Latitudinal and Scan-dependent Biases of Microwave Humidity Sounder Measurements and Their Dependences on Cloud Ice Water Path

The relationship between differences in microwave humidity sounder(MHS)–channel biases which represent measured brightness temperatures and model-simulated brightness temperatures, and cloud ice water path(IWP) as well as the influence of the cloud liquid water path(LWP) on the relationship is examined. Seven years(2011–17) of NOAA-18 MHS-derived measured brightness temperatures and IWP/LWP data generated by the NOAA Comprehensive Large Array-data Stewardship System Microwave Surface and Precipitation Products System are used. The Community Radiative Transfer Model, version2.2.4, is used to simulate model-simulated brightness temperatures using European Center for Medium-Range Weather Forecasts reanalysis data as background fields. Scan-angle deviations of the MHS window channel biases range from-1.7 K to1.0 K. The relationships between channels 2, 4, and 5 biases and scan angle are symmetrical about the nadir. The latitudedependent deviations of MHS window channel biases are positive and range from 0–7 K. For MHS non-window channels,the latitudinal deviations between measured brightness temperatures and model-simulated brightness temperatures are larger when the detection height is higher. No systematic warm or cold deviations are found in the global spatial distribution of difference between measured brightness temperatures and model-simulated brightness temperatures over oceans after removing scan-angle and latitudinal deviations. The corrected biases of five different MHS channels decrease differently with respect to the increase in IWP. This decrease is stronger when LWP values are higher.     

GRAPES全球集合预报系统模式扰动随机动能补偿方案初步探究

为了体现次网格尺度能量升尺度转换过程中存在的不确定性, 文中将随机动能补偿(Stochastic Kinetic Energy Backscatter, SKEB)方案应用于GRAPES(Global/Regional Assimilation and Prediction System)全球集合预报系统(GRAPES-GEPS), 以更好地表征模式误差并且增大集合离散度。使用的SKEB方案基于具有一定时、空相关特征的随机型以及由数值扩散导致的局地动能耗散率来构造随机流函数强迫。并根据流函数与水平风速旋转分量的关系, 将SKEB方案中的流函数强迫转化为适用于GRAPES全球模式的水平风速扰动。结果表明, SKEB方案的使用一方面能够提高GRAPES对大气动能谱的模拟能力; 另一方面能够改善GRAPES-GEPS的集合离散度与集合平均误差的关系, 增加了集合离散度, 并在一定程度上减小了集合平均误差, 尤其是在热带地区这种改进更为显著。而且该方案使得热带地区连续分级概率评分(CRPS评分)显著减小。就降水预报而言, 从Brier评分与相对作用特征面积(AROC, Area under the Relative Operating Characteristics)的结果来看, SKEB方案有助于改善中国地区小雨[0.1 mm, 10 mm)、中雨[10 mm, 25 mm)与大雨[25 mm, 50 mm)量级降水的概率预报技巧, 而对暴雨[50 mm, ∞)量级降水预报技巧影响很小(24 h降水量)。总体上, 模式扰动随机动能补偿方案提高了GRAPES-GEPS的概率预报技巧。      

内蒙古冬季极端多雪气候事件环流演变特征及季节预测信号

文章研究关注了内蒙古冬季极端多雪气候事件的季节预测问题,在对大量降水观测资料、海温及大气环流场资料进行统计、分析、研究的基础上,确定了历史上58a(1960—2017年)内蒙古冬季极端多雪和少雪气候事件样本,通过对大气环流场的对比分析发现极端多雪或少雪冬季环流场特征显著不同,分析后确定了影响内蒙古冬季降雪的主要环流系统,包括西太平洋副热带高压、极涡、东亚大槽、环流E型及南方涛动等系统。同时,探索了对这些主要环流系统具有预测意义的来自海洋和大气场的预测信号,对预测信号关键区做了标准化定量提取,确定了预测信号综合指数分段判别阈值,给出了预测概念模型,取得了较好预测效果。     

