Mr. Vishnu R. Profile

Vishnu R.

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Author

Publications (4)

Proceedings Article | 5 May 2016 Paper

Retrieval of mixed layer height (MLH) from lidar using analytical methods and estimation of MLH growth rates over a tropical site Gadanki

Vishnu R., Bhavani Kumar Y., P. R. Sinha, Narayana Rao T., James Jebaseelan Samuel E.

Proceedings Volume 9879, 98790U (2016) https://doi.org/10.1117/12.2223304

KEYWORDS: LIDAR, Testing and analysis, Wavelets, Atmospheric particles, Aerosols, Analytical research, Laser development, Neodymium, YAG lasers, Atmospheric sensing, Interference (communication), Backscatter, Signal to noise ratio, Signal detection, Signal processing

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Proceedings Article | 5 May 2016 Paper

Measurements of long range transport using two wavelength and polarization lidar over tropical rural site Gadanki (13.450 N, 79.170 E)

Vishnu R., Y. Bhavani Kumar, E. James Jebaseelan Samuel

Proceedings Volume 9879, 98790Z (2016) https://doi.org/10.1117/12.2223686

KEYWORDS: LIDAR, Aerosols, Polarization, Backscatter, Atmospheric particles, Nd:YAG lasers, Mirrors, Atmospheric monitoring, Clouds, Telescopes, Particles, Signal detection, MODIS, Mass attenuation coefficient

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Proceedings Article | 5 May 2016 Paper

Development of lidar sensor for cloud-based measurements during convective conditions

R. Vishnu, Y. Bhavani Kumar, T. Narayana Rao, Anish Kumar Nair, A. Jayaraman

Proceedings Volume 9876, 987619 (2016) https://doi.org/10.1117/12.2223674

KEYWORDS: LIDAR, Clouds, Atmospheric laser remote sensing, Convection, Aerosols, Backscatter, Atmospheric sensing, Sensors, Remote sensing, Atmospheric particles

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Proceedings Article | 5 May 2016 Paper

Lidar measurements of aerosol at Varanasi (25.28 N, 82.96 E), India during CAIPEEX scientific campaign

R. Vishnu, Y. Bhavani Kumar, Y. Jaya Rao, E. James Samuel, P. Thara, A. Jayaraman

Proceedings Volume 9876, 98761Y (2016) https://doi.org/10.1117/12.2223308

KEYWORDS: LIDAR, Aerosols, Remote sensing, Polarization, Receivers, Atmospheric laser remote sensing, Clouds, Satellites, Atmospheric modeling, Atmospheric particles, Backscatter, MODIS, Telescopes, Transmitters

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A compact dual polarization lidar (DPL) was designed and developed at National Atmospheric Research Laboratory (NARL) for daytime measurements of the boundary layer aerosol distribution and depolarization properties with very high vertical and temporal resolution. The lidar employs a compact flashlamp pumped Q-switched Nd:YAG laser and operates at 532 nm wavelength. The lidar system uses a stable biaxial configuration between transmitter and receiver units. The receiver utilizes a 150 mm Schmidt Cassegranin telescope for collecting laser returns from the atmosphere. The collected backscattered light is separated into co and cross-polarization signals using a polarization beam splitter cube. A set of mini-PMTs have been used for detection of light from atmosphere during daylight period. A two channel transient recorder system with built-in ADC has been employed for recording the detected light. The entire lidar system is housed in a compact cabinet which can be easily transported for field measurements. During 2014, the lidar system was installed at the Banaras Hindu University (BHU) campus, Varanasi (25.28° N, 82.96° E, 82 m AMSL) and operated for a period of three months in to support the cloud aerosol interaction and precipitation enhancement experiment (CAIPEEX) conducted by Indian Institute of tropical meteorology (IITM). During this campaign period, the lidar measurements were carried out in the vertical direction with spatial resolution of 7.5 m and time sampling of 30s. The lidar measurements revealed the occurrence of boundary layer growth during convective periods and also detected the long-range transport dust layers with significant depolarization. In the present paper, we present the lidar measurements obtained during the campaign period and discuss the observation of transport of dust layer over the experimental site with support of back trajectory analysis and satellite data. The Lidar observations were compared with the available satellite observations also presented here.

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