Browsing by Author "Gupta, Priyanshu"
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Publication An evaluation of long-term gridded datasets of total columnar ozone retrieved from MERRA-2 and AIRS over the Indian region(Springer Science and Business Media Deutschland GmbH, 2023) Gupta, Priyanshu; Payra, Swagata; Bhatla, R.; Verma, SunitaAccurately determining the spatiotemporal variability of ozone on a regional to intercontinental scale is essential for air quality studies. In the present study, a first systematic evaluation and analysis of long-term (2009�2020) gridded datasets (0.5� � 0.625�) of total columnar ozone (TCO) retrieved from Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2TCO) is evaluated for the Indian region. The MERRA-2TCO is first validated with observations (IMDTCO) and then further compared with the Atmospheric Infrared Sounder (AIRSTCO) satellite datasets. For an in-depth comparison and statistical analysis, the dataset has been segregated into seven distinct regions, i.e., Western Himalaya (WH), North East (NE), North Central (NC), North West (NW), West Peninsula India (WPI), East Peninsula India (EPI), and South Peninsula India (SPI). Descriptive statistics (NMSE, FB, R, FA2, and d) reveals a significant correlation of MERRA-2TCO against IMDTCO for Delhi with NMSE (0.0013), FB (? 0.029) and Varanasi NMSE (0.0008), FB (? 0.014). The results of simple linear regression analysis show an increasing TCO trend value of 0.31% and 0.44% per decade in both the cities, respectively. A comparison of MERRA-2TCO with AIRSTCO shows a significant correlation of 0.62�0.87 in different regions of India. Furthermore, in support of Brewer�s circulation pattern, an increasing shift of columnar ozone from low (SPI) to high (WH) latitudinal regions is observed. Our results show that the MERRA-2 ozone dataset can be effectively used for ozone air quality studies over India and this analysis may strengthen the need for independent, high-quality, and consistent ozone measurements with small uncertainties. � 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.Publication Changes in the mechanism of the South-Asian summer monsoon onset propagation induced by the pre-monsoon aerosol dust storm(Elsevier Ltd, 2023) Ghosh, Soumik; Sarkar, Abhijit; Bhatla, R.; Mall, R.K.; Payra, Swagata; Gupta, PriyanshuA modeling effort is considered to understand the effect of dust aerosol storms in the Indian summer monsoon (ISM) onset propagation over the Indian subcontinent. The study found how the dust aerosol loading during the pre-monsoon period over the Indian subcontinent positively impacts the advancing ISM onset. The heavy loading of dust aerosol from middle east Asia to the northwest (NW) Indian region boosts the temperature gradient over the mid-troposphere. This sudden rise in the mid-tropospheric atmospheric temperature triggers the low-pressure belt over the monsoon trough. It amplifies the Elevated Heat Pump mechanism and loads enough dust for the dust storm over north India. The formation of the monsoon trough over the Indo-Gangetic Plain (IGP) pulls the moisture-loaded wind towards the Indian subcontinent and the IGP, followed by the onset of monsoon over Kerala within a week. Due to this storm, the intense heat gradient in the troposphere also induces the monsoon propagation and the monsoon advancement from Kerala to BoB within a short time. However, it makes up for the naturally delayed monsoon on time. Plain language summary: Study shows how the pre-monsoon dust storm modulates the Indian summer monsoon (ISM) propagation over the Indian region. The onset of the monsoon was delayed in a particular year, and the pre-monsoon dust storm over northwest India changed the regular monsoon mechanism and generated an entirely different mechanism. The elevated heat pump theory applies that pushes the monsoon advancement faster than usual. A dust storm over north India causes a sudden rise in the mid-tropospheric temperature gradient and more rapid monsoon advancement than usual. � 2023Publication Changes in tropospheric ozone concentration over Indo-Gangetic Plains: the role of meteorological parameters(Springer, 2022) Payra, Swagata; Gupta, Priyanshu; Sarkar, Abhijit; Bhatla, R.; Verma, SunitaThis study seeks to understand and quantify the changes in tropospheric ozone (O3) in lower troposphere (LT), middle troposphere (MT) and upper middle troposphere (UMT) over the Indo-Gangetic Plains (IGPs), India during the COVID-19 lockdown 2020 with that of pre-lockdown 2019. The gridded datasets of ozone from the European Centre for Medium-range Weather Forecasts (ECMWF) reanalysis product, ERA5 in combination with statistical