Strengthened Indian summer monsoon brought more rainfall to the western Tibetan Plateau during the early Holocene

The spatial and temporal variability, effects, and mechanisms of the Indian Summer Monsoon (ISM) have been investigated intensively during the past few decades. The pattern of a relatively strong ISM during the early to middle Holocene, and a relatively weak ISM in the late Holocene, has been widely demonstrated in both marine and continental records. However, the timing of the ISM onset during the early Holocene remains controversial. Here, we present oxygen isotope record from ostracods and hydrogen isotope record from sedimentary leaf waxes from a sediment core at Linggo Co, a glacier-fed lake on the central Tibetan Plateau, in order to investigate the onset of the ISM. The ostracod δ18O record indicates an early ISM onset at ~11.7 ka, whereas the leaf wax δD record indicates a later ISM onset at ~10 ka. This apparent two-step development of the ISM revealed by aquatic and terrestrial records is confirmed by principal component analysis of nine marine records from the ISM domain. The comparison between isotope records from Linggo Co and the marine records implies that the early ISM onset was likely linked to elevated temperatures in the Northern Hemisphere, while the later ISM onset may be related to intensified precipitation.

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Lake Level Reconstruction for 12.8–2.3 ka of the Ngangla Ring Tso Closed-Basin Lake System, Southwest Tibetan Plateau

Quaternary Research ◽

10.1016/j.yqres.2014.07.012 ◽

2015 ◽

Vol 83 (1) ◽

pp. 66-79 ◽

Cited By ~ 30

Author(s):

Adam M. Hudson ◽

Jay Quade ◽

Tyler E. Huth ◽

Guoliang Lei ◽

Hai Cheng ◽

...

Keyword(s):

Tibetan Plateau ◽

Summer Monsoon ◽

Indian Summer Monsoon ◽

Lake Level ◽

Closed Basin ◽

Lake System ◽

Proxy Records ◽

Monsoon Intensity ◽

Western Tibetan Plateau ◽

Millennial Scale

AbstractWe present a shoreline-based, millennial-scale record of lake-level changes spanning 12.8–2.3 ka for a large closed-basin lake system on the southwestern Tibetan Plateau. Fifty-three radiocarbon and eight U–Th series ages of tufa and beach cement provide age control on paleoshorelines ringing the basin, supplemented by nineteen ages from shell and aquatic plant material from natural exposures generally recording lake regressions. Our results show that paleo-Ngangla Ring Tso exceeded modern lake level (4727 m asl) continuously between ~ 12.8 and 2.3 ka. The lake was at its highstand 135 m (4862 m asl) above the modern lake from 10.3 ka to 8.6 ka. This is similar to other closed-basin lakes in western Tibet, and coincides with peak Northern Hemisphere summer insolation and peak Indian Summer Monsoon intensity. The lake experienced a series of millennial-scale oscillations centered on 11.5, 10.8, 8.3, 5.9 and 3.6 ka, consistent with weak monsoon events in proxy records of the Indian Summer Monsoon. It is unclear whether these events were forced by North Atlantic or Indian Ocean conditions, but based on the abrupt lake-level regressions recorded for Ngangla Ring Tso, they resulted in significant periodic reductions in rainfall over the western Tibetan Plateau throughout the Holocene.

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Regulation of Tibetan Plateau heating on variation of Indian summer monsoon in the last two millennia

Geophysical Research Letters ◽

10.1029/2004gl021246 ◽

2005 ◽

Vol 32 (2) ◽

Cited By ~ 20

Author(s):

Song Feng

Keyword(s):

Tibetan Plateau ◽

Summer Monsoon ◽

Indian Summer Monsoon ◽

The Last Two Millennia

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Modulation of coupled modes of Tibetan Plateau heating and Indian Summer Monsoon on summer rainfall over Central Asia

Journal of Climate ◽

10.1175/jcli-d-20-0813.1 ◽

2021 ◽

pp. 1-54

Keyword(s):

Water Vapor ◽

Tibetan Plateau ◽

Central Asia ◽

Summer Monsoon ◽

Indian Summer Monsoon ◽

Diabatic Heating ◽

Summer Rainfall ◽

Hadley Cell ◽

Vapor Transport ◽

Water Vapor Transport

Abstract It has been suggested that summer rainfall over Central Asia (CA) is significantly correlated with the summer thermal distribution of the Tibetan Plateau (TP) and the Indian summer monsoon (ISM). However, relatively few studies have investigated their synergistic effects of different distribution. This study documents the significant correlations between precipitation in CA and the diabatic heating of TP and the ISM based on the results of statistical analysis and numerical simulation. Precipitation in CA is is dominated by two water vapor transport branches from the south which are related to the two primary modes of anomalous diabatic heating distribution related to the TP and ISM precipitation, that is, the “+-” dipole mode in the southeastern TP and the Indian subcontinent (IS), and the “+-+” tripole mode in the southeastern TP, the IS, and southern India. Both modes exhibit obvious mid-latitude Silk Road pattern (SRP) wave trains with cyclone anomalies over CA, but with different transient and stationary eddies over south Asia. The different locations of anomalous anticyclones over India govern two water vapor transport branches to CA, which are from the Arabian Sea and the Bay of Bengal. The water vapor flux climbs while being transported northward and can be transported to CA with the cooperation of cyclonic circulation. The convergent water vapor and ascending motion caused by cyclonic anomalies favor the precipitation in CA. Further analysis corroborates the negative South Indian Ocean Dipole (NSIOD) in February could affect the tripole mode distribution of TP heating and ISM via the atmospheric circulation, water vapor transport and an anomalous Hadley cell circulation. The results indicate a reliable prediction reference for precipitation in CA.

