Prediction of primary climate variability modes at the Beijing Climate Center   总被引：3，自引：2，他引：1       下载免费PDF全文

Hong-Li Ren  Fei-Fei Jin  Lianchun Song  Bo Lu  Ben Tian  Jinqing Zuo  Ying Liu  Jie Wu  Chongbo Zhao  Yu Nie  Peiqun Zhang  Jin Ba  Yujie Wu  Jianghua Wan  Yuping Yan  Fang Zhou 《Acta Meteorologica Sinica》2017,31(1):204-223

Climate variability modes, usually known as primary climate phenomena, are well recognized as the most important predictability sources in subseasonal–interannual climate prediction. This paper begins by reviewing the research and development carried out, and the recent progress made, at the Beijing Climate Center (BCC) in predicting some primary climate variability modes. These include the El Niño–Southern Oscillation (ENSO), Madden–Julian Oscillation (MJO), and Arctic Oscillation (AO), on global scales, as well as the sea surface temperature (SST) modes in the Indian Ocean and North Atlantic, western Pacific subtropical high (WPSH), and the East Asian winter and summer monsoons (EAWM and EASM, respectively), on regional scales. Based on its latest climate and statistical models, the BCC has established a climate phenomenon prediction system (CPPS) and completed a hindcast experiment for the period 1991–2014. The performance of the CPPS in predicting such climate variability modes is systematically evaluated. The results show that skillful predictions have been made for ENSO, MJO, the Indian Ocean basin mode, the WPSH, and partly for the EASM, whereas less skillful predictions were made for the Indian Ocean Dipole (IOD) and North Atlantic SST Tripole, and no clear skill at all for the AO, subtropical IOD, and EAWM. Improvements in the prediction of these climate variability modes with low skill need to be achieved by improving the BCC’s climate models, developing physically based statistical models as well as correction methods for model predictions. Some of the monitoring/prediction products of the BCC-CPPS are also introduced in this paper.  相似文献   

Distribution of winter-spring snow over the Tibetan Plateau and its relationship with summer precipitation in Yangtze River     

Zhuo G  Tao Chen  La B  PuBuCiRen  Ba Sang 《寒旱区科学》2017,9(1):20-28

The distribution of winter-spring snow cover over the Tibetan Plateau(TP) and its relationship with summer precipitation in the middle and lower reaches of Yangtze River Valley(MLYRV) during 2003–2013 have been investigated with the moderate-resolution imaging spectrometer(MODIS) Terra data(MOD10A2) and precipitation observations. Results show that snow cover percentage(SCP) remains approximately 20% in winter and spring then tails off to below 5% with warmer temperature and snow melt in summer. The lower and highest percentages present a declining tendency while the middle SCP exhibits an opposite variation. The maximum value appears from the middle of October to March and the minimum emerges from July to August. The annual and winter-spring SCPs present a decreasing tendency. Snow cover is mainly situated in the periphery of the plateau and mountainous regions, and less snow in the interior of the plateau, basin and valley areas in view of snow cover frequency(SCF) over the TP. Whatever annual or winter-spring snow cover, they all have remarkable declining tendency during 2003–2013, and annual snow cover presents a decreasing trend in the interior of the TP and increasing trend in the periphery of the TP. The multi-year averaged eight-day SCP is negatively related to mean precipitation in the MLYRV. Spring SCP is negatively related to summer precipitation while winter SCP is positively related to summer precipitation in most parts of the MLYRV. Hence, the influence of winter snow cover on precipitation is much more significant than that in spring on the basis of correlation analysis. The oscillation of SCF from southeast to northwest over the TP corresponds well to the beginning, development and cessation of the rain belt in eastern China.  相似文献   

Development of local authorities in EU-member states between 1950–2011     

Michal Klobučník  Vladimír Bačík 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2016,116(2):159-175

The aim of the submitted study was to illustrate the development of the number of local authorities in all current EU states in the long period between 1950 and 2011 comprehensively, and also by particular decades, thus demonstrating the originality and uniqueness of the topic analysed in this context. Thus, we obtain a more detailed picture of the development of the number of local authorities in EU countries, and we can monitor how local authorities within a specific country gradually developed. (The stabilisation of the number of local units and an increase or gradual or sudden drop in local units are shown, for example). A sudden drop in local units can be associated with significant administrative reforms and with the development of large units of the so-called municipalities. When it becomes necessary to merge local authorities, many countries look to other countries where extensive reforms took place in the past for inspiration. However, it must be borne in mind that in a general European context, we cannot apply a universal system of public administration reforms, and solutions in the form of these reforms inspired by other countries may not always be appropriate.  相似文献   

藏北高原蒸发皿蒸发量及其影响因素的变化特征   总被引：17，自引：2，他引：15       下载免费PDF全文

杜军  边多  鲍建华  拉巴  路红亚 《水科学进展》2008,19(6):786-791

采用气候倾向率方法,对藏北高原1971-2006年6个气象站年、季小型蒸发皿蒸发量及其影响气候因子的变化趋势进行了分析。结果表明:近36年藏北高原年蒸发皿蒸发量各站点均呈现显著的减少趋势,平均减少61.7mm/10a(通过99%显著性检验),以夏季减幅最明显。就地域分布而言,蒸发皿蒸发量的下降主要表现在藏北高原的中西部。蒸发量减少幅度随经度的增加减小,随海拔高度的升高而加大。影响蒸发皿蒸发量的主要气候因子日照时数、平均风速呈现显著下降趋势,平均相对湿度、降水量表现为显著增加,平均气温显著升高,平均最低气温的升温速率(0.54℃/10a)明显比平均最高气温的升温速率(0.17℃/10a)大,导致气温日较差的减小(-0.37℃/10a)。藏北高原平均气温日较差和日照时数的显著减小,以及平均相对湿度的明显增加可能是蒸发皿蒸发量显著下降的主要原因,降水量的增加和平均风速的明显减小在蒸发量减少趋势中的作用也不可忽视。  相似文献   

