scholarly journals Floods in Karnataka during 2009 : A synoptic study

MAUSAM ◽  
2021 ◽  
Vol 63 (2) ◽  
pp. 223-230
Author(s):  
B. PUTTANNA ◽  
GEETA AGNIHOTRI
Keyword(s):  
Interannual Variation ◽  
Monsoon Rainfall ◽  
Monsoon Season ◽  
Low Pressure ◽  
The State ◽  
Annual Rainfall ◽  
The West ◽  
Peninsular India ◽  
Synoptic Features ◽  
Pressure Area

Karnataka a State in south peninsular India receives 73% of its annual rainfall during southwestmonsoon season. Because of the complex physiographical features, the rainfall pattern over the State shows large spatialvariation from 50 to 350 cms. The coefficient of interannual variation of the monsoon rainfall is about 15% over coastalKarnataka (CK) and between 20-30% over interior Karnataka. The precipitation over this State is mainly dominated bysemi permanent systems like off shore trough running along the west coast, low pressure systems forming over the Bay ofBengal during the monsoon season. A well marked low pressure area during 28 September - 3 October 2009 over the Bayof Bengal caused widespread damage to life and property in north Karnataka. In this study, an attempt has been made toexamine the synoptic features of this system that caused heavy rainfall over many districts of the State leading towidespread destruction.

scholarly journals A Synoptic analogue model to issue QPF over Gangetic West Bengal and adjoining Jharkhand

MAUSAM ◽  
2021 ◽  
Vol 69 (2) ◽  
pp. 297-308
Author(s):  
S. CHATTOPADHYAY ◽  
S. SENGUPTA
Keyword(s):  
West Bengal ◽  
Monsoon Season ◽  
Low Pressure ◽  
Precipitation Forecast ◽  
Analogue Model ◽  
Cyclonic Storm ◽  
Damodar Valley ◽  
Synoptic Features ◽  
Pressure Area ◽  
River Catchments

 In this study the Areal Average Precipitation (AAP) data for each day over each of the six catchments of Gangetic West Bengal (GWB) and adjoining Jharkhand namely river catchments of Mayurakhshi, Ajoy, Kansabati, Damodar, Barakar and Lower Valley of Damodar Valley Corporation during monsoon season for  25  years from  1990 to 2014 have been analyzed by grouping the AAP in three different ranges (11-25 mm, 26-50 mm, 51-100 mm and more), excluding Mainly Dry and 01-10 mm. The associated main synoptic features viz., trough at mean sea level, low pressure area, well marked low pressure area, cyclonic storm and cyclonic circulation for each day and their location with respect to the river catchments, viz., over the catchment, neighbourhood of the catchment (within 200 km South or North) and outside the catchment (more than 200 km South or North) have also been studied. The association of AAP ranges over six catchments with different categories of synoptic features has been examined. The distribution of percentage frequency of AAPs associated with the category of synoptic feature for the period 1990 to 2014 has led to development of a Synoptic Analogue Model (SAM) for issue of Quantitative Precipitation Forecast (QPF). The results obtained from SAM have been verified for rainfall data and calculated AAPs of monsoon season of 2015 over all the catchments and different skills scores also presented in this study.  

scholarly journals Interannual Variation of the Summer Rainfall Center in the South China Sea

2017 ◽  
Vol 30 (19) ◽  
pp. 7909-7931 ◽  
Author(s):  
Tsing-Chang Chen ◽  
Jenq-Dar Tsay ◽  
Jun Matsumoto
Keyword(s):  
Summer Monsoon ◽  
Interannual Variation ◽  
Monsoon Rainfall ◽  
Monsoon Season ◽  
Summer Rainfall ◽  
The Philippines ◽  
Monsoon Trough ◽  
Summer Monsoon Rainfall ◽  
Tropical Depression ◽  
Easterly Wave

