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

Abstract

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.

Trends in the rainfall pattern over India

“…However most of these studies were based on the rainfall series constructed by Parthasarathy (1984). The monsoon rainfall is without any trend and mainly random in nature over a long period of time, particularly on the all India time scale (Mooley and Parthasarathy, 1984). Since rainfall is having high spatial variability, existence of long-term trend in smaller spatial scale was already reported by Koteswaram and Alvi (1969), Jagannathan and Parthasarathy (1973), Jagannathan and Bhalme (1973).…”

“…Many researchers used these precious data for examining the spatial and temporal variation of rainfall across the country. Later, Mooley and Parthasarathy (1984), Parthasarathy et al (1993), Parthasarathy et al (1994), constructed all India rainfall series (denoted by Indian Institute of Tropical Meteorology Series (IITMS) here after) based on 306 uniformly distributed stations in the country. They have also used area weighted method to calculate all India rainfall using rainfall data of the 306 districts outside the hilly regions like Jammu and Kashmir, Himachal Pradesh, Hills of west Uttar Pradesh, Sikkim and Arunachal Pradesh, Bay Islands and Arabian Sea Island.…”

Decadal to multi-decadal scale variability of Indian summer monsoon rainfall in the coupled ocean-atmosphere-chemistry climate model SOCOL-MPIOM

“…Understanding the variability of the ISMR on decadal to multidecadal timescales is essential for adequate planning of farming and relevant infrastructure development, and for adapting to the consequences of future climate change (Krishnamurthy et al 2014;Joshi and Rai 2015). Other than on inter-annual timescales the ISMR varies on decadal to multi-decadal timescales as various studies identified the presence of a ~60-year cycle in it (see, Mooley and Parthasarathy 1984;Verma et al 1985;Kripalani et al 1997;Krishnamurthy and Goswami 2000;Goswami 2006a;Zhou et al 2009a). The potential factors which cause the decadal to multi-decadal scale variability of the ISMR are Pacific decadal oscillation (PDO), Atlantic multi-decadal oscillation (AMO), and external climate forcings i.e.…”

The tropospheric biennial oscillation in the East Asian monsoon region and its influence on the precipitation in China and large‐scale atmospheric circulation in East Asia

“…The variability of the Asian-Australian monsoon rainfall is known to exhibit a remarkable biennial oscillation characteristics (Mooley and Parthasarathy, 1984;Meehl, 1987;Webster et al, 1998;Loschnigg et al, 2003). This biennial oscillation is referred to as the tropospheric biennial oscillation (TBO) (Meehl, 1994(Meehl, , 1997 that is different from the equatorial stratospheric biennial oscillation (QBO) (Reed et al, 1961) and its signal rainfall has a period of 2-3 year and is characterized by a strong monsoon followed by a weak one, and vice versa .…”