Instrumental period rainfall series of the Indian region (AD 1813—2005): revised reconstruction, update and analysis

Abstract

Sontakke and Singh ( The Holocene 6, 315—31, 1996) developed instrumental period summer monsoon (June—September total) rainfall series (1813—1995) for six homogeneous zones and all of India using 306 raingauge stations. This reconstruction has been revised and updated. Besides reconstructing backward and updating to 2005 the longest possible summer monsoon rainfall series (1813—2005), post-monsoon (October— December total) and annual rainfall series have also been developed for seven homogeneous zones: North Mountainous India (NMI), Northwest India (NWI), North Central India (NCI), Northeast India (NEI), West Peninsular India (WPI), East Peninsular India (EPI), South Peninsular India (SPI), and the whole country using data from 316 well-spread stations. The different series are reported here. The underlying mechanism of the possible cause of the recent decreasing trend in monsoon rainfall and increasing trend in post-monsoon rainfall is described.

Decreasing Indian summer monsoon on the northern Indian sub-continent during the last 180 years: evidence from five tree-ring cellulose oxygen isotope chronologies

“…8). Other highresolution ISM-related records from monsoonal Asia also exhibit similar interannual periodicities (Sun et al, 2016;Xu et al, 2013a;Yadava and Ramesh, 2007). In addition, meteorological data indicates that ENSO has had a significant influence on changes in the ISM (Kumar et al, 1999;Webster et al, 1998).…”

“…Monsoon season drying trend in the Himalaya revealed by the H5 regional tree-ring δ 18 O record may indicate that inland areas appear to be particularly sensitive to the weakening of monsoon circulation, as indicated by Sano et al (2013). The H5 record suggests a decreasing trend of ISM strength, which is supported by most of the other well-dated and high-resolution ISM records in ISM margin areas Sun et al, 2016;Xu et al, 2012Xu et al, , 2013a. A previous study has indicated that solar irradiance has a significant influence on the ISM on multi-decadal to centennial timescales, and that reduced solar output is correlated with weaker ISM winds (Gupta et al, 2005).…”

“…We suggest that further high-resolution and well-dated ISM records from western India are needed to improve our understanding of the behavior of the ISM. Although reconstructed All India monsoon rainfall does not show a significant decreasing trend during the period of 1813(Sontakke et al, 2008, only four stations have data extending back to 1826 CE, and are located in central or southern India. Monsoon season drying trend in the Himalaya revealed by the H5 regional tree-ring δ 18 O record may indicate that inland areas appear to be particularly sensitive to the weakening of monsoon circulation, as indicated by Sano et al (2013).…”

“…A reduction in the monsoon precipitation and relative humidity of the ISM in the last 200 years is also evident in other areas influenced by the ISM. Maar lake sediments in Myanmar exhibit a decreasing trend of monsoonal rainfall since 1840 CE (Sun et al, 2016); a tree-ring δ 18 O record from southeast Asia exhibits a drying trend since 1800 CE (Xu et al, 2013a); a stalagmite δ 18 O record from southwest China reveals an overall decreasing trend in monsoon precipitation since 1760 CE (Tan et al, 2016); tree-ring δ 18 O and maar lake records in southwest China indicate reduced monsoon precipitation, relative humidity and cloud cover since 1840 or 1860 CE (Chu et al, 2011;Grießinger et al, 2017;Liu et al, 2014;Wernicke et al, 2015;Xu et al, 2012). Monsoon precipitation in northwestern India shows a significant decreasing trend during the period of 1866(Bhutiyani et al, 2010.…”

A 70-yr record of oxygen-18 variability in an ice core from the Tanggula Mountains, central Tibetan Plateau

“…Monthly averages were obtained from Monthly average temperature and total precipitation data were obtained from the daily measurements reported by the meteorological administration. In order to evaluate possible monsoon influence on the TGL05 ice core δ 18 O values, annual average isotope ratios were compared to the average monsoon precipitation (JJAS) in North India (Sontakke et al, 2008) for the period 1935-2004. The precipitation sum of the four homogenous rainfall regions north of 21 • N (North Mountainous India, Northwest India, North Central India, and Northeast India) defined by Sontakke et al (2008) was used since these monsoon-impacted regions are directly adjacent to the TP (Fig.…”