Kandula Subrahmanyam

• M.Sc., Ph.D
• Scientist at National Remote Sensing Centre

Plain Language Summary Global warming is causing changes in the weather patterns of India during the Indian Summer Monsoon (ISM) period from 2001 to 2020. This change is leading to more extreme precipitation events and variability in rainfall patterns. These changes affect the timing of peak rainfall occurrence and the hydrological cycle in evolvin...

The atmospheric nitrogen dioxides (NO2) play an important role in tropospheric chemistry and climate change. The present study focused on utilizing the space based atmospheric NO2 observations and investigated variability in hotspots of NO2 concentration using Google Earth Engine over Indian regionThe predominant variability in NO2concentrations (~...

The vertical profiles of specific humidity in the troposphere measured by the millimetre-wave humidity sounder (MHS) onboard of the Earth Observation Satellite (EOS)-07 (Microsoft 2B) are validated using ground-based radiosonde observations during July-August 2023. MHS onboard EOS-07 (hereafter referred as EOS-07/MHS) is a 6-channel cross-track sca...

Accurate predictions are vital for various applications, such as weather, climate, energy supply, transportation, and agriculture. The estimates of air temperature have been considered a crucial parameter in climate impact, and its prediction is challenging due to random changes and the non-linear relationship with other meteorological parameters s...

Raindrop size distribution (DSD) plays a significant role in understanding the microphysical process of rainfall and the quantitative precipitation estimation (QPE) in hydrology, especially in urban environments which has spatial and temporal variability. In this study, the seasonal variation in DSD and its response to cloud regimes over two contra...

Weather forecasting is predicting the state of the atmosphere for a given location and time, and it depends on many meteorological parameters, which is a challenging task. In recent years, the use of artificial intelligence (AI) technology has grown leaps and bounds in understating data-driven Earth systems. The main objective of the present paper...

Studies of atmospheric trace gases in remote, pristine environments are critical for assessing the accuracy of climate models and advancing our understanding of natural processes and global changes. We investigated the surface ozone (O3) variability over East Antarctica during the austral summer of 2015–2017 by combining surface and balloon-borne m...

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 rockets during the annular solar eclipse of 26 December 2019. We present the eclipse‐induced changes in the th...

The rainfall spell patterns of the Indian Summer Monsoon (ISM) and their respective intensities have been analyzed in light of changing climate by using climatology of gridded rainfall data during the period 1901–2022. The active and break days over the monsoon core zone are identified for peak monsoon months for each year based on the standard cri...

Processes governing surface ozone variability over east Antarctica

Snow is a major source of water and its monitoring is important for hydrological applications. It provides meltwater to various rivers such as the Indus, Ganges, and Brahmaputra in the Himalayan region. Sig- nificant changes in snowfall variability play a pivotal role in climate. The present study investigates the temporal variability of snowfall,...

Earth Observation Satellite (EOS)‐04 launched on 14 February 2022, carries a C‐band Synthetic Aperture Radar (SAR) for Agriculture, Forestry, Hydrology, and Flood mapping applications. In this paper, we have used C‐band SAR images and near‐simultaneous observations from the global precipitation measurements (GPM) to study the signatures of multiple...

In the present communication, C-band polarimetric Doppler Weather Radar (C-DWR) observations are used to investigate the structure and evolution of organized precipitation bands during the Indian summer monsoon (ISM) of 2017, 2018 and 2019 over Thumba (8.50 N, 770 E), a coastal location in south India. The C-DWR observations show organized high rad...

Clouds have an enormous influence on the Earth's energy balance, climate and weather and key factor of the planet's temperature. The observations of clouds are more important for improving and validating the numerical models of Earth's weather and climate predictions. There has been plethora of studies on the spatial and vertical distribution of cl...

The INSAT-3DR hosts an advanced atmospheric sounder on-board in the geostationary orbit measuring vertical profiles of temperature, water vapor and ozone in the troposphere and stratosphere over the Indian region. The INSAT-3DR provides these observations at very high spatial and temporal resolution, which can be used to infer some of the dynamical...