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Signatures of Tibetan Plateau heating on Indian summer monsoon rainfall variability

Journal of Geophysical Research Atmospheres ◽

10.1002/jgrd.50124 ◽

2013 ◽

Vol 118 (3) ◽

pp. 1170-1178 ◽

Cited By ~ 33

Author(s):

Balaji Rajagopalan ◽

Peter Molnar

Keyword(s):

Tibetan Plateau ◽

Summer Monsoon ◽

Indian Summer Monsoon ◽

Monsoon Rainfall ◽

Indian Summer Monsoon Rainfall ◽

Rainfall Variability ◽

Summer Monsoon Rainfall

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Association of the pre-monsoon thermal field over north India and the western Tibetan Plateau with summer monsoon rainfall over India

Annales Geophysicae ◽

10.5194/angeo-33-1051-2015 ◽

2015 ◽

Vol 33 (8) ◽

pp. 1051-1058 ◽

Cited By ~ 1

Author(s):

S. D. Bansod ◽

S. Fadnavis ◽

S. P. Ghanekar

Keyword(s):

Tibetan Plateau ◽

Summer Monsoon ◽

Asian Summer Monsoon ◽

Summer Monsoon Rainfall ◽

North India ◽

Monsoon Region ◽

The North ◽

Western Tibetan Plateau ◽

Asian Summer ◽

Summer Monsoon Region

Abstract. In this paper, interannual variability of tropospheric air temperatures over the Asian summer monsoon region during the pre-monsoon months is examined in relation to Indian summer monsoon rainfall (ISMR; June to September total rainfall). For this purpose, monthly grid-point temperatures in the entire troposphere over the Asian summer monsoon region and ISMR data for the period 1949–2012 have been used. Spatial correlation patterns are investigated between the temperature field in the lower tropospheric levels during May over the Asian summer monsoon region and ISMR. The results indicate a strong and significant northwest–southeast dipole structure in the spatial correlations over the Indian region, with highly significant positive (negative) correlations over the regions of north India and the western Tibetan Plateau region – region R1 (north Bay of Bengal: region R2). The observed dipole is seen significantly up to a level of 850 hPa and eventually disappears at 700 hPa. Thermal indices evaluated at 850 hPa level, based on average air temperatures over the north India and western Tibetan Plateau region (TI1) and the north Bay of Bengal region (TI2) during May, show a strong, significant relationship with the ISMR. The results are found to be consistent and robust, especially in the case of TI1 during the period of analysis. A physical mechanism for the relationship between these indices and ISMR is proposed. Finally the composite annual cycle of tropospheric air temperature over R1 during flood/drought years of ISMR is examined. The study brings out the importance of the TI1 in the prediction of flood/drought conditions over the Indian subcontinent.

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First measurement of atmospheric mercury species in Qomolangma Natural Nature Preserve, Tibetan Plateau, and evidence oftransboundary pollutant invasion

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-1373-2019 ◽

2019 ◽

Vol 19 (2) ◽

pp. 1373-1391 ◽

Cited By ~ 5

Author(s):

Huiming Lin ◽

Yindong Tong ◽

Xiufeng Yin ◽

Qianggong Zhang ◽

Hui Zhang ◽

...

Keyword(s):

