山东省极端气温偏态性分布和变化特征

采用山东省1961—2010年夏季日最高气温和冬季日最低气温数据,基于Box-Cox变换,分析了山东省极端高温、极端低温偏态性分布特征与变化趋势。结果显示,极端高温偏态系数具有较为显著的海陆分布特征,呈现由东南向西北左偏相对减弱,且夏季异常高温出现几率有所增加。极端低温偏态指数分布受地形和纬度的双重影响,左偏和右偏的地区接近,各占半数。在气候态,由Ⅰ态经Ⅱ态过渡到Ⅲ态的过程中,山东省大部分地区夏季极端高温偏态指数和冬季极端低温偏态指数均处于不断升高的状态,表明大部分地区夏季出现异常高温的几率处在增加的趋势中,而冬季出现异常低温的几率处在减少的趋势中。     

The influence of seasonal snow on soil thermal and water dynamics under different vegetation covers in a permafrost region

Seasonal snow is one of the most important influences on the development and distribution of permafrost and the hydrothermal regime in surface soil. Alpine meadow, which constitutes the main land type in permafrost regions of the Qinghai-Tibet Plateau, was selected to study the influence of seasonal snow on the temperature and moisture in active soil layers under different vegetation coverage. Monitoring sites for soil moisture and temperature were constructed to observe the hydrothermal processes in active soil layers under different vegetation cover with seasonal snow cover variation for three years from 2010 to 2012. Differences in soil temperature and moisture in areas of diverse vegetation coverage with varying levels of snow cover were analyzed using active soil layer water and temperature indices. The results indicated that snow cover greatly influenced the hydrothermal dynamics of the active soil layer in alpine meadows. In the snow manipulation experiment with a snow depth greater than 15 cm, the snow cover postponed both the freeze-fall and thawrise onset times of soil temperature and moisture in alpine LC （lower vegetation coverage） meadows and of soil moisture in alpine HC （higher vegetation coverage） meadows; however, the opposite response occurred for soil temperatures of alpine HC meadows,where the entire melting period was extended by advancing the thaw-rise and delaying the freeze-fall onset time of the soil temperature. Snow cover resulted in a decreased amplitude and rate of variation in soil temperature, for both alpine HC meadows and alpine LC meadows, whereas the distinct influence of snow cover on the amplitude and rate of soil moisture variation occurred at different soil layers with different vegetation coverages. Snow cover increased the soil moisture of alpine grasslands during thawing periods. The results confirmed that the annual hydrothermal dynamics of active layers in permafrost were subject to the synergistic actions of both snow cover and vegetation coverage.     

黄河三角洲高效生态经济区卤水资源开采潜力评价

黄河三角洲高效生态经济区卤水资源较为丰富,历经几十年的集中开采后,已出现卤水开采水位下降、卤度及有益离子含量下降等问题,该文在核算研究区卤水资源量的基础上,结合开发利用现状进行了开采潜力评价,以期为当地卤水资源开采规划提供科学依据。     

EMD与分形相结合的遥感影像水体信息提取方法

提出一种基于经验模态分解(empirical mode decomposition,EMD)和分形理论相结合的遥感影像水体信息提取方法,该方法尝试结合影像的光谱特征和纹理特征以提高分类提取精度。对影像进行主成分分析得到有效信息量最大的第一主分量,计算每个像元的分维数得到分维图,同时将第一主分量EMD分解得到有效信息量较大的前3个经验模态函数,再结合原有的波段信息作为研究数据,利用极大似然法分类器提取水体信息。该方法充分结合了EMD在降噪和区分相似光谱特征中的优势和分形理论在纹理信息提取中的优势。研究表明,该方法可有效提高水体信息的提取精度,Kappa最高到0.932 5。     

广东省级公共地理框架数据生产技术方案

详细介绍广东省省级公共地理框架数据生产的内容及技术方法,总结经验并提出今后改进的方向,为同行提供参考。     

Markov-random-field-based super-resolution mapping for identification of urban trees in VHR images

Identification of tree crowns from remote sensing requires detailed spectral information and submeter spatial resolution imagery. Traditional pixel-based classification techniques do not fully exploit the spatial and spectral characteristics of remote sensing datasets. We propose a contextual and probabilistic method for detection of tree crowns in urban areas using a Markov random field based super resolution mapping (SRM) approach in very high resolution images. Our method defines an objective energy function in terms of the conditional probabilities of panchromatic and multispectral images and it locally optimizes the labeling of tree crown pixels. Energy and model parameter values are estimated from multiple implementations of SRM in tuning areas and the method is applied in QuickBird images to produce a 0.6 m tree crown map in a city of The Netherlands. The SRM output shows an identification rate of 66% and commission and omission errors in small trees and shrub areas. The method outperforms tree crown identification results obtained with maximum likelihood, support vector machines and SRM at nominal resolution (2.4 m) approaches.     

