Temporal and spatial evolution trends of drought in northern Shaanxi of China: 1960–2100

Theoretical and Applied Climatology - Drought prediction and assessment are the basis for addressing climate change and extreme weather. Northern Shaanxi is an important energy base and ecological...     

基于EPS2008航迹图制作

通航流量试验研究领导小组在三峡—葛洲坝两坝间组织开展大流量实船试航,我队承担本次任务航迹测量工作。本文提出了航迹数据自动处理流程,基于VB6.0开发航迹处理软件,并基于EPS2008,制作航迹符号。最后,通过实验数据,验证了数据处理的准确性和成图的快速性。     

关于低空数字航空摄影质量检验的研究

低空数字航空摄影在应急抢险、地质灾害防治、土地监测及新农村建设规划等中、小范围大比例尺地形测绘中发挥了积极有效的作用。本文结合国家相关标准及工作实践,探讨低空数字航空摄影质量检查的内容及检查方式与方法。     

地磁日变观测仪器的对比分析

当前海洋磁力探测中为了消除或减小地磁日变化的影响,必须设立地磁日变观测站（简称日变站）测量磁场变化,提供日变校正资料。依据多年工作经验,对作为基站使用的G882磁力仪和Sentinel磁力仪在工作原理、仪器技术性能、工作使用体会等方面进行综合比较分析。结果表明,Sentinel磁力仪比G882磁力仪对环境适应性更好、灵活性更强,进行日变观测时应优先选用。     

干旱胁迫下不同地理种源蒙古沙拐枣(Calligomum mongolicum)光合及荧光特性比较

以3个地理种源(武威、张掖、酒泉)蒙古沙拐枣(Calligomum mongolicum)两年生苗木为试材,研究干旱胁迫对其光合及荧光参数的影响,并采用投影寻踪法对其进行了抗旱性评价。结果表明:干旱胁迫导致3个地理种源蒙古沙拐枣光合作用均有所下降,但下降幅度不同,尤其在张掖和酒泉种源间差异显著(p0.05)。在重度干旱时,3个种源的光合速率(Pn)酒泉武威张掖,蒸腾速率(Tr)张掖武威酒泉,气孔导度(Gs)酒泉武威张掖。干旱胁迫下,3个地理种源蒙古沙拐枣的荧光特性表现为初始荧光(Fo)和非光化学淬灭系数(qN)升高,最大光学效率(Fv/Fm)、实际光能转化效率(ФPSⅡ)和光化学淬灭系数(qP)降低。在重度胁迫下,3个种源的Fo和qP大小排序分别为张掖武威酒泉,Fv/Fm、ФPSⅡ和qN为酒泉武威张掖。以投影寻踪法对3个地理种源蒙古沙拐枣的抗旱性排序结果为酒泉武威张掖。     

Electronic geothermal atlases of Asian Russia

Generalized geothermal data was used to produce two electronic atlases for Asian Russia,Geothermal Atlas of Siberia（GAS）（1995-2000） and Geothermal Atlas for Siberia and Russian Far East（GASRFE）（2009-2012）.The atlases include heat flow maps,temperatures at depths of 0.5,1,2,3,5 km and lower boundary of permafrost.Quantitative values of parameters are presented as isolines（GAS） and symbols（GASRFE）.GAS website is located at the Trofimuk Institute（www.ipgg.sbras.ru/ru/institute/structure/geophysics/natural-fields）.GASRFE provides the most complete geothermal data on Asian Russia,which has been growing for the last 50 years,and is published on the Internet at http：//maps.nrcgit.ru/geoterm.In this atlas,data about the depth of permafrost lower boundary（ ＂zero＂ isotherm） are presented for the first time.     

Simulated perturbation in the sea-to-air flux of dimethylsulfide and the impact on polar climate