Abstract A northwest–southeast-oriented summer monsoon trough exists between northern Indochina and northwestern Borneo. Ahead of this the South China Sea (SCS) trough is located at a convergent center west of the Philippines, which provides an environment favorable for rain-producing synoptic systems to produce rainfall over this center and form the SCS summer rainfall center. Revealed from the x–t diagram for rainfall, this rainfall center is developed by multiple-scale processes involved with the SCS trough (TR), tropical depression (TY), interaction of the SCS trough with the easterly wave/tropical depression (EI), and easterly wave (EW). It is found that 56% of this rainfall center is produced by the SCS trough, while 41% is generated by the other three synoptic systems combined. Apparently, the formation of the SCS summer monsoon rainfall center is contributed to by these four rain-producing synoptic systems from the SCS and the Philippines Sea. The Southeast Asian summer monsoon undergoes an interannual variation and exhibits an east–west-oriented cyclonic (anticyclonic) anomalous circulation centered at the western tropical Pacific east of the Luzon Strait. This circulation change is reflected by the deepening (filling) of the SCS summer monsoon trough, when the monsoon westerlies south of 15°N intensify (weaken). This interannual variation of the monsoon westerlies leads to the interannual variation of the SCS summer monsoon rainfall center to follow the Pacific–Japan oscillation of rainfall. The rainfall amount produced over this rainfall center during the weak monsoon season is about two-thirds of that produced during the strong monsoon season. The rain-production ratio between TR and TY + EI + EW is 60:38 during the strong monsoon season and 47:49 during the weak monsoon season.

scholarly journals Effects of annual rainfall on dengue incidence in the Indian state of Rajasthan

2018 ◽  
Author(s):  
Nasir Salam
Keyword(s):  
Public Health ◽  
Monsoon Season ◽  
The State ◽  
Annual Rainfall ◽  
Strong Positive Correlation ◽  
The Past ◽  
Cumulative Rainfall ◽  
Dengue Outbreaks ◽  
Indian State ◽  
The Impact

AbstractDengue has become a major public health problem in the last few decades with India contributing significantly to the overall disease burden. Most of the cases of Dengue from India are reported during Monsoon season. The vector population of dengue is affected by seasonal rainfall, temperature and humidity fluctuations. Rajasthan is northwestern state of India, which has shown several dengue outbreaks in the past. In this paper we have tried to analyze the effects of annual cumulative rainfall on Dengue incidence in one of the largest and severely affected states of India. Retrospective data for Dengue incidence and Rainfall for the state of Rajasthan was collected and Pearson’s coefficient correlation was calculated as a measure of association between the variables. Our results indicate that annual cumulative rainfall shows a strong positive correlation with dengue incidence in the state of Rajasthan. Such analyses have the potential to inform public health official about the control and preparedness for vector control during monsoon season. This is the first study from the Indian state of Rajasthan to assess the impact of annual rainfall on dengue incidence, which has seen several dengue outbreaks in the past.

scholarly journals Analysis of rainfall by using Mann-Kendall trend, Sen’s slope and variability at five districts of south Gujarat, India

MAUSAM ◽  
2021 ◽  
Vol 68 (2) ◽  
pp. 205-222 ◽  
Author(s):  
NEERAJ KUMAR ◽  
C. C. PANCHAL ◽  
S. K. CHANDRAWANSHI ◽  
J. D. THANKI
Keyword(s):  
Standard Deviation ◽  
Monsoon Rainfall ◽  
Monsoon Season ◽  
Rainfall Variability ◽  
Winter Season ◽  
Annual Rainfall ◽  
Present Contribution ◽  
Sen’S Slope ◽  
Post Monsoon ◽  
Data Points

On the basis of past 115 years (1901-2015) rainfall data of five districts of south Gujarat, the Mann-Kendall trend, Sen’s slope and regression slope showed that annual and monsoon rainfall at Valsad, Dang and Surat shows the increasing trend while, that of Navsari and Bharuch districts are declining. The monsoon season (summer monsoon) rainfall variability of Valsad, Dang, Surat, Navsari and Bharuch districts was recorded is 30.1%, 30.9%, 35.9%. 33.3% and 38.6%. The high coefficient of variation (CV) denoted that the variability of rainfall is not equally distributed and the amount of rainfall is lowest. The Bharuch district the annual and monsoon CV per cent denoted that the variability of rainfall in both seasons are very high. Valsad was recorded lowest CV with highest rainfall while the data are represent that variability of rainfall which can varies Bharuch to Dang in different districts of south Gujarat. The data shows that Dang district comes under high rainfall and Bharuch under low rainfall on south Gujarat. A low standard deviation indicates that the data points tend to be close to the mean of the set, while a high standard deviation indicates that the data points are spread out over a wider range of values. Similarly high SD is reported at Dang district because of high range of rainfall and lowest SD is found at Bharuch district because of low rainfall variability. The rainfall distribution different season viz., pre monsoon, monsoon post monsoon and winter season, the highest present contribution of rainfall is observed during monsoon season followed by post monsoon in all the five districts of south Gujarat. Rainfall contribution during remaining months was less than one per cent. While month wise analysis shows during monsoon season highest rainfall per cent contribution to annual rainfall is in July followed by August and June months at all the five districts of south Gujarat.

