CHARACTERISTICS OF EVAPOTRANSPIRATION IN THE YANGTZE DELTA REGION FOR PAST 40 YEARS AND MAIN INFLUENCE FACTORS^*          下载免费PDF全文

LIU Jingmiao  ZHOU Xiuji  DING Guoan  LU Longhua 《Acta Meteorologica Sinica》2003,17(2):178-189

The Kotoda-Bortan (KB) model (Liu and Kotoda 1998) used for estimating evapotranspiration was modified.The monthly evapotranspiration for various surfaces in the Yangtze Delta (118-123°E,28-33°N) was calculated using the modified model,and the annual regional average of evapotranspiration from 1961 to 1998 was obtained using a weighting method.The spatial and temporal distribution characteristics of evapotranspiration were analyzed.It is found that the regional averaged annual evapotranspiration has a decreasing trend over the past 40 years;the value dropped by about 24mm from 1961 to 1998.The main reason for this tendency is due to the change of land surface condition.Compared with the case of 1980,the current proportions of paddy field,farmland and water surface have decreased by 1.353%,4.42% and 2.597% respectively,while the proportions of urban area and non-agriculture land have increased by 3.345%.These changes clearly result in a decrease of the regional averaged evapotranspiration.  相似文献   

全球地震纬度分布特征和北纬35°峰值异常浅析   总被引：1，自引：0，他引：1  

唐燕娟 《华北地震科学》1997,(2)

本文取1900年─1980年全球Ms≥6．0地震7936次分析后发现，地震发生在南北回归线（23°5N—23°5S）之间占49．69％，发生在南北极因（63°5N—63°5S）之间占99．17％，发生在南北极圈外只占0．83％，即很少发生地震；其中8级地震98次，在35°N线为高峰。又分析了公元648年─1979年全球M≥8级地震257次主要亦集中在35°N线附近。尤其是历史上破坏性极大的地震在35°N线附近者多。这些现象可能和地球自转有一定关系。  相似文献   

FURTHER STUDY ON THE PROPERTIES OF OPERATORS OF ATMOSPHERIC EQUATIONS AND THE EXISTENCE OF ATTRACTOR   总被引：1，自引：0，他引：1       下载免费PDF全文

李建平  丑纪范 《Acta Meteorologica Sinica》1997,(2)

The equivalent operator equation is derived from the full primitive nonlinear equations of theatmospheric motion and the properties and physical senses of the operators are studied.In theinfinite dimensional Hilbert space,the global asymptotic behavior of the atmosphere system withthe non-stationary external forcing is studied under the assumption of the bounded externalforcing.The existence theorems of the global absorbing set and the global attractor are obtained.Thus,the conclusions deduced from the large-scale atmosphere(Li and Chou 1996 a;1996 b)areextended to the general atmosphere.  相似文献   

Tropospheric Ozone in a Global-Scale Three-Dimensional Lagrangian Model and Its Response to NOX Emission Controls     

W. J. Collins  D. S. Stevenson  C. E. Johnson  R. G. Derwent 《Journal of Atmospheric Chemistry》1997,26(3):223-274

A three-dimensional Lagrangian tropospheric chemistry modelis used toinvestigate the impact of human activities on the tropospheric distributionofozone and hydroxyl radicals. The model describes the behaviour of 50 speciesincluding methane, carbon monoxide, oxides of nitrogen, sulphur dioxide andnineorganic compounds emitted from human activities and a range of other sources.Thechemical mechanism involves about 100 chemical reactions of which 16 arephotochemical reactions whose diurnal dependence is treated in full. The modelutilises a five minute chemistry time step and a three hour advection timestepfor the 50,000 air parcels. Meteorological data for the winds, temperatures,clouds and so on are taken from the UK Meteorological Office global model for1994 onwards. The impacts of a 50% reduction in European NO_Xemissions onglobal ozone concentrations are assessed. Surface ozoneconcentrations decrease in summertime and rise in wintertime, but to differentextents.  相似文献   

