The difference between ground soil and air temperature （Ts-Ta） was studied by using the data of ground and air temperature of 99 stations over the Qinghai-Xizang （Tibet） Plateau from 1960 to 2000,and its spatial d...The difference between ground soil and air temperature （Ts-Ta） was studied by using the data of ground and air temperature of 99 stations over the Qinghai-Xizang （Tibet） Plateau from 1960 to 2000,and its spatial distribution and time changing tendency have been diagnosed by principal component analysis and power spectral analysis methods. The results show that the values of （Ts-Ta） are the maximum in June and the minimum in December. The first three loading eigenvectors, which reflect the main spatially anomalous structure of （Ts-Ta） over the Qinghai-Xizang Plateau, contain the contrary changing pattern between the northwestern and the southeastern regions, the pattern response of the sea level elevation and the geography, and the pattern response of the distribution of the permafrost. There are four patterns of time evolution including the patterns of monotonous increasing or decreasing trends, the basic stability pattern and the parabola pattern with the minimum value. （Ts-Ta） has a periodic variation about 2 years. According to the spatial distribution of the third loading eigenvectors of （Ts-Ta） over the Qinghai-Xizang Plateau in cold season, the permafrost response region and the seasonal frozen ground response region are identified.展开更多
The objective of this study was to understand the effects of forest gap and variations in different seasons, gap size, locations and diurnal variations on forest microclimate and soil water content. Spatial and tempor...The objective of this study was to understand the effects of forest gap and variations in different seasons, gap size, locations and diurnal variations on forest microclimate and soil water content. Spatial and temporal distribution features of air temperature (TA ), soil temperature (TS ), relative humidity (h) and soil water content (Ψ) were measured in Castanopsis kawakamii natural forest gaps created by a severe typhoon or fallen dead trees. The results showed that: (1) the variations of TA , h, and TS in four seasons were extremely significant. The variations of Ψ in four seasons were extremely significant except for those between spring and summer. (2) The diurnal variations of TA and T S were expressed with a single peak curve. The diurnal variations of h and Ψ presented a high-low-high trend. (3) The variations of TA , h, and TS were extremely significant among the large, medium and small gaps in C. kawakamii natural forest. Medium gaps had the highest TA and the lowest h while small gaps were just contrary to medium gaps. The variations of Ψ were extremely significant for large, medium and small gaps except those between the medium and large gaps. (4) The TA , h, TS and Ψ were decreased from the gap center, canopy gap, expanded gap to understory. These results will help further our understanding of the abiotic and consequent biotic responses to gaps in the mid-subtropical broadleaved forests, which also provide a theoretical basis for the scientific management and population restoration of C. kawakamii natural forest.展开更多
地气温差对大气边界层热力交换起着极为重要的作用,对局地气候、城市边界层结构和大气污染有着重要影响,因此有必要对城市下垫面地气温差进行相应研究。本文以典型盆地城市成都为例,利用2014年成都市地表温度、气温逐时观测资料分析了...地气温差对大气边界层热力交换起着极为重要的作用,对局地气候、城市边界层结构和大气污染有着重要影响,因此有必要对城市下垫面地气温差进行相应研究。本文以典型盆地城市成都为例,利用2014年成都市地表温度、气温逐时观测资料分析了该地区地气温差的变化特征,讨论了中尺度数值模式WRF(Weather Research and Forecasting Model)对盆地城市地气温差的模拟能力。结论表明:成都市平均地气温差为2. 20℃,多分布在0～2℃区间,与地表温度和气温变化不同,温差春季最大,夏、冬季次之,秋季最小;各季节温差日变化大致相似,均为中午较大,夜间在0℃左右,但极值大小不同。利用WRF对成都市典型夏季晴天地气温差进行了模拟研究,对比分析三种常用陆面过程参数化方案的模拟结果,三种方案模拟的变化趋势均与观测吻合,其中Noah方案能较好的模拟成都市地气温差的变化特征,通过参数化方案的组合方式,改进了模式对地气温差的WRF模拟能力。展开更多
