Numerical study on the mixed model in the GOCE polar gap problem

Gravity gradients acquired by the Gravity field and steady-state Ocean Circulation Explorer(GOCE) do not cover the entire earth because of its sun-synchronous orbit leaving data gaps with a radius of about 6.5° in the polar regions.Previous studies showed that the loss of data in the polar regions deteriorates the accuracy of the low order(or near zonal) coefficients of the earth gravity model,which is the so-called polar gap problem in geodesy.In order to find a stable solution for the earth gravity model from the GOCE gravity gradients,three models,i.e.the Gauss-Markov model,light constraint model and the mixed model,are compared and evaluated numerically with the gravity gradient simulated with the EGM2008.The comparison shows that the Best Linear Uniformly Unbiased Estimation(BLUUE) estimator of the mixed model can solve the polar gap problem as effectively as the light constraint model;furthermore,the mixed model is more rigorous in dealing with the supplementary information and leads to a better accuracy in determining the global geoid.     

全球油气勘探研究进展及对沉积储层研究的需求

近年来,全球油气勘探的重大发现和突破主要集中在被动大陆边缘深水区、岩性地层、海相碳酸盐岩、前陆盆地冲断带、成熟勘探地区、新勘探地区以及非常规油气等领域。勘探对象既包括常规构造、岩性地层、构造一岩性复合油气藏,也包括致密砂岩、页岩等非常规油气;勘探部位既包括被动大陆边缘、克拉通、前陆冲断带、前陆斜坡等常规油气藏分布区,又...     

强震作用下岩质斜坡动力响应特性的大型振动台试验方案设计

为了深入研究斜坡变形破坏机理,为汶川地震诱发次乍地质灾害提供理论解释,通过振动台试验模拟汶川地震过程.在参考已有实验和研究成果的基础上,对大型振动台物理模型进行设计,介绍模型箱、模拟范围、模型相似关系、模型岩层材料、各监测断面的位置和传感器的布置,编制地震波加载制度.结果表明,拟定的大型振动台模型试验设计方案是合理的.     

A study on the water vapor transport trend and water vapor source of the Tibetan Plateau

This study presents results of the pilot experiments made with new parametric multi-site multi-variable stochastic daily weather generator (WG) SPAGETTA. The experiments are performed for eight European regions and we focus on spatial characteristics of temperature. The WG is calibrated using the gridded weather data E-OBS. In evaluating the generator, the spatial and temporal temperature autocorrelations derived from the synthetic series were found to perfectly fit the values derived from the calibration data. Next, the WG is validated in terms of the frequency of “spatial hot days” and the annual maximum length of “spatial hot spells”. The results indicate a very good correspondence between characteristics derived from synthetic and calibration data. As part of the validation tests, the performance of the WG is compared with a regional climate model (RCM), which shows a similar performance as the generator. In a final experiment, the use of the WG for the future climate is demonstrated, the WG parameters (including the temperature autocorrelations) calibrated with the observed data are modified according to the RCM-based changes in these parameters. While analyzing synthetic series produced with the modified generator, we discuss partial impacts due to changes in individual WG parameters on the spatial hot days and spells. We show that the impacts are mainly (but not only) due to changes in temperature averages. The projected changes in temperature autocorrelations have also some impacts, larger for the spatial hot spells than for the spatial hot days. Climate change impacts on spatial hot days/spells based on the WG are compared with impacts based on the RCM, and we conclude that the differences are mainly due to simplifying assumptions adopted in our pilot experiment.     

Development of Climate and Earth System Models in China: Past Achievements and New CMIP6 Results

The Earth-Climate System Model (ECSM) is an important platform for multi-disciplinary and multi-sphere integration research, and its development is at the frontier of international geosciences, especially in the field of global change. The research and development (R&D) of ECSM in China began in the 1980s and have achieved great progress. In China, ECSMs are now mainly developed at the Chinese Academy of Sciences, ministries, and universities. Following a brief review of the development history of Chinese ECSMs, this paper summarized the technical characteristics of nine Chinese ECSMs participating in the Coupled Model Intercomparison Project Phase 6 and preliminarily assessed the basic performances of four Chinese models in simulating the global climate and the climate in East Asia. The projected changes of global precipitation and surface air temperature and the associated relationship with the equilibrium climate sensitivity under four shared socioeconomic path scenarios were also discussed. Finally, combined with the international situation, from the perspective of further improvement, eight directions were proposed for the future development of Chinese ECSMs.     