Accuracy assessment of the GPS-TEC calibration constants by means of a simulation technique

During the last 2 decades, Global Positioning System (GPS) measurements have become a very important data-source for ionospheric studies. However, it is not a direct and easy task to obtain accurate ionospheric information from these measurements because it is necessary to perform a careful estimation of the calibration constants affecting the GPS observations, the so-called differential code biases (DCBs). In this paper, the most common approximations used in several GPS calibration methods, e.g. the La Plata Ionospheric Model (LPIM), are applied to a set of specially computed synthetic slant Total Electron Content datasets to assess the accuracy of the DCB estimation in a global scale scenario. These synthetic datasets were generated using a modified version of the NeQuick model, and have two important features: they show a realistic temporal and spatial behavior and all a-priori DCBs are set to zero by construction. Then, after the application of the calibration method the deviations from zero of the estimated DCBs are direct indicators of the accuracy of the method. To evaluate the effect of the solar activity radiation level the analysis was performed for years 2001 (high solar activity) and 2006 (low solar activity). To take into account seasonal changes of the ionosphere behavior, the analysis was repeated for three consecutive days close to each equinox and solstice of every year. Then, a data package comprising 24 days from approximately 200 IGS permanent stations was processed. In order to avoid unwanted geomagnetic storms effects, the selected days correspond to periods of quiet geomagnetic conditions. The most important results of this work are: i) the estimated DCBs can be affected by errors around ±8 TECu for high solar activity and ±3 TECu for low solar activity; and ii) DCB errors present a systematic behavior depending on the modip coordinate, that is more evident for the positive modip region.     

EXCEL计算概率积分法预计参数

EXCEL软件是最常用的办公软件之一,本文介绍一种利用EXCEL软件规划求解功能计算开采沉陷预计概率积分法预计参数的方法,很方便地得到了预计参数的优化解,通过实例验证,运用该方法得到的这些参数的解满足开采沉陷预计精度的要求,有很好的应用价值。     

基于CBERS-02B星HR与CCD数据的喀斯特山区影像融合研究

喀斯特山区海拔高且相对高差大,地块破碎,地表覆盖类型多样,常年多云多雨,卫星遥感数据质量因此常受到严重影响.国产自主卫星CBERS-02B获取的高分辨率全色影像(HR)和多光谱(CCD)影像能更快捷.更方便地提供喀斯特山区遥感影像.采用HIS变换、PCA变换、HPF等图像融合方法,对CBERS-02B星HR和CCD影像...     

Climatic trends and different drought adaptive capacity and vulnerability in a mixed Abies pinsapo�CPinus halepensis forest

The projected temperature rise, rainfall decrease and concentration of rainfall in extreme events could induce growth decline and die-off on tree populations located at the geographical distribution limit of the species. Understanding of adaptive capacity and regional vulnerability to climate change in Mediterranean forests is not well developed and requires more focused research efforts. We studied the relationships between spatiotemporal patterns of temperature and precipitation along the southwestern edge of the Betic range (southern Spain) and measured basal area increment (BAI) and carbon isotope (??) in tree ring series of Abies pinsapo and Pinus halepensis, two Mediterranean conifer trees with contrasting drought adaptive capacity. Climatic information was obtained from a network covering a wide range of elevations and distances from the Atlantic and Mediterranean coasts. Temperature trends were tested by the Mann?CKendall test, and precipitation was thoroughly analyzed by quantile regression. Climatic data showed a warming trend, enhanced since the 1970s, while quantile regressions revealed that drought events worsened during the course of the twentieth century. Long-term decrease of A. pinsapo BAI was related to regional warming and changing precipitation patterns, suggesting increasing drought stress on this species. Both temperature and precipitation in the summer influenced wood ?? in P. halepensis, whereas negative correlation between wood ?? and current autumn temperature was yielded for A. pinsapo. Increased intrinsic water use efficiency was inferred from wood ?? in both species; however, A. pinsapo showed sudden growth reductions under drier conditions, while pine trees were able to maintain almost constant BAI values and lower water costs under increasing long-term water stress.