基金Foundation： National Natural Science Foundation of China, No.40471026 National Fund for ＂Western Major Plan＂ Broadly Item, No.90302006+1 种基金 Knowledge Innovation Project of CAS, No.220014-03 The National Basic Research Program （973 Program）, No.2005CB422003
文摘The difference between ground soil and air temperature （Ts-Ta） was studied by using the data of ground and air temperature of 99 stations over the Qinghai-Xizang （Tibet） Plateau from 1960 to 2000,and its spatial distribution and time changing tendency have been diagnosed by principal component analysis and power spectral analysis methods. The results show that the values of （Ts-Ta） are the maximum in June and the minimum in December. The first three loading eigenvectors, which reflect the main spatially anomalous structure of （Ts-Ta） over the Qinghai-Xizang Plateau, contain the contrary changing pattern between the northwestern and the southeastern regions, the pattern response of the sea level elevation and the geography, and the pattern response of the distribution of the permafrost. There are four patterns of time evolution including the patterns of monotonous increasing or decreasing trends, the basic stability pattern and the parabola pattern with the minimum value. （Ts-Ta） has a periodic variation about 2 years. According to the spatial distribution of the third loading eigenvectors of （Ts-Ta） over the Qinghai-Xizang Plateau in cold season, the permafrost response region and the seasonal frozen ground response region are identified.
基金supported by the Key Program of Natural Science Foundation of Fujian Province of China (Grant No. 2008J0008)Doctoral Fund of Ministry of Education of China (Grant No.200803890011)China Postdoctoral Science Foundation (Grant No. 20070410796)
文摘The objective of this study was to understand the effects of forest gap and variations in different seasons, gap size, locations and diurnal variations on forest microclimate and soil water content. Spatial and temporal distribution features of air temperature (TA ), soil temperature (TS ), relative humidity (h) and soil water content (Ψ) were measured in Castanopsis kawakamii natural forest gaps created by a severe typhoon or fallen dead trees. The results showed that: (1) the variations of TA , h, and TS in four seasons were extremely significant. The variations of Ψ in four seasons were extremely significant except for those between spring and summer. (2) The diurnal variations of TA and T S were expressed with a single peak curve. The diurnal variations of h and Ψ presented a high-low-high trend. (3) The variations of TA , h, and TS were extremely significant among the large, medium and small gaps in C. kawakamii natural forest. Medium gaps had the highest TA and the lowest h while small gaps were just contrary to medium gaps. The variations of Ψ were extremely significant for large, medium and small gaps except those between the medium and large gaps. (4) The TA , h, TS and Ψ were decreased from the gap center, canopy gap, expanded gap to understory. These results will help further our understanding of the abiotic and consequent biotic responses to gaps in the mid-subtropical broadleaved forests, which also provide a theoretical basis for the scientific management and population restoration of C. kawakamii natural forest.
文摘地气温差对大气边界层热力交换起着极为重要的作用,对局地气候、城市边界层结构和大气污染有着重要影响,因此有必要对城市下垫面地气温差进行相应研究。本文以典型盆地城市成都为例,利用2014年成都市地表温度、气温逐时观测资料分析了该地区地气温差的变化特征,讨论了中尺度数值模式WRF(Weather Research and Forecasting Model)对盆地城市地气温差的模拟能力。结论表明:成都市平均地气温差为2. 20℃,多分布在0～2℃区间,与地表温度和气温变化不同,温差春季最大,夏、冬季次之,秋季最小;各季节温差日变化大致相似,均为中午较大,夜间在0℃左右,但极值大小不同。利用WRF对成都市典型夏季晴天地气温差进行了模拟研究,对比分析三种常用陆面过程参数化方案的模拟结果,三种方案模拟的变化趋势均与观测吻合,其中Noah方案能较好的模拟成都市地气温差的变化特征,通过参数化方案的组合方式,改进了模式对地气温差的WRF模拟能力。
