H. Sarkar

Bio: H. Sarkar is an academic researcher from University of Calcutta. The author has contributed to research in topics: Squall & Glycogen. The author has an hindex of 4, co-authored 7 publications receiving 55 citations.

Sharp depletion of atmospheric refractive index associated with Nor’wester over Gangetic West Bengal: a possible method of forecasting Nor’wester

Abstract: The paper presents the nature of the variation of refractive index of atmospheric medium with time and altitude before, during and after the onset of thunderstorms over Gangetic West Bengal during the pre-monsoon period. A critical analysis shows that sharp depletion of the refractive index takes place before the onset of Nor’westers and possible explanations are also offered for the said occurrence.

Seasonal variation of daily total column ozone (TCO) and role of its depletion and formation rate on surface temperature over Dumdum at Kolkata, India

Abstract: The purpose of the paper is to present the variation of total ozone concentration over Dumdum at Kolkata, India during different seasons. It is concluded that the trend of ozone concentration during different seasons are different. A critical analysis is done and following important results are obtained. (i) The total ozone concentration increases during the pre-monsoon and winter periods. During pre-monsoon period rate of formation of ozone increases sharply with the rise of surface temperature. (ii) TCO decreases during the monsoon and post-monsoon periods, throughout the period of study. During monsoon period rate of depletion of ozone increases and during post-monsoon period rate of depletion of ozone decreases with the increase of temperature. (iii) Possible explanations are also presented.

Sharp Depletion of Absolute Humidity associated with Squall over Kolkata (22°34'N, 88°26'E): A Possible Method of Forecasting Squall.

Abstract: The paper presents the nature of the variation of absolute humidity of the atmospheric medium with time before, during, and after the onset of squall with thunderstorms, only squall event, squall but no thunderstorm days, and normal days having no squall or thunderstorm over Kolkata, West Bengal, India (22°34′N, 88°26′E) during the pre-monsoon period. A critical analysis shows that a sharp depletion of the atmospheric absolute humidity takes place before the onset of squall occurrences which can be a possible method for forecasting the phenomena. Possible explanations are also offered for the said occurrence.

Sharp depletion of attenuation of 22.235 GHz associated with Nor’wester over Kolkata, India and possible method of forecasting Nor’wester

Abstract: The sharp depletion of attenuation of 22.235 GHz signal before the onset of Nor’wester over Kolkata, India is observed and possible explanation of such type of variation is presented. It is concluded that this may be taken as one possible method of forecasting severe thunderstorm associated with Nor’wester. Physical explanations based on the formation and dissipation mechanisms of thunderstorm are also presented.

Study of atmospheric refractivity prior to squall onset and its strong association with surface temperature and relative humidity over Kolkata (22°34′N, 88°22′E)

Abstract: The paper presents the nature of variation of refractive index of atmospheric medium before the onset of squall over kolkata (22°34′N 88°22′E), India. The variation of the refractive index with surface temperature and relative humidity during squall is also presented. It is concluded that sharp decrease of the refractivity may be taken as a possible method of forecasting squall. This kind of study is very much helpful from the standpoint of aviation hazards and communication. Possible explanation for the observed results is also presented.

East-west coastal asymmetry in the summertime near surface wind speed and its projected change in future climate over the Indian region

Abstract: The behaviors of various meteorological parameters during 1981–2010 are investigated to obtain any asymmetric variability of summertime near surface wind over Indian coastal boundaries. No significant changes were obtained in the trends of surface pressure, surface relative humidity, 2-metre temperature and surface precipitation; although, near surface wind speed is found to have significantly declined on the eastern coast with respect to the western coast during this period. Summertime surface wind speed on the eastern coast have decreased from 3.5 to 2.5 m s − 1 (7 to 5 knots) whereas 4.5 to 4 m s − 1 (9 to 8 knots) during the last three decades (statistical significance level ~ 95%). A decrease in the atmospheric instability may serve as the potential reason for the suppression of severe convective occurrences manifested by a parallel decrease in surface wind speeds over these regions. The local heating up of middle atmosphere (300–500 hPa pressure level) due to increased humidity and the difference in net heat flux over Arabian Sea and Bay of Bengal due to the variance of temperature gradient (1000–925 hPa) along the coastal boundaries might be responsible for this climatic disparity between the coastal regions of India since the last three decades. Summertime near surface wind speed projections for Indian sub-continent based on 7 best climate models, for RCP8.5 scenarios, has been calculated to show a mean increase by ~ 10–15% on the eastern coast (Eastern Ghats), ~ 1–2% on the western coasts (Western Ghats), ~ 1–5% decrease in the Indo-Gangetic Basin and ~ 3% decrease in the Gangetic West Bengal and adjoining Bangladesh.