भारतीय उष्णदेशीय मौसम विज्ञान संस्थान
Indian Institute of Tropical Meteorology
पृथ्वी विज्ञान मंत्रालय, भारत सरकार का एक स्वायत्त संस्थान An Autonomous Institute of the Ministry of Earth Sciences, Govt. of India
Radar and Satellite Meteorology
To better understand orographic convection precipitation processes and microphysical processes of cloud and precipitation using radar and satellite remote sensing
To develop spatial distribution of rainfall from radar data sets and to retrieve cloud micro/macro physical parameters using X and Ka-band radar
To utilize satellite remote sensing data for better understanding on aerosol-cloud-precipitation interactions.
The program aims for understanding the water vapour, clouds, precipitation, energy balance and associated thermo-dynamical and feedback processes by using the remote sensing techniques. The remote sensing techniques make use of a sensors that can take the measurement of the objects or areas from a distance without coming into physical contact with the observed objects. Example of remote sensors are radar, lidar, satellite etc.
Radar is an acronym for RAdio Detection And Ranging. IITM has two mobile polarimetric radars operating at X-band (~9.53 GHz) and Ka-band (~35.23 GHz). Both are scanning radars. The polarization capability of radar gives better estimation of rainfall as compared to conventional radar systems. In addition, the shape and size of the hydrometeors can also be estimated.
The Western Ghats (WGs) located parallel to the west coast of India receives a huge amount of rainfall during the Indian summer monsoon (ISM) in which topography plays a huge role in it. To understand the dynamics and microphysics of monsoon precipitating clouds over the WGs, a High Altitude Cloud Physics Laboratory (HACPL) has been setup at Mahabaleshwar (17.92 oN, 73.6 oE, ~1.4 km AMSL) in 2012. The HACPL is a natural laboratory to understand the fundamental properties of clouds, as during the monsoon, the clouds can be at the surface level and can be examined with ground based monitoring system. To supplement HACPL in-situ measurements, the IITM’s, ground based, X- and Ka-band radars are deployed at Mandhardev (18.04 oN, 73.87 oE, ~1.3 km AMSL), hills of the Western Ghats. Both radar operates in volume of plane position indicator (PPI) and range height indicator (RHI) mode and are vital instruments to understand the 3-D cloud structures along with the dynamics and microphysics of monsoon precipitating clouds over the WGs. We also have interest to validate the numerical models by comparing with radar derived products.
The space based remote sensing payloads on satellites can an unique platform for monitoring the Earth’s atmosphere. This group focuses to use satellite data (e.g., A-Train, COSMIC, GPM, INSAT-3D, ISCCP, KALPANA, MODIS, SMMR-SSM/I, VHRR, TRMM, etc) to understand the spatial characteristics of the water vapour, clouds, precipitation, thermodynamics, tropical tropopause and associated dynamics. The dataset provide climatologies of the three-dimensional distribution of clouds and precipitation, their characteristics, their variabilities at various time and spatial scales and impact on atmospheric energetics. Also, utilisation of multi-satellite data for teleconnection studies of polar, mid and tropical varibailities in understanding the large-scale dynamical effects of clouds- and aerosol-precipitation interactions over the Asian domain, in particular, over India.
Established Radar remote sensing facility at Mandhardev (MDV), complex terrain of the Western Ghats (WG). Both radars (X- and Ka-band) with complementary surface meterological observations usually operate during the Monsoon seasons. Till now four years (2012-2016) of radar data has been collected. Apart from routine radar operations, we perform routine Calibrations (Sun calibration, Metal Sphere calibration, corner reflector etc) and Hardware troubleshooting and maintanence of IITM Radars.
Radar facility is being used to supplement the High Altitude Cloud Physics Laboratory (HACPL) observations during the monsoon season. Also supplemented the CAIPEEX-2014 and 2015 Aircraft observations over the WG.
Automatic Weather Station, Tipping bucket rain gauges, Optical Rain Gauge (ORG) and Disdrometer have been installed nearby the X-band coverage area to validate the radar ref-lectivity. This will give a better estimation of rainfall (Quantative Precipitation Estimation) and its spatial distribution.
Documented gridded storm climatology (storm number, storm volume, storm duration, cloud type) from the X-band radar data. Developed an algorithm to identify meteorological and non-meteorological targets from cloud radar observations.
Investigated the statistical properties of clouds over the rain-shadow region which is useful for the diagnostic studies of the rainfall and for the enhancement of precipitation through cloud seeding operations.
Several research papers have been published in refereed international journals using the radar data continues to contribute to improve undertsnading of clouds and precipitation processes.
There are three PhD students and several Master and Bachelor students using the radar data-set for their degree.
