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

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Chinese Science Bulletin 2002年第8期47卷 691-696页

作者： keqin duan Ninglian Wang Jianchen Pu Chinese Acad Sci Cold & Arid Regions Environm & Engn Res Inst Lanzhou 730000 Peoples R China

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.

关键词： Dasuopu ice core accumulation monsoon abrupt change.

Changes in equilibrium-line altitude and implications for glacier evolution in the Asian high mountains in the 21st century

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Science China Earth Sciences 2022年第7期65卷 1308-1316页

作者： keqin duan Tandong YAO Ninglian WANG Peihong SHI Yali MENG School of Geography and Tourism Shaanxi Normal UniversityXi'an 710062China Institute of Tibetan Plateau Research Chinese Academy of SciencesBeijing 100101China College of Urban and Environmental Sciences Northwest UniversityXi'an 710127China

In the context of global warming,glaciers in the Asian High Mountains(AHMs)are shrinking at an accelerating *** their future change is helpful for understanding the hydrological and climatic effects related to glacier ***,we projected glacier change in the AHMs from 1979 to 2100 under shared socioeconomic pathway(SSP)scenarios from the perspective of temperature,equilibrium-line altitude(ELA),and accumulation *** annual mean temperature in the AHMs increased by 1.26℃ from 1979 to 2014,corresponding to an increase of 210 m in the mean ELA and a decrease of 1.7×10^(4)km^(2) in the glacier accumulation *** the SSP2-4.5(SSP5-8.5)scenario,the annual mean temperature in the AHMs would increase by 2.84℃(3.38℃)in 2040–2060 relative to that in 1850–1900,leading to the mean ELA reaching an elevation of5661 m(5777 m).The accumulation area in the AHMs decreased by 46.3%from 1995 to 2014 and was projected to decrease by60.1%in 2040–***,the annual mean temperature in the AHMs was projected to increase by 3.76℃(6.44℃)in2080–2100 relative to that in 1850–1900,corresponding to the ELA reaching an elevation of 5821 m(6245 m)and the accumulation area decreasing to 1.8×10^(4)km^(2)(0.5×10^(4)km^(2)).These data suggest that the conditions for glacier development will disappear in most of the AHMs,except for extreme high-altitude regions in the Tianshan,Pamir,and Himalaya *** the SSP2-4.5(SSP5-8.5)scenario,when the global mean temperature increases 1.5℃(2℃)above pre-industrial levels,the annual mean temperature will increase by 2.12℃(2.86℃)and the accumulation area will decrease by 15%(48%)in the AHMs compared with that in 1995–***,a 1.5℃ increase in global warming would keep 40%more of the glacial accumulation area(1.5×10^(4)km^(2))in the AHMs compared to a 2℃ increase in global warming.

关键词： Asia High Mountains Glacier Equilibrium-line altitude Accumulation area CMIP6

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Response of monsoon vari-ability in Himalayas to global warming

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Chinese Science Bulletin 2002年第21期47卷 1842-1845页

作者： duan keqin YAO Tandong PU Jianchen SUN Weizhen Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of SciencesLanzhou 730000China

Reconstructed annual net accumulation from the Dasuopu ice core recovered in Himalayas, with a good correlation to Indian monsoon, reflects a major precipitation trend in central Himalayas. The Dasuopu accumulation (DSP An) also shows a strong correlation to the Northern Hemispheric temperature. Generally, as the Northern Hemispheric temperature increases by 0.1 K, the accumulation decreases by about 90 mm and vise versa. Under the condition of global warming, especially since 1920, the Northern Hemispheric mean temperature has increased by about 0.5 K, whereas accumulation in Dasuopu ice core has decreased by about 450 mm. According to the relationship between accumulation and temperature, a scenario prediction of monsoon rainfall in central Himalayas is made.

关键词： Dasuopu ice core accumulation global warming.

Accumulation in Dasuopu ice core in Qinghai-Tibet Plateau and solar activity

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Chinese Science Bulletin 2000年第11期45卷 1038-1042页

作者： keqin duan Ninglian Wang Yuefang Li Weizheng Sun Lanzhou Inst Glaciol & Geocryol Ice Core & Cold Reg Res Lab Lanzhou 730000 Peoples R China

The time series of accumulation in recent 300 years correlated well with solar activity in Dasuopu ice core. Results of spectrum analysis on the accumulation time series of the Dasuopu ice core shows that there are some periods that coincide with the periods of solar activity. By comparing the long-time change trend of the accumulation in the Dasuopu ice core with various kinds of indexes of solar activity intensity, a negative correlation is found between the trend and solar activity.

关键词： Dasuopu ice core accumulation solar activity.

