| Air temperature lapse rate(?)is taken as one of the key input parameters when evaluating the mountain ecosystem's response to climate change and its accuracy is very important to the related researches in the future.In this paper,based on the datasets from 11 standard meteorological stations that built on the both southern and northern and in the different altitude regions of Mt.Taibai(3771.2 m),the prominent peak of the Qinling Mountains,the tempo-spatial distribution characteristics for the variations of ? were evaluated by using DEM images at 25 m resolution as well as daily average temperature during the period of 2013?2015.Since instantaneous land surface temperature field was retrieved from Landsat 8 images by the method of radioactive transfer equation,? field at a raster-cell level in the entire Mt.Taibai was achieved by a custom neighborhoods difference operation.And its distribution characteristics and the influencing degree of terrain factors were analyzed qualitatively and quantitatively by GIS spatial analysis techniques.Then on this basis,this paper obtained the raster datasets of air temperature and revealed the spatial-temporal variations of temperature in recent 57 years that laid the foundation for the quantitative researches on responses of the ecosystem to climate change under globe warmingin Qinling Mountains.The results and progress are as follows:(1)The average value of annual ?on the northern slope were larger than that on the southern slope during the period of 2013?2015,and higher variation in different altitude regions was found on the northern slope than on the southern slope.The temperature showed extremely significant decreases with increasing altitude in Mt.Taibai,and annual ? of three years has a very little fluctuation.Annual ? on the northern of Qinling Mountains are 0.522 ?/100 m,0.515 ?/100 m,0.501 ?/100 m from 2013 to 2015,while 0.508 ?/100 m,0.502 ?/100 m and 0.487 ?/100 m on the southern slope in turn.Therefore,the averages on the northern and southern of Qinling Mountains for three years are 0.513 ?/100 m and 0.499 ?/100 m,respectively.Annual y on the northern slope had more differences with the variations of altitude than that on the southern.Annual y were obviously higher in the low elevation areas below 2000 m and the extremely high elevation areas above 3000 m than in the middle elevation areas between 2000 m and 3300 m,and annual ? showed steadily on the southern slope.(2)The variability of y was significant at the seasonal and monthly scales,and the trends of ? were inconsistent on the southern and northern slope in Qinling Mountains.On the seasonal scale,the ?max of the southern and northern slope appeared at different time.At the seasonal scale,the peak of ?(0.619?/00 m)on the northern slope occurred in summer,while the peak of ?(0.546?/100 m)on the southern slope appeared in spring.Meanwhile,the minimums of ? on both slopes(0.390?/100 m on the northern slope and 0.449?/100 m on the southern slope)were found in winter.Compared with that on the southern slope,the values of ? on the northern slope were higher in spring and summer,smaller in winter and almost the same in autumn,respectively.On the monthly scale,the larger values of ? appeared in the warmer months on both slopes,and the larger variation in ?was found on the northern slope.The values of ? were higher on the southern slope than on the northern slope in January,February,November and December of each year,while lower during May to September.(3)The results of ? clarified the rule of temperature-altitude variations in Mt.Taibai in recent 60 years,which could provide a theoretical basis for the quantitative researches on temperature distribution characteristics and the response of ecosystem to climate change in the mountain areas.The consistency analysis results showed that there was no significant difference between the monthly ? in 2013,2014,and 2015,so the mean-value of ? could more accurately respented the actual state of ? at different time scale in Mt.Taibai.The difference test results of samples data also indicated that the climate during the three years in Mt.Taibai was normal condition under global climate change,and it had been verified that the trends of monthly temperature were highly consistent with the long-term trend at the selected two stations.Therefore,the ? calculated from temperature data of 11 meterological stations in Mt.Taibai was in accordance with the general rules that temperature changed with elevation.In addition,the measured meteorological data test proved that average error of O-Kriging based on monthly y was only 0.56 ?,and most of errors were within 1? which demonstrated ? calculated in this paper could be generally applied in the whole Qinling Mountains.(4)? showed a high value strip in the vicinity of the ridge and valley,and it gradually increased from sunny slope to shady in Mt.Taibai.The land surface temperature retrieved from Landsat 8 TIRS based on radioactive transfer equation method reflected the realistic distribution pattern of temperature to some extent.The distribution of ? in Mt.Taibai approximately was consistent with mountains and valleys range.? had higher values in the ridge,valley and the low elevation area on the northern slope,while lower in the middle altitude region.? is 0.913 ?/100 m in the high altitude areas,0.471 ?/100 m in the middle altitude zones,and 0.75 ?/100 m in the low altitude areas.Effects of altitude on the vertical variation of air temperature are more significant than that of aspect.? affected by aspect gradually becomes stronger from sunny to shady slope,which is 0.515 ?/100 m?0.541 ?/100m?0.617 ?/100,respectively.(5)The annual temperature for 92.1%showed an extremely significant increasing in recent 57 years and it has the fastest rising rates in spring and winter.There existed a remarkable warming center in Qining MountainsThe average temperature is 10.49 ? in the whole Qinling Mountains and higher on the southern slope than on the northern slope.The average rising rates of annual temperature is 0.186 ?/10 a,which was greater on the northern slope than on the southern slope.Mutation analysis showed that the saltation of temperature on the northern slope occurred in 1994,while 1997 on the southern slope.The warming rates of annual temperature for 92.1%reached significant level(P?0.05),and there existed clearly warming center in Mt.Taibai,Zhashui and Zhenan County.The most obvious warming seasons were spring and winter when the warming rates for 97.1%and 96.1%reached significant level.The temperature tendency rates were 0.253 ?/10 a and 0.352 ?/10 a on the southern and northern slope in spring,and 0.317 ?/10 a and 0.302 ?/10 a in winter.It also accounted for 69.6%that temperature rising rates arrived significant level in autumn,while only 29.8%in summer.The temperature showed significant upward trends in January to April and September,but not in May to August. |
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