Cloud characteristics over the peninsular India during monsoon withdrawal and post withdrawal periods
Cloud characteristics over the rain-shadow region of the north central peninsular India has been studied using C-band radar data for the period 21 September–30 October 2011. The period covers withdrawal and post-withdrawal periods of monsoon 2011. Though the study has been carried out for one season, it has been shown that it is representative of climatic feature over the region. The cloud characteristics have been discussed in the context of large scale dynamical and thermodynamical conditions over the region using NCEP wind data and radiosonde data, respectively. The large scale dynamic and thermodynamical conditions were found favorable for occurrence of widespread and deep convection. The cloud top heights show tri-modal distribution with peaks at 2–3, 4–6 and 8–12 km which are associated with cumulus, congestus and cumulonimbus clouds, respectively. The tops of these three types of the clouds are found to be associated with the stable layers in the atmosphere. The frequency of congestus clouds was the highest. The cloud characteristics over the region differ from other tropical land and oceanic regions in respect of maximum height, mean duration and cumulative frequency distribution. Distribution of cloud top height and duration show deviation from lognormality in the lower ends. It indicates that the cloud growth mechanism is different than that observed over other tropical land and oceanic regions and also due to the large wind shear prevailed over the region. During the period, a large number of suitable clouds were found available for hygroscopic and glaciogenic cloud seeding.[Morwal S.B., Narkhedkar S.G., Padmakumari B., Maheskumar R.S., Kothawale D.R., Dani K.K., Burger R., Bruintjes R.T., Kulkarni J.R., Cloud characteristics over the rain-shadow region of North Central peninsular India during monsoon withdrawal and post-withdrawal periods, Climate Dynamics, 46, January 2016, DOI:10.1007/s00382-015-2595-0, 495-514]
Satellite observed large-scale cloud features over the Indo-Pacific: A manifestation of linkage between SAM and ISMR
Relationship between the Southern Annular Mode (SAM) and the India summer monsoon rainfall (ISMR) has been examined based on the data period 1949–2013. While the entire data period indicates a significant increasing trend in SAM, recent decades 1983–2013 indicate no trend. The relationship between the two strengthened considerably since 1983. Results reveal that the February–March SAM is significantly related with the subsequent ISMR. A positive (negative) SAM during February–March is favorable (unfavorable) for the ensuing summer monsoon rainfall over the Indian sub-continent. The delayed response is relayed through the central Pacific Ocean. We propose a hypothesis that states: when a negative (positive) phase of February–March SAM occurs, it gives rise to an anomalous meridional circulation in a longitudinally locked air–sea coupled system over the central Pacific that persists up to the subsequent boreal summer and propagates from the sub-polar latitudes to the equatorial latitudes inducing a warming (cooling) effect over the central equatorial Pacific region. In turn, this effect concomitantly weakens (strengthens) the monsoon rainfall over the Indian sub-continent. Thus, the February–March SAM could possibly serve as a new precursor to foreshadow the subsequent behavior of the Indian summer monsoon. [Prabhu Amita, Kripalani R.H., Preethi B., Pandithurai G., Potential role of the February–March Southern Annular Mode on the Indian summer monsoon rainfall: a new perspective, Climate Dynamics, 47, August 2016, DOI:10.1007/s00382-015-2894-5, 1161-1179]
Shri M. Mahakur received an Indian Meteorological Society (IMS) award for the best paper published on “Application of Satellite Data in Meteorology and Remote Sensing” at TROPMET-2016. The title of the paper is “High-resolution outgoing longwave radiation dataset from Kalpana-1 satellite during 2004-2012” published in Current Science. The other contributors to this paper are A. Prabhu, A. K. Sharma, V. R. Rao, S. Senroy, R. Singh, and B. N. Goswami.
Shri U. Bhowmik received a first prize for his oral presentation entitled “Analysis of radar and lightning observations of convection over the Western Ghats” authored by U. Bhowmik, S. M. Deshpande and G. Pandithurai in the 1st India Radar Meteorology Conference (iRAD-2017).
Dr. G. Pandithurai elected as a Treasurer, India Radar Meteorological Society formed during the 1st India Radar Meteorology Conference (iRAD-2017).
Dr. Amita Prabhu Awarded with “Postdoctoral Fellowship” at Pukyong National University, Busan, South Korea during Jan.-Dec., 2016.