Recently, the state of Kerala (India) experienced extreme rainfall events during August 2018. These heavy rains led to major flooding, which was one of the worst natural disasters experienced by the state in the last hundred years. The present study focuses on investigating the spatial and vertical structure of precipitating clouds and their microp...

Snow is a major source of water and its monitoring is important for hydrological applications. It provides a large amount of meltwater to various rivers such as Indus, Ganges and Brahmaputra in the Himalayan region. Significant changes in snowfall variability play a pivotal role in climate as well as socioeconomic development. The present study inv...

In the present communication, diurnal evolution of vertical structure of precipitating clouds over the southernmost part (7°–11°N) of the Western Ghats (WG) of Indian region during summer and winter monsoon periods is discussed using 17 years of Tropical Rainfall Measuring Mission (TRMM) precipitation radar measurements. This part of the WG experie...

Tropical cloud clusters (TCC) play a vital role in earth’s climate by not only releasing a large amount of latent heat into the atmosphere but also by forming the basis for development of tropical cyclones (TC). However, not all the TCCs can be developed into cyclones and only a few of them develop into TC, selectively. There are large uncertaintie...

Advance prediction of heavy rainfall days over a given location is of paramount importance as heavy rainfall impacts ecosystems, leads to floods, accounts largely for the total rainfall over the region and its prediction is highly desired for the efficient management of weather-dependent activities. Traditionally, Numerical Weather Prediction model...

Identifying the core of the convective cloud is paramount important to the identification of the Mesoscale Convective System (MCS) and its evolution is of great significance in the weather and climate system. To study the initiation and development of convective core systems, an automatic tracking algorithm named “Convective cell Identification and...

This paper reports, for the “first time,” the delayed response of O¹D 630.0 nm dayglow emissions over Trivandrum (8.5°N, 77°E, 0.5°N dip lat.), a geomagnetic dip equatorial station in India, to the noontime X‐class solar flare event of July 30, 2005. The dayglow measurements were made using a unique dayglow photometer operating at three wavelengths...

Recently, a C-band polarimetric Doppler weather radar (DWR) was installed and commissioned at Thumba (8.5° N, 77° E), a west coastal station in the southern peninsula of India known as ‘Gateway of Indian Summer Monsoon’, for monitoring severe weather events and tropical cyclones. The DWR operates in the frequency range of 5.6 to 5.65 GHz with a pea...

This paper deals with the observations of stratospheric ozone intruding into the troposphere over the Bharati (69.41° S, 76.19° E) station in Antarctica, made during 35th Indian Scientific Expeditions to Antarctica (ISEA-35) during jet stream conditions. High-resolution multiplatform measurements from radiosonde coupled with ozonesonde, Very High-F...

The latent heat (LH) released in�clouds plays a pivotal role in driving atmospheric circulations at various spatial scales ranging from mesos- cale to synoptic scales. In the present communication, using cloud-type distribution derived from CloudSat observations during the years 2006–2010 and vertical structure of LH derived from Tropical Rain Meas...

Recently, a C-band dual-polarization Doppler weather radar (C-DWR) was installed at Thumba (8.537°N, 76.865°E), a coastal station in the southern peninsula of India known as “Gateway of Indian Summer Monsoon.” The C-DWR operates in the frequency range of 5.6 to 5.65 GHz with a peak transmitting power of 250 kW at 0.004 duty ratio and employs the st...

Recently, a C-band dual-polarization Doppler weather radar (C-DWR) was installed at Thumba (8.537°N, 76.865°E), a coastal station in the southern peninsula of India known as “Gateway of Indian Summer Monsoon.” The C-DWR operates in the frequency range of 5.6 to 5.65 GHz with a peak transmitting power of 250 kW at 0.004 duty ratio and employs the st...

Climatology of lunar semidiurnal (LSD) oscillations is constructed using a decade of meteor radar observations over low and equatorial latitudes, and their response to sudden stratospheric warming (SSW) events is discussed. Meteor radar‐measured hourly zonal and meridional winds in the 80–100 km region over Thumba (8.5°N, 76.9°E) and Kototabang (0....

