Current Science

Ram Sagar ¹, U. C. Dumka ¹, Manish Naja ¹, Narendra Singh ¹, D. V. Phanikumar ¹

Affiliations
1 Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital 263 002, IN

Abstract

ARIES, acronym for Aryabhatta Research Institute of Observational Sciences, located in the Central Gangetic Himalayan (CGH) region is emerging as one of the unique sites for climate change studies. The long-term, in situ, precise measurements of aerosols and trace gases obtained from this region provide valuable inputs for climate studies. Atmospheric scientists from ARIES are actively involved in nearsurface measurements for meteorology, aerosols and trace gases as well as vertical profiling. The Institute is also providing the observational infrastructure and research support to three major projects of the Indian Space Research Organization, Geosphere Biosphere Programme, which basically deals with the measurement of aerosols, trace gases and boundary-layer experiments. The upcoming stratosphere-troposphere radar and high-power micro-pulse lidar observational facilities will be utilized for the continuous vertical profiling of winds, aerosol and cloud properties at a very fine resolution in time and space. Apart from this, atmospheric scientists of ARIES also have active national and international research collaborations. The important results obtained from these research activities are highlighted and upcoming major observational facilities in the field of atmospheric sciences are discussed. They clearly demonstrate the importance of the unique geographical location of ARIES for climate change studies in the CGH region. These measurements and routine meteorological observations provide the necessary atmospheric corrections to the astrophysical observations taken using optical telescopes located at the site.

Keywords

Aerosols, Air Pollution, Climate Change, Trace Gases, Wind Profiler.

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Manish Naja ¹, Piyush Bhardwaj ¹, Narendra Singh ¹, Phani Kumar ¹, Rajesh Kumar ², N. Ojha ¹, Ram Sagar ³, S. K. Satheesh ⁴, K. Krishna Moorthy ⁵, V. R. Kotamarthi ⁶

Affiliations
1 Aryabhatta Research Institute of Observational Sciences, Nainital 263 002, IN
2 National Center for Atmospheric Research, Boulder, Colorado, US
3 Indian Institute of Astrophysics, Bengaluru 560 034, IN
4 Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bengaluru 560 012, IN
5 Indian Space Research Organization, Head Quarters, Bengaluru 560 231, IN
6 Argonne National Laboratory, Argonne, IL, US

Abstract

An extensive field study, RAWEX-GVAX, was carried out during a 10-month (June 2011-March 2012) campaign at ARIES, Nainital and observations on a wide range of parameters like physical and optical properties of aerosols, meteorological parameters and boundary layer evolution were made. This work presents results obtained from high-frequency (four launches per day), balloon-borne observations of meteorological parameters (pressure, temperature, relative humidity, wind speed and wind direction). These observations show wind speed as high as 84 m/s near the subtropical jet. It is shown that reanalysis wind speeds are in better agreement at 250 hPa (altitude of subtropical jet) than those above or below this value (100 hPa or 500 hPa). These observations also demonstrate that AIRS-derived temperature profiles are negatively biased in the lower altitude region, whereas they are positively biased near the tropopause. WRF simulated results are able to capture variations in temperature, humidity and wind speed profile reasonable well. WRF and AIRS-derived tropopause height, tropopause pressure and tropopause temperature also show agreement with radiosonde estimates.

Keywords

Aerosols, Radiosonde, Subtropical Jet, Tropopause Folding, Vertical Profiling.

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Prajjwal Rawat ¹, Manish Naja ¹, Pradeep K. Thapliyal ², Shuchita Srivastava ³, Piyush Bhardwaj ⁴, Rajesh Kumar ⁴, Samaresh Bhatacharjee ¹, S. Venkatramani ⁵, S. N. Tiwari ⁶, Shyam Lal ⁵

Affiliations
1 Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital 263 002, IN
2 Space Applications Centre, Jodhpur Tekra, Ahmedabad 380 015, IN
3 Indian Institute of Remote Sensing, 4 Kalidas Road, Dehradun 248 001, IN
4 National Center for Atmospheric Research, 3450 Mitchell Lane, Boulder, CO 80301, US
5 Physical Research Laboratory, Navrangpura, Ahmedabad 380 009, IN
6 DDU Gorakhpur University, Gorakhpur 273 009, IN

Abstract

Vertical distribution of ozone has been obtained for the first time using INSAT-3D for the period 2013-2017 over the central Himalaya and validated utilizing balloon-borne observations from a high-altitude site in Nainital (29.4°N, 79.5°E, 1793 m amsl). The INSAT-3D retrieved ozone profiles captured ozone gradient and ozone peak altitude successfully, despite only one IR channel for ozone. This demonstrates the capability of the INSAT-3D Sounder in capturing the observed features, with a smaller bias in the stratosphere and somewhat larger bias in the troposphere. Total ozone column from INSAT-3D showed maximum difference of 8% with ozonesonde-derived total ozone column. Larger ozone bias in the lower troposphere could be attributed to lower reliability of regression coefficient and INSAT-3D channel constraints itself, whereas high variability near the tropopause is possibly due to low ozone, poor temperature retrieval near the tropo-pause and stratosphere–troposphere transport process in the Himalayan region.