Radar derived Meoscale Kinematics in terms of divergence profiles
Single Doppler analysis techniques known as velocity azimuth display (VAD) and volume velocity processing (VVP) are used to analyze kinematics of mesoscale flow such as horizontal wind and divergence using X-band Doppler weather radar observations, for selected cases of convective, stratiform, and shallow cloud systems near tropical Indian sites Pune (18.58°N, 73.92°E, above sea level (asl) 560 m) and Mandhardev (18.51°N, 73.85°E, asl 1297 m). The vertical profiles of horizontal wind estimated from radar VVP/VAD methods agree well with GPS radiosonde profiles, with the low-level jet at about 1.5 km during monsoon season well depicted in both. The vertical structure and temporal variability of divergence and reflectivity profiles are indicative of the dynamical and microphysical characteristics of shallow convective, deep convective, and stratiform cloud systems. In shallow convective systems, vertical development of reflectivity profiles is limited below 5 km. In deep convective systems, reflectivity values as large as 55 dBZ were observed above freezing level. The stratiform system shows the presence of a reflectivity bright band (~35 dBZ) near the melting level. The diagnosed vertical profiles of divergence in convective and stratiform systems are distinct. In shallow convective conditions, convergence was seen below 4 km with divergence above. Low-level convergence and upper level divergence are observed in deep convective profiles, while stratiform precipitation has midlevel convergence present between lower level and upper level divergence. The divergence profiles in stratiform precipitation exhibit intense shallow layers of “melting convergence” at 0°C level, near 4.5 km altitude, with a steep gradient on the both sides of the peak. The level of nondivergence in stratiform situations is lower than that in convective situations. These observed vertical structures of divergence are largely indicative of latent heating profiles in the atmosphere, an important ingredient of monsoon dynamics. [Deshpande S.M., Dhangar N., Das Subroto Kumar, Kalapureddy M.C.R., Chakravarty K., Sonbawne S., Konwar M., Mesoscale kinematics derived from X-band Doppler radar observations of convective versus stratiform precipitation and comparison with GPS radiosonde profiles, Journal of Geophysical Research, 120, November 2015, 11536–11551]
Murali Krishna U.V., Das Subrata Kumar, Uma K.N., Jha Abhishek K., Pandithurai G., Dynamical links of convective storms associated with tropospheric biennial oscillation in the Indian monsoon regime, Scientific Reports, 12: 12050, July 2022, DOI:10.1038/s41598-022-15772-9, 1-11 (Impact Factor 4.379)
Jha Ambuj K., Kalapureddy M.C.R., Bhat G.S., Pandithurai G., Characteristics of rain events of different durations at a high‑altitude site in the Western Ghats of India, Meteorology and Atmospheric Physics, 134: 63, June 2022, DOI:10.1007/s00703-022-00902-9, 1-11 (Impact Factor 2.065)
Jha A.K., Das Subrata Kumar, Murali Krishna U.V., Deshpande S.M., Role of thermodynamics and dynamics in the diurnal cycle, propagation, and progression of convective storms in the eastern flank of the Indian monsoon trough, Journal of the Atmospheric Sciences, Online, May 2022, DOI:10.1175/JAS-D-21-0159.1 (Impact Factor 3.184)
Jha Ambuj K., Analysing Seasonal Variations in the Tropical Tropopause and the Impact of Deep Convection on the Tropopause Structure Over a High-Altitude Station in the Western Ghats, Pure and Applied Geophysics, 179, February 2022, DOI:10.1007/s00024-021-02940-7, 845–861 (Impact Factor 2.335)
Sunilkumar K., Das Subrata K., Kalekar P., Kolte Y., MuraliKrishna U. V., Deshpande S., Dani K.K., Nitha T.S., Hosalikar K.S., Narvekar M., Mohan K.N., Pandithurai G., A MESO-scale Rain gauge NETwork-MESONET over Mumbai: Preliminary results and applications, Urban Climate, 41: 101029, January 2022, DOI:10.1016/j.uclim.2021.101029, 1-12 (Impact Factor 5.731)
Jha A.K., Das Subrata Kumar, Deshpande S.M., Murali Krishna U.V., Understanding the relationship of storm- to large-scale environment in the monsoon trough region: results inferred from long-term radar and reanalysis datasets, Quarterly Journal of the Royal Meteorological Society, 148, January 2022, DOI:10.1002/qj.4194, 97-116 (Impact Factor 3.739)
Project: Physics and Dynamics of Tropical Clouds
Project Director: Dr. G. Pandithurai, Scientist-F,
Sub-project: Radar & Satellite Meteorology
Dr. G. Pandithurai Scientist-F & Project Director of Radar & Satellite Meteorology
Atmospheric Aerosol Measurements
Phone No - +91-(0)20-25904251 View profile
Dr. K. Madhuchandra Reddy Scientist-E
Remote sensing in Atmosphere, Cloud & Precipitation studies
Phone No - +91-(0)20-25904482 View profile
Dr. Sachin M. Deshpande Scientist-E
Phone No - +91-(0)20-25904234 View profile
Dr. Kaustav Chakravarty Scientist-E
Doppler Weather Radar Meteorology
Phone No - +91-(0)20-25904481 View profile
Dr. Subrata Kumar Das Scientist-E
Laser Remote Sensing, Radar and Satellite Meteorology techniques
Phone No - +91-(0)20-25904480 View profile