V. Sivakumar

Retrieval of atmospheric boundary layer height by CSIRNLC mobile lidar, pretoria (25.5° S; 28.2° E), South Africa

In this paper, we present the preliminary methods for detection of the boundary layer based on backscattered signals from a mobile LIDAR (LIght Detection And Ranging) developed at Council for Scientific and Industrial Research (CSIR) National Laser Centre (NLC), Pretoria (25.5° S; 28.2° E), South Africa. We have concentrated on two different methods, such as (a) statistical and (b) slope. The preliminary study concludes that the statistical method provides a reasonable temporal evolution of the boundary layer height in comparison with the slope method.

De-noising LiDAR signal using wavelet technique

LiDAR (Light Detection And Ranging) has emerged as one of the most powerful and versatile remote sensing techniques for high resolution atmosphere studies. In most cases, the LiDAR backscattered signal is affected by various noises and extracting the weak signal from the noisy backscatter is a fundamental problem in the LiDAR system. This paper presents a new LiDAR de-noising technique which is based on wavelet transform. The technique is applied to the backscattered signal obtained from low power laser transmission (order of few mJ). Results prove that the technique is effective by retrieving even weak signals.

CSIR-NLC mobile LIDAR — first scientific result

In this paper, we present the obtained first scientific results from CSIR-NLC mobile LIDAR (LIght Detection And Ranging) and its validation/comparison with other ground and space-borne measurements. The LIDAR results are compared using aerosol measurements from the Stratosphere Aerosol Gas Experiment (SAGE) and Optical depth derived from sun-photometer employed under AErosol RObotic NETwork (AERONET).

CSIR-NLC mobile LIDAR for atmosphere remote sensing

A mobile LIDAR (LIght Detection And Ranging) system is being developed and employed for atmosphere remote sensing at the Council for Scientific and Industrial Research (CSIR) National Laser Centre (NLC), Pretoria (25.45 S; 28.16 E), South Africa. In this paper, we describe the results obtained using the CSIR-NLC mobile LIDAR in a 23 hour field campaign at the University of Pretoria.

Rayleigh Lidar investigation of stratospheric sudden warming over a low latitude station, Gadanki (13.5ºN; 79.2ºE): a statistical study

In this paper, we report the statistical characteristics of Stratospheric Sudden Warming (SSW) events observed over a low latitude station, Gadanki; 13.5°N, 79.2°E. The study uses 7 years (1998 to 2004) of quasi-continuous nighttime LiDAR temperature measurements, which corresponds to 312 observations. The statistical characteristics are presented in terms of major or minor, magnitude of warming, height of occurrence and stratopause descent with reference to the mean climatological profile. The warming events are classified into major or minor warming with respect to the observed warm temperature magnitude and reversal in the zonal wind direction in the polar region using National Centre for Environmental Prediction (NCEP) reanalysis data. In total, 14 SSW events observed and have been classified into 2 (14.3 %) major and 12 (85.7 %) minor warming events. The magnitudes of warm temperatures with respect to the mean winter temperature is in the range from 8.2 K to 18.1 K. Occurrence of SSWs are observed to accompany with the descent of stratopause layer from 0 km to 6.3 km with respect to the calculated mean winter stratopause height.