近200a来珠穆朗玛峰北坡远东绒布冰芯气候记录

１９９７年 ５月中美联合珠穆朗玛峰地区绒布冰川考察期间，在远东绒布冰川海拔 ６ ５００ ｍ的北 支冰流粒雪盆内钻取到一支４１ｍ长冰芯．通过数年层法并根据β活化度的参照年（１９５４年和 １９６３ 年），对远东绒布冰芯实施定年，冰芯底部为 １８１４年，冰芯年平均净积累量为 ２２４ ｍｍ（冰当 量）．根据远东绒布冰芯 （δ１８Ｏ的变化，重建了珠穆朗玛峰北坡地区近 ２００ ａ气候变化，发现有 ５次冷 期和５次暖期，且总趋势为变暖，这与本世纪北半球气候变暖的趋势相一致．远东绒布冰芯气候记 录同古里雅冰芯比较，两者的冷暖波动较为一致，说明青藏高原西北部和南部地区的气候变化具有 共性．但是，远东绒布冰芯中δ１８Ｏ的变化在短时间尺度上与降水量变化存在某些反相关性，这种关 系并未影响到δ１８Ｏ反映气温的长期变化趋势．

Recent temperature increase recorded in an ice core in the source region of Yangtze River

Interests on climate change in the source region of Yangtze River have been raised since it is a region with the greatest warming over the Tibetan Plateau (TP). A 70-year history of precipitation δ^(18)O has been recovered using an ice core record retrieved in a plat portion of the firn area in the Guoqu Glacier (33°34′37.8″N, 91°10′35.3″E, 5720 m a.s.l.), Mt. Geladaindong (the source region of Yangtze River), in November, 2005. By using a significant positive relationship between ice core δ^(18)O record and summer air temperature (July to September) from the nearby meteorological stations, a history of summer air temperature has been reconstructed for the last 70 years. Summer temperature was relatively low in 1940s and high in 1950s to the middle of 1960s. The lowest temperature occurred in the middle of 1970s. Temperature was low in 1980s and dramatically increased since 1990s, keeping the trend to the begin-ning of the 21st century. The warming rate recorded in the ice core with 0.5℃/10 a since 1970s is much higher that that in the central TP and the Northern Hemisphere (NH), and it becomes 1.1℃/10 a since 1990s which is also higher than these from the central TP and the NH, reflecting an accelerated warm-ing and a more sensitive response to global warming in the high elevation region.

Influencing domain of peripheral sources in the urban heavy pollution process of Beijing

The effect of city’s peripheral pollution sources is one of the key issues urgent to be solved in the decision-making of Beijing’s environmental pollution control. This paper comprehensively analyses the surface observations, and the satellite remote sensing data of Moderate Resolution Imaging Spectroradiometer (MODIS) and Total Ozone Mapping Spectrometer (TOMS) during the Beijing City Atmospheric Pollution Experiment (BECAPEX) from January to March, 2001, presents an "upstream" wind field resultant vector method for tracing peripheral pollution sources, and finds that the features of the urban heavy pollution processes of Beijing are significantly correlated with the impact of the emission sources of southern peripheral cities, and the pollutants transferred northwards from distant upstream sources are retarded by the U-shaped "Valley" topography in Beijing’s periphery. The two factors are responsible for the formation of the S-N zonal influencing domain of pollutants from the southern peripheral areas to Beijing. The paper also comprehensively analyses the features of flow field in the heavy pollution process in the Beijing region, and compares the heavy pollution process with samples of good air-quality days from January to March, 2001. The experiment of Hybrid Single-Particle Lagrangian Integrated Trajectory model (HYSPLIT-4) further reveals the diffusion trajectory of pollutants of the cities in Hebei and Shandong provinces and Tianjin city in the heavy pollution process of Beijing, and the simulations of the Regional Atmosphere Model System (RAMS) confirm the possible contribution of peripheral sources to the exceptionally heavy pollution process of the urban area of Beijing, thus revealing that the input of pollutants from southern peripheral cities is one of the important factors responsible for aggravating urban heavy pollution processes.

Climatic significance of δ^(18)O records from an 80.36 m ice core in the East Rongbuk Glacier, Mount Qomolangma (Everest)

The δ18O variations in an 80.36 m ice core retrieved in the accumulation zone of the East Rongbuk Glacier, Mount Qomolangma (Everest), is not consistent with changes of air temperature from both southern and northern slopes of Himalayas, as well as these of the temperature anomalies over the Northern Hemisphere. The negative relationship between the δ18O and the net accumulation records of the ice core suggests the "amount effect" of summer precipitation on the δ18O values in the region. Therefore, the δ18O records of the East Rongbuk ice core should be a proxy of Indian Summer Monsoon intensity, which shows lower δ18O values during strong monsoon phases and higher values during weak phases.