M. Venkat Ratnam
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View article: Cloud fraction estimation using random forest classifier on sky images
Cloud fraction estimation using random forest classifier on sky images Open
Cloud fraction (CF) is an integral aspect of weather and radiation forecasting, but real time monitoring of CF is still inaccurate, expensive and exclusive to commercial sky imagers. Traditional cloud segmentation methods, which often rely…
View article: Assessing the accuracy of meteorological transport model ensemble towards estimating Indian carbon fluxes
Assessing the accuracy of meteorological transport model ensemble towards estimating Indian carbon fluxes Open
The climate crisis necessitates urgent action to reduce greenhouse gas (GHG) emissions with a better understanding of their regional carbon sources and sinks. However, considerable uncertainties in current multi-data modeling approaches fo…
View article: Shortwave radiative impacts of the Asian Tropopause Aerosol Layer (ATAL) using balloon-borne in situ measurements at three distinct locations in India
Shortwave radiative impacts of the Asian Tropopause Aerosol Layer (ATAL) using balloon-borne in situ measurements at three distinct locations in India Open
This study aims to investigate the direct shortwave (SW) radiative forcing (RF) and heating rates of the Asian Tropopause Aerosol Layer (ATAL) in the upper troposphere–lower stratosphere (UTLS) using in situ observations from the Balloon m…
View article: Investigating the Effects of the Solar Eclipse on the Atmosphere over Land and Oceanic Regions: Observations from Ground Stations and COSMIC2 Data
Investigating the Effects of the Solar Eclipse on the Atmosphere over Land and Oceanic Regions: Observations from Ground Stations and COSMIC2 Data Open
The impacts of the solar eclipse that occurred on 8 April 2024 over the United States on various atmospheric parameters are investigated. We analyzed surface and vertical profiles of temperature and humidity to understand how this eclipse …
View article: Mesopause Insights: Unraveling Temperature and Height Trends Through SABER/TIMED and SD WACCM X Simulations
Mesopause Insights: Unraveling Temperature and Height Trends Through SABER/TIMED and SD WACCM X Simulations Open
As human activities and climate change continue to affect the middle atmosphere, understanding long‐term changes in atmospheric parameters has become critical. This study uses the data from the SABER/TIMED satellite to analyze global varia…
View article: Cloud Fraction estimation using Random Forest classifier on Sky Images
Cloud Fraction estimation using Random Forest classifier on Sky Images Open
Cloud fraction (CF) is an integral aspect of weather and radiation forecasting, but real time monitoring of CF is still inaccurate, expensive and exclusive to commercial sky imagers. Traditional cloud segmentation methods, which often rely…
View article: Causes of the Abnormally Strong Easterly Phase of the Mesopause Semiannual Oscillation During the March Equinox of 2023 Revealed by a New Reanalysis Data Covering the Entire Middle Atmosphere
Causes of the Abnormally Strong Easterly Phase of the Mesopause Semiannual Oscillation During the March Equinox of 2023 Revealed by a New Reanalysis Data Covering the Entire Middle Atmosphere Open
During the March equinox of 2023, a strong easterly wind of ∼80 m s −1 appeared at an altitude of ∼82 km in the equatorial upper mesosphere, which is regarded as an enhancement of the mesopause semi‐annual oscillation. In this study, a new…
View article: Indian Land Carbon Sink Estimated from Surface and GOSAT Observations
Indian Land Carbon Sink Estimated from Surface and GOSAT Observations Open
The carbon sink over land plays a key role in the mitigation of climate change by removing carbon dioxide (CO2) from the atmosphere. Accurately assessing the land sink capacity across regions should contribute to better future climate proj…
View article: Investigating the role of typhoon-induced waves and stratospheric hydration in the formation of tropopause cirrus clouds observed during the 2017 Asian monsoon
