There exist thermal differences between the Tibetan Plateau (TP) and the plain east of the TP, and between land and sea in East Asia. The influence of the land-sea thermal contrast on the precipitation in East China h...There exist thermal differences between the Tibetan Plateau (TP) and the plain east of the TP, and between land and sea in East Asia. The influence of the land-sea thermal contrast on the precipitation in East China has been widely investigated; however, a few studies have paid attention to the role of the TP-plain thermal difference. Thus, using the National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis data and the observation data of China from 1951 to 2007, the area-mean temperature difference between the TP (27.5°-40°N, 80°-100°E) and the plain (27.5° -40°N,110°-120°E) at 500 hPa is defined as an index (dexT-C) of the TP-plain thermal difference in East Asia. The relationship between the dexT-C and East Asian general circulation and the rainfall in China in the summer has been explored. Diagnostic analysis and numerical simulation show that the TP-plain thermal difference is closely related to the rainfall over West China (90°-110°E) in the summer. High values of the dexT-C correspond to the large thermal difference between the TP and the plain, strengthening the heat low over the TP, southward of the northwestern Pacific subtropical high, southern flood and northern drought in West China (90°-110°E), and vice versa. From 1951 to 2007, the variation in dexT-C exhibits a remarkable oscillation and ascending trend, and the abnormal rainfall pattern over West China (90°-110°E) also changes from "northern flood and southern drought" to "southern flood and northern drought". The above research is favorable to knowing how the two-stage thermal differences influence summer rainfall in China.展开更多
The United Arab Emirates (UAE) has undergone major urban transformation after the establishment of the country in 1971. One noticeable change is urban expansion in terms of massive infrastructure, including new reside...The United Arab Emirates (UAE) has undergone major urban transformation after the establishment of the country in 1971. One noticeable change is urban expansion in terms of massive infrastructure, including new residential areas, highways, airports, and sophisticated transportation systems. Major landscape changes and disturbances, such as urban development, are among the major contributors to global climate change. Urban areas can be 3.5<span style="white-space:nowrap;">°</span>C - 4.5<span style="white-space:nowrap;">°</span>C warmer than neighboring rural areas, a phenomenon known as urban heat islands (UHIs). As such, urban development in the UAE was expected to follow a similar pattern and to be a major contributor to the country’s impact on global climate change. Analyses of multi-temporal (1988-2017) land surface temperature (LST) data obtained from Landsat satellite datasets over a desert city in the UAE showed unexpected results. Urbanization of desert surfaces in the study area led to a decrease of 3<span style="white-space:nowrap;">°</span>C - 5<span style="white-space:nowrap;">°</span>C in the overall LST. This was attributed to the associated expansion of green spaces in the newly developed urban areas, the expansion of date plantations and perhaps a cooling in the previously desert surface. Therefore, the UHI effect was not well demonstrated in the studied desert surfaces converted to urban areas.展开更多
为对东亚夏季风强弱年青藏高原、东亚及太平洋地区热力作用以及不同区域热力差进行对比研究,对进一步研究关键区热力差异对东亚季风的影响提供一些参考,采用相关分析,合成分析等统计方法。结果表明:东亚夏季风偏强时,孟加拉湾、华南、...为对东亚夏季风强弱年青藏高原、东亚及太平洋地区热力作用以及不同区域热力差进行对比研究,对进一步研究关键区热力差异对东亚季风的影响提供一些参考,采用相关分析,合成分析等统计方法。结果表明:东亚夏季风偏强时,孟加拉湾、华南、南海及热带西太平洋大气热源异常偏强,印度东部、青藏高原、中南半岛及中纬度西太平洋地区大气热源异常偏弱;且高原东部与东亚关键区热力差偏大,垂直方向上热力差在600 h Pa达到最大,东亚关键区与热带西太平洋热力差偏小,热力差在250 h Pa左右达到最大;高原东部与热带西太平洋热力差为负,热力差在400 h Pa达到最大。反之亦然。东亚夏季风强度变化对高原与热带西太平洋上空高层大气热源影响更大,对东亚关键区上空低层大气热源影响更大。展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 40505014 and 90711003) Special Scientific Research Project for Public Interest (Grant No.GYHY20070 6010)
文摘There exist thermal differences between the Tibetan Plateau (TP) and the plain east of the TP, and between land and sea in East Asia. The influence of the land-sea thermal contrast on the precipitation in East China has been widely investigated; however, a few studies have paid attention to the role of the TP-plain thermal difference. Thus, using the National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis data and the observation data of China from 1951 to 2007, the area-mean temperature difference between the TP (27.5°-40°N, 80°-100°E) and the plain (27.5° -40°N,110°-120°E) at 500 hPa is defined as an index (dexT-C) of the TP-plain thermal difference in East Asia. The relationship between the dexT-C and East Asian general circulation and the rainfall in China in the summer has been explored. Diagnostic analysis and numerical simulation show that the TP-plain thermal difference is closely related to the rainfall over West China (90°-110°E) in the summer. High values of the dexT-C correspond to the large thermal difference between the TP and the plain, strengthening the heat low over the TP, southward of the northwestern Pacific subtropical high, southern flood and northern drought in West China (90°-110°E), and vice versa. From 1951 to 2007, the variation in dexT-C exhibits a remarkable oscillation and ascending trend, and the abnormal rainfall pattern over West China (90°-110°E) also changes from "northern flood and southern drought" to "southern flood and northern drought". The above research is favorable to knowing how the two-stage thermal differences influence summer rainfall in China.
文摘The United Arab Emirates (UAE) has undergone major urban transformation after the establishment of the country in 1971. One noticeable change is urban expansion in terms of massive infrastructure, including new residential areas, highways, airports, and sophisticated transportation systems. Major landscape changes and disturbances, such as urban development, are among the major contributors to global climate change. Urban areas can be 3.5<span style="white-space:nowrap;">°</span>C - 4.5<span style="white-space:nowrap;">°</span>C warmer than neighboring rural areas, a phenomenon known as urban heat islands (UHIs). As such, urban development in the UAE was expected to follow a similar pattern and to be a major contributor to the country’s impact on global climate change. Analyses of multi-temporal (1988-2017) land surface temperature (LST) data obtained from Landsat satellite datasets over a desert city in the UAE showed unexpected results. Urbanization of desert surfaces in the study area led to a decrease of 3<span style="white-space:nowrap;">°</span>C - 5<span style="white-space:nowrap;">°</span>C in the overall LST. This was attributed to the associated expansion of green spaces in the newly developed urban areas, the expansion of date plantations and perhaps a cooling in the previously desert surface. Therefore, the UHI effect was not well demonstrated in the studied desert surfaces converted to urban areas.
文摘为对东亚夏季风强弱年青藏高原、东亚及太平洋地区热力作用以及不同区域热力差进行对比研究,对进一步研究关键区热力差异对东亚季风的影响提供一些参考,采用相关分析,合成分析等统计方法。结果表明:东亚夏季风偏强时,孟加拉湾、华南、南海及热带西太平洋大气热源异常偏强,印度东部、青藏高原、中南半岛及中纬度西太平洋地区大气热源异常偏弱;且高原东部与东亚关键区热力差偏大,垂直方向上热力差在600 h Pa达到最大,东亚关键区与热带西太平洋热力差偏小,热力差在250 h Pa左右达到最大;高原东部与热带西太平洋热力差为负,热力差在400 h Pa达到最大。反之亦然。东亚夏季风强度变化对高原与热带西太平洋上空高层大气热源影响更大,对东亚关键区上空低层大气热源影响更大。
