Intense rainfall events over the west coast of India

Francis, P. A.; Gadgil, Sulochana

doi:10.1007/s00703-005-0167-2

Cited by 159 publications

(98 citation statements)

References 26 publications

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“…Also the active monsoon trough and the movement of synoptic scale systems (low pressure area and depression) from the Bay of Bengal inland over India gives heavy rainfall events over many parts of the country along the path of the systems (Rao, 1976;Soman and Krishna Kumar, 1990;Gadgil, 2000;Francis and Gadgil, 2006). Similarly, orographic lifting over the northeast parts of the country causes heavy rainfall events over the region (Rao, 1976).…”

Section: Spatial Distribution Of Extreme Rainfall Eventsmentioning

confidence: 99%

“…The high rainfall over the west coast of India and the heavier rainfall over the Western Ghats is generally attributed to forced ascent over the orography of the Western Ghats. Francis and Gadgil (2006) have also found one or more of four types of systems associated with these events: (1) organized convection over a large scale zonal belt; (2) off-shore convective systems; (3) midtropospheric cyclone (MTC) and (4) an off-shore vortex. The orographic features over the west coast and northeast India and the movement of synoptic scale systems from the Bay of Bengal region to the central parts of India (Rao, 1976;Soman and Krishna Kumar, 1990;Gadgil, 2000;Sikka, 2006;Pattanaik, 2007) also contribute to heavy rainfall events over different parts of India.…”

Section: Introductionmentioning

confidence: 99%

“…On occasion the rainfall is exceptionally heavy at some stations. It is believed that these intense rainfall events over the west coast regions are often associated with small vortices embedded in offshore troughs, or with convective systems/bands associated with mesoscale vortices embedded in larger scale systems over the Arabian Sea (Rao, 1976;George, 1956;Mukherjee et al, 1978;Mukherjee, 1980;Francis and Gadgil, 2006). The high rainfall over the west coast of India and the heavier rainfall over the Western Ghats is generally attributed to forced ascent over the orography of the Western Ghats.…”

Section: Introductionmentioning

confidence: 99%

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Variability of extreme rainfall events over India during southwest monsoon season

Pattanaik

Rajeevan

2009

Meteorological Applications

135

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ABSTRACT:The spatial and temporal variability of extreme rainfall events over India and their long-term trend have been analysed during the southwest monsoon season from June to September (JJAS) by taking daily rainfall data for 55 years . The contribution of extreme rainfall events (Category iii with rainfall >124.4 mm day −1 ) to the total seasonal rainfall is also analysed for the same period. The analysis shows that the occurrence of extreme rainfall events over India during JJAS shows spatial variations with preferred regions of occurrence over the west coast, central parts of India and northeast India. The average frequency of extreme rainfall events along with the contribution of extreme rainfall events to the seasonal rainfall shows a significant increasing trend (above the 98% confidence level) over the Indian region during JJAS, and also during June and July. It is also found that the increasing trend of contribution from extreme rainfall events during JJAS is balanced by a decreasing trend in Category i (rainfall ≤ 64.4 mm day −1 ) rainfall events. Using the filtered data it is found that the increasing trend of extreme rainfall over central India is mainly contributed by synoptic scale systems (periodicity between 3 and 7 days). The seasonal mean moist convective instability (CI) during JJAS averaged over central India indicates a significant increasing trend (99.9% confidence level) and is basically due to the increasing trend of the number of days with greater degree of moist CI during JJAS, which may be one possible cause for the increasing trend in the frequency of extreme rainfall events over the region. Copyright  2009 Royal Meteorological Society KEY WORDS extreme rainfall events; monsoon season; Indian monsoon rainfall; linear trend and band pass filter

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Section: Spatial Distribution Of Extreme Rainfall Eventsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Variability of extreme rainfall events over India during southwest monsoon season

Pattanaik

Rajeevan

2009

Meteorological Applications

135

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“…They have further shown that the frequency of extreme events has increased in the western half of the country (Sen Roy and Balling 2006). The probability of intense rainfall events over the west coast of India is high from mid-June to mid-August (Francis and Gadgil 2006). These studies, in detail, investigated the variability of precipitation events, however, the impacts of these redistributions on agriculture over India is not clearly known.…”

