Study on Comparison of Indian Ozonesonde Data with Satellite Data

This paper assesses the quality of ozone data of modified Brewer Mast (MBM) balloonborne ozonesonde and its comparison with MOZAIC Data (version 4), TES data (version 6), UARS MLS (version 5), EOS Aura MLS Data (version 5) and SBUV (version 8.1). The stations that have been used for this analysis: Delhi (28.58N, 77.20E) (Ozonesonde, MOZAIC, TES, UARS MLS, AURA MLS and SBUV), Pune (18.53N, 73.85E) Ozonesonde, UARS MLS, AURA MLS, SBUV and MOZAIC over Bombay presently called Mumbai (20.19N, 72.34E)), Madras presently called Chennai (13N, 80.18E) (MOZAIC and MLS) and Trivandrum (8.48N, 76.95E) (Ozonesonde, UARS MLS, AURA MLS and SBUV). Analysis shows that reasonable amounts of ozonesonde data are of good quality according to WMO criteria (1982) as 70–80 % of data over all the three stations are within the normalization factor of 1.3–0.8 ± (0.05–0.1) although some major changes in instrumentation e.g., new fast running nonreactive Teflon pump, modernized electronics, and smaller case since 1971. Several international intercomparisons carried out in 1970, 1982, 1991 and 1996 respectively, has also been confirmed the same, in spite of fundamental differences among the methods of these intercomparisons as well as ozonesonde types on procedure for sonde preparation, data processing and analysis. The intercomparison of Indian ozonesonde data (1995–1999) is made at troposphere with MOZAIC data (1995–2000) over Delhi and Pune/Mumbai, ozonesonde data (2013–2014) also compare with TES (2013–2014) special observation data over particular station Delhi at troposphere and at stratosphere with UARS MLS (1995–1999), EOS Aura MLS (2005–2014) and SBUV (2005–2013) data at Delhi, Pune and Trivandrum. Tropospheric value of Ozonesonde shows on average 10–20 % higher value than MOZAIC value over Delhi and Pune except in the lower height (<800 hPa) but ozonesonde show 10–15 % higher value than TES over Delhi in the lower height (<800 hPa). The percentage difference between ozonesonde data and UARS MLS data at Delhi, Pune and Trivandrum show variation of ±15 % and ozonesonde data, EOS Aura MLS and SBUV data at Delhi, Pune and Trivandrum show variation of ±45 % in the vertical range of 46 to 10 hPa, where, MLS data show highest accuracy.     

Measurements of Particulate (PM2.5), BC and Trace Gases Over the Northwestern Himalayan Region of India

Ambient trace gases (NH₃, NO, NO₂ and SO₂) and black carbon (BC) were measured along with particulate matter (PM_2.5) over the northwestern Himalayan region (Palampur, Kullu, Shimla, Solan and Nahan) of Himachal Pradesh (HP), India in a campaign mode during 12–22 March 2013 to evaluate the ambient air quality of the region. The average mixing ratio of ambient NH₃, NO, NO₂ and SO₂ were recorded as 7.1 ± 2.6, 3.1 ± 1.3, 3.9 ± 1.4 and 1.7 ± 0.7 ppb respectively over the northwestern Himalayan region. The average concentration of BC was estimated as 2.2 ± 0.5 µg m^?3 over the region whereas average concentration of PM_2.5 mass was estimated as 41.8 ± 7.9 µg m^?3. The spatial variation of ambient trace gases (NH₃, NO, NO₂ and SO₂), BC and PM_2.5 over the northwestern Himalayan region, India reveals that the region is mainly influenced by local activities, i.e., tourism activities, agricultural activities, biomass burning and vehicular emission. A significant positive linear correlation of NH₃ and NH₄ ⁺ with SO₄ ^2?, NO₃ ^? and Cl^? (NH₄ ⁺ vs. SO₄ ^2? , r ² = 0.652; NH₄ ⁺ vs. NO₃ ^?, r ² = 0.701; and NH₄ ⁺ vs. Cl^?, r ² = 0.627) of the PM_2.5 indicates the possible formation of (NH₄)₂SO₄, NH₄NO₃ and NH₄Cl aerosols over the region.     