Investigating the role of typhoon-induced waves and stratospheric hydration in the formation of tropopause cirrus clouds observed during the 2017 Asian monsoon Open
We investigate the formation mechanism of a tropopause cirrus cloud layer observed during the Balloon measurement campaigns of the Asian Tropopause Aerosol Layer (BATAL) over Hyderabad (17.47° N, 78.58° E), India, on 23 August 2017. Simult…
View article: Role of QBO and MJO in Sudden Stratospheric Warmings: A Case Study
Role of QBO and MJO in Sudden Stratospheric Warmings: A Case Study Open
The impact of the quasi-biennial oscillation (QBO) and Madden–Julian oscillation (MJO) on the dynamics of major sudden stratospheric warmings (SSWs) observed in the winters of 2018, 2019, and 2021 is investigated. Using data from the MERRA…
View article: Shortwave Radiative Impacts of the Asian Tropopause Aerosol Layer (ATAL) using Balloon-borne In-situ measurements at three distinct locations in India
Shortwave Radiative Impacts of the Asian Tropopause Aerosol Layer (ATAL) using Balloon-borne In-situ measurements at three distinct locations in India Open
The recurring presence of the Asian Tropopause Aerosol Layer (ATAL) in the Upper Troposphere Lower Stratosphere (UTLS) region, strongly linked with the Asian Summer Monsoon Anticyclone (ASMA), has garnered significant attention over the pa…
View article: On the Abnormally Strong Westward Phase of the Mesospheric Semiannual Oscillation at Low Latitudes During March Equinox 2023
On the Abnormally Strong Westward Phase of the Mesospheric Semiannual Oscillation at Low Latitudes During March Equinox 2023 Open
Different meteor radars at low latitudes observed abnormally strong westward mesospheric winds around the March Equinox of 2023, that is, during the first phase of the Mesospheric Semiannual Oscillation. This event was the strongest of at …
View article: Identification of Convection as a Source for the Gravity Waves Observed in the Upper Mesosphere during Indo-French Campaign on Coupling of Lower and Middle Atmospheres
Identification of Convection as a Source for the Gravity Waves Observed in the Upper Mesosphere during Indo-French Campaign on Coupling of Lower and Middle Atmospheres Open
An Indo-French campaign was conducted during May 2014 at Gadanki (13.5oN, 79.2oE), India, for investigating gravity wave (GW) coupling between the lower and middle atmospheres using a suite of experimental techniques. In this paper we are …
View article: Spatial, temporal features and influence of meteorology on PM2.5 and O3 association across urban and rural environments of India
Spatial, temporal features and influence of meteorology on PM2.5 and O3 association across urban and rural environments of India Open
This study provides an extensive analysis of the spatio-temporal association between particulate matter of 2.5 μm or less (PM2.5) and ground-level Ozone (O3) across four selected urban settlements (Delhi, Bengaluru, Ahmedabad, and Kolkata)…
View article: Seasonal estimates of ozone and secondary organic aerosol formation from volatile organic compounds in a rural atmosphere of India
Seasonal estimates of ozone and secondary organic aerosol formation from volatile organic compounds in a rural atmosphere of India Open
Volatile Organic Compounds (VOCs) serve as precursors for tropospheric ozone (O3) and Secondary Organic Aerosol (SOA) formation. The formation of O3 and SOA are the indicators of the oxidative capacity specific to a given chemical environm…
View article: Source apportionment of black carbon and the impact of COVID-19 lockdown over a semi-urban location in India
Source apportionment of black carbon and the impact of COVID-19 lockdown over a semi-urban location in India Open
To reduce emissions and thereby decrease the effect of black carbon (BC) on human health and the climate, the knowledge of BC concentrations and quantification of its contributions from different sources are necessary for establishing stra…
View article: Comment on egusphere-2023-2236
Comment on egusphere-2023-2236 Open
