scholarly journals Development of nowcasting technique and evaluation of convective indices for thunderstorm prediction in Gangetic West Bengal (India) using Doppler Weather Radar and upper air data

MAUSAM ◽  
2021 ◽  
Vol 63 (2) ◽  
pp. 299-318
Author(s):  
DEVENDRA PRADHAN ◽  
U.K. DE ◽  
U.V. SINGH
Keyword(s):  
Lead Time ◽  
West Bengal ◽  
Doppler Radar ◽  
Monsoon Season ◽  
Weather Radar ◽  
Doppler Weather Radar ◽  
Monsoon Period ◽  
Cumulonimbus Cloud ◽  
Very High ◽  
Fair Degree

Thunderstorm and hailstorm are well known short term severe weather phenomena which sometimes turn in to natural hazard especially in Gangetic West Bengal region of India. Large vertical extent of the cumulonimbus cloud, very high reflectivity, squally wind speed sometimes exceeding 100 km/h and heavy rainfall are the main features of these thunderstorms during pre-monsoon period in this region. A study of 70 thunderstorms has been carried out during the pre-monsoon season (March-May) of the year 2005 around Kolkata (22.5° N, 88.5° E) using Doppler Weather Radar and Upper air data. Standard convective indices like CAPE, CINE, LI, BRN and VGP have been evaluated and analyzed statistically. As no definite thresholds of the convective indices are available for thunderstorm prediction in this region, an attempt has been made to find threshold of these indices for possible occurrences of thunderstorms in Gangetic West Bengal region after the analysis of the thunderstorms during year 2005. The validity of these convective indices has been checked with 34 occurrences of thunderstorms during 2006-2007 recorded by Doppler Weather Radar Kolkata. The study reveals that nowcasting of thunderstorms may be done at least 2-3 hrs in advance witha fair degree of accuracy using Doppler radar products only. However, the lead time of nowcasting may be further improved if the convective indices are also analyzed and used in addition to the DWR data. A simple technique has been suggested by the authors for better prediction of thunderstorms at least three to four hours in advance.

scholarly journals Thumb Rule for Nowcast of Dust Storm and Strong Squally Winds over Delhi NCR using DWR Data

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Kuldeep Srivastava
Keyword(s):  
Monsoon Season ◽  
Human Life ◽  
Weather Radar ◽  
Doppler Weather Radar ◽  
National Capital Region ◽  
North West ◽  
Maximum Reflectivity ◽  
Vertical Extension ◽  
Severe Thunderstorms ◽  
Dwr Data

ABSTRACTSqually winds are the natural hazards and are often associated with the severe thunderstorms (TS), which mostly affects plains of North West India during pre monsoon season (March to May). Squally winds of the order more than 60 kmph are very devastating. Under influence of these strong squally winds trees, electricity poles, advertisement sign boards fall, sometimes human life is also lost. The main objective of this study is to find out the thumb rule based on Doppler Weather Radar (DWR) Data to Nowcast the squally winds over a region. To detect thumb rule, five cases of thunder storm accompanied with squally winds ranging from (55 kmph to 110 kmph) are taken in to consideration. These TS’s occurred over Delhi NCR (National Capital Region) during May – June 2018. Maximum reflectivity (Max Z) data of Delhi DWR, Cloud Top Temperature (CTT) data from INSAT and squally winds along with other weather parameters observed at Safdarjung and Palam observatories are utilized to find out the Thumb Rule.Based on the analysis, it is concluded that presence of a western disturbance (WD), presence of East-West trough from North-west Rajasthan upto East UP through south Haryana and very high temperature of the order of 40 degree Celsius over the nearby area are very conducive for occurrence of squally winds accompanied with thunderstorms. Thumb rule find out in this study is that, squally winds of the order of 55 kmph or more will effect a station if a thunderstorm (having Max Z echo with vertical extension of cell >7 km, reflectivity >45 dBz and at a distance of more than 100 km from the station) moving towards station is present in one to two hour before images of Doppler Weather Radar.

