What controls precipitation δ18O in the southern Tibetan Plateau at seasonal and intra-seasonal scales?

Abstract HKT-ISTP 2013 B

Monsoon and Dust Signals Recorded in Dasuopu Glacier, Tibetan Plateau

During summer 1997, a 15m firn core was recovered from Dasuopu glacier (28°23\u27N, 85° 44\u27 E; 7000 m a.s.l.) on the northwest margin of Xixabangma Feng in the central Himalaya. Oxygen isotope values and concentrations of Ca2+, Mg2+, NH4+, SO42- and NO3- were measured over the 10 years of snow accumulation captured in the firn core. The seasonal variations of δ18O values and major-ion concentrations in the Dasuopu core indicated that summer monsoon and dust signals are clearly recorded in Dasuopu glacier. Annual variations in the δ18O values are controlled by the amount effect, with more negative (i.e. lighter) δ18O values representing summer monsoon precipitation characteristic of tropical regions. Higher concentrations of Ca2+, Mg2+ and SO42- reflect the influx of mineral aerosols from the vast arid and semi-arid desert regions to the north and west during the spring dust-storm period. High spring concentrations of NH4+ and NO3- appear to reflect changes in regional biogenic-source strength

Glaciological and climatological drivers of heterogeneous glacier mass loss in the Tanggula Shan (Central-Eastern Tibetan Plateau), since the 1960s

This study was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (grant no. XDA20100300), the Swiss National Science Foundation (200021E_177652/1) within the framework of the DFG Research Unit GlobalCDA (FOR2630) and the Dragon 5 program supported by ESA and NRSCC (4000136930/22/I-NB). A. B. acknowledges research funding (grant no. CRG/2021/002450) received from Science & Engineering Research Board (SERB), Department of Science & Technology (DST), India.Despite their extreme elevation, glaciers on the Tibetan Plateau are losing mass in response to atmospheric warming, the pattern of which purportedly reflects regional contrasts in climate. Here we examine the evolution of glaciers along ~500 km of the Tanggula Shan, Central-Eastern Tibetan Plateau. Using remotely sensed datasets, we quantified changes in glacier mass, area and surface velocity, and compared these results to time series of meteorological observations, in order to disentangle drivers of glacier mass loss since the 1960s. Glacier mass loss has increased (from −0.21 ± 0.12 m w.e. a−1 in 1960s–2000s, to −0.52 ± 0.18 m w.e. a−1 in 2000s–2015/18) in association with pervasive positive temperature anomalies (up to 1.85°C), which are pronounced at the end of the now lengthened ablation season. However, glacier mass budget perturbations do not mirror the magnitude of temperature anomalies in sub-regions, thus additional factors have heightened glacier recession. We show how proglacial lake expansion and glacier surging have compounded glacier recession over decadal/multi-decadal time periods, and exert similar influence on glacier mass budgets as temperature changes. Our results demonstrate the importance of ice loss mechanisms not often incorporated into broad-scale glacier projections, which need to be better considered to refine future glacier runoff estimates.Publisher PDFPeer reviewe

Stable-Isotopic Composition of Precipitation Over the Northern Slope of the Central Himalaya

Stable-water-isotope data (deltaD and delta(18)O) from three groups of samples (fresh-snow and snow-pit samples collected on Qomolangma (Mount Everest) and Xixabangma during field seasons 1997,1998 and 2001, and precipitation samples collected at Tingri station during summer 2000) are presented and used to survey the isotopic composition of precipitation over the northern slope of the central Himalaya. Multi-year snow-pit samples on Qomolangma have a local meteoric water-line (slope = 8) close to the global value. Deuterium excess (d = deltaD - 8delta(18)O) values at Tingri are much lower than those in fresh snow from Qomolangma, probably due to differences in moisture source and air-mass trajectories as well as local weather conditions. There is no obvious seasonal trend for d values in the Qomolangma region. A negative relationship exists between delta(18)O and d values in both fresh snow on Qomolangma and precipitation at Tingri. Fresh-snow samples collected from different altitudes on Xixabangma allow us to investigate the altitude effect on delta(18)O values in snow. Of four storm events, only one has an obvious altitude effect on delta(18)O variation and a very low gradient of -0.1% per 100 in elevation