Abstract. We investigate the formation mechanism of a tropopause cirrus cloud layer observed during the Balloon measurement campaigns of the Asian Tropopause Aerosol Layer (BATAL) over Hyderabad (17.47° N, 78.58° E), India on 23 August 201…
View article: Comment on egusphere-2023-2236
Comment on egusphere-2023-2236 Open
Abstract. We investigate the formation mechanism of a tropopause cirrus cloud layer observed during the Balloon measurement campaigns of the Asian Tropopause Aerosol Layer (BATAL) over Hyderabad (17.47° N, 78.58° E), India on 23 August 201…
View article: Comment on egusphere-2023-2236
Comment on egusphere-2023-2236 Open
Abstract. We investigate the formation mechanism of a tropopause cirrus cloud layer observed during the Balloon measurement campaigns of the Asian Tropopause Aerosol Layer (BATAL) over Hyderabad (17.47° N, 78.58° E), India on 23 August 201…
View article: Investigating the role of typhoon-induced gravity waves and stratospheric hydration in the formation of tropopause cirrus clouds observed during the 2017 Asian monsoon
Investigating the role of typhoon-induced gravity waves and stratospheric hydration in the formation of tropopause cirrus clouds observed during the 2017 Asian monsoon Open
We investigate the formation mechanism of a tropopause cirrus cloud layer observed during the Balloon measurement campaigns of the Asian Tropopause Aerosol Layer (BATAL) over Hyderabad (17.47° N, 78.58° E), India on 23 August 2017. Simulta…
View article: Impact of Annular Solar Eclipse on the Trace Gases and Dynamics of the Lower and Middle Atmosphere: Results Inferred From an Integrated Campaign “<i>Suryagrahan</i>‐2019”
Impact of Annular Solar Eclipse on the Trace Gases and Dynamics of the Lower and Middle Atmosphere: Results Inferred From an Integrated Campaign “<i>Suryagrahan</i>‐2019” Open
An integrated campaign “Suryagrahan‐2019” with multi‐institutional support was conducted by launching a series of radiosondes/ozonesondes over 6‐different locations in India along with the operation of ST/MST radars and launching of RH‐200…
View article: Correction to: Michelson Interferometer for Global High-Resolution Thermospheric Imaging (MIGHTI) On-Orbit Wind Observations: Data Analysis and Instrument Performance
Correction to: Michelson Interferometer for Global High-Resolution Thermospheric Imaging (MIGHTI) On-Orbit Wind Observations: Data Analysis and Instrument Performance Open
This correction stands to correct the original article.The caption for Fig. 27 references 10 km vertical sampling for green, but actually the plot shows results for 5 km vertical sampling.
View article: Intriguing Aspects of Polar-to-Tropical Mesospheric Teleconnections during the 2018 SSW: A Meteor Radar Network Study
Intriguing Aspects of Polar-to-Tropical Mesospheric Teleconnections during the 2018 SSW: A Meteor Radar Network Study Open
Using a network of meteor radar observations, observational evidence of polar-to-tropical mesospheric coupling during the 2018 major sudden stratosphere warming (SSW) event in the northern hemisphere is presented. In the tropical lower mes…
View article: Impact of Hunga Tonga-Hunga Ha’apai Volcanic Eruption on Stratospheric Water Vapour, Temperature, and Ozone
Impact of Hunga Tonga-Hunga Ha’apai Volcanic Eruption on Stratospheric Water Vapour, Temperature, and Ozone Open
Despite being rare, large volcanic eruptions can have a long-lasting impact on the chemistry, radiation, and dynamics of the stratosphere. This study attempts to quantify the changes in the stratospheric water vapour and its relationship t…
View article: Michelson Interferometer for Global High-Resolution Thermospheric Imaging (MIGHTI) On-Orbit Wind Observations: Data Analysis and Instrument Performance
Michelson Interferometer for Global High-Resolution Thermospheric Imaging (MIGHTI) On-Orbit Wind Observations: Data Analysis and Instrument Performance Open
The design, principles of operation, calibration, and data analysis approaches of the Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) on the NASA Ionospheric Connection (ICON) satellite have been document…