Prediction of convective events using multi-frequency radiometric observations at Kolkata
TL;DR: In this article, the effectiveness of nowcasting convective activities using a microwave radiometer has been examined for Kolkata (22.65° N, 88.45° E), a tropical location.
About: This article is published in Atmospheric Research.The article was published on 2016-03-01. It has received 26 citations till now. The article focuses on the topics: Nowcasting.
Citations
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TL;DR: In this article, a random forest based machine learning algorithm is tested for nowcasting of convective rain with a ground-based radiometer and the results indicate that the proposed model is very sensitive to the boundary layer instability as indicated by the variable importance measure.
36 citations
TL;DR: In this article, an evaluation of convective cloud forecasts performed with the numerical weather prediction (NWP) model COSMO and extrapolation of cloud fields is presented using observed data derived from the geostationary satellite Meteosat Second Generation (MSG).
27 citations
01 May 2017
TL;DR: In this paper, the authors investigated the behavior of various meteorological parameters during 1981-2010 to obtain any asymmetric variability of summertime near surface wind over Indian coastal boundaries, and found that no significant changes were obtained in the trends of surface pressure, surface relative humidity, 2-metre temperature and surface precipitation.
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.
26 citations
TL;DR: In this article, the authors analyzed thermodynamic indices variation over three sites of eastern Indian region: Bhubaneswar, Kolkata and Ranchi, associated with pre-monsoon thunderstorms for 20-year period (1987-2006) for Bhubaneh and Kolkatha and 15-years (1996-2010) for Ranchi.
Abstract: The present study analyses thermodynamic indices variation over three sites of eastern Indian region: Bhubaneswar, Kolkata and Ranchi, associated with pre-monsoon thunderstorms for 20-year period (1987–2006) for Bhubaneswar and Kolkata and 15 years (1996–2010) for Ranchi. All three sites are showing a rise in humidity over the period, unveiling the climate change over the region. We evaluated the threshold values of various thermodynamic indices for periods of 5-year intervals at each site based on skill score analysis. The indices associated with potential, convective, latent instability and moisture are showing varying threshold values over all the sites, and some of the indices are showing a definite increase/decrease in these threshold values. All three sites are showing a decrease in thunderstorm frequency over the study period. The work identifies the thermodynamic indices, which tend to capture the global warming impact in the threshold values by either showing an increase or decrease with the time at each site. The results advocate that for a long-term analysis of thermodynamic indices, the threshold values may change from one period to another.
23 citations
TL;DR: In this paper, three retrieval techniques have been used to obtain the temperature and relative humidity profiles from brightness temperatures, namely; piecewise linear regression, feed forward neural network and neural back propagation network.
21 citations
References
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01 Aug 2014
TL;DR: In this paper, 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.
Abstract: 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.
19 citations
Proceedings Article•
11 Dec 2009TL;DR: A system of short-term rainfall prediction over Ireland using rainfall radar image processing is presented in this paper and a series of experimental evaluations demonstrate the ability and efficiency of using the rainfall radar imaging in a nowcasting system.
Abstract: As one of the most useful sources of quantitative precipitation measurement, rainfall radar analysis can be a very useful focus for research into developing methods for rainfall prediction. Because radar can estimate rainfall distribution over a wide range, it is thus very attractive for weather prediction over a large area. Short lead time
rainfall prediction is often needed in meteorological and hydrological applications where accurate prediction of rainfall can help with flood relief, with agriculture and with event planning. A system of short-term rainfall prediction over Ireland using rainfall radar image processing is presented in this paper. As the only input, consecutive rainfall radar images are processed to predict the development of rainfall by means of morphological methods and movement extrapolation. The results of a series of experimental evaluations demonstrate the ability and efficiency of using our rainfall radar imaging in a nowcasting system.
17 citations
TL;DR: In this article, a pan-European database of severe weather reports in a homogeneous data format has become available only recently: the European Severe Weather Database (ESWD), demonstrating the large potential of ESWD applications for storm detection and forecast evaluation purposes.
14 citations
TL;DR: In this paper, the seasonal variability of the rate of change of total ozone column TOC and surface relative humidity RH over Dum Dum 22° 38′ N, 88° 26′ E during different seasons of the period 1997-2005 was studied.
Abstract: This article presents a study of the seasonal variability of the rate of change of total ozone column TOC and the rate of change of surface relative humidity RH over Dum Dum 22° 38′ N, 88° 26′ E during different seasons of the period 1997–2005. The rate of formation of TOC was a maximum during the pre-monsoon and winter seasons and the rate of decrease of TOC was a maximum during the monsoon and post-monsoon seasons throughout the period of study. The rate of increase of surface RH was a maximum in the pre-monsoon season and the rate decreased during the other seasons. At the monsoon and post-monsoon seasons the rate of decrease of TOC increased with the rate of decrease of surface RH.
13 citations
01 Jan 2012
TL;DR: In this article, the authors present 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.
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.
13 citations