scholarly journals Sub-divisional summer monsoon rainfall over India in relation to low pressure systems over the Bay of Bengal and adjoining land regions during 1982-1999

MAUSAM ◽  
2021 ◽  
Vol 59 (3) ◽  
pp. 327-338
Author(s):  
M. MOHAPATRA
Keyword(s):  
Summer Monsoon ◽  
Bay Of Bengal ◽  
West Coast ◽  
Monsoon Rainfall ◽  
Monsoon Season ◽  
Central India ◽  
Low Pressure ◽  
Seasonal Rainfall ◽  
West Central ◽  
The Impact

A study is undertaken to find out characteristic features of relationship of the low pressure system (LPS) over the Bay of Bengal and adjoining land regions with the rainfall over different meteorological sub-divisions of India during summer monsoon season (June-September). For this purpose, rainfall over 35 meteorological sub-divisions in India and LPS days over west central (WC) Bay, northwest (NW) Bay, northeast (NE) Bay, Bangladesh (BDS), Gangetic West Bengal (GWB), Orissa, north coastal Andhra Pradesh (NCAP), east Madhya Pradesh and Chattisgarh (EMPC) and Jharkhand (JKD) during different monsoon months and the season as a whole over a period of 18 years (1982-1999) are analysed. There is large month to month variation in the impact of the LPS on the sub-divisional monsoon rainfall over India. However, the results presented in the study including developed correlation maps may be helpful to predict 24 hours rainfall based on the location of the LPS and associated monsoon trough.   The frequent development and persistence of LPS over NW Bay are favourable for higher seasonal monsoon rainfall over east central India. The development and persistence of LPS over WC Bay adversely affect the seasonal rainfall over this region. On the other hand, the frequent development and persistence of LPS over WC Bay and its subsequent westward movement across NCAP are favourable for higher seasonal rainfall over the peninsular region excluding west coast. The seasonal rainfall over northwest India decreases with increase in LPS days over EMPC. The seasonal rainfall over west central India, northeast India and west coast are not significantly related with the number of LPS days over the regions under consideration.

scholarly journals On some aspects of southwest monsoon rainfall over Tamilnadu

MAUSAM ◽  
2022 ◽  
Vol 46 (4) ◽  
pp. 377-382
Author(s):  
S. K. SUBRAMANIAN ◽  
V. N. THANKAPPAN
Keyword(s):  
Monsoon Rainfall ◽  
Monsoon Season ◽  
Southwest Monsoon ◽  
Point Of View ◽  
Annual Rainfall ◽  
Northeast Monsoon ◽  
The North ◽  
Rainfall Occurrence ◽  
Southwest Monsoon Rainfall ◽  
Southwest Monsoon Season

The rainfall during southwest monsoon season over Tamilnadu is quite significant from the point of view of water storage in major reservoirs as northeast monsoon rainfall, which is about half of the annual rainfall, is not stable enough due to its large interannual variability. The southwest monsoon rainfall, on the other hand, is more stable. The north-south oriented trough over Tamilnadu and adjoining Bay togetherwith upper air cyclonic circulation/trough in lower tropospheric levels account for three fourths of significant rainfall occurrence during southwest monsoon season. Rainfall during southwest monsoon and northeast monsoon seasons was found to be independent with a small negative correlation of -0.18. This shows that the southwest monsoon rainfall may not be of much use to predict the pattern of northeast monoon rainfall over Tamilnadu.  

scholarly journals Binary classification of rainfall time-series using machine learning algorithms

2022 ◽  
Vol 12 (2) ◽  
pp. 1945
Author(s):  
Shilpa Hudnurkar ◽  
Neela Rayavarapu
Keyword(s):  
Summer Monsoon ◽  
Monsoon Rainfall ◽  
Binary Classification ◽  
Summer Monsoon Rainfall ◽  
The State ◽  
Misclassification Rate ◽  
Annual Rainfall ◽  
Support Vector ◽  
Weather Variables