interpolated (IDWs) surface NO2 observations, present a consistent picture and indicate a significant tropospheric ozone enhancement over IGP during COVID-19 lockdown restrictions in May 2020. The�Paper also examines the influencing role of meteorological parameters on increasing ozone concentration. Over LT, an increase in O3 concentration (23%) is observed and in MT to UMT an enhancement of about 9�18% in O3 concentration have been seen during May 2020 with respect to May 2019. An investigation on causes�of�increasing ozone concentration (35�85�ppbv) from MT to UMT during May 2020 reveals that there was significant rise (by 1�6%) in low cloud cover (LCC). Notably, higher LCC increases the backscattering of upward solar radiation from the top of the�atmosphere. A positive difference of 5�25�W/m2 in upward solar radiation (USR) is observed across the entire study region. The�result suggests that higher LCC significantly contributed to the enhanced USR. Thereby, resulting in higher photolysis rate�that lead to an increase in mid tropospheric ozone concentration during May 2020. The results highlight the importance of LCC as an�important pathway in ozone formation and aid in scientific understanding of it. � 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.Publication Evaluation of MERRA-2 Total columnar ozone from ground based and AIRS satellite product(Institute of Electrical and Electronics Engineers Inc., 2022) Gupta, Priyanshu; Verma, Sunita; Payra, Swagata; Bhatla, R.In the present study, a first systematic evaluation and analysis of long-term (2009-2020) gridded datasets (0. 5� � 0.625) of total columnar ozone (TCO) from Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2TCO) is carried out over the Indian subcontinent. The MERRA-2TCO is first validated with observed (IMDTCO) and then further compared with Atmospheric Infrared Sounder (AIRSTCO) satellite dataset. For an in-depth comparison and statistical analysis, the dataset has been segregated into seven distinct regions, i.e. Western Himalaya (WH), Northeast (NE), North Central (NC), Northwest (NW), West Peninsula India (WPI), East Peninsula India (EPI), and South Peninsula India (SPI). Descriptive statistics (NMSE, FB, R, FA2 and d) reveals significant correlation of MERRA-2TCO with IMDTCO over Delhi (NMSE=0.0013, FB=-0.029) and Varanasi (NMSE=0.0008, FB=-0.014) cities. Further, a comparison of MERRA-2TCO with AIRSTCO represents the NMSE values ranging from 0.0023-0.0047 DU and a correlation coefficient of 0.62-0.87 in different regions of India. In support of Brewer's circulation pattern, an increasing strong shift of columnar ozone from low (SPI) to high (WH) latitudinal regions in annual variation (2009-2020) is observed. Our finding indicate that the MERRA-2 ozone dataset can be effectively used for ozone air quality studies over the Indian regions and the analysis may highlight the necessity for independent, reliable, consistent, and accurate ozone observations. � 2022 International Radio Science Union (URSI).Publication Impact of climate change and water quality degradation on food security and agriculture(Elsevier, 2021) Gupta, Priyanshu; Singh, Janhavi; Verma, Sunita; Chandel, Amit Singh; Bhatla, RajeevThe gradual increase in climate change leads to a serious concern toward food security and agriculture production. Despite considerable progress, around 800 million people are malnourished, 161 million under age of five are considered obese and 2 billion do not receive the essential micronutrients in their healthy life. � 2021 Elsevier Inc. All rights reserved.Publication Impact of covid-19 on the air quality over china and india using long-term (2009-2020) multi-satellite data(AAGR Aerosol and Air Quality Research, 2021) Soni, Manish; Verma, Sunita; Jethava, Hiren; Payra, Swagata; Lamsal, Lok; Gupta, Priyanshu; Singh, JanhaviWe have examined the air quality over China, India and demonstrated marked differences in levels of air pollution resulted from the COVID-19 restrictions during December�April, 2019�20 to that of 11 years mean of 2009�19. The criteria air quality indicators i.e., nitrogen dioxide (NO2), sulphur dioxide (SO2), Aerosol Index (AI) and aerosol optical depth (AOD) data are retrieved from the Ozone Monitoring Instrument (OMI), TROPOspheric Monitoring Instrument (TROPOMI), and MODerate Resolution Imaging Spectroradiometer (MODIS) sensor on the Terra and Aqua satellites, respectively. Over China, during COVID-19 lockdown a significant drop in columnar abundances of tropospheric NO2 (�37%), SO2 (�64%) and AOD (�8%) for 2020 in comparison to 11 years mean (2009�19) has been observed. A noticeable difference in NO2 column burden is seen over SE (�35%), NE (�33%), NW (�13%) and SW (�5%) China. Over the SE and NE China, both NO2 and SO2 levels decreased dramatically in 2020 from that of 2009�19, by more than 40% and 65%, respectively, because of both stricter regulations of emissions and less traffic activity due to reduced social and industrial activities during COVID-19 restrictions. In contrast, the curve of monthly mean tropospheric columnar burden of NO2 and SO2 over India has shown moderate reduction of 16% and 20%, respectively because lockdown came into effect much later in March 2020. The mean NO2 and SO2 over IGP region is found to be 25% higher than whole India�s mean concentration due to large scale urban settlement and crop burning events. The statistical t-test analysis results confirm significant (p < 0.05) improvements in AQ during lockdown. The COVID-19 pandemic provided an unprecedented opportunity to investigate such large-scale reduction in emissions of trace gases and aerosols. Therefore, it is important to further strengthen environmental policies to tackle air quality, human health, and climate change in this part of the world. � The Author(s).Publication Rapid flash flood calamity in Chamoli, Uttarakhand region during Feb 2021: an analysis based on satellite data(Springer Science and Business Media B.V., 2022) Verma, Sunita; Sharma, Ajay; Yadava, Pramod Kumar; Gupta, Priyanshu; Singh, Janhavi; Payra, SwagataThe present study investigates the accelerating factors for extreme flash flood at Chamoli district of Uttarakhand on 7 February 2021. The Sentinel-2A and 2B satellite data have been used to depict changes in pre-flood (16th of January) i.e., 5�years of 2016 to 2021 to post-flood (10 February, 2021) situation over the study domain. Vegetation and snow-cover from 2016 to 2021 has been obtained using Normalized Difference Vegetation Index (NDVI) classification over study area. Normalized Difference Water Index (NDWI) is used to extract the pre and post-flood water pixels for flood inundation mapping. The Cartosat-1 digital elevation model (DEM) product is used for drainage pattern and stream order mapping. Correlation between the meteorological parameters such as snowfall, wind speed and wind direction of Nanda Gunti peak during the time of flood with the flood event is analysed. The overall results indicate heavy snowfall (4.22�mm/day) over Nanda Gunti hills followed by high wind speed (23�km/hr.) that might have led to initiation of avalanche/landslide, giving rise to massive flash flood and eroded approximately 0.0263 km3 volume of landmass along with snow cover. Further, the 5�years NDVI analysis shows decrease in vegetation near Rishiganga and Alaknanda, a higher order river streams, is also crucial factor for flood intensification that caused massive destruction within the study area. The work highlights the importance of mapping of intense events and underline factors to reduce the impact and losses in case of future events. � 2022, The Author(s), under exclusive licence to Springer Nature B.V.Publication Temporal and spatial variability in aerosol optical depth (550 nm) over four major cities of India using data from MODIS onboard the Terra and Aqua satellites(Springer Science and Business Media Deutschland GmbH, 2021) Payra, Swagata; Gupta, Priyanshu; Bhatla, Rajeev; El Amraoui, Laaziz; Verma, SunitaThe paper evaluates long-term (2007�2018) temporal and spatial variations in aerosol optical depth (AOD) over four major cities of India, i.e., Delhi, Kolkata, Chennai, and Jaipur, by using Collection 6, Moderate Resolution Imaging Spectroradiometer (MODIS) Terra and Aqua Level-3, 1��1� gridded dataset. Annual analysis reveals a significant increasing trend from 2007 to 2018 and aerosol loading in the Indo-Gangetic Plain (IGP). Interestingly, in Northern India, i.e., Delhi, AOD values peaked during monsoon season (0.95�1.05), whereas over Kolkata, Eastern India, higher AOD is observed in winter season (0.95�1.05). Chennai, Southern India, reflects low to moderate mean AOD during all the seasons. A prominent increase in AOD percentage from 2007 to 2018 is observed over Kolkata (39%), followed by Delhi (27.34%), Chennai (26.30%), and Jaipur (16.53%). Further, cumulative effects of different meteorological parameters along with 12-year mean AOD reflected a peak in aerosol concentration (0.82 � 0.06) over Delhi, closely followed by Kolkata (0.81 � 0.08) and then Chennai (0.43 � 0.03) and Jaipur (0.43 � 0.03). Results depict a significant increase in AOD due to a wide range of anthropogenic events and call for improved policy programs to tackle the increasing AOD emissions over these megacities in India. � 2021, Saudi Society for Geosciences.