In the present communication, characteristics of mean winds and planetary waves in the mesosphere lower thermosphere (MLT) region during sudden stratospheric warming (SSW) events using observations from four meteor wind radars located at high, middle, low and equatorial latitudes are discussed. The response of the respective MLT regions to three SS...

Abstract. Extreme precipitation events have been cynosure for many meteorologists as well as for common men as it causes severe weather hazards and affects the densely populated regions, especially urban cities. It is now well known that these extreme events have been increasing over the Indian region during the past few years. It becomes very impo...

High height resolution GPS sonde measurements have been utilized to understand the characteristics of internal inertia gravity waves (IGWs) over a low-latitude station Trivandrum (8.5°N, 76.9°E) during an intensive campaign “Research on OrganisatioN of Atmospheric convection (RONAC), which was initiated to understand the organization of convective...

Atmospheric gravity waves over the Polar Regions are found to have myriad effects on the dynamics and chemistry of the middle atmosphere. Data collected from high vertical resolution radiosonde measurements carried out in campaign mode from the Indian research base in Antarctica, Bharati (69.4°S, 76.2°E) during the austral summer seasons of 2014–20...

Elevated ozone (O3) pollution is observed every spring over the Northern Indian region including the Himalayan foothills, with a maximum typically in the month of May. However, studies investigating influences of photochemistry and dynamics in the valleys of Central Himalaya are limited. Here, in situ surface O3 observations conducted at Dehradun (...

Owing to its importance of role played by multi-layered clouds in climate of earth’s atmosphere, a decadal observation (January, 2000 to December, 2009) from India Meteorological Department, Trivandrum regular radiosonde (00 & 12 UTC) ascents and CloudSat observations were used to study the distribution of multi-layered cloud formation at this loca...

Seasonal variation of raindrop size distribution (DSD) is examined using long-term (2007–2015) observations made with Joss-Waldvogel disdrometer at Thumba (8.53°N, 76.87°E), a tropical coastal station. Data sets were classified based on the rain rate and studied the DSD variations for pre-monsoon (PRE) season, post-monsoon (POST) season and summer...

The characteristics of convective systems over the Indian summer monsoon (ISM) region derived by using a unique combination of four satellites METEOSAT, TRMM, COSMIC and CloudSat comprising of both active and passive remote sensing sensors are discussed for the first time. Six years of observations during ISM brought out the preferential geographic...

The behavior of ionization in the topside ionosphere above F region peak is quite different from the lower ionosphere owing to the diverse processes operational there. This paper presents a comprehensive study on the topside ionosphere and brings out the role of F3 layers as well as increase in solar flux in modulating the topside ionization. Data...

Simultaneous observations of the mesosphere lower thermosphere (MLT) winds in the 80–100 km height region over a low-latitude station Thumba (8.5°N, 77°E) and an equatorial station Kototabang (0.2°S, 100.3°E) during 2006–2012 are used to study the climatology of mean winds and the quasi 2-day waves (QTDW). The 7 year mean annual cycle of the zonal...

The changes in zonal mean circulation and meridional temperature gradient brought about by Sudden Stratospheric Warming (SSW) events in polar middle atmosphere are found to significantly affect the low latitude counterparts. Several studies have revealed the signatures of SSW events in the low latitude Mesosphere- Lower Thermosphere (MLT) region. U...

Five years of CloudSat observations during the Indian summer monsoon (ISM) season are used to investigate the vertical structure of stratocumulus (Sc) clouds and associated dynamics over the western part of Arabian Sea. The amount of Sc clouds formed over these regions are quantified in terms of their frequency of occurrence (FOC) and the same is u...

In spite of technological advancement in predicting and tracking them, devastation caused by the tropical cyclones is deadliest and intensifying in recent times. Though there is an appreciable advancement in adaptation, the efforts towards mitigation are in their infancy. In our recent paper, we attempted to bring out the anatomy of the tropical cy...

The present study investigates the three-dimensional distribution of various cloud types in tropical cyclones formed in the North Indian Ocean surrounding the Indian subcontinent using CloudSat observations of 25 cyclones occurred during 2006–2014. A composite cloud type distribution of cirrus (Ci), altostratus (As), altocumulus, stratocumulus, cum...

