Multi-centennial scale SST and Indian summer monsoon precipitation variability since the mid-Holocene and its nonlinear response to solar activity

Abstract

Indian Summer Monsoon (ISM) shows a weak correlation with solar variability in the 20th century. However, such climatological observations on solar activity-monsoon relationship are very short and hence uncertain. A few paleomonsoon records also exhibit prominent correspondence with solar activity during early Holocene and beyond. But despite the strong recent solar minima (e.g. Maunder, Spörer, Oort, Wolf), their correlation with monsoon precipitation is weak and inconclusive. Additionally, many of the earlier studies have been from the western Arabian Sea that provides records of the ISM wind intensity instead of the ISM precipitation. We present here mid-Holocene to recent sea surface temperature (SST) reconstructed from Mg/Ca measurements of planktic foraminifera (Globigerinoides ruber; white, sensu stricto) on a centennial-scale resolution from the southeastern Arabian. These measurements are used to correct the oxygen isotope ratios of G. ruber to reconstruct salinity related to monsoon runoff in this region more precisely than hitherto. The long-term trend indicates that the ISM precipitation has declined since the mid-Holocene similar to the solar activity. On shorter multi-centennial timescale, we show that the ISM precipitation declined concurrently with the recent periods of strong solar minima, but lagged by a couple of hundred years beyond 1300 yr BP toward the mid-Holocene -confirmed statistically using wavelet analysis. This nonstationary phase relationship between the ISM and the solar activity indicates the possible influence of the tropical coupled ocean-atmosphere phenomenon.

Glacial–interglacial changes and Holocene variations in Arabian Sea denitrification

“…All original data and all calculations are presented as Tables S1 and S2 in the Supplement. In our compilation, temperature reconstructions from the eastern and southeastern Arabian Sea are based on Mg / Ca ratios of planktonic foraminifera (see methods in, e.g., Govil and Naidu, 2010;Mahesh and Banakar, 2014;Saraswat et al, 2013;Tiwari et al, 2015) except core MD90963, which has alkenone temperatures . All other records are alkenone temperatures calculated with the core top calibration of Sonzogni et al (1997b).…”

Organic carbon preservation in Southeastern Arabian Sea sediments since mid‐Holocene: Implications to South Asian Summer Monsoon variability

“…Thus, the nonconsistent long‐term trend of sedimentation rate observed in the present study is could be due to fewer numbers of dates and the same could be improved by dating few more number of samples in between to get a clear picture. Therefore, we note that, although there were few periods of enhanced SASM intensity, the long‐term trend shown by surface run‐off/detrital influx suggests decline in the SASM intensity since mid‐Holocene, which corroborates the previously determined decline in SASM precipitation [ Kessarkar et al ., ; Saraswat et al ., ; Tiwari et al ., ].…”

“…However, the quantitative estimates of SASM intensity (based on δ 18 O of foraminifera, Mg/Ca, a proxy for seawater temperature) are limited and have coarse resolution [ Saraswat et al ., ; Anand et al ., ; Banakar et al ., ; Govil and Naidu , ; Saraswat et al ., ]. Recently, past salinity values determined from the same core used in the present study at a high‐resolution of centennial scale has shown declining SASM precipitation intensity since mid‐Holocene [ Tiwari et al ., ] (Figure j). This is further accompanied by the declining long‐term trend shown by Ti/Al (Figure i) in the present study, which suggests a decline in surface runoff/detrital influx with the declining SASM precipitation intensity.…”

“…The details of the chronology have been reported in Tiwari et al . []. The Age‐depth model (Figure ) shows that the core‐top (0–1 cm) is dated at 154 ± 44 yr BP (1σ) while the last dated section (35–36) age is 4772 yr BP.…”

Can Open Science save us from a solar-driven monsoon?

“…Neff et al 2001;Fleitmann et al 2003;Gupta et al 2005;Wang et al 2005;Agnihotri et al 2011;Tiwari et al 2015;Xu et al 2015), from reanalysis data (e.g. Kodera 2004) and from modern observational data (e.g.…”