Ammonium record over the last 96 years from the Muztagata glacier in Central Asia

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Chinese Science Bulletin 2008年第8期53卷 1255-1261页

作者： ZHAO HuaBiao YAO TanDong XU BaiQing LI Zhen duan keqin State Key Laboratory of Cryospheric Science Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China Graduate University of Chinese Academy of Sciences Beijing 100049 China Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing 100085 China

As a major alkaline gas in the atmosphere, ammonia (NH3) plays an important role in atmospheric chemistry. However, there is little knowledge about NH3 variations in the Central Asia. Here we ana- lyzed the ammonium (NH+4) history recorded in an ice core from the East Pamir in Central Asia, which was drilled on the Mt. Muztagata at the elevation of 7010 m a.s.l. in 2003. The core was carefully dated and NH4+ concentration history during 1907―2002 was reconstructed. The result shows that NH4+ con- centration remained approximately constant until the 1930s after a sudden decrease at the very begin- ning of the 20th century, followed by a minimum in 1940 before increasing steadily to the peak at the end of 1990s. It is found that the annual mean NH4+ concentration was strongly associated with the Northern Hemisphere temperature, suggesting the impact of temperature on NH3 emissions in the Central Asia. Moreover, an increase of NH+4 concentration after 1940 also reflects the enhancement of NH3 emissions from anthropogenic sources such as fertilizer applications and livestock wastes in the 20th century.

关键词：冰块核心铵含量氨水散发冰川

Seasonal variations of dust record in the Muztagata ice cores

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Chinese Science Bulletin 2008年第16期53卷 2506-2512页

作者： WU GuangJian YAO TanDong XU BaiQing TIAN LiDe LI Zhen duan keqin Laboratory of Environment and Process on Tibetan Plateau Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing 100085 China State Key Laboratory of Cryospheric Science Chinese Academy of Sciences Lanzhou 730000 China

Based on the oxygen isotope ratio and microparticle record in ice cores recovered at Mt. Muztagata, Eastern Pamirs, the seasonal variations of atmospheric dust have been reconstructed for the past four decades. High dust concentrations and coarser particle grains have the similar trend with oxygen iso- tope value. Our statistical results indicate that 50%―60% high dust concentration samples occur dur- ing the season with high oxygen isotope values (summer), while low dust storm frequency during spring and winter. Back-trajectory analysis shows that the air mass hitting Muztagata predominately came from West Asia (such as Iran-Afghanistan Plateau) and Central Asia, which are the main dust source area for Muztagata. Dust storms in those source areas most frequently occur during summer (from May to August), while frequent dust storm events in northern China mainly occur during spring (March to May). Regions in the path of Asian dust transport, such as in Japan, the North Pacific, and Greenland, also show high dust concentrations during spring (from March to May). Our results indicate that dust storms have different seasonality in different regions within Asia.

关键词：灰尘季节变化冰层氧同位素

Improved Land Use and Leaf Area Index Enhances WRF-3DVAR Satellite Radiance Assimilation： A Case Study Focusing on Rainfall Simulation in the Shule River Basin during July 2013

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Advances in Atmospheric Sciences 2018年第6期35卷 628-644页

作者： Junhua YANG Zhenming JI Deliang CHEN Shichang KANG Congshen FU keqin duan Miaogen SHEN State Key Laboratory of Cryospheric Sciences Northwest Institute of Eco-Environment and ResourcesChinese Academy of Sciences (CAS) Lanzhou 730000 China School of Atmospheric Sciences Sun Yat-sen University Guangzhou 510275 China Department of Earth Sciences University of Gothenburg Gothenburg 40530 Sweden Yale School of Forestry and Environmental Studies Yale University New Haven Connecticut 06511 USA College of Tourism and Environment Shaanxi Normal University Xi'an 710000 China Key Laboratory of Alpine Ecology and Biodiversity Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing 100101 China CAS Center for Excellence in Tibetan Plateau Earth Sciences Beijing 100101 China

The application of satellite radiance assimilation can improve the simulation of precipitation by numerical weather prediction models. However, substantial quantities of satellite data, especially those derived from low-level（surface-sensitive）channels, are rejected for use because of the difficulty in realistically modeling land surface emissivity and energy ***, we used an improved land use and leaf area index（LAI） dataset in the WRF-3 DVAR assimilation system to explore the benefit of using improved quality of land surface information to improve rainfall simulation for the Shule River Basin in the northeastern Tibetan Plateau as a case study. The results for July 2013 show that, for low-level channels（e.g., channel 3）,the underestimation of brightness temperature in the original simulation was largely removed by more realistic land surface information. In addition, more satellite data could be utilized in the assimilation because the realistic land use and LAI data allowed more satellite radiance data to pass the deviation test and get used by the assimilation, which resulted in improved initial driving fields and better simulation in terms of temperature, relative humidity, vertical convection, and cumulative precipitation.