In the present communication, a record breaking duration (23 months) of the eastward phase of the QBO at 20 hPa is reported and details of the tropical wave activity during the recent anomalous QBO event are discussed. Two-dimensional Fourier analysis revealed the presence of 30-40 and 10-15 day westward propagating wave number 1 structures at 40 h...

Detection of multilayered clouds using satellite observations is important for climate-related applications. The present results provide the quantitative information about the percentage of occurrence of one to five-layered clouds across the globe using CloudSat observations. Multilayered clouds occur most frequently in Tropics. Double-layered and...

We investigate the solar flare effects on the D-region of the ionosphere with the help of VLF (Very Low Frequency) radio waves using a portable E-field system from Antarctica during the summer period of 34th Indian scientific expedition. Two GPS time synchronized VLF receivers, one located at Bharati, Antarctica (geographical latitude 69.40⁰S, long...

Hadley circulation (HC) is a planetary scale circulation spanning one-third of the globe from tropics to the sub-tropics. Recent changes in HC width and its temporal variability is a topic of paramount interest because of the climate implications it carry alongside. The present study attempts to bring out the subtropical climate change indications...

We analyzed 17 years (1993–2009) of horizontal winds measured by the medium frequency (MF) radar located at Tirunelveli (8.7 °N, 77.8 °E) and 10 years (2005–2014) of horizontal winds measured by a meteor radar located at Thumba (8.5 °N, 77 °E) to examine the seasonal, inter-annual, and solar cycle variability of the Quasi-Two Day Wave (QTDW) in the...

As a part of the MEGHA-2700 validation after programme, Doppler weather radar (DWR) at Sriharikota (13.66 ° N, 80.23 ° E) is validated with the Chennai (13.07 ° N, 80.28 ° E DWR) (hereafter CHENNAI-DWR) and simultaneous observations along with Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) measurements. Many simultaneous observ...

The present study examines the role of tropical cyclones in the enhancement of tropospheric ozone. The most significant and new observation reported is the increase in the upper-tropospheric (10–16 km) ozone by 20–50 ppbv, which has extended down to the middle (6–10 km) and lower troposphere ( < 6 km). The descent rate of enhanced ozone layer durin...

The latent heat released/absorbed in the Earth’s atmosphere due to phase change of water molecule plays a vital role in various atmospheric processes. It is now well established that the latent released in the clouds is the secondary source of energy for driving the atmosphere, the Sun being the primary. In this context, studies on latent heat rele...

This article discusses different plausible mechanisms to account for the intrusion of dry ozone-rich stratospheric air into the troposphere during the passage of the tropical cyclone Nilam-2012. The present study shows that the overshooting convection associated with Nilam is found to be the prime candidate for the generation of turbulence in the v...

The present study examines the role of tropical cyclones in the enhancement of tropospheric ozone. The most significant and new observation is the increase in the upper tropospheric (10–16 km) ozone by 20–50 ppbv, which has extended down to the middle (6–10 km) and lower troposphere (< 6 km). The descending rate of enhanced ozone layer is found to...

Characteristics of turbulence in the troposphere and lower stratosphere at Trivandrum (8.5°N, 76.9°E) and Gadanki (13.5°N, 79.2°E), two tropical stations located in the Indian Peninsula, are studied using GPS-radiosonde observations during the period of December 2010 to March 2014 as part of the Tropical Tropopause Dynamics (TTD) Experiment under t...

The phase relation between convection and precipitation at diurnal scales is essential for convective parameterization in numerical weather prediction models. For the first time in a meteorological study, we quantified the phase relationship between convective available potential energy (CAPE) and precipitation over the Indian summer monsoon region...

The characteristics of convective systems over Indian summer monsoon (ISM) region derived by using a unique combination of four satellites comprising of both active and passive remote sensing sensors are discussed for the first time. Six years of observations during ISM brought out the preferential geographical regions and time for formation of sha...

The vertical profiles of humidity measured by SAPHIR (Sondeur Atmospherique du Profil d’ Humidité Intropicale par Radiométrie) on-board Megha-Tropiques satellite are validated using Atmosphere Infrared Sounder (AIRS) and ground based radiosonde observations during July–September 2012. SAPHIR provides humidity profiles at six pressure layers viz., 1...