Assimilation of Doppler weather radar data and their impacts on the simulation of squall events during pre-monsoon season

2015 ◽  
Vol 77 (2) ◽  
pp. 901-931 ◽  
Author(s):  
Mohan K. Das ◽  
Md. Abdul Mannan Chowdhury ◽  
Someshwar Das ◽  
Sujit K. Debsarma ◽  
Samarendra Karmakar
Keyword(s):  
Monsoon Season ◽  
Weather Radar ◽  
Radar Data ◽  
Doppler Weather Radar

scholarly journals DIAGNOSTIC ANALYSIS OF CATASTROPHIC FLOOD OVER EASTERN INDIA IN JULY 2017 - A CASE STUDY

MAUSAM ◽  
2021 ◽  
Vol 71 (3) ◽  
pp. 513-522
Author(s):  
Sharma R S ◽  
Mandal B K ◽  
Das G K
Keyword(s):  
Heavy Rainfall ◽  
West Bengal ◽  
Monsoon Season ◽  
Geographical Location ◽  
River Basins ◽  
Southwest Monsoon ◽  
Eastern India ◽  
Monsoon Period ◽  
Indian States ◽  
South West Monsoon

Floods are very common in eastern India during southwest monsoon season. It brings a lot of misery to the people of this region. Every year eastern Indian states namely West Bengal, Odisha and Bihar witness such types of flood during monsoon period. Major river basins in eastern India are Ganga river basin in Bihar and West Bengal area, Odisha has three river basins namely Mahanadi, Subarnarekha, Brahmani and Baitarani        [Fig. 1(a)]. As majority of tributary rivers of Ganga passing through Bihar and West Bengal; these two states are more prone to massive flood during monsoon season. The abnormal occurrence of rainfall generally causes floods. It occurs when surface runoff exceeds the capacity of natural drainage. The heavy rainfall is frequently occurring event over the area during South-West Monsoon (SWM) every year. The geographical location of the area, orography and its interaction with the basic monsoon flow is considered as one of prime factors of these heavy rainfall activities. Synoptically, the latitudinal oscillation of eastern end of the Monsoon Trough and the synoptic disturbances formed or passing over the eastern India region and / or its neighbourhood that brings moisture laden Easterly or South-Easterly winds over the area are the main causes responsible for heavy rainfall in this area.

scholarly journals A Study of hailstorm of 19th April 2010 over Delhi using Doppler Weather Radar observations

MAUSAM ◽  
2021 ◽  
Vol 62 (3) ◽  
pp. 433-440
Author(s):  
HARI SINGH ◽  
R. K. DATTA ◽  
SURESH CHAND ◽  
D.P. MISHRA ◽  
B.A.M. KANNAN
Keyword(s):  
India Meteorological Department ◽  
Weather Radar ◽  
Threshold Value ◽  
Radar Data ◽  
Detection Algorithm ◽  
Doppler Weather Radar ◽  
Radar Observations ◽  
Freezing Level ◽  
Function Diagram ◽  
Very High

Hailstorm of 19th April 2010 over Delhi has been studied using observations from Doppler Weather Radar (DWR) installed at Palam. The data was analysed at Central Server located at India Meteorological Department HQ using IRIS software (of M/s SIGMET-VAISALA, Finland) installed in the server. Reflectivity of 45 dBZ level was found to be 6.3 km above freezing level at the time of hailstorm which corresponds to 100% (obtained from probability function diagram of Witt et al. (1998)) probability of hail. Reflectivity was more than 55 dBZ upto 10 km and 7 km at 1110 UTC and 1120 UTC respectively which exceeds the hail threshold limit adopted in NEXRAD (USA). Maximum of 62 dBZ was observed at about 3 km at 1110 UTC and 64 dBZ at 3.5 km at 1120 UTC in Radar Data. Very high values of Vertical Integrated Liquid (VIL) ranging from 58.7 kg/m2 to 64.1 kg/m2 were observed between 1040 UTC and 1120 UTC which is higher than 43 kg/m2, the threshold value for occurrence of hail. Severe Hail Index (SHI), Probability of Severe Hail (POSH) and Maximum Expected Hail Size (MEHS) were computed to verify the applicability of enhancedHail Detection Algorithm (HDA) outlined by Witt et al. (1998) to Indian conditions. The Maximum Expected Hail Size (MEHS) computed using Doppler Weather Radar observations were 2.5 cm, 2.6 cm and 2.0 cm respectively at 1050 UTC, 1100 UTC and 1110 UTC which are in close agreement with the reported hail size. The study confirms that HDA and other thresholds of reflectivity and VIL used for hail detection and warnings in NEXRAD (USA) can be used in Indian conditions also.

