The El Nino‐Southern Oscillation and winter precipitation extremes over India

Revadekar, J. V.; Kulkarni, Ashwini

doi:10.1002/joc.1639

Cited by 54 publications

(22 citation statements)

References 15 publications

(15 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At the same time, variability decreases. Similar results are reported for winter monsoon season (OND) (Revadekar and Kulkarni, 2008), but the mean values for all indices are lower and the variability is higher than that during summer monsoon season. The table depicts that on average there are 59 rainy, 21 moderate, 15 heavy and 9 very heavy rainfall days over India.…”

Section: Frequencies Based On Fixed Thresholdssupporting

confidence: 83%

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

Revadekar

Preethi

2011

Intl Journal of Climatology

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Section: Frequencies Based On Fixed Thresholdssupporting

confidence: 83%

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

Revadekar

Preethi

2011

Intl Journal of Climatology

Self Cite

View full text Add to dashboard Cite

show abstract

“…Krishna Kumar et al 1999). There is also an influence of ENSO on the northeast monsoon (Ropelewski and Halpert 1987, 1989, Nageswara Rao 1999, Kripalani and Pankaj Kumar 2004, Pankaj Kumar et al 2007, Revadekar and Kulkarni 2008, with an El Niño being associated with increased northeast monsoon rainfall over southern India and Sri Lanka between October and December. This relation seems to have strengthened during the last decades, unlike the ENSOsouthwest monsoon teleconnection Ropelewski 2006, Pankaj Kumar et al 2007), and is generally attributed to ENSO-induced changes in the Walker circulation.…”

Section: Introductionmentioning

confidence: 99%

Factors controlling January–April rainfall over southern India and Sri Lanka

et al. 2011

View full text Add to dashboard Cite

Most of the annual rainfall over India occurs during the Southwest (June-September) and Northeast (October-December) monsoon periods. In March 2008, however, Southern peninsular India and Sri Lanka received the largest rainfall anomaly on record since 1979, with amplitude comparable to summer-monsoon interannual anomalies. This anomalous rainfall appeared to be modulated at intraseasonal timescale by the Madden Julian Oscillation, and was synchronous with a decaying La Niña event in the Pacific Ocean. Was this a coincidence or indicative of a teleconnection pattern? In this paper, we explore factors controlling rainfall over southern India and Sri Lanka between January and April, i.e., outside of the southwest and northeast monsoons. This period accounts for 20% of annual precipitation over Sri Lanka and 10 % over the southern Indian states of Kerala and Tamil Nadu. Interannual variability is strong (about 40% of the January-April climatology). Intraseasonal rainfall anomalies over southern India and Sri Lanka are significantly associated with equatorial eastward propagation, characteristic of the Madden Julian oscillation. At the interannual timescale, we find a clear connection with El Niño-Southern Oscillation (ENSO); with El Niños being associated with decreased rainfall (correlation of -0.46 significant at the 98% level). There is also a significant link with local SST anomalies over the Indian Ocean, and in particular with the inter-hemispheric sea surface temperature (SST) gradient over the Indian Ocean (with colder SST south of the equator being conducive to more rainfall, correlation of 0.55 significant at the 99% level). La Niñas / cold SSTs south of the equator tend to have a larger impact than El Niños. We discuss two possible mechanisms that could explain these statistical relationships: 1) subsidence over southern India remotely forced by Pacific SST anomalies; 2) impact of ENSOforced regional Indian Ocean SST anomalies on convection. However, the length of the observational record does not allow distinguishing between these two mechanisms in a statistically significant manner.2

show abstract

“…Differences in the frequencies of 0 to 20 mm rainfall days The frequency differences for 0 mm to 20 mm rainfall days between the periods 1970 to 2008and 1951to 1969. The distribution of the differences pinpoints an increase of frequency of rainfall during 1970 to 2008 over many parts of the SP India [except a small region over Tamil Nadu and adjoining area [77°E to 78°E; 10°N to 11°N], a small region over western parts of northern Coastal Andhra Pradesh, western parts of South Interior Karnataka and the northern most region & southern parts of Kerala].…”

Section: Frequencies Of Above 100 MM Rainfall Daysmentioning

confidence: 99%

“…Very heavy rainfall events posses a very strong relationship with April SSTs over NINO3.4 region. Hence it is possible to predict very heavy rainfall events well in advance (Revadekar and Kulkarni, 2008). Goswami et al (2006) show [i] significant rising trends in the frequency and the magnitude of extreme rain events and [ii] a significant decreasing trend in the frequency of moderate events over central India during the summer monsoon seasons from 1951 to 2000.…”

Section: Introductionmentioning

confidence: 99%