University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Rain events can be characterized by rain drop size distribution (DSD) that denotes the number of drops as a function of diameter per unit size interval and per unit volume of space. DSD (at ground level) describes the microstructure of precipitation during different phases of rain varying both spatially and temporally. DSD can be influenced by the nature and origin of rain. The present study investigates the role of continental and maritime airflow in influencing the precipitation features near the land-sea boundary. The data of the rain DSD used in the present analysis are collected from a ground-based disdrometer located at Kolkata, India, near land-sea boundary during the year of 2011–2017. The dataset is divided into two categories, namely, maritime and continental rainfall, based on the airflow trajectories associated with rain events exclusively from Bay of Bengal or land region in the west of Kolkata as derived from TRAJSTAT software. The events with trajectories extending both over land and sea region are excluded for the present study. Variations of the DSD parameters using the gamma model are presented showing the abundance of smaller drops during maritime rain events whereas dominance of larger rain drops in the case of the continental rain events. The Z-R relations are also found to be significantly different for these two types of rain. The present study reveals the microstructures of rain at a location where the influences of both land and sea climatic features prevail. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.

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Radio Physics and Electronics

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Theoretical and Applied Climatology

Rain drop size distribution analysis at a tropical location near land-sea boundary

An active phased-array VHF Doppler radar operated at 53 MHz is being established by University of Calcutta, Kolkata, at Ionosphere Field Station (latitude: 22.93 °N, longitude: 88.50 °E), Haringhata of the University near the transition between tropical-to-sub-tropical regions. A Pilot Array is presently operational. When completed, the main radar will be a unique facility to study the lower atmospheric dynamics over the eastern and north-eastern parts of India. Initial results of three components of wind profiles, i.e. zonal wind (u), meridional wind (v), and vertical wind (w) and their validation through balloon-borne GPS Radiosonde measurements made during July 2019 have been presented in this paper. © 2021, Springer Nature Singapore Pte Ltd.

Lecture Notes in Networks and Systems

Lower Atmospheric Wind Profile Studies and Validation of VHF Doppler Radar of University of Calcutta

A fully active phased-array Stratosphere Troposphere (ST) radar at 53 MHz is being established by University of Calcutta at Ionosphere Field Station (22.93 °N, 88.50 °E geographic; magnetic dip: 34 °N), Haringhata, near the northern crest of equatorial ionization anomaly (EIA). When completed, this will be a unique facility at this frequency in the eastern and north-eastern parts of India and also in the south-east Asian longitude sector. Initial results of ionospheric backscatter of irregularities observed at the range of 120–140 km during early evening hours to midnight of the months of May through June 2019 from a Pilot Array are presented in this paper. © 2021, Springer Nature Singapore Pte Ltd.

Summer Night-Time E-Layer Echoes Observed Using University of Calcutta ST Radar

Tropical region experiences a variety of rainfall types throughout the year. The rain can vary from stratiform to convective even within a single event. The rain parameters have been separately investigated for stratiform and convective cases. The rain phases have been classified into stratiform and convective on the basis of bright band signature in the rain rate profile of the micro rain radar. The rain drop size distributions exhibit discernible difference for stratiform and convective cases. The drop size distribution parameters consequently demonstrate distinguishable variations for the two types of rain. © 2015 IEEE.

GENERAL

2015 6th International Conference on Computers and Devices for Communication, CODEC 2015

Rain microphysical features as observed from ground based radar and disdrometer at a tropical location

A priori estimation of delays with error variance of atmospheric radio wave propagation is important for precise position estimation and integrity of the system like Global Positioning System (GPS). Tropospheric effects are less severe than the ionospheric counterpart, but behave in a complex manner, making it difficult to isolate them. In this present paper, a ground based radiometer has been utilized to study the characteristics of tropospheric delay and compared it with the MODIS satellite observations over Kolkata (22.57°N, 88.37°E). Results indicate a good agreement between radiometer and MODIS data except the monsoon months. A climatology of spatial and temporal variation of dry and wet tropospheric delay over the Indian subcontinent have also been estimated using MODIS data and NCEP-NCAR reanalysis data for 2008-2012. The spatial variations of dry delay over Indian region are observed to be in the range of 120-250 cm with limited seasonal variability. However, the wet delay varies from 20 cm in winter months to 45 cm during monsoon period in the coastal and central Indian region. Further analysis reveals that the contribution of wet delays in total delay is significant only along the Indo-Gangetic plain. This indicates that extra precaution is needed in handling tropospheric delay for this region due to fast varying nature of water vapor. © 2015 COSPAR. Published by Elsevier Ltd. All rights reserved.

Advances in Space Research

Study of tropospheric delay over Indian region from MODIS, NCEP/NCAR data and ground based water vapor measurements at Kolkata

Precipitable water vapour (PWV) is an important input for numerical weather prediction model, meteorology and highprecision navigational applications. Conventional methods for the determination of PWV using radiosonde are not sufficient owing to poor temporal resolution, whereas radiometer-derived PWV is reliable only in fair weather conditions. Global positioning system (GPS) is a very useful and cost-effective tool to determine PWV continuously in all weather conditions. The processing of GPS data to extract the PWV information is, however, very complicated due to very small effect of the PWV (~0.5% of total delay) on GPS frequencies than other sources of delay and errors and requires a network of GPS in differential configuration for such purpose. The authors show how the problem can be handled in a standalone dual-frequency GPS receiver in a relatively less complicated manner with reasonable accuracy. The performances of different dry tropospheric delay models are also investigated. The methodology is tested with GPS measurements at Kolkata (22.57°N, 88.37°E) and Bangalore (13.01°N, 77.5°E). The results indicate that the proposed methodology can be implemented for PWV estimation using single GPS receiver with satisfactory performance. © The Institution of Engineering and Technology 2014.

IET Radar, Sonar and Navigation

Simplistic approach for water vapour sensing using a standalone global positioning system receiver

The effects of the convective rain on various atmospheric parameters have been investigated at Kolkata (22.57°N, 88.37°E), India, during pre-monsoon and monsoon period of 2013. Various parameters like cloud base height and depth, liquid water content, rain rate and rain drop size distribution (DSD) are observed concurrently. The atmospheric electric field measured with an electric field monitor and the attenuation and depolarisation of satellite signals measured by a Ku-band receiving system are also studied during rain events. The instability indices obtained from radiometric measurements and the rain height profiles from micro rain radar are used to classify rain into two types, namely, convective and stratiform. The signatures of rain events on multi-technique observations are studied to indicate the various aspects of convective processes at a tropical location. © 2014 IEEE.