近44 a中国冬夏气温变率及其对区域变暖性的影响   总被引：6，自引：2，他引：4  

吴胜安  江志红  屠其璞 《南京气象学院学报》2002,25(6):830-836

利用近44a中国85个测站冬夏季逐日平均、最高和最低气温序列,研究冬夏季温度季节变率及其时空演变特征,探讨其对区域变暖稳定性的影响。结果表明：冬季,除高原、西南、东北以外的中国大部分地区,温度的季节变率存在显著下降趋势,是近期变暖的稳定区,其中变暖最为稳定、显著的区域是西北、华北地区,东北北部虽变暖幅度很大,但稳定性最差;夏季,长江中下游及其江南地区温度变率存在显著上升趋势,20世纪70年代后年际变幅明显增大,表明该地区80年代降温的稳定性差。  相似文献   

Comparison of three mathematical models for the estimation of 10-day drain discharge     

K. Pandžić  I. Šimunić  F. Tomić  S. Husnjak  T. Likso  D. Petošić 《Theoretical and Applied Climatology》2006,85(1-2):107-115

Summary This paper presents an the evaluation of three mathematical models for the estimation of 10-day drain discharge using weather, pedological and phenological parameters. One model uses modified Palmer’s procedure for the calculation of water balance components and the second two use empirical multiple linear regression. The models have been applied to data of an amelioration experimental field in central Croatia (south-western part of the Pannonian Lowland), where a set of average 10-day air temperature and relative humidity data, average wind speed, cumulative precipitation and drain discharge amounts, insolation and soil moisture data and vegetation indices have been collected. The experiment has been performed during the period 1990–1992. The models have been tested by comparing estimated and observed 10-day drain discharge amounts. All models mainly give acceptable cumulative results although their accuracy depends on the season.  相似文献   

Recent Progress in the Impact of the Tibetan Plateau on Climate in China   总被引：14，自引：0，他引：14  

刘屹岷  包庆  段安民  钱正安  吴国雄 《大气科学进展》2007,24(6):1060-1076

Studies of the impacts of the Tibetan Plateau （TP） on climate in China in the last four years are reviewed. It is reported that temperature and precipitation over the TP have increased during recent decades. From satellite data analysis, it is demonstrated that most of the precipitation over the TP is from deep convection clouds. Moreover, the huge TP mechanical forcing and extraordinary elevated thermal forcing impose remarkable impacts upon local circulation and global climate. In winter and spring, stream flow is deflected by a large obstacle and appears as an asymmetric dipole, making East Asia much colder than mid Asia in winter and forming persistent rainfall in late winter and early spring over South China. In late spring, TP heating contributes to the establishment and intensification of the South Asian high and the abrupt seasonal transition of the surrounding circulations. In summer, TP heating in conjunction with the TP air pump cause the deviating stream field to resemble a cyclonic spiral, converging towards and rising over the TP. Therefore, the prominent Asian monsoon climate over East Asia and the dry climate over mid Asia in summer are forced by both TP local forcing and Eurasian continental forcing.
Due to the longer memory of snow and soil moisture, the TP thermal status both in summer and in late winter and spring can influence the variation of Eastern Asian summer rainfall. A combined index using both snow cover over the TP and the ENSO index in winter shows a better seasonal forecast.
On the other hand, strong sensible heating over the Tibetan Plateau in spring contributes significantly to anchor the earliest Asian monsoon being over the eastern Bay of Bengal （BOB） and the western Indochina peninsula. Qualitative prediction of the BOB monsoon onset was attempted by using the sign of meridional temperature gradient in March in the upper troposphere, or at 400 hPa over the TP. It is also demonstrated by a numerical experiment and theoretical study that the heating over the TP lea  相似文献   

Utilisation of the image analysis method for the detection of the morphological anisotropy of calcite grains in marble     

Boguslaw Obara  Alena Kožušníková 《Computational Geosciences》2007,11(4):275-281

This paper presents the development and utilisation of an automated image processing algorithm for detection and analysis of grains. Using optical polarising microscopy, a set of colored images are collected from an area on a thin section. A filtering operation, using rotation of a morphological alternating sequence filter (based on a structuring element), is used to remove twinning features within individual grains. Filtering is followed by the watershed segmentation technique to determine grain boundaries. The method is used for the identification of calcite grains in marble and the subsequent analysis of morphological anisotropy.  相似文献   