Tibetan Plateau ◽

Summer Monsoon ◽

Indian Summer Monsoon ◽

Transition Period ◽

Atmospheric Pollutants ◽

Mercury Species ◽

The Tibetan Plateau ◽

Monsoon Period ◽

Air Masses ◽

Nature Preserve

Abstract. Located in the world's “third pole” and a remote region connecting the Indian plate and the Eurasian plate, Qomolangma National Nature Preserve (QNNP) is an ideal region to study the long-range transport of atmospheric pollutants. In this study, gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM) and particle-bound mercury (PBM) were continuously measured during the Indian monsoon transition period in QNNP. A slight increase in the GEM concentration was observed from the period preceding the Indian summer monsoon (1.31±0.42 ng m−3) to the Indian summer monsoon period (1.44±0.36 ng m−3), while significant decreases were observed in the GOM and PBM concentrations, with concentrations decreasing from 35.2±18.6 to 19.3±10.9 pg m−3 (p < 0.001) for GOM and from 30.5±12.5 to 24.9±19.8 pg m−3 (p < 0.001) for PBM. A unique daily pattern was observed in QNNP with respect to the GEM concentration, with a peak value before sunrise and a low value at noon. Relative to the (low) GEM concentrations, GOM concentrations (with a mean value of 21.4±13.4 pg m−3, n=1239) in this region were relatively high compared with the measured values in some other regions of China. A cluster analysis indicated that the air masses transported to QNNP changed significantly at different stages of the monsoon, and the major potential mercury (Hg) sources shifted from northern India and western Nepal to eastern Nepal and Bangladesh. As there is a large area covered in glaciers in QNNP, local glacier winds could increase the transboundary transport of pollutants and transport polluted air masses to the Tibetan Plateau. The atmospheric Hg concentration in QNNP in the Indian summer monsoon period was influenced by transboundary Hg flows. This highlights the need for a more specific identification of Hg sources impacting QNNP and underscores the importance of international cooperation regarding global Hg controls.

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Tree-ring-inferred glacier mass balance variation in southeastern Tibetan Plateau and its linkage with climate variability

Climate of the Past ◽

10.5194/cp-9-2451-2013 ◽

2013 ◽

Vol 9 (6) ◽

pp. 2451-2458 ◽

Cited By ~ 6

Author(s):

J. Duan ◽

L. Wang ◽

L. Li ◽

Y. Sun

Keyword(s):

Tibetan Plateau ◽

Climate Variability ◽

Mass Balance ◽

Tree Ring ◽

Summer Monsoon ◽

Indian Summer Monsoon ◽

Dominant Factor ◽

Glacier Mass Balance ◽

Monsoon Precipitation

Abstract. A large number of glaciers in the Tibetan Plateau (TP) have experienced wastage in recent decades. And the wastage is different from region to region, even from glacier to glacier. A better understanding of long-term glacier variations and their linkage with climate variability requires extending the presently observed records. Here we present the first tree-ring-based glacier mass balance (MB) reconstruction in the TP, performed at the Hailuogou Glacier in southeastern TP during 1868–2007. The reconstructed MB is characterized mainly by ablation over the past 140 yr, and typical melting periods occurred in 1910s–1920s, 1930s–1960s, 1970s–1980s, and the last 20 yr. After the 1900s, only a few short periods (i.e., 1920s–1930s, the 1960s and the late 1980s) were characterized by accumulation. These variations can be validated by the terminus retreat velocity of Hailuogou Glacier and the ice-core accumulation rate in Guliya and respond well to regional and Northern Hemisphere temperature anomaly. In addition, the reconstructed MB is significantly and negatively correlated with August–September all-India monsoon rainfall (AIR) (r1871-2008 = −0.342, p < 0.0001). These results suggest that temperature variability is the dominant factor for the long-term MB variation at the Hailuogou Glacier. Indian summer monsoon precipitation does not affect the MB variation, yet the significant negative correlation between the MB and the AIR implies the positive effect of summer heating of the TP on Indian summer monsoon precipitation.

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Regionalization of seasonal precipitation over the Tibetan Plateau and associated large-scale atmospheric systems

Journal of Climate ◽

10.1175/jcli-d-20-0521.1 ◽

2020 ◽

pp. 1-45

Author(s):

Hui-Wen Lai ◽

Hans W. Chen ◽

Julia Kukulies ◽

Tinghai Ou ◽

Deliang Chen

Keyword(s):

Tibetan Plateau ◽

Summer Monsoon ◽

Indian Summer Monsoon ◽

Large Scale ◽

Late Summer ◽

Early Summer ◽

The Tibetan Plateau ◽

Summer Peak ◽

Precipitation Seasonality ◽

Winter Peak

AbstractPrecipitation over the Tibetan Plateau (TP) has major societal impacts in South and East Asia, but its spatiotemporal variations are not well understood mainly because of the sparsely distributed in-situ observation sites. With help of the Global Precipitation Measurement satellite product IMERG and ERA5 reanalysis, distinct precipitation seasonality features over the TP were objectively classified using a self-organizing map algorithm fed with ten-day averaged precipitation from 2000 to 2019. The classification reveals three main precipitation regimes with distinct seasonality of precipitation: winter peak, centered at the western plateau; early summer peak, found on the eastern plateau; and late summer peak, mainly located on the southwestern plateau. On a year-to-year basis, the winter peak regime is relatively robust, while the early summer and late summer peak regimes tend to shift mainly between the central and northern TP, but are robust in the eastern and southwestern TP. A composite analysis shows that the winter peak regime experiences larger amounts of precipitation in winter and early spring when the westerly jet is anomalously strong to the north of the TP. Precipitation variations in the late summer peak regime are associated with intensity changes in the South Asian High and Indian summer monsoon. The precipitation in the early summer peak regime is correlated with the Indian summer monsoon together with anticyclonic circulation over the western North Pacific. The results provide a basic understanding of precipitation seasonality variations over the TP and associated large-scale conditions.

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