新疆月太阳总辐射气候学计算方法的研究   总被引：22，自引：0，他引：22  

刘绍民  李银芳 《干旱区地理》1997,20(3):75-81

本文先对现有各种太阳总辐射气候学计算公式进行讨论，并确定Ｑ＝Ｑ２为新疆最佳计算公式，然后根据新疆９个月日射站的资料分南疆，北疆两大区域按月给出区域统一式，最后验证了它们的计算效果。  相似文献   

台湾恒春半岛的隆起珊瑚礁台地          下载免费PDF全文

王鑫 《第四纪研究》1997,17(4):327-332

台湾本岛南端的恒春半岛,出露隆起珊瑚礁石灰岩和现代珊瑚礁海岸。隆起珊瑚礁石灰岩在地貌上的表现是多阶的台地。最高的公园面可达海拔300m,依次向下,是海拔约100～160m的笼仔埔面,海拔70～80m的埔顶面以及海拔10～20m的垦丁面。在恒春半岛的西侧,珊瑚礁台地面已经倾斜,因此高度的表现不同。ESR及¹⁴C定年表明,抬升的更新世珊瑚礁台地形成于0.5Ma B.P.前后及0.13Ma B.P.两时期;海拔10～20m的全新世珊瑚礁台地约形成于6 000a B.P.的时期。这些证据显示了地质时期里全球变迁的蛛丝马迹。  相似文献   

中国荒漠化气候类型划分与潜在发生范围的确定   总被引：45，自引：6，他引：45  

兹龙骏  吴波 《中国沙漠》1997,17(2):107-111

根据联合国防治荒漠化公约的有关规定，运用Ｔｈｏｒｎｔｈｗａｉｔｅ计算可能蒸散量的方法作出了第一张中国荒漠化气候类型分布图，首次确定了中国荒漠化的潜在发生范围。结果表明，中国荒漠化潜在发生范围约３３１７０３２．２ｋｍ２，占国土面积的３４．６％，分布于全国１８个省（自治区，直辖市），４７０个县（市、旗）。其中亚湿润干旱区总面积为７５１１６１．９ｋｍ２，占国土面积的７．８％；半干旱区总面积为１１３９２１４．２ｋｍ２，占国土面积的１１．９％；干旱区总面积为１４２６６５６．１ｋｍ２，占国土面积的１４．９％。  相似文献   

Observability of the isotropic component of a moment tensor     

Hitoshi Kawakatsu 《Geophysical Journal International》1996,126(2):525-544

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Determination of the isotropic component of deep focus earthquakes by inversion of normal-mode data     

Tatsuhiko Hara  Keiko Kuge  Hitoshi Kawakatsu 《Geophysical Journal International》1996,127(2):515-528

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扬子板块石炭纪沉积层序及其全球性对比研究   总被引：8，自引：3，他引：8  

李儒峰  刘本培 《沉积学报》1997,15(3):23-28

通过对石炭纪扬子板块内部、扬子板块与华北板块及扬子板块与欧美板块之间的不同级别沉积层序对比研究，编制了扬子板块、华北板块和欧美板块石炭纪的海平面变化曲线。在扬子板块内部，上、下扬子区２级沉积层序可以进行对比，但下扬子区海进和海岸上超滞后于上扬子区，由于资料的限制，３级沉积层序的对比还有困难；华北板块Ｆｕｓｕｌｉｎａ－Ｆｕｓｕｌｉｎｅｌａ带内的一个３级沉积层序和Ｔｒｉｔｉｃｉｔｅｓ－Ｐｅｕｄｏｓｃｈｗａｇｅｒｉｎａ带内的四个３级沉积层序，可以和扬子板块同期的３级沉积层序对比；扬子板块和北美中大陆不仅３级沉积层序可以对比，而且在晚石炭世Ｇｚｈｅｌｉａｎ期４级沉积层序也可以进行对比，但由于它们大地构造背景的差异，导致沉积层序组成内容的不同。上述对比结果被认为是冰川型全球海平面变化所形成全球沉积记录同时性的证据。并以冰期与非冰期、联合古陆形成前后等方面对相同板块内和不同板块间沉积层序的数量和级别的异同原因进行了探讨，认为石炭纪冈瓦纳大陆冰川消长是控制全球海平面变化的主要因素，因此，沉积层序应具全球同时性和可对比性，但局部沉积条件差异也将影响沉积层序组成。  相似文献