the world having 40 % of total Indian population. The eastern part of IGP contains several coal based thermal power plants and numerous medium and small industries Domestic cooking is another significant contributor for CO emission. The ten year continuous measurements have been used to study the long term trend of CO over the IGP basin
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