Yin Yunhe

Climatic trends over the Tibetan Plateau during 1971-2000

Trends of annual and monthly temperature, precipitation, potential evapotranspiration and aridity index were analyzed to understand climate change during the period 1971–2000 over the Tibetan Plateau which is one of the most special regions sensitive to global climate change. FAO56-Penmen-Monteith model was modified to calculate potential evapotranspiration which integrated many climatic elements including maximum and minimum temperatures, solar radiation, relative humidity and wind speed. Results indicate generally warming trends of the annual averaged and monthly temperatures, increasing trends of precipitation except in April and September, decreasing trends of annual and monthly potential evapotranspiration, and increasing aridity index except in September. It is not the isolated climatic elements that are important to moisture conditions, but their integrated and simultaneous effect. Moreover, potential evapotranspiration often changes the effect of precipitation on moisture conditions. The climate trends suggest an important warm and humid tendency averaged over the southern plateau in annual period and in August. Moisture conditions would probably get drier at large area in the headwater region of the three rivers in annual average and months from April to November, and the northeast of the plateau from July to September. Complicated climatic trends over the Tibetan Plateau reveal that climatic factors have nonlinear relationships, and resulte in much uncertainty together with the scarcity of observation data. The results would enhance our understanding of the potential impact of climate change on environment in the Tibetan Plateau. Further research of the sensitivity and attribution of climate change to moisture conditions on the plateau is necessary.

The climate regionalization in China for 1981-2010

The scheme of climate regionalization in China was conducted by the classification criteria of temperature zone, arid/humid region and climatic sub-region, and the variables used in the criteria were calculated as mean values of the 30 years by using the daily meteorological data of 658 stations from 1981 to 2010. In the classification criteria, the temperature zones were classified by the general guideline of the days with daily temperature steady above 10℃, and the secondary guideline of January mean temperature, or by their referenced variables including the accumulated temperature with daily temperature steady above 10℃ and annual minimum temperature, respectively. The arid/humid regions were classified by the annual aridity index and annual precipitation amount in turn. The climatic sub-regions were classified by the July mean temperature. The result shows that China can be divided into 12 temperature zones, 24 arid/humid regions and 56 climatic sub-regions. Compared with the climate regionalization scheme for the period of 1951- 1980, several boundaries of temperature zones in eastern China shifted northward in 1981-2010 due to the climate warming. The east part of the northern boundary of warm temperate zone shifted more than 1.0° at a maximum. On average, the east part of the northern boundary of north subtropical zone shifted 1.0°. The middle part of the northern boundary of mid-subtropical zone shifted 2.0° at a maximum. The west part of the northern boundary of south subtropical zone shifted 0.5°-2.0°. In West China, the shift of temperature zone was not significant in horizontal due to the vertical landform. However, the plateau sub-cold zone was shrunk while the plateau temperate zone was enlarged in the Tibetan Plateau. Because precipitation decreased in North China, southeastern part of Northeast China and eastern part of Northwest China, the boundary of the semi-arid and sub-humid region in Northern China shifted eastward and southward, and in which, the boundary between 36°-41°N shifted 0.5°-2.5°at longitude. Moreover, the climate in the most of arid regions and semi-arid regions in Hexi Corridor, Xinjiang and the Tibetan Plateau changed to be more humid.

Amplitude and velocity of the shifts in the Chinese terrestrial surface regions from 1960 to 2011

A terrestrial surface is characterized by a set of elements such as landform, climate, water, and soil and vegetation. The interaction of such elements forms a series of systematic regions on a terrestrial surface with a geographical zonation distribution; this is known as a terrestrial pattern. Realization of the internal relationship between the terrestrial elements and knowledge of their interaction and pattern formation would be helpful to further understand the physical geographical processes and the state of sustainable resource use and environmental protection planning.

Advances in terrestrial system research in China

Land surface is of spatial-temporal heterogeneity. Terrestrial system (TS) comprehensively studies on land surface and physical regionalization objectively describes geographical zonation of the system. China has a vast area with apparent spatial variations in resources and environmental conditions, which highly influence on socio-economic development. In this paper, progress of the TS studies in China is overviewed and research priorities in the near future are prospected. Since the 1950s, China has paid great attention to the TS study as its socio-economic development, and conducted research on physical geographical regionalization, eco-geographical regionalization and comprehensive regionalization. Along with the deepening of global change research, dynamics of TS have been highly concerned. During the studies, methodology has been developed from qualitative research of integration of experts’ brainpower gradually to quantitative research based on field observation and experiments of the natural processes, including physical, chemical and biological processes, as well as application of information technology and mathematical simulation. In the near future, TS would combine with the ideology, objectives and key researches of Future Earth program, to focus on the mechanism and regional effects of interaction among land surface elements, the response of TS to global change, the quantitative recognition on regional unit boundary, and the application to TS in sustainable socio-economic development.