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Changes in vegetation and moisture in the northern Tianshan of China over the past 450 years

Frontiers of Earth Science 2020年第2期14卷 479-491页

作者： Weihe REN Yan ZHAO Quan LI Jianhui CHEN Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of West China’s Environmental System(Ministry of Education) College of Earth and Environmental SciencesLanzhou UniversityLanzhou 730000China

Knowledge of historical changes in moisture within semi-arid and arid regions is the basis of climatic change predictions and strategies in response to long-term drought.In this study,a multiproxy peat record with highresolution from Sichanghu in the northern Tianshan was used to document the changes in vegetation and climate over the past 450 years in the arid Central Asia.The pollen,grain size,and loss on ignition(LOI)records indicate that the productivity of local peat began to increase at^1730 AD.The vegetation in the Sichanghu area experienced several transitions,from temperate desert to dense desert,marsh meadow,and steppe desert vegetation.The climate in the study area was extremely dry during the early stages of the Little Ice Age(LIA)(before 1730 AD)and relatively wet during the late stages(1730–1880 AD).The inferred changes in the moisture conditions of the Sichanghu peatland since the LIA may have been controlled by the extent of Arctic sea ice,the North Atlantic Oscillation,and the Siberian High via the connections of large-scale atmospheric circulations such as the Westerlies.

关键词： Little Ice Age pollen vegetation change moisture condition Tianshan arid Central Asia

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Effects of Intraseasonal Oscillation on the Anomalous East Asian Summer Monsoon During 1999

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Advances in Atmospheric Sciences 2008年第2期25卷 279-296页

作者：孙颖丁一汇 Laboratory for Climate Studies National Climate CenterChina Meteorological Administration

The 1999 East Asian summer monsoon was very unusual for its weak northward advance and remarkably anomalous climate conditions. The monsoonal southwesterly airflow and related rain belt in East Asia were blocked south of the Yangtze River Valley. The monsoonal airflow and major moisture transport conduct shifted eastward and turned northward to Japan from the tropical western Pacific rather than to East China from the South China Sea （SCS） as in normal years. Severe and prolonged drought occurred over extensive areas of North China and heavy precipitation in South China and Japan. The investigation on the possible intrinsic mechanisms related to such an anomalous monsoon year has shown that the unique behavior of intraseasonal oscillation may play an essential role during this process. During this year, the northward propagation of 30-60-day anomalous low-level cyclone/anticyclone collapsed in the region around 20°N and did not extend beyond the latitudes of the Yangtze River basin due to the barrier of strong cold air intrusion from the mid-latitudes. The southwesterly moisture flux on the northwestern flank of the anticyclonic moisture transport system in the western North Pacific, which was regulated by the northward shift of 30-60-day cyclonic/anticyclonic moisture transport, also did not reach the region north of 30°N as well. Under this circumstance, the weak northward advance of the monsoon westerlies and associated northward moisture transport could not arrive in North China and led to the severe droughts there in 1999. The SCS and South China were mostly affected by the airflow in the southern and northern flanks of the same 30-60-day cyclones or anticyclones, respectively, and thus controlled by the nearly reverse zonal wind and moisture convergent/divergent conditions. The rainfall in the SCS and South China showed out-of-phase oscillation through the transient local Hadley circulation, with the rainfall maximum occurring in the SCS （South China） when the 30-60-day anticyclone （cyclone） reached its pea

关键词： 30-60-day intraseasonal oscillation anomalous East Asian summer monsoon moisture transport moisture condition

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A STUDY ON moisture conditionS FOR WINTER WHEAT AND SUMMER MAIZE PRODUCTION IN THE HEILONGGANG AREA OF HEBEI PROVINCE

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Journal of Geographical Sciences 1993年第3期 79-84页

作者： Zhang Hongye Institute of Geography CAS

Winter wheat and summer maize are two important crops in the Heilonggang area which is the driest part of the North China Plain.The thermal-light conditions are satisfactory for double cropping of winter wheat-summer maize,but rainfall is deficient for two crops.In winter wheat growing period,the rainfall is very limited and the soil moisture conditions are poor.Wheat has to be irrigated in order to obtain better yields.Rainfall in summer maize growing period is high,and no irrigation is required for maize.Wheat production in this area should be restricted to a scale which is suitable to water resources conditions,while maize production can be further developed.

关键词： moisture condition winter wheat summer maize Heilonggang area

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