Keywords

Ozone Profiles, Ozonesonde, Satellite Data, Vertical Distribution.

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Mukunda M. Gogoi ¹, S. Suresh Babu ¹, B. S. Arun ¹, K. Krishna Moorthy ², A. Ajay ³, P. Ajay ⁴, Arun Suryavanshi ⁵, Arup Borgohain ⁶, Anirban Guha ⁷, Atiba Shaikh ⁸, Binita Pathak ⁴, Biswadip Gharai ⁹, Boopathy Ramasamy ¹⁰, G. Balakrishnaiah ¹¹, Harilal B. Menon ⁸, Jagdish Chandra Kuniyal ¹², Jayabala Krishnan ¹³, K. Rama Gopal ¹¹, M. Maheswari ¹³, Manish Naja ¹⁴, Parminder Kaur ⁷, Pradip K. Bhuyan ⁴, Pratima Gupta ¹⁵, Prayagraj Singh ¹⁶, Priyanka Srivastava ¹⁴, R. S. Singh ¹⁷, Ranjit Kumar ¹⁵, Shantanu Rastogi ¹⁶, Shyam Sundar Kundu ⁶, Sobhan Kumar Kompalli ¹, Subhasmita Panda ¹⁰, Tandule Chakradhar Rao ¹¹, Trupti Das ¹⁰, Yogesh Kant ¹⁸

Affiliations
1 Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram 695 022, IN
2 Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bengaluru 560 012, IN
3 Divecha Centre for Climate Change, Indian Institute of Science, Bengaluru 560 012, IN
4 Centre for Atmospheric Studies, Dibrugarh University, Dibrugarh 786 004, IN
5 Regional Remote Sensing Centre, Indian Space Research Organisation, Nagpur 440 033, IN
6 North Eastern – Space Application Centres, Shillong 793 103, IN
7 Department of Physics, Tripura University, Suryamaninagar, Agartala 799 022, IN
8 Department of Marine Sciences, Goa University, Goa 403 206, IN
9 National Remote Sensing Centre, Indian Space Research Organisation, Hyderabad 500 037, IN
10 Indian Institute of Mineral and Materials Technology, Bhubaneswar 751 013, IN
11 Sri Krishna Devaraya University, Anantapur 515 003, IN
12 G. B. Pant Institute of Himalayan Environment and Development, Kullu 175 126, IN
13 Tamil Nadu Agricultural University, Coimbatore 641 003, IN
14 Aryabhatta Research Institute of Observational Sciences, Nainital 263 002, IN
15 Department of Chemistry, Dayalbagh Educational Institute, Agra 282 005, IN
16 Department of Physics, D.D.U. Gorakhpur University, Gorakhpur 273 009, IN
17 Department of Chemical Engineering, IIT-BHU, Varanasi 221 005, IN
18 Indian Institute of Remote Sensing, Indian Space Research Organisation, Dehradun 248 001, IN

Abstract

In this study, we assess the response of ambient aero-sol black carbon (BC) mass concentrations and spec-tral absorption properties across Indian mainland during the nation-wide lockdown (LD) in connection with the Coronavirus Disease 19 (COVID-19) pan-demic. The LD had brought near to total cut-off of emissions from industrial, traffic (road, railways, ma-rine and air) and energy sectors, though the domestic emissions remained fairly unaltered. This provided a unique opportunity to delineate the impact of fossil fuel combustion sources on atmospheric BC characte-ristics. In this context, the primary data of BC meas-ured at the national network of aerosol observatories (ARFINET) under ISRO-GBP are examined to assess the response to the seizure of emissions over distinct geographic parts of the country. Results indicate that average BC concentrations over the Indian mainland are curbed down significantly (10–40%) from pre-lockdown observations during the first and most in-tense phase of lockdown. This decline is significant with respect to the long-term (2015–2019) averaged (climatological mean) values. The drop in BC is most pronounced over the Indo-Gangetic Plain (>60%) and north-eastern India (>30%) during the second phase of lockdown, while significant reduction is seen during LD1 (16–60%) over central and peninsular Indian as well as Himalayan and sub-Himalayan regions. De-spite such a large reduction, the absolute magnitude of BC remained higher over the IGP and north-eastern sites compared to other parts of India. Notably, the spectral absorption index of aerosols changed very little over most of the locations, indicating the still persisting contribution of fossil-fuel emissions over most of the locations.

Keywords

ARFINET, Black Carbon, COVID-19.

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