Spatial distribution of the persistent organic pollutants across the Tibetan Plateau and its linkage with the climate systems: a 5-year air monitoring study

The Tibetan Plateau (TP) has been contaminated by persistent organic pollutants (POPs), including legacy organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) through atmospheric transport. The exact source regions, transport pathways and time trends of POPs to the TP are not well understood. Here polystyrene–divinylbenzene copolymer resin (XAD)-based passive air samplers (PASs) were deployed at 16 Tibetan background sites from 2007 to 2012 to gain further insight into spatial patterns and temporal trends of OCPs and PCBs. The southeastern TP was characterized by dichlorodiphenyltrichloroethane (DDT)-related chemicals delivered by Indian monsoon air masses. The northern and northwestern TP displayed the greatest absolute concentration and relative abundance of hexachlorobenzene (HCB) in the atmosphere, caused by the westerly-driven European air masses. The interactions between the DDT polluted Indian monsoon air and the clean westerly winds formed a transition zone in central Tibet, where both DDT and HCB were the dominant chemicals. Based on 5 years of continuous sampling, our data indicated declining concentrations of HCB and hexachlorocyclohexanes (HCHs) across the Tibetan region. Inter-annual trends of DDT class chemicals, however, showed less variation during this 5-year sampling period, which may be due to the ongoing usage of DDT in India. This paper demonstrates the possibility of using POP fingerprints to investigate the climate interactions and the validity of using PAS to derive inter-annual atmospheric POP time trends

Reconstruction of Indian Ocean summer monsoon dynamicsat Nam Co using lipid biomarkers since 24 cal ka BP

Abstract HKT-ISTP 2013 B

Occurrence and characteristics of rock glaciers in the Poiqu River basin – Central Himalaya

Funding: This study was conducted within the framework of the Dragon 4 program funded by ESA (4000121469/17/I-NB) and further supported by the Strategic Priority Research Program of Chinese Academy of Sciences (XDA20100300), Swiss National Science Foundation (Grant No. IZLCZ2_169979/1) and the Hong Kong Research Grants Council (CUHK14303417 and HKPFS PF16-03859).Rock glaciers are important to study as they can be of hydrological importance and could have serious hazard potentials. Existing investigations about rock glaciers in High Mountain Asia indicate that the landforms are abundant, but information is still rare for large parts of the region. We compiled a rock glacier inventory for the Poiqu River basin, Central Himalaya. The mapping was conducted using very high-resolution Pléiades imagery and digital elevation model and imagery available from Google Earth. Rock glaciers were classified either active or inactive based on interferograms generated using ALOS-1 PALSAR data. Moreover, we developed a new method to automatically map the frontal slopes of the rock glaciers to investigate their activity. The results reveal 370 rock glaciers including 148 active and 222 inactive ones. We found nine rock glaciers damming lakes, three of which could be potentially dangerous. The overall rock glacier area is about 20.9 km which is more than 10% of the glacier area. The two largest rock glaciers cover 0.50 and 0.45 km². The rock glaciers are located at elevations between ~4000 and ~6000 m above sea level (mean elevations ~5100 m). Most of the rock glaciers face towards East and Southwest. The mean overall slope is 19.3° with the active ones being on average only slightly steeper (active: 19.7°, inactive: 19.0°). Their frontal slopes, however, are clearly steeper. The availability of very high-resolution data was key to generate a rock glacier inventory and allowed assessment of the rock glacier characteristics with high accuracy.PreprintNon peer reviewe

Role of glacier runoff in the Heihe Basin

We estimated the fluctuation of precipitation and air temperature from Dunde ice core data since 1606 comparing to meteorological data taken near the July 1st glacier since 1930s. Then, we calculated the discharges from glaciers and glacier-free areaFurthermore, we analyzed the sensitivity of those discharges to meteorological factor. The result revealed that calculated discharge from glacier-free area increased with precipitation. Meanwhile, calculated discharge from glaciers decreased with precipitation. Since little precipitation cause expose the glacier ice surface, which can absorb almost solar radiation, then glacier melt accelerated. Then, relatively large discharge from glacier can be provided when the discharge from glacier-free area is less. Therefore, discharge from glacier make up for the shortage of discharge from glacier-free area due to less precipitation. Then, water supply for living people in the oasis and desert would have been maintained from ancient days