Dasuopu Glacier Research Articles

Monsoon Variability in the Himalayas under the Condition of Global Waming

An ice core-drilling program was carried out at the accumulation area of Dasuopu glacier (28°23'N, 85°43'E, 7100 m a.s.l.) in the central Himalayas in 1997. The ice core was analyzed continuously for stable isotopes (δ18O), and major ions throughout the core. Cycles indicated by δ18O, cations were identified and counted as seasonal fluctuations as annual increment from maximum to maximum values. Reconstructed 300-year annual net accumulation (water equivalent) from the core, with a good correlation to Indian monsoon, reflects a major precipitation trend in the central Himalayas. The accumulation trend, separated from the time series, shows a strong negative correlation to Northern Hemisphere temperature. Generally, as northern hemisphere temperature increases 0.1°C, the accumulation decreases about 80 mm, reflecting monsoon rainfall in the central Himalayas has decreased over the past decades in the condition of global warming.

Precipitation variability in central Himalayas and its relation to Northern Hemisphere temperature

A 149.8-m-long ice core was drilled at the accumulation area of Dasuopu glacier (28°23′N, 85°43′E, 7100 m a.s.l.) in the central Himalayas in 1997. The ice core was analyzed continuously for stable isotopes (δ 18O), cations (Na+, K+, Mg2+, Ca2+) and anions (Cl−, SO 4 − , NO 3 − ) throughout the core. Cycles indicated by δ18O, cations and anions were identified and counted as seasonal fluctuations as annual increment from maximum to maximum values. Reconstructed 300-year annual net accumulation from the core reveals a major precipitation trend for the central Himalayas with an average precipitation 750 mm per year. The trend, separated from the time series, shows a strong correlation to global temperature. Generally, as northern global temperature increases 0.1δC, the accumulation decreases about 80mm and vise versa. This may suggests that monsoon precipitation in Himalayas have decreased continuously in past decade as a response to global warming.

On the relationship between Dasuopu Snow Accumulation and the Asian Summer Monsoon

The Asian summer monsoon (ASM) is an important component of the global climate system. We investigate the relationship that exists between it and the snow accumulation record from an ice core drilled on the Dasuopu glacier in the Himalayas. This ice core record has been proposed as a proxy to study variability in the ASM. We argue that there is a weak direct expression of the ASM in the snow accumulation time series from the ice core. This is the result of the extreme elevation of the ice core site and the surface‐trapped characteristic of the atmospheric moisture transport associated with the ASM. We will present evidence of a coupling between Dasuopu snow accumulation (DSA) and the Hadley and Walker circulations. In particular, we argue that the recent reduction in snow accumulation at the site is the result of an intensification of the regional Hadley circulation.

Recent change of the ice core accumulation rates on the Qinghai-Tibetan Plateau

Three ice cores recovered from the Himalayas (i.e. the East Rongbuk Glacier and the Far East Rongbuk Glacier at Mt. Qomolangma (Everest), and the Dasuopu Glacier at Xixiabangma) show a sharp decline in the accumulation rates since the 1950s, which is consistent with the precipitation fluctuation over India and the low northern latitude zone (5°–35°N). Correspondingly, an increasing trend is observed for the ice core accumulations from the central and northern Qinghai-Tibetan Plateau (i.e. the Xiao Dongkemadi Glacier in the central Tanggula Mountains, the Guliya Ice Cap in the western Kunlun Mountains, and the Dunde Ice Cap in the Qilian Mountains) since the 1950s, which is consistent with the precipitation fluctuation over the middle-high northern latitude zone (35°–70°N). However, the variation magnitude of the high-elevation ice core accumulations is more significant than that of precipitation at the low-elevation places, suggesting its extra sensitivity of high-elevation areas to climatic change. The inter-decadal abrupt change of the African-Asian summer monsoon in the 1960s may attribute to the recent ice core accumulation change during the recent decades.