关键词： WRF-3DVAR land use leaf area index radiance assimilation rainfall simulation

Water isotope variations in the snow pack and summer precipitation at July 1 Glacier, Qilian Mountains in northwest China

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Chinese Science Bulletin 2007年第21期52卷 2963-2972页

作者： ZHOU ShiQiao NAKAWO Masayoshi SAKAI Akiko MATSUDA Yoshihiro duan keqin PU JianChen Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing 100085 China Institute of Plateau Meteorology China Meteorological Administration Chengdu 610071 China Research Institute for Humanity and Nature Kyoto 606-8502 Japan Graduate School of Environmental Studies Nagoya University Nagoya 464-8601 Japan Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China

This paper presents the stable isotope data of the snow pack and summer precipitation collected at the July 1 Glacier, Qilian Mountains in northwest China and analyses their relationships with meteorologi- cal factors. On an event scale, there is no temperature effect on the δ 18O values in the summer pre- cipitation, whereas the amount effect is shown to be clear. By tracing the moisture transport history and comparing the precipitation with its isotopic composition, it is shown that this amount effect not only reflects the change in moisture trajectory, which is related to the monsoon activities, but is also associated with the cooling degree of vapor in the cloud, the evaporation of falling raindrops and the isotopic exchange between the falling drops and the atmospheric vapor. As very little precipitation occurs in winter, the snow pack profile mainly represents the precipitation in the other three seasons. There are low precipitation δ 18O ratios in summer and high ratios in spring and autumn. The Meteoric Water Line (MLW) for the summer precipitation is δ D = 7.6 δ 18O + 13.3, which is similar to that at Delingha, located in the south rim of the Qilian Mountains. The MWL for the snow pack is δ D = 10.4 δ 18O + 41.4, showing a large slope and intercept. The deuterium excess (d) of the snow pack is positively correlated with δ 18O, indicating that both d and δ 18O decrease from spring to summer and increase from early autumn to early spring. This then results in the high slope and intercept of the MWL. Sea- sonal fluctuations of d in the snow pack indicate the change of moisture source and trajectory. During spring and autumn, the moisture originates from continental recycling or rapid evaporation over rela- tively warm water bodies like Black, Caspian and Aral Seas when the dry westerly air masses pass over them, hence very high d values in precipitation are formed. During summer, the monsoon is responsi- ble for the low d values. This indicates that the monsoo

关键词：青藏高原祁连山冰川降水粒雪

Projected Regional 1.50℃and 2.00℃Warming Threshold-crossing Time Worldwide Using the CMIP6 Models

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Chinese Geographical Science 2023年第6期33卷 1095-1108页

作者： MENG Yali duan keqin SHANG Wei SHI Peihong LI Shuangshuang CHENG Ying CHEN Rong ZHANG Zhaopeng School of Geography and Tourism Shaanxi Normal UniversityXi’an710119China

The Paris Agreement aims to limit global warming to well below 2.00℃and pursue efforts to limit the temperature increase to 1.50℃.However,the response of climate change to unbalanced global warming is affected by spatial and temporal *** better understand the regional warming response to global warming at 1.50℃and 2.00℃,we detected the 1.50℃and 2.00℃warming threshold-crossing time(WTT)above pre-industrial levels globally using the Coupled Model Intercomparison Project phase 6(CMIP6)*** findings indicate that the 1.50℃or 2.00℃WTT differs substantially *** warming rate of land would be approximately 1.35–1.46 times that of the ocean between 60°N–60°S in 2015–***,the land would experience a 1.50℃(2.00℃)warming at least 10–20 yr earlier than the time when the global mean near-surface air temperature reaches 1.50℃(2.00℃)***,the Southern Ocean between 0°and 60°S considerably slows down the global 1.50℃and 2.00℃*** 2040–2060,over 98.70%(77.50%),99.70%(89.30%),99.80%(93.40%),and 100.00%(98.00%)of the land will have warmed by over 1.50℃(2.00℃)under SSP(Shared Socioeconomic Pathway)1–2.6,SSP2-4.5,SSP3-7.0,and SSP5-8.5,*** conclude that regional 1.50℃(2.00℃)WTT should be fully considered,especially in vulnerable high-latitude and high-altitude regions.

关键词： CMIP6(Coupled Model Intercomparison Project phase 6) global warming 1.50℃warming time 2.00℃warming time regional differences