348-YEAR PRECIPITATION RECONSTRUCTION FROM TREE-RINGS FOR THE NORTH SLOPE OF THE MIDDLE TIANSHAN MOUNTAINS

Correlation census shows that the correlation between the tree-ring chronologies in the Urumqi River Basin and precipitation during July in the last year to February in the concurrent year is significant,and the best single correlation coefficient is 0.74,with significance level of 0.0001. Using two residual chronologies collected from west Baiyanggou and Boerqingou,precipitation for 348 years can be reconstructed in the North Slope of middle Tianshan Mountains,its explained variance is 62%.According to much verification from independent precipitation data,historical climate records,glacier and other data.it shows that the reconstructed precipitation series of 348 years is reliable.Analysis of precipitation features indicates that there were three wet periods occurring during 1671(?)—1692,1716—1794 and 1825—1866 and three dry periods during 1693 —1715,1795—1824 and 1867—1969.Two wet periods,during 1716—1794 and 1825—1866, correspond to the times of the second and the third glacial terminal moraine formation,which is in front of No.1 glacier in Urumqi River source.According to computation,corresponding annual precipitation amounts are 59mm and 30mm more than now.The reconstructed precipitation series has a significant drying trend from 1716 to 1969.and has better representativeness to the precipitation of Urumqi and Changji Prefecture on the North Slope of Tianshan Mountains.

Spatio-temporal correlation between human activity intensity and land surface temperature on the north slope of Tianshan Mountains

Research on the spatio-temporal correlation between the intensity of human activities and the temperature of earth surfaces is of great significance in many aspects,including fully understanding the causes and mechanisms of climate change,actively adapting to climate change,pursuing rational development,and protecting the ecological environment.Taking the north slope of Tianshan Mountains,located in the arid area of northwestern China and extremely sensitive to climate change,as the research area,this study retrieves the surface temperature of the mountain based on MODIS data,while characterizing the intensity of human activities thereby data on the night light,population distribution and land use.The evolution characteristics of human activity intensity and surface temperature in the study area from 2000 to 2018 were analyzed,and the spatio-temporal correlation between them was further explored.It is found that:(1)The average human activity intensity(0.11)in the research area has kept relatively low since this century,and the overall trend has been slowly rising in a stepwise manner(0.0024·a-1);in addition,the increase in human activity intensity has lagged behind that in construction land and population by 1-2 years.(2)The annual average surface temperature in the area is 7.18℃with a pronounced growth.The rate of change(0.02℃·a-1)is about 2.33 times that of the world.The striking boost in spring(0.068℃·a-1)contributes the most to the overall warming trend.Spatially,the surface temperature is low in the south and high in the north,due to the prominent influence of the underlying surface characteristics,such as elevation and vegetation coverage.(3)The intensity of human activity and the surface temperature are remarkably positively correlated in the human activity areas there,showing a strong distribution in the east section and a weak one in the west section.The expression of its spatial differentiation and correlation is comprehensively affected by such factors as scopes of human activities,manifestations,and land-use changes.Vegetation-related human interventions,such as agriculture and forestry planting,urban greening,and afforestation,can effectively reduce the surface warming caused by human activities.This study not only puts forward new ideas to finely portray the intensity of human activities but also offers a scientific reference for regional human-land coordination and overall development.