Temperature and methane changes over the past 1000 years recorded in Dasuopu glacier (central Himalaya) ice core

AbstractIn 1997, three ice cores were recovered from Dasuopu glacier on the northern slope of the central Himalaya. the first core, 159.9 m long, was drilled at 7000ma.s.l. down the flowline from the top of the col. the second core, 149.2m long, was drilled on the col at 7200ma.s.l. the third core, 167.7 m long, was also drilled on the col at 7200ma.s.l., 100 maway from the second core. the present paper discusses the δ18O and methane results reconstructed for the past 1000 years based on the second core. the δ18O can be interpreted as an air-temperature signal. the methane concentration is mainly representative of atmospheric methane concentration. Both δ18O and methane records show an obvious increasing trend in the past 1000 years. Methane concentration in the record is similar to the fluctuations of δ18O, decreasing during cold periods and increasing during warm periods. the Little Ice Age was well recorded in the core by both δ18O and methane. the coldest period appeared in the late 18th century, accompanied by a decrease in methane concentration. the abrupt methane-concentration increase starting after the 18th century is no doubt due to anthropogenic input. the observed methane-concentration decrease during World Wars I and II clearly demonstrates the importance of the anthropogenic input to atmospheric methane concentration if further measurements prove that it is a true atmospheric signal.

Indian monsoon and North Atlantic Oscillation signals reflected by Cl– and Na+ in a shallow ice core from Dasuopu glacier, Xixabangma, Himalaya

AbstractInformation about past atmospheric circulation and climate change can be revealed by the chemical constituents of ice cores. Based on the analytical results of Cl– and Na+ concentrations in an 18.5 m ice core, which contains 14 annual layers, from the Dasuopu glacier, central Himalaya, a significant correlation is found between Cl– and Na+ concentrations. This, along with the average Cl–/Na+ weight ratio of 1.9, indicates that moisture at the drilling site came mostly from oceans. Furthermore, there was a high positive correlation between the Cl–/Na+ ratio in the summer monsoon layers and the monsoon rainfall in northeast India, and there exists a teleconnection between the Cl– and Na+ concentrations in this shallow ice core and the North Atlantic Oscillation.

Events of abrupt change of Indian monsoon recorded in Dasuopu ice core from Himalayas

Three ice cores distributed across Dasuopu glacier in Himalayas were recovered. A 400-year net annual accumulation record reconstructed from one of the cores reflects the major precipitation trend in the central Himalayas. This record is related closely to the Indian monsoon precipitation. Wavelet and moving T-test were applied to the 400-year-long Dasuopu accumulation record, and significant staggered variability and abrupt change of the record on interannual to centennial time scales are identified. Finally the possible reason for abrupt change of the accumulation record is discussed.

Indian monsoon variability in the Himalaya since AD 1800

AbstractThree ice cores distributed across Dasuopu (DSP) glacier in the Himalaya were recovered. the annual net accumulation (An) record reconstructed from one of the cores reflects major precipitation variability for the central Himalaya. This record agrees well with precipitation records from Nepal and northeast India, while it does not compare well with the all-India precipitation record. Singular spectrum analysis applied to the 200 year long Dasuopu accumulation (DSP An) record indicates significant variability on interannual and inter-decadal time-scales. the record shows that the early 18th century was dry, wet conditions prevailed during the period 1820–1930, and after 1930 An decreased to its present value. Distinct secular trends were not found in the record. for the period 1950– 94, the variability of DSP An is found to correlate significantly with the thermal contrast between the Tibetan Plateau and the Indian Ocean surface temperature. Additionally, a significant relationship between DSP An and solar activity is detected.

Transport of atmospheric impurities over the Qinghai–Xizang (Tibetan) Plateau as shown by snow chemistry

Chemical records were recovered from samples collected from snow pits over two transects (S–N and SE–NW) across the Qinghai–Xizang (Tibetan) Plateau. The records show that the flux of major ions in the regions to the north of Mt Tanggula is, on the average, 6–30 times higher than that of the regions to the south, and 0.6–5 times higher than regions to the southeast. It appears that Mt Tanggula provides a barrier to continental dust transported across the plateau from the north and to marine aerosols transported from the southeast. The spatial patterns of snow chemistry as well as the total suspended particle (TSP) distribution along the northern Qinghai–Xizang Highway demonstrate that continental dust originates mainly from the deserts to the north, while monsoon sources of moisture exert greater influence on snow chemistry on the southern part of the plateau.Seasonal variations of the major ions were also examined in a firn core drilled at a height of 7000m on the Dasuopu Glacier and in a snow pit from the Meikuang Glacier (eastern Kunlun). The choice of a high altitude site at Dasuopu, and the sampling season (before snowmelt) at Meikuang, avoided post-depositional modification processes (mainly the elution effect of meltwater), thus guaranteeing the reliable recovery of the distribution of impurities in different seasons. The peak of the impurities appear at Dasuopu during the spring and at Meikuang in the winter/spring, coinciding with the Asian dust season. However, the amplitude of the seasonal variations at Meikuang is much higher than at Dasuopu.pH values at the Dongkemadi Glacier are greater than 6, but at the Dasuopu Glacier (Himalayas) they range between 4 and 7.5. The liquid conductivity (LC) from Dongkemadi is positively correlated with the pH, while at Dasuopu, LC is positively correlated with pH when pH is below 6 and negatively correlated with pH when it is greater than 6. This implies that during August to September the Himalayan range is a transition zone between the transportation of continental dust and marine aerosols.