台站闪电定位仪维护方法与技巧

通过对闪电定位仪的基本构造、日常维护、常见故障等进行分析,找出闪电定位仪维护中存在的问题,提出一些有实用价值的维护维修方法,供台站在工作中参考.     

Climatic responses to anthropogenic groundwater exploitation: a case study of the Haihe River Basin,Northern China

In this study, a groundwater exploitation scheme is incorporated into the regional climate model, RegCM4, and the climatic responses to anthropogenic alteration of groundwater are then investigated over the Haihe River Basin in Northern China where groundwater resources are overexploited. The scheme models anthropogenic groundwater exploitation and water consumption, which are further divided into agricultural irrigation, industrial use and domestic use. Four 30-year on-line exploitation simulations and one control test without exploitation are conducted using the developed model with different water demands estimated from relevant socioeconomic data. The results reveal that the groundwater exploitation and water consumption cause increasing wetting and cooling effects on the local land surface and in the lower troposphere, along with a rapidly declining groundwater table in the basin. The cooling and wetting effects also extended outside the basin, especially in the regions downwind of the prevailing westerly wind, where increased precipitation occurs. The changes in the four exploitation simulations positively relate to their different water demands and are highly non-linear. The largest changes in climatic variables usually appear in spring and summer, the time of crop growth. To gain further insights into the direct changes in land-surface variables due to groundwater exploitation regardless of the atmospheric feedbacks, three off-line simulations using the land surface model Community Land Model version 3.5 are also conducted to distinguish these direct changes on the land surface of the basin. The results indicate that the direct changes of land-surface variables respond linearly to water demand if the climatic feedbacks are not considered, while non-linear climatic feedbacks enhance the differences in the on-line exploitation simulations.     

30-Year atmospheric temperature record derived by one-dimensional variational data assimilation of MSU/AMSU-A observations

In the past, satellite observations of the microwave radiation emitted from the atmosphere have been directly utilized for deriving the climate tends of vertical-layer-averaged atmospheric temperatures. This study presents the 30-year atmospheric temperature trend derived by one-dimensional variational (1D-Var) data assimilation of Microwave Sounding Unit/Advanced Microwave Sounding Unit-A (MSU/AMSU-A) observations. Firstly, the radiance measurements from MSU on board the early National Oceanic and Atmospheric Administration (NOAA)-6 to NOAA-14 and AMSU-A on board NOAA-15 to -19 have been inter-calibrated to form a fundamental climate data record. A 1D-Var method is then employed to establish the thematic climate data record of atmospheric temperature profiles that are appropriate for climate change study. Verification of the MSU/AMSU-A derived temperature profiles with collocated Global Positioning System radio occultation data confirms a reasonable good accuracy of the derived atmospheric temperature profiles in the troposphere and low stratosphere. Finally, the global climate trend of the atmospheric temperature in clear-sky conditions is deduced, showing not only a global warming in the troposphere and a cooling in the stratosphere, but also a stronger warming in the upper troposphere than in the low troposphere.     

福建区域性暴雨过程综合强度定量化评估方法

该文以福建省为例,探讨了区域性暴雨过程的识别方法和综合强度评估模型。采用福建省66个国家级气象观测站1961—2010年逐日降水量资料,首先在给定区域性暴雨过程识别方法的基础上,筛选出941次区域性暴雨过程;其次选取区域最大日降水量、区域最大过程降水量、区域暴雨范围和区域暴雨持续时间4项暴雨过程指标,采用百分位数方法分别确定4项指标的等级划分标准;采用相关系数法确定各指标权重,构建福建区域性暴雨过程的综合强度评估模型,并给出福建区域性暴雨过程的综合强度等级划分标准。业务服务和历史事件验证表明:采用该方法的评估结果较为合理,且与历史重大暴雨事件具有良好的一致性。     

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