Marine biogenic emission of dimethylsulfide(DMS) has been well recognized as the main natural source of reduced sulfur to the remote marine atmosphere and has the potential to affect climate,especially in the polar regions.We used a global climate model(GCM) to investigate the impact on atmospheric chemistry from a change to the contemporary DMS flux to that which has been projected for the late 21~(st) century.The perturbed simulation corresponded to conditions that pertained to a tripling of equivalent CO_2, which was estimated to occur by year 2090 based on current worst-case greenhouse gas emission scenarios.The changes in zonal mean DMS flux were applied to 50°S-70°′S Antarctic(ANT) and65°N-80°N Arctic(ARC) regions.The re sults indic ate that the re are clearly diffe rent impacts after perturb ation in the southern and northern polar regions.Most quantities related to the sulfur cycle show a higher increase in ANT.However,mo st sulfur compounds have higher peaks in ARC.The perturbation in DMS flux leads to an increase of atmo spheric DMS of about 45% m ANT and 33.6% in ARC.The sulfur dioxide(S02) vertical integral increases around 4 3 % in ANT and 7.5% in ARC.Sulfate(S04) vertical integral increases by 17% in ANT and increases around 6% in ARC.Sulfur emissions increases by 21% in ANT and increases by 9.7%in ARC.However,oxidation of DMS by OH increases by 38.2% in ARC and by 15.17% in ANT.Aerosol optical depth(AOD) increases by 4% in the ARC and by 17.5% in the ANT,and increases by 22.8% in austral summer.The importance of the perturbation of the biogenic source to future aerosol burden in polar regions leads to a cooling in surface temperature of 1 K in the ANT and 0.8 K in the ARC.Generally,polar regions in the Antarctic Ocean will have a higher offsetting effect on warming after DMS flux perturbation.     

Similarity Relations for C_{T}^2 in the Unstable Atmospheric Surface Layer: Dependence on Regression Approach,Observation Height and Stability Range

A great variety of similarity functions for the structure parameter of temperature ( \(C_{T}^2\) ) have been proposed in the literature. They differ in the way they were derived from the data and in the characteristics of the dataset used for their derivation (surface type, observation level, stability range). In this study, we use one single dataset (CASES-99 experiment) and investigate the impact on the similarity functions of applying various regression approaches, and measuring at different heights and within different stability ranges. We limit ourselves to similarity functions under unstable conditions, and evaluate only the most common shape that describes the relation with two coefficients ( \(f\left( z/L\right) =c_{1} \left( 1-c_{2} {z}/{L}\right) ^{-2/3}\) , where \(z\) is the height, and \(L\) is the Obukhov length and a measure of the stability, and \(c_{1}\) and \(c_{2}\) are the regression coefficients). The results show that applying various regression approaches has an impact on the regression coefficients \(c_{1}\) and \(c_{2}\) . Thus studies should always specify the regression approach when presenting similarity relations. We suggest use of an orthogonal distance regression method such that uncertainties in \(-z/L\) are also taken into account, to apply this to the logarithmic transformation of both dimensionless groups, and to use a weighted dataset such that unreliable data points have a smaller influence on the fit. Dividing the dataset into eight height ( \(z\) ) and eight stability ( \(-{1/L}\)  classes) classes, we show that the observation height and the stability range has an impact on the coefficients too. This implies that variations in \(c_{1}\) and \(c_{2}\) found in the literature may result from variations in the height and stability ranges among the datasets. Furthermore, application of the coefficients on a dataset obtained at a different height or within a different stability range has to be made with care. Finally, the variation in the coefficients between the classes indicates that the Monin–Obukhov similarity function for \(C_{T}^2\) is not sufficiently described by the two-coefficient function used here.     

The Third GABLS Intercomparison Case for Evaluation Studies of Boundary-Layer Models. Part B: Results and Process Understanding

We describe and analyze the results of the third global energy and water cycle experiment atmospheric boundary layer Study intercomparison and evaluation study for single-column models. Each of the nineteen participating models was operated with its own physics package, including land-surface, radiation and turbulent mixing schemes, for a full diurnal cycle selected from the Cabauw observatory archive. By carefully prescribing the temporal evolution of the forcings on the vertical column, the models could be evaluated against observations. We focus on the gross features of the stable boundary layer (SBL), such as the onset of evening momentum decoupling, the 2-m minimum temperature, the evolution of the inertial oscillation and the morning transition. New process diagrams are introduced to interpret the variety of model results and the relative importance of processes in the SBL; the diagrams include the results of a number of sensitivity runs performed with one of the models. The models are characterized in terms of thermal coupling to the soil, longwave radiation and turbulent mixing. It is shown that differences in longwave radiation schemes among the models have only a small effect on the simulations; however, there are significant variations in downward radiation due to different boundary-layer profiles of temperature and humidity. The differences in modelled thermal coupling to the land surface are large and explain most of the variations in 2-m air temperature and longwave incoming radiation among models. Models with strong turbulent mixing overestimate the boundary-layer height, underestimate the wind speed at 200 m, and give a relatively large downward sensible heat flux. The result is that 2-m air temperature is relatively insensitive to turbulent mixing intensity. Evening transition times spread 1.5 h around the observed time of transition, with later transitions for models with coarse resolution. Time of onset in the morning transition spreads 2 h around the observed transition time. With this case, the morning transition appeared to be difficult to study, no relation could be found between the studied processes, and the variation in the time of the morning transition among the models.