Some Features of a Long Homogeneous Series of Indian Summer Monsoon Rainfall

Parthasarathy, Balaji; Mooley, D. A.

doi:10.1175/1520-0493(1978)106<0771:sfoalh>2.0.co;2

Cited by 94 publications

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“…Since the summer rainfall in China is basically subject to the Asian monsoon circulation system, we compared the time series of the principal modes derived above to the Indian monsoon rainfall index (IMR). The IMR is adopted from Parthasarathy (1987) and is defined as the area-averaged total precipitation from June to September over the whole of India (for details see Parthasarathy and Mooley, 1978). Fluctuations with periods longer than 10 years involved in the IMR are removed and the series obtained is then normalized.…”

Section: Harmonic Analysismentioning

confidence: 99%

Time and Space Structure of Interannual Variations in Summer Rainfall over China

Tian

Yasunari

1992

Journal of the Meteorological Society of Japan

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The time and space structure of interannual fluctuations of summer rainfall (May to September) for the period from 1951 to 1990 over China is described. First, a harmonic analysis is applied to the summer rainfall series. The variation with periods of two to four years (hereafter, refered to 2-4 year component) accounts for more than 40 percent of the total variance for all stations, and more than 70 percent of the total variance for 61 percent of stations. The three-year period seems most prevailent among this period band.An EOF (Empirical Orthogonal Function) technique is applied to the 2-4 year period series. The first two EOF modes account for 12.8 and 10.7 percent of the total variance, respectively. EOF mode 1 reveals the seesaw between the Yangtze River valley and the Northern part of China. The spatial pattern of EOF mode 2 is more complicated, but it may be characterized by the oscillation between the Mei-yu region including the Yangtze River valley, and the rest of the country. Although the contribution proportion of the two principle modes is not high, composite maps show that they present the situations (before applying the EOF analysis) well. These two EOF modes exhibit large amplitude modulations. The amplitudes or the squares of the time coefficients tend to become large or small alternatively.Correlation and composite analyses show that EOF mode 1 correlates with the Indian summer monsoon and the SOI (Southern Oscillation Index). This result agrees with that of preceding studies and suggests that the summer rainfall over China is associated with the ENSO (El Nino and Southern Oscillation) events on the time-scale of two to four years. EOF mode 1 seems to precede the anomaly of the SOI. This result supports the previous proposals that the ENSO signals in the eastern equatorial Pacific may originate in the central Asia or the Indian Ocean region. EOF mode 2 seems not to be related to the Indian monsoon and the ENSO.

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Section: Harmonic Analysismentioning

confidence: 99%

Time and Space Structure of Interannual Variations in Summer Rainfall over China

Tian

Yasunari

1992

Journal of the Meteorological Society of Japan

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“…Some studies on the trends and persistence in precipitation have been carried out for the whole of India (Parthasarathy & Dhar, 1975;Shukla, 1987;Sarker & Thapliyal, 1988;Parthasarathy & Mooley, 1978). However, none of these studies examined the combined Ganges-Brahmaputra-Meghna (GBM) basins, nor have any studies been conducted for Nepal in the upstream Ganges basin nor downstream in Bangladesh where the three river basins meet.…”

Section: Introductionmentioning

confidence: 99%

Trends and persistence in precipitation in the Ganges, Brahmaputra and Meghna river basins

Mirza

Warrick

Ericksen

et al. 1998

Hydrological Sciences Journal

149

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The Ganges, Brahmaputra and Meghna (GBM) river basins occupy about 1.75 x 10 6 km 2 of the Himalayan region. More than half a billion people in Nepal, India, Bhutan and Bangladesh are directly or indirectly dependent on the water resources of the GBM rivers. These river basins are characterized by diversified climatic patterns. Analyses of trends and persistence in precipitation over these river basins are necessary for sound water resources planning. Time series of annual precipitation for each of the 16 meteorological subdivisions covering the three river basins were examined for trends using the Mann-Kendall rank statistic, Student's f-test and regression analysis, and for persistence using first order autocorrelation analysis. Results indicate that precipitation in the Ganges basin is by-and-large stable. Precipitation in one subdivision in the Brahmaputra basin shows a decreasing trend and another shows an increasing trend. One of the three subdivisions in the Meghna basin shows a decreasing trend while another shows an increasing trend. Markovian persistence is not present in the precipitation series in the Ganges basin but it is present in two common subdivisions in the Brahmaputra and Meghna basins. Tendances et persistance des précipitations des bassins des fleuves Gange, Brahmapoutre et MeghnaRésumé Les bassins des fleuves Gange, Brahmapoutre et Meghna (GBM) occupent une surface d'à peu près 1.75 x 10 6 de km 2 dans la région Himalayenne. Plus d'un demi milliard de personnes au Népal, en Inde, au Bhoutan et au Bangladesh dépendent directement ou indirectement des ressources d'eau des fleuves GBM. Les bassins de ces fleuves sont caractérisés par des contextes climatiques variés. Des analyses de tendances et de persistance des précipitations de ces bassins se sont révélées nécessaires en vue de réaliser une planification efficace des ressources en eau. Nous avons étudié les séries chronologiques des précipitations annuelles de chacune des seize sous-divisions météorologiques couvrant les trois bassins fluviaux en utilisant la statistique de Mann-Kendall, le test t de Student et l'analyse de régression ainsi que l'auto-corrélation du premier ordre pour les problèmes de persistance. Les résultats indiquent que les précipitations du bassin du Gange sont relativement stables. Les précipitations de l'une des sous-divisions du bassin du Brahmapoutre présentent une tendance décroissante alors que celles d'une autre sous-division présentent une tendance croissante. Il en est de même de deux des trois sous-divisions du bassin du Meghna. La série des précipitations du bassin du Gange ne montre aucune persistance Markovienne que l'on peut au contraire mettre en évidence sur deux sous-divisions communes aux bassins du Brahmapoutre et du Meghna.

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“…After Walker's studies, little work was done during the next fifty years. The analysis of average rainfall of India (as one unit) has been done by Parthasarathy and Dhar (1976), Parthasarathy and Mooley (1978b) and Mooley and Parthasarathy (1979) with a variable number of raingauge stations.…”

Section: Introductionmentioning

confidence: 99%

Fluctuations in All-India summer monsoon rainfall during 1871?1978

1984

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Analysis of the All-India summer monsoon (June to September) rainfall for the period 1871 to 1978 has been made in order to understand the interannual and long-term variability of the monsoon. On a country level, India receives 85.31 cm mean monsoon rainfall which is 78% of the annual rainfall. The coefficient of variation of monsoon rainfall at the country level is 9.5%. The highest and lowest rainfall country level were observed in the years 1961 and 1877 respectively, the range being 41 cm about 48% of the long term average. There are 13/9 years of large-scale deficit/excess in the 108-yr period. There is a continuous rise in the 10-yr mean rainfall from 1899 to 1953. There are four major climatic rainfall periods in the series. Correlogram and spectrum analysis showed significant 14-yr and 2.8-yr cycles respectively in 108-yr series; however detailed exam:mation indicated that these cycles have developed during the last 30 yr of the data period.

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Some Features of a Long Homogeneous Series of Indian Summer Monsoon Rainfall

Cited by 94 publications

References 0 publications

Time and Space Structure of Interannual Variations in Summer Rainfall over China

Time and Space Structure of Interannual Variations in Summer Rainfall over China

Trends and persistence in precipitation in the Ganges, Brahmaputra and Meghna river basins

Fluctuations in All-India summer monsoon rainfall during 1871?1978

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