Section: Introductionmentioning

confidence: 99%

Statistical analysis of the relationship between summer monsoon precipitation extremes and foodgrain yield over India

Revadekar

Preethi

2011

Intl Journal of Climatology

100

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ABSTRACT:The Indian economy largely depends on agriculture which is highly influenced by the spatio-temporal variability of precipitation. Kharif and rabi are the two main crop-growing seasons which require major proportion of rainfall. Increase in heavy precipitation events, however, can have adverse effects on the crops. This study, therefore, is mainly focused on understanding the variation of extremes in precipitation during summer monsoon season and its impact on kharif foodgrain yield over India. For this, several objectively defined indices of observed precipitation extremes, in terms of frequencies and intensities, have been computed for the period 1951-2003 using daily gridded data of 1°latitude ×1°longitude resolution. Efforts have also been made to prepare the climatology of extremes in precipitation to determine their basic characteristics over the Indian region.Correlation analysis reveals that a large part of the country exhibits positive relationship between kharif foodgrain yield and the indices of extreme precipitation, significant at 5% level. Correlations with the indices of frequencies defined as seasonal count of days when rainfall exceeds 85th, 75th, and 65th percentiles (and 30, 20, and 10 mm) show that spatial extent and strength of the positive relationship decreases with increase in threshold values. This indicates that very heavy daily rainfall is less useful than the moderate daily rainfall. Strong negative relationship between the yield and indices of extreme precipitation observed over heavy precipitation areas of northeastern parts of the country indicate that very heavy daily rainfall have an adverse effect on crop. The study also points out that increase in heavy rainfall activities during July are favourable for the yield, but correlations become weak and statistically insignificant during the month of August. Individual crops show similar results as that obtained from aggregate kharif foodgrain, however, magnitude of the correlations varies from crop to crop.

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“…However, it may be noted, that unlike the cloudiness over the Bay of Bengal, the anomalies of Q1 and Q2 over this region are less intense and the maximum values are in-phase with the onset of the active phase. Studies using the data of INSAT 1B satellite indicate that the cloud systems over WCI region are characterized by weather systems which have their greatest intensity between 700 and 500 hPa (francis and Gadgil, 2006).…”

Section: Variation Of Heat Source (Q1) and Moisture Sink (Q2) In Relamentioning

confidence: 99%

Intra-seasonal variability of cloud amount over the Indian subcontinent during the monsoon season as observed by TRMM precipitation radar

et al. 2014

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The intra-seasonal variability of the Indian summer monsoon, which manifests in the form of "active" and "break" phases in rainfall, is investigated with respect to the variability of the convective and stratiform precipitating cloud pattern over the region. Long period data from TRMM PR satellite (2A23 and 3B42 datasets) for the monsoon season of 2002 to 2010 over the Indian subcontinent is used for this purpose. The study reveals that the most significant spatial variation in convective and stratiform cloud amount in relation to the active and break phase occurs over the monsoon trough region in central India. The active phase is characterized by positive convective (~5%) and stratiform (~20%) precipitating cloud anomalies over this region. However, the maximum of the former precedes the latter by 1-2 days leading up to the active phase, indicating that the stratiform build up, is due to the gradual organization of the convective cloud systems over the region. The days leading up to the break phase are marked by negative anomalies in the convective and stratiform fractions of cloudiness over this region, which are in phase with each other, unlike the lead-up to the active phase. Analysis of the pattern of atmospheric heat source and sinks over the region from the NCEP-NCAR re-analysis data indicates that the engine for the growth/decay of convection over the monsoon trough region lies primarily in the Bay of Bengal and adjacent east India. The active phase is preceded by a heating pattern that promotes large scale, organized convective cloud growth over the Bay of Bengal preceding the actual onset, while the heating pattern leading up to the break phase promotes the formation of isolated convective clouds and decay of cloud organization over the monsoon trough region.

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Intense rainfall events over the west coast of India

Cited by 159 publications

References 26 publications

Variability of extreme rainfall events over India during southwest monsoon season

Variability of extreme rainfall events over India during southwest monsoon season

Statistical analysis of the relationship between summer monsoon precipitation extremes and foodgrain yield over India

Intra-seasonal variability of cloud amount over the Indian subcontinent during the monsoon season as observed by TRMM precipitation radar

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