Measurement of Ambient Ammonia over the National Capital Region of Delhi,India

Mixing ratio of ambient ammonia (NH₃) was measured at various locations of the National Capital Region (NCR) of Delhi, India using a NH₃-analyzer during January 2010 to June 2012 in campaign mode. The present study has been carried out on campaign based measurement of mixing ratios of NH₃ and NO _x for short period of time over the NCR of Delhi represent the indicative values over the region. The average mixing ratio of ambient NH₃ was 20.9 ± 1.6 ppb during the period. The maximum average mixing ratio of ambient NH₃ (28.8 ± 3.0 ppb) was recorded in an industrial area surrounded by intensive vehicular traffic followed by an agricultural farm (27.5 ± 2.1 ppb), whereas the minimum (6.4 ± 1.2 ppb) was recorded in the semi-urban area. The diurnal trend of NH₃ depended on the ambient temperature at most of the sites and was affected by wind direction. Ambient NH₃ was correlated with the NO _x mixing ratio suggesting that the vehicular emission may be one of the sources of ambient NH₃ in the NCR of Delhi. However, long-term measurements of ambient NH₃ and their precursors will lead to seasonal variation of source apportionment over the NCR, Delhi, India.     

Measurement of Ambient NH<Subscript>3</Subscript>, NO and NO<Subscript>2</Subscript> at an Urban Area of Kolkata,India

Mixing ratios of ambient NH₃, NO and NO₂ were measured in campaign mode at Kolkata a megacity of Indo-Gangetic plain of India to study the diurnal variation and mixing ratios of NH₃, NO and NO₂ during 24–27 February 2012. The present study has been carried out on campaign based measurement of mixing ratios of NH₃, NO and NO₂ for short period of time at Kolkata represent the indicative values over the region. The average mixing ratios of ambient NH₃, NO and NO₂ were recorded as 43.4 ± 7.0 ppb, 46.0 ± 8.7 ppb and 31.9 ± 5.5 ppb at Kolkata. In the present case, significant diurnal variation of NH₃, NO and NO₂ were recorded at Kolkata during study. Mixing ratio of ambient NH₃ reaches its maxima (78.9 ppb) at night and minimum during daytime. Result reveals that the ambient NH₃ mixing ratio is positively correlated with ambient NO (r ² = 0.395) and NO₂ (r ² = 0.404) mixing ratio and significant negatively correlated with ambient temperature (r ² = –0.669). Surface wind direction and wind speed analysis indicates that the local acitivities (livestock, drainage, agriculture, vehicles etc.,) may be the possible sources of ambient NH₃ at the observational site of Kolkata.     

Atmospheric Fine and Coarse Mode Aerosols at Different Environments of India and the Bay of Bengal During Winter-2014: Implications of a Coordinated Campaign

In this paper, we present mass concentrations of particulate matter [PM_2.5, PM₁₀ size fractions and total suspended particulates (TSP)] measured simultaneously over land stations (Kullu, Patiala, Delhi, Ajmer, Agra, Lucknow, Varanasi, Giridih, Kolkata, Darjeeling, Jorhat, Itanagar, Imphal, Bhubaneswar, and Kadapa), mostly distributed across the Indo-Gangetic plain (IGP) of India as well as in the marine atmosphere over Bay of Bengal (BoB) in the period from 20 January to 3 February, 2014. The main objective of this study was to quantify the continental outflow of particulates (PM_2.5, PM₁₀ and TSP) from IGP and associated regions into the BoB along with low level north-east wind flow during winter monsoon period. The present study provides a glimpse of the aerosol loading over the IGP region. During this campaign, the highest average PM_2.5 (187.8 ± 36.5 µg m^?3, range 125.6–256.2 µg m^?3), PM₁₀ (272.6 ± 102.9 µg m^?3, range 147.6–520.1 µg m^?3) and TSP (325.0 ± 71.5 µg m^?3, range 220.4–536.6 µg m^?3) mass concentrations were recorded at Varanasi, Kolkata and Lucknow over middle and lower IGP regions. The PM_2.5 (average 41.3 ± 11.9 µg m^?3; range 15.0–54.4 µg m^?3), PM₁₀ (average 53.9 ± 18.9 µg m^?3; range 30.1–82.1 µg m^?3) and TSP (average 78.8 ± 29.7 µg m^?3; range 49.1–184.5 µg m^?3) loading over BoB were found to be comparable to land stations and suggests possible continental outflow. Over the continental region, the highest PM_2.5/PM₁₀ ratio was recorded at Delhi (0.87). The PM_2.5/PM₁₀ ratio over BoB (0.77) was found to be quite high and comparable to Varanasi (0.80) and Agra (0.79).