A Method to Determine the Solar Synodic Rotation Rate and the Height of Tracers     

Roša  D.  Vršnak  B.  Božić  H.  Brajša  R.  Ruždjak  V.  Schroll  A.  Wöhl  H. 《Solar physics》1998,179(2):237-252

The dependence of the measured apparent synodic solar rotation rate on the height of the chosen tracer is studied. A significant error occurs if the rotation rate is determined by tracing the apparent position of an object above the photospheric level projected on the solar disc. The centre-to-limb variation of this error can be used to determine simultaneously the height of the object and the true synodic rotation rate. The apparent (projected) heliographic coordinates are presented as a function of the height of the traced object and the coordinates of its footpoint. The relations obtained provide an explicit expression for the apparent rotation rate as a function of the observed heliographic coordinates of the tracer, enabling an analytic least-squares fit expression to determine simultaneously the real synodic rotation rate and the height of the tracer.  相似文献   

Seismic Zoning of Croatia     

Markušić  Snježana  Herak  Marijan 《Natural Hazards》1998,18(3):269-285

The territory of Croatia and neighboring regions is divided into 17 seismic source zones, considering available seismological and geological data. On this basis, seismic hazard elements (seismicity rate, maximum magnitude, b-value, probabilities of exceedance and return periods for a predefined set of magnitudes) are computed using the maximum likelihood method appropriate for treating data-sets with variable completeness thresholds. The values of long term expected peak horizontal acceleration obtained by using a combination of the deterministic and the probabilistic procedure are the highest in the Dubrovnik zone, while the Zagreb zone has the highest earthquake hazard in the continental part of the country. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

Electromagnetic induction of a three-dimensional conductivity inhomogeneity in the two-layered earth     

Milan Hvoždara  Reviewer V. Petr 《Studia Geophysica et Geodaetica》1981,25(2):167-180

Summary The calculation of the elements of Green's tensor function is presented for solving the problem of the electromagnetic induction by means of a vector integral equation. A two-layered Earth is considered as the medium, the surface layer including a three-dimensional conductivity inhomogeneity. Use is made of the boundary condition requiring the vertical component of the electric current to be zero at the Earth's surface which partly simplifies the theoretical computation. Long-period asymptotics of the individual complicated functions, occurring in Green's tensor function as well as in the tensor function required to calculate the components of the anomalous magnetic field at the surface of the halfspace, were effected. With the aid of these asymptotics one can obtain estimates of the functions occurring in the theoretical analysis of the problem.  相似文献   

Numerical modelling in laterally inhomogeneous geoelectrical structures   总被引：2，自引：0，他引：2  

Václav Červ  Oldřich Praus  Reviewer M. Hvoždara 《Studia Geophysica et Geodaetica》1978,22(1):74-81

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Dedicated to RNDr. Jan Pícha, CSc., on his 60th Birthday  相似文献   

Spectral analysis of oscillations with a time-variable frequency     

Jaroslav Střeštík  Reviewer M. Hvoždara 《Studia Geophysica et Geodaetica》1979,23(4):333-348

Summary The paper presents a method of evaluating oscillations with a time-variable frequency using a computer. The given function is first interpolated at points which are not distributed equidistantly in time, but the digitizing step varies with time according to a known optional regularity. The spectrum of the obtained function is computed for various of these interpolations and tests are run to determine when the interpolation best compensates the time variation of the frequency. The initial and terminal frequency in the given sample is then determined. The usability of this method with respect to various types of oscillations with a variable frequency and its accuracy in comparison to sonagrams are discussed.  相似文献   

The use of laboratory measurements of electric resistivity of rocks for evaluating the magnetotelluric method     

Marcela Laštovičková  Josef Pek  Reviewer M. Hvoždara 《Studia Geophysica et Geodaetica》1979,23(1):94-98

Summary A profile model of electric resistivity as a function of depth was compiled, the initial parameters being the values of the electric resistivity determined experimentally for basaltic and eclogitic rocks from the Bohemian Massif. The curves of the apparent resistivity were computed for this model and the measure of information evaluated for the various model layers. The dominant influence of the subsurface layer was proved.  相似文献