视觉皮层振荡神经网络在遥感影像分割中的应用

对于具有复杂场景的遥感影像,提出了基于各向异性扩散特征保持平滑的简化LEGION算法,弥补传统LEGION图像分割算法对噪声敏感的不足。对于多(高)光谱影像,则采用马氏距离计算光谱向量间的连接权得到扩展LEGION算法进行分割。实验结果表明,LEGION算法较传统的图像分割方法对单波段灰度遥感影像目标及其重要细节部分的分割效果更显著;扩展LEGION算法适用于多光谱遥感影像分割。     

Classifying Human Activity Patterns from Smartphone Collected GPS data: A Fuzzy Classification and Aggregation Approach

Smartphones have emerged as a promising type of equipment for monitoring human activities in environmental health studies. However, degraded location accuracy and inconsistency of smartphone‐measured GPS data have limited its effectiveness for classifying human activity patterns. This study proposes a fuzzy classification scheme for differentiating human activity patterns from smartphone‐collected GPS data. Specifically, a fuzzy logic reasoning was adopted to overcome the influence of location uncertainty by estimating the probability of different activity types for single GPS points. Based on that approach, a segment aggregation method was developed to infer activity patterns, while adjusting for uncertainties of point attributes. Validations of the proposed methods were carried out based on a convenient sample of three subjects with different types of smartphones. The results indicate desirable accuracy (e.g. up to 96% in activity identification) using of this method. Two examples are provided in the Appendix to illustrate how the proposed methods could be applied in environmental health studies. Researchers could tailor this scheme to fit a variety of research topics.     

GIS数字图形产品生产的质量过程控制

数字产品的批量采集是ＧＩＳ应用的基础工作,为保证图形数据批量采集的精度和可靠性,本文探讨以质量过程控制的方法应用于数字图形的批量生产过程中,并给出了一些具体方法。     

Past,present and future vegetation-cloud feedbacks in the Amazon Basin

To begin exploring the underlying mechanisms that couple vegetation to cloud formation processes, we derive the lifting condensation level (LCL) to estimate cumulus cloud base height. Using a fully coupled land–ocean–atmosphere general circulation model (HadCM3LC), we investigate Amazonian forest feedbacks on cloud formation over three geological periods; modern-day (a.d. 1970–1990), the last glacial maximum (LGM; 21 kya), and under a future climate scenario (IS92a; a.d. 2070–2090). Results indicate that for both past and future climate scenarios, LCL is higher relative to modern-day. Statistical analyses indicate that the 800 m increase in LCL during the LGM is related primarily to the drier atmosphere promoted by lower tropical sea surface temperatures. In contrast, the predicted 1,000 m increase in LCL in the future scenario is the result of a large increase in surface temperature and reduced vegetation cover.     

北半球4月份500hPa月平均场遥相关型及其与我国降水异常的关系

用一点相关法计算了春季４月份北半球５００ｈＰａ遥相关型，得出４月存在５个遥相关型。它们的中心位置与冬季相比已有了较大的改变。计算了１９５１￣１９９０年各遥相关型的逐年强度指数。研究了它们的年际变化，指出４月的西太平洋型（ＷＰ）、欧亚型（ＥＵ）的强、弱是我国４月份大范围旱涝的主要原因。     

气象场经验正交函数不同展开方案收敛性问题的探讨

本文从理论上证明EOFs(经验正交函数)用于气象场时,三种不同计算方案特征值的相互关系.指出利用原始场积和矩阵展开的特征值λ_j等于用协方差阵展开的特征值λ_j~*加上平均场方差引起的特征值λ_j.进而论证了收敛速度差舁的原因.最后又以实例表明,不同展开方案的典型场意义及其与时间权重系数的对应关系.     

Temperature trends in the skin/surface, mid-troposphere and low stratosphere near Korea from satellite and ground measurements

Various types of satellite (AIRS/AMSU, MODIS) and ground measurements are used to analyze temperature trends in the four vertical layers (skin/surface, mid-troposphere, and low stratosphere) around the Korean Peninsula (123–132°E, 33–44°N) during the period from September 2002 to August 2010. The ground-based observations include 72 Surface Meteorological Stations (SMSs), 6 radiosonde stations (RAOBs), 457 Automatic Weather Stations (AWSs) over the land, and 5 buoy stations over the ocean. A strong warming (0.052 K yr^?1) at the surface, and a weak warming (0.004～0.010 K yr^?1) in the mid-troposphere and low stratosphere have been found from satellite data, leading to an unstable atmospheric layer. The AIRS/AMSU warming trend over the ocean surface around the Korean Peninsula is about 2.5 times greater than that over the land surface. The ground measurements from both SMS and AWS over the land surface of South Korea also show a warming of 0.043～0.082 K yr^?1, consistent with the satellite observations. The correlation average (r = 0.80) between MODIS skin temperature and ground measurement is significant. The correlations between AMSU and RAOB are very high (0.91～0.95) in the anomaly time series, calculated from the spatial averages of monthly mean temperature values. However, the warming found in the AMSU data is stronger than that from the RAOB at the surface. The opposite feature is present above the mid-troposphere, indicating that there is a systematic difference. Warming phenomena (0.012～0.078 K yr^?1) are observed from all three data sets (SMS, AWS, MODIS), which have been corroborated by the coincident measurements at five ground stations. However, it should also be noted that the observed trends are subject to large uncertainty as the corresponding 95% confidence intervals tend to be larger than the observed signals due to large thermal variability and the relatively short periods of the satellitebased temperature records. The EOF analysis of monthly mean temperature anomalies indicates that the tropospheric temperature variability near Korea is primarily linked to the Arctic Oscillation (AO), and secondarily to ENSO (El Niño and Southern Oscillation). However, the low stratospheric temperature variability is mainly associated with Southern Oscillation and then additionally with Quasi-Biennial Oscillation (QBO). Uncertainties from the different spatial resolutions between satellite data are discussed in the trends.     

Fatty acid profiles of benthic environment associated with artificial reefs in subtropical Hong Kong

Artificial reefs can enhance habitat heterogeneity, especially in seabed degraded by bottom-dredging and trawling. However, the trophodynamics of such reef systems are not well understood. This study provided baseline data on trophic relationships in the benthic environment associated with artificial reefs in late spring and mid summer of subtropical Hong Kong, using fatty acid profiles as an indicator. Data from sediments collected at the reef base, materials from sediment traps deployed on top and bottom of the reefs, total particulate matter from the water column and oyster tissues from reef surface were subjected to principal component analysis. Results showed variations of fatty acid profiles in the total particulate matter, upper sediment trap and oyster tissue samples collected in the two samplings, indicating seasonal, trophodynamic changes within the reef system. The wastes produced by fish aggregating at the reefs can also contribute a source of biodeposits to the nearby benthic environment.     

南方涛动(SO)与北大西洋涛动(NAO)百年变化特征的正交小波分析

利用“南海季风科学试验”（SCSMEX）所获得的可靠资料，对1998年区域海陆热力状况进行了分析与对比，并着重讨论了西太平洋和青藏高原地区热力作用对1998年季风爆发及发展的可能影响。结果发现：大气热源分布与海陆分布有密切联系，由于地形的阻挡使得在包含有南北海陆分布差异的地区，热源主要大值带较全海洋区域明显偏南。表面加热存在明显的季节变化和海陆差异。西太平洋地区与夏季风爆发之间的联系主要表现在海温和潜热加热的变化上。高原在亚洲夏季风爆发过程中的作用机制不同：在南海季风爆发期间以感热加热为主，印度季风爆发期间以水汽凝结释放潜热为主。