The longest annular solar eclipse of the millennium occurred on 5 January 0 0 and was visible over Thumba around noon time. A host of experiments were carried out to study the eclipse induced changes on various geophysical parameters, right from ground to ionospheric heights. The present study focused on the eclipse induced changes in the horizonta...

The three-dimensional distribution of various cloud types over the Indian summer monsoon (ISM) region using five years (2006–2010) of CloudSat observations during June-July-August-September months is discussed for the first time. As the radiative properties, latent heat released and microphysical properties of clouds differ largely depending on th...

The three-dimensional distribution of various cloud types over the Indian summer monsoon (ISM) region using five years (2006–2010) of CloudSat observations during June-July-August-September months is discussed for the first time. As the radiative properties, latent heat released and microphysical properties of clouds differ largely depending on the...

The annular solar eclipse of 15th January 2010, which was the longest solar eclipse of the millennia, was visible at several parts of South India and China. A host of experiments were carried out at Thumba (8.5° N, 76.9°E) and Gadanki (13.51° N, 79.21° E) in India to study the effect of annular solar eclipse on various atmospheric processes taking...

The annular solar eclipse of 15th January 2010, which was the longest solar eclipse of the millennia, was visible at several parts of South India and China. A host of experiments were carried out at Thumba (8.5° N, 76.9°E) and Gadanki (13.51° N, 79.21° E) in India to study the effect of annular solar eclipse on various atmospheric processes taking...

For the first time, height profiles of meteor trail decay time due to the ambipolar diffusion process are estimated using temperature and pressure measurements by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on-board Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite. The comparison...

Radar echoes from underdense meteor trails have been used to infer the temperature of the 80-100 km region of the atmosphere. Different methods have been used in the past to derive mesospheric temperature values from the meteor decay times and the method of retrieving temperature has gone through several modifications since its inception. The direc...

Owing to the importance of cloud type and their role in driving the mesoscale circulation, a study is carried out to investigate the distribution of various clouds with an emphasis on deep convective (DC) clouds over the Indian monsoon region during 2006- 2010 (five years). It is known that the depending upon the cloud type, the radiative propertie...

Meteor radar measurements of zonal and meridional winds over a low-latitude station, Thumba (8.5N, 77E), during March 2006 to March 2009 are used to study the quasi 2 day wave structure in the mesosphere-lower thermosphere (MLT) region. Emphasis is placed on the study of the day-to-day variations of quasi 2 day waves and their interaction with diur...

The All-Sky interferometric meteor (SKYiMET) radar (MR) derived winds in the vicinity of the equatorial electrojet (EEJ) are discussed. As Thumba (8.5° N, 77° E; dip lat. 0.5° N) is under the EEJ belt, there has been some debate on the reliability of the meteor radar derived winds near the EEJ height region. In this regard, the composite diurnal va...

Using a unique set of satellite based observations of the vertical distribution of ozone during the recent annular solar eclipse of 15 January 2010, we demonstrate for the first time, a complete picture of the response of stratospheric ozone to abrupt changes in solar forcing. The stratospheric ozone decreased after the maximum obscuration of the S...

Measurements of atmospheric temperature pro- files in the troposphere and lower stratosphere were made over Thumba Equatorial Rocket Launching Station (TERLS) (8.5◦ N, 76.9◦ E) during a partial solar eclipse (22 July 2009) and an annular solar eclipse (15 January 2010). It was ob- served that during the partial solar eclipse, the temperature decrea...

Measurements of atmospheric temperature profiles in the troposphere and lower stratosphere were made over Thumba Equatorial Rocket Launching Station (TERLS) (8.5° N, 76.9° E) during a partial solar eclipse (22 July 2009) and an annular solar eclipse (15 January 2010). It was observed that during the partial solar eclipse, the temperature decreased...

This paper presents a detailed review of observational studies conducted in the Mesospheric Lower Thermospheric (MLT) Region over an equatorial station Thumba. The equatorial region being significantly different from mid and high latitudes, the studies on dynamics of this region especially that of mesospheric lower thermospheric region are very cru...