scholarly journals Significance of the Coupled Term in the Doppler Weather Radar Spectrum Width Equation

2011 ◽  
Vol 28 (4) ◽  
pp. 539-547 ◽  
Author(s):  
Ming Fang ◽  
Richard J. Doviak ◽  
Bruce A. Albrecht
Keyword(s):  
Wind Shear ◽  
Doppler Radar ◽  
Weather Radar ◽  
Random Variable ◽  
Doppler Weather Radar ◽  
Significant Contributor ◽  
Spectrum Width

Abstract There is an additional zero mean random variable term that couples mean wind shear and turbulence in the Doppler radar spectrum width equation. This random variable, labeled the “coupled term,” has been neglected heretofore in the literature. Herein, the variance of the squared spectrum width ascribed to this coupled term is determined from data collected with a Weather Surveillance Radar-1988 Doppler (WSR-88D) in two snowstorms; it can exceed 1 m4 s−4. Thus, this coupled term can be a significant contributor to the variance of the spectrum width and must be considered when using spectrum width to deduce turbulence.

scholarly journals Early Operational Successes of the University of Louisiana Monroe’s Polarimetric S-band Doppler Radar

2019 ◽  
pp. 105-116
Author(s):  
Todd A. Murphy ◽  
Cynthia Palmer ◽  
Chad Entremont ◽  
James D. Lamb
Keyword(s):  
Real Time ◽  
Doppler Radar ◽  
Weather Radar ◽  
Weather Forecast ◽  
Radar Data ◽  
Doppler Weather Radar ◽  
Low Level ◽  
Coverage Gap ◽  
University Of Louisiana ◽  
The University

In October 2016, the University of Louisiana Monroe (ULM) began operating a polarimetric S-band Doppler weather radar to help close the low-level radar coverage gap across northern Louisiana by increasing the quantity of data sampled below 3.0 km AGL. Data are delivered in near-real time to local National Weather Service (NWS) Weather Forecast Offices to help meteorologists accomplish their mission of protecting life and property. The inclusion of ULM radar data into NWS operations has led to improved detection of severe and hazardous weather across northern Louisiana. This paper details how the ULM radar has been incorporated into NWS operations, the improvement in operational radar coverage, and the challenges of using a non-NWS radar in the NWS operational setting.

scholarly journals Technical a Gaussian Mixture Model to Separate Birds and Insects in Single-Polarization Weather Radar Data

2021 ◽  
Vol 13 (10) ◽  
pp. 1989
Author(s):  
Raphaël Nussbaumer ◽  
Baptiste Schmid ◽  
Silke Bauer ◽  
Felix Liechti
Keyword(s):  
Gaussian Mixture Model ◽  
Mixture Model ◽  
Doppler Radar ◽  
Animal Movement ◽  
Weather Radar ◽  
Gaussian Mixture ◽  
Radar Data ◽  
Volume Data ◽  
Simple Method ◽  
Single Polarization

Recent and archived data from weather radar networks are extensively used for the quantification of continent-wide bird migration patterns. While the process of discriminating birds from weather signals is well established, insect contamination is still a problem. We present a simple method combining two Doppler radar products within a Gaussian mixture model to estimate the proportions of birds and insects within a single measurement volume, as well as the density and speed of birds and insects. This method can be applied to any existing archives of vertical bird profiles, such as the European Network for the Radar surveillance of Animal Movement repository, with no need to recalculate the huge amount of original polar volume data, which often are not available.

Direct measurement of air and precipitation particle motion by very high frequency Doppler radar

Nature ◽  
1985 ◽  
Vol 316 (6030) ◽  
pp. 712-714 ◽  
Author(s):  
S. Fukao ◽  
K. Wakasugi ◽  
T. Sato ◽  
S. Morimoto ◽  
T. Tsuda ◽  
...  
Keyword(s):  
Direct Measurement ◽  
Particle Motion ◽  
High Frequency ◽  
Doppler Radar ◽  
Very High Frequency ◽  
Very High
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