Evidence of the Kuwaiti oil fires in the Dasuopu glacier ice core, central Himalaya

Evidence of the Kuwaiti oil fires in the Dasuopu glacier ice core, central Himalaya

Monsoon and dust signals recorded in Dasuopu glacier, Tibetan Plateau

AbstractDuring summer 1997, a 15 m firn core was recovered from Dasuopu glacier (28°23′ N, 85°44′ E; 7000 m a.s.l.) on the northwest margin of Xixabarngma 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 indicate that summer monsoon and dust signals are clearly recorded in Dasuopu glacier. Annual variations in 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.

Geochemical analyses of a Himalayan snowpit profile: implications for atmospheric pollution and climate

Organic compounds, extracted from snow and ice from the Dasuopu glacier, on the Qinghai-Tibetan Plateau in Southwest China at an altitude of 7000 m above sea level (asl), were identified through pre-enrichment, solvent extraction and subsequent GC–MS analysis. The average concentration of the extractable organic matter reached 45.4 μg/l. C 15–C 33 n-alkanes, C 6–C 18 n-alkanoic acids, C 24–C 31 n-alkan-2-ones and esters were derived from subtropical higher plants, as well as marine algae and bacteria. Organic compounds, indicative of petroleum residues such as automobile and diesel exhaust were also unexpectedly identified in the glacial snow. These included n-alkanes, alkylcyclohexanes, pristane, phytane, extended C 19–C 29 tricyclic terpanes, a C 24 tetracyclic terpane, C 27–C 35 αβ hopanes, and C 27–C 29 steranes. Their presence indicates that the remote mountainous region and, to some extent, the middle-upper troposphere are polluted by human activities. Concentrations of some organic compounds, and total extractable organic matter, display a weak seasonal variation, postulated to be related to the location of middle-upper troposphere. The C 17 n-alkane abundance and some molecular ratios exhibit a stronger seasonal variation, which may signify strong climatic change.

Evidence for recent climate change from ice cores in the central Himalaya

AbstractComparison of the terminus locations of Rongbuk Glacier, Mount Everest, measured in 1966 and 1997 shows that in the past 30 years the glacier has retreated 170–270 m equivalent to a retreat speed of 5.5–8.7 m a–1 . During summer 1997, a 15 m firn core was recovered from Dasuopu glacier (28°23’ N, 85°44’ E; 7000 m a.s.D on the northwest margin of Xixabangma Feng, Xizang (Tibet). The seasonal variations of δ18O values in the core indicate that monsoon signals are clearly recorded in the glacier. δ18O values are controlled by the amount effect in the monsoon season; more negative δ18O is representative of the monsoon season in snow layers. Analysis of the relationship between ice-core δ18O, sampled from 6500 m a.s.l. on the north side of Mount Everest, and instrumental series representing regional-scale precipitation, atmospheric circulation and temperature suggests a change in the relative influence of these parameters on δ18O since the 1940s. The results of the comparison add to and lengthen the sparse array of instrument data available for the Tibetan (Qinghai-Xizang) Plateau and demonstrate a recent decline in moisture flux for at least the southern part of the plateau. Glacier retreat, associated with a recent increase in temperature in the region, is coincident with this period of decreased moisture flux.