Summer monsoon rainfall contributes more than 75% of the annual rainfall in India. For the state of Maharashtra, India, this is more than 80% for almost all regions of the state. The high variability of rainfall during this period necessitates the classification of rainy and non-rainy days. While there are various approaches to rainfall classification, this paper proposes rainfall classification based on weather variables. This paper explores the use of support vector machine (SVM) and artificial neural network (ANN) algorithms for the binary classification of summer monsoon rainfall using common weather variables such as relative humidity, temperature, pressure. The daily data, for the summer monsoon months, for nineteen years, was collected for the Shivajinagar station of Pune in the state of Maharashtra, India. Classification accuracy of 82.1 and 82.8%, respectively, was achieved with SVM and ANN algorithms, for an imbalanced dataset. While performance parameters such as misclassification rate, F1 score indicate that better results were achieved with ANN, model parameter selection for SVM was less involved than ANN. Domain adaptation technique was used for rainfall classification at the other two stations of Maharashtra with the network trained for the Shivajinagar station. Satisfactory results for these two stations were obtained only after changing the training method for SVM and ANN.

scholarly journals Rainfall Types in the West African Sudanian Zone during the Summer Monsoon 2002

2006 ◽  
Vol 134 (8) ◽  
pp. 2143-2164 ◽  
Author(s):  
A. H. Fink ◽  
D. G. Vincent ◽  
V. Ermert
Keyword(s):  
Summer Monsoon ◽  
Monsoon Season ◽  
Integrated Approach ◽  
West African ◽  
Annual Rainfall ◽  
Major Type ◽  
Synoptic Situation ◽  
The West ◽  
Convective Systems ◽  
Sudanian Zone

Abstract Enhanced surface and upper-air observations from the field campaign of the Integrated Approach to the Efficient Management of Scarce Water Resources in West Africa (IMPETUS) project are used to partition rainfall amounts over the West African Sudanian zone during the 2002 summer monsoon season into several characteristic types and subtypes of precipitating systems. The most prominent rainfall subtype was fast-moving, long-lived, and extensive cloud clusters that often developed far upstream over the central Nigerian highlands in the afternoon hours and arrived at the Upper Ouémé Valley (UOV) after midnight. These organized convective systems (advective OCSs, subtype Ia) accounted for 50% of the total rain amount in the UOV catchment in Benin. Subtypes Ia and IIa (i.e., locally developing OCSs) were found to pass by or organize when a highly sheared environment with deep and dry midtropospheric layers was present over the UOV. These systems were most frequent outside the peak of the monsoon season. The second major type of organized convection, termed mesoscale convective systems (subtypes Ib, IIb, and IIIb) in the present study, contributed 26% to the annual UOV precipitation. They occurred in a less-sheared and moister tropospheric environment mainly around the height of the rainy season. A third distinct class of rainfall events occurred during an unusual synoptic situation in which a cyclonic vortex to the north of the UOV led to deep westerly flow. During these periods, the African easterly jet was lacking. The so-called vortex-type rainfalls (subtypes IIIa, IIIb, and IIIc) contributed about 9% to the annual rainfall totals.

scholarly journals Summer monsoon low pressure systems over the Indian region and their relationship with the sub-divisional rainfall

MAUSAM ◽  
2022 ◽  
Vol 53 (2) ◽  
pp. 177-186
Author(s):  
S. K. JADHAV
Keyword(s):  
Summer Monsoon ◽  
Monsoon Season ◽  
Correlation Coefficients ◽  
Central India ◽  
Low Pressure ◽  
Northeast India ◽  
Indian Region ◽  
Pressure System ◽  
Peninsular India ◽  
Latitude Belt

In the present paper performance of the monthly sub-divisional summer monsoon rainfall is studied in association with the position of the Low Pressure System (LPS) over the Indian region. Existence of the LPS over a particular location increases the rainfall activities in certain parts of the country while decreases in some other parts. For this study, the Indian region (5°-35° N and 60° -100° E) is divided into 5°  Lat. ´ 5° Long. grids. The duration of LPS is taken in terms of LPS days with respect to the location of LPS in a particular grid. Monthly total number of LPS days in each of the grids are computed during the summer monsoon season, June to September for the period 1891 – 1990. Maximum number of LPS days (more than half of the total) are observed in the latitude belt between 20°-25°N. The percentages of total LPS days in this area are higher in July and August which are peak monsoon months as compared to June and September. When there is a LPS are in the area 20°-25° N and 80°-90° E, there is significant increase in the rainfall activities in the sub-divisions along mean monsoon trough while northeast India and southeast peninsular India experience significant decrease in rainfall in the months of July and August. Owing to the movement of LPS from east to west through central India, most parts of the country, excluding northeast India and south peninsular India get good rainfall activity. Correlation coefficients between monthly LPS days over the different grids and monthly sub-divisional rainfall are computed to study the relationships. The performance of sub-divisional rainfall mostly related with the occurrence of LPS in certain grid- locations. The correlation field maps may give some useful information about rainfall performance due to LPS in a particular grid locations.

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