High-resolution simulations for Vietnam - methodology and evaluation of current climate     

Jack Katzfey  Kim Nguyen  John McGregor  Peter Hoffmann  Suppiah Ramasamy  Hiep Van Nguyen  Mai Van Khiem  Thang Van Nguyen  Kien Ba Truong  Thang Van Vu  Hien Thuan Nguyen  Tran Thuc  Doan Ha Phong  Bang Thanh Nguyen  Tan Phan-Van  Trung Nguyen-Quang  Thanh Ngo-Duc  Long Trinh-Tuan 《Asia-Pacific Journal of Atmospheric Sciences》2016,52(2):91-106

To assist the government of Vietnam in its efforts to better understand the impacts of climate change and prioritise its adaptation measures, dynamically downscaled climate change projections were produced across Vietnam. Two Regional Climate Models (RCMs) were used: CSIRO’s variable-resolution Conformal-Cubic Atmospheric Model (CCAM) and the limited-area model Regional Climate Model system version 4.2 (RegCM4.2). First, global CCAM simulations were completed using bias- and variance-corrected sea surface temperatures as well as sea ice concentrations from six Coupled Model Intercomparison Project Phase 5 (CMIP5) global climate models. This approach is different from other downscaling approaches as it does not use any atmospheric fields from the GCMs. The global CCAM simulations were then further downscaled to 10 km using CCAM and to 20 km using RegCM4.2. Evaluations of temperature and precipitation for the current climate (1980-2000) were completed using station data as well as various gridded observational datasets. The RCMs were able to reproduce reasonably well most of the important characteristics of observed spatial patterns and annual cycles of temperature. Average and minimum temperatures were well simulated (biases generally less than 1oC), while maximum temperatures had biases of around 1oC. For precipitation, although the RCMs captured the annual cycle, RegCM4.2 was too dry in Oct.-Nov. (-60% bias), while CCAM was too wet in Dec.- Mar. (130% bias). Both models were too dry in summer and too wet in winter (especially in northern Vietnam). The ability of the ensemble simulations to capture current climate increases confidence in the simulations of future climate.  相似文献   

Hydrochemical and isotopic properties of Heybeli geothermal area (Afyon,Turkey)     

Can Başaran  Ali Gökgöz 《Arabian Journal of Geosciences》2016,9(11):586

The thermal waters at the Heybeli (K?z?lkirse) low-temperature geothermal field located in the Afyonkarahisar Province (western Turkey) are discharged from Paleozoic recrystallized limestone. The temperature, specific electrical conductivity, and pH values of the thermal waters are within the range of 28.9 to 54.7 °C, 587 to 3580 μS/cm, and 6.32 to 7.37, respectively. The Heybeli geothermal system is fed by meteoric waters. The waters are heated at depth by high geothermal gradient caused by the neotectonic activity in the deep and ascend to the surface through fractures and faults by convection. The thermal waters are of Na-Ca-HCO₃-SO₄ type and their chemical composition of the waters is mainly controlled by water-rock interaction and mixing processes. The δ¹⁸O, δ²H and tritium compositions show that the thermal waters are of meteoric origin and the residence time at the reservoir is longer than 50 years. Isotope data (δ³⁴S and δ¹³C) indicate recrystallized limestones as origin of CO₂ and structural substitution of sulfate into marine carbonates (CAS) as origin of sulfur. Chemical, \( {\updelta}^{18}{\mathrm{O}}_{\left({\mathrm{SO}}_4-{\mathrm{H}}_2\mathrm{O}\right)} \) isotope geothermometers and mineral equilibrium diagrams applied to thermal waters gave reservoir temperatures between 62 and 115 °C. Saturation index calculations show that the most expected minerals causing scaling at outflow conditions during the production and utilization of Heybeli geothermal waters are calcite, aragonite, dolomite, quartz, and chalcedony.  相似文献   

Photoprotective role of inflorescence and UV-radiation effects on pollen viability of different freshwater plants     

Rafael M. Conde-Álvarez  Félix L. Figueroa  Elena Bañares-España  José M. Nieto-Caldera 《Aquatic Sciences - Research Across Boundaries》2008,70(1):57-64

  相似文献   

实验室频段的双孔岩石模型与喷射流   总被引：8，自引：6，他引：2  

巴晶  曹宏  姚逢昌  聂建新  杨慧珠 《应用地球物理》2008,5(4):261-276

  相似文献   

Determination of Electron Density and Filling Factor for Soft X-Ray Flare Kernels     

J.?Jakimiec  U.?Ba?k-St??lickaEmail author 《Solar physics》2011,272(1):91-100

In the standard method of electron density determination for soft X-ray (SXR) flare kernels, it is necessary to assume what the extent is of a kernel along the line of sight. This is a source of significant uncertainty of the obtained densities.  相似文献   

Asymptotic solution for the two-body problem with constant tangential thrust acceleration   总被引：1，自引：0，他引：1  

Claudio Bombardelli  Giulio Baù  Jesus Peláez 《Celestial Mechanics and Dynamical Astronomy》2011,110(3):239-256

An analytical solution of the two body problem perturbed by a constant tangential acceleration is derived with the aid of perturbation theory. The solution, which is valid for circular and elliptic orbits with generic eccentricity, describes the instantaneous time variation of all orbital elements. A comparison with high-accuracy numerical results shows that the analytical method can be effectively applied to multiple-revolution low-thrust orbit transfer around planets and in interplanetary space with negligible error.  相似文献