Summer monsoon and dust signals recorded in the Dasuopu firn core, central Himalayas

In September 1997, a 15-m firn core was recovered from an elevation of 7 000 m a. s. I, from the Dasuopu Glacier in the central Himalayas. The analysis of 6Is0 values and major ion ( Ca2 + , Mg2 + , NH,' , SO:- and NO, ) concentrations shows that average annual accumu- lation is 0.75 m (water equivalent) in the Dasuopu firn core. The seasonal variations of 6180 values and major ion concentrations in the core indicate that present summer monsoon and dust signals are recorded with high-resolution in the Dasuopu Glacier. 6180 in precipitation are con- trolled by amount effect in summer monsoon season, more negative 6180 is representative of summer monsoon signal in snow layers. Higher concentrations of Ca2 + , Mg2 + , SO: - and NO; are dominated by spring dust storm imput derived from the arid and semi-arid desert regions in central Asia. Also EOF analysis verifies that high spring concentrations of major ions are consis- tent. Due to the possibly different sources, the secondary variations of NH,' and NO, are neg- atively relevant with that of Ca2+ and Mg2 + . CAUSED by the variations of summer monsoon strength and arid and semi-arid environment, the change of precipitation in monsoon area and atmospheric dust is closed to human being life. Ice core records with high-resolution may provide luxuriant infonnation about the monsoon and dust change. Due to its high el- evation, the Himalayas acts as a boundary between the Indian summer monsoon region to the south and the cold and arid Qinghai-Tibetan Plateau controlled by continental climate to the north, and therefore ice core records from such sites can provide insight into the change of summer monsoon and atmospheric envi- ronment.

Climatic and environmental implications from organic matter in Dasuopu glacier in Xixiabangma in Qinghai-Tibetan Plateau

A series of organic compounds in snow and ice were identified from Dasuopu glacier in Xixiabangma in Qinghai-Tibetan Plateau. Organic compounds derived from natural organisms include n-alkanes ranging from C15 to C33, normal monocarboxylic acids of C 6 -C 18 , n-alkan-2-ones of C 24 -C 31 and esters. The unstable compounds widely present in lower troposphere disppear in the middle-upper troposphere. I^ots of other organic compounds from petroleum residues were also unexpectedly identified from the glacier, covering pristane, phytane, extended tricyclic terpanes of C 19 -C 29 , C 24 tetracyclic terpane, αβ hopane compounds of C 27 -C 35 , and cholestanes of C 27 -C 29 . The remote Xixiabangma region is unambiguously polluted from anthropology activities. The petroleum residues were proposed to be mainly from the Mideast and India, not from China. The organic pollutants from oil fires ignited during the well-known Gulf War which broke out in 1991 were also recorded in the glacier. Such organic indexes as n C 29 / n C1 7 , nC29/nC27 , n C29/ nC 24 , C 30 -ketone/C 30 -ester, C 24 -tetracyclic-/C 24 -tricyclic-terpane and CPIn ( n standing for n -alkanes) exhibit the same strong seasonal variation as δ 18 0, providing information on the atmospheric circulation of the plateau. These ratios decrease in summer half year when the monsoon dominated, and increase in winter half year when the westerly stream jet dominated.

Increasing atmospheric pollution revealed by Pb record of a 7 000-m ice core

Concentrations of Pb in Dasuopu ice core in the Qinghai-Tibetan Plateau have been directly measured by ICP-MS at pg/g level. The Pb profile shows a very significant increase in modern times due to anthropogenic input. The use of leaded gasoline in the South Asian countries may be a main source of Pb in this region. The input of Pb to the Dasuopu Glacier is mainly supplied by Indian summer monsoon moisture which traverses the pass at the head of the Dasuopu Glacier.

A new type of ice formation zone found in the Himalayas

Ice formation was studied on the Dasuopu Glacier located in the Mount Xixabangrna (28°23′ N, 85°43′E) in the Himalayas. Snow pits and shallow ice cores are analyzed to reveal ice formation process. The results show that the ice formation process, or in other words, the process of densitification, on the col (7 000 m a. s. I.) of the Dasuopu Glacier is a stable, slow and gradual process. The snow-ice transformation on the glacier is estimated to be 30–40 m below the surface. The temperature on the Dasuopu Glacier is very low (~ - 14°C at 10 m) and similar to that in polar type ice cap. We, therefore, speculate that the process of snow-ice transformation is undertaken under snow pressure, and that there is a percolation zone on the Dasuopu Glacier. The high altitude of the col and monsoon snow fall accompnied by heavy cloud and high albedo favorite the percolation zone formation.

Environmental information recorded in shallow ice core of Dasuopu glacier in the Qinghai-Tibetan Plateau

Environmental information recorded in shallow ice core of Dasuopu glacier in the Qinghai-Tibetan Plateau