冰核观测中两种滤膜采样方法的比较

大气冰核观测是研究自然冷云降水和人工影响天气的一项基础性工作,滤膜—扩散云室法是观测冰核浓度的主要方法之一。为检测分析两种滤膜采集方法对冰核观测结果的影响,2011—2015年用自制的大气颗粒物采样器和FA-3型撞击式9级采样器开展了平行采样试验,采集的滤膜样本均在同一静力扩散云室中进行冰核活化显现分析。结果表明：自制采样器较9级采样器观测的冰核浓度高数倍甚至数十倍,但两者随季节和不同气象条件的变化表现出一致的起伏特征。自制采样器适用于对大气中总的冰核浓度分布及理化特征研究;9级采样器适用于对PM₁₀中不同粒径段大气冰核浓度和尺度分布以及理化特征的研究。滤膜法对冰核数量的低估与采样体积成正比,改变采样器气泵的抽气流量和控制采样体积对改进“体积效应”影响均有明显效果。     

基于ENVI-met的福州大学校区冬季热环境模拟与热舒适度变化分析

选取福州大学校园教学区为研究区域,基于典型冬季日背景,运用三维非静力微气候模型ENVI-met,分析模拟校园热环境的差异变化及其热舒适度响应。结合实地勘测,对模型进行校准和验证。结果表明：ENVI-met模型能较好地表征室外热环境,准确预测温度和相对湿度的日变化趋势。混凝土路面、灰色地砖路面行人高度的日平均气温分别比草地高出0.1 ℃和0.3 ℃,逐时最大温差分别为0.68 ℃和0.65 ℃。建筑物阴影和树阴可降低行人高度的气温1.1—1.9 ℃;同一组团在有无遮阴的条件下,平均辐射温度（T_mrt）相差最大可达30 ℃;树木附近和建筑物组团内部生理等效温度（PET）值较小,比硬质路面低2—3个等级。无植被方案下,高温低湿区范围有所扩张,在垂直方向上的增温效应可伸展至10.5 m;风速最大增幅可达1.23 m·s^-1,平均辐射温度较高区域的面积增加了69.25%;热舒适区和热不适区面积分别增加了19.78%和2.03%。     

线性向量半参数模型与标量半参数模型最小二乘估计的比较

研究了最小二乘准则下线性向量半参数模型的核估计、近邻估计及样条估计3种估计方法,分析了向量半参数模型与标量半参数模型在这几种估计方法中的差异。     

大气水分循环方程

任何地点的降水量可能来自地球的任何地点的水分蒸发。为了定量描述大气中的这种水分循环的复杂过程,我们引入了两个概念性的工具:大气水分辐合函数和大气水分辐散函数,并且建立了用它们描述大气水分循环的方程组。     

浙江省县域旅游经济增长的空间溢出效应

论文以浙江省65个县域单元为例,综合运用探索性空间数据分析和空间杜宾模型,实证了2004—2016年浙江省县域旅游经济增长及其影响因素的空间溢出效应。结果表明:① 研究期内浙江省县域旅游经济整体表现出较强的空间依赖性,局部空间关联类型以高—高和低—低集聚为主,高—高集聚区主要位于中心市区,低—低集聚区主要位于浙西和浙南等地。旅游经济增长的空间自相关性表明考察其演化路径时不可忽视空间效应的存在。② 浙江省县域入境和国内旅游经济增长均存在显著的空间溢出效应,本地入境和国内旅游经济每增长1%,将会带动邻近县域入境和国内旅游经济分别增长0.192%和0.249%。经济发展水平、旅游资源禀赋、旅游基础设施和区位交通条件等均具有显著的空间溢出效应,忽视旅游经济增长的空间效应,将会高估这些因素的作用强度。③ 驱动旅游经济增长的各影响因素的作用强度和影响路径存在显著差异,未来应充分关注入境和国内旅游经济增长的空间依赖特征,将驱动旅游经济增长的各因素齐抓并举,方可实现县域旅游经济的高质量发展。     

Detection of coffee berry necrosis by digital image processing of landsat 8 oli satellite imagery

Coffee berry necrosis is a fungal disease that, at a high level, significantly affects coffee productivity. With the advent of surface mapping satellites, it was possible to obtain information about the spectral signature of the crop on a time scale pertinent to the monitoring and detection of plant phenological changes. The objective of this paper was to define the best machine learning algorithm that is able to classify the incidence CBN as a function of Landsat 8 OLI images in different atmospheric correction methods. Landsat 8 OLI images were acquired at the dates closest to sampling anthracnose field data at three times corresponding to grain filling period and were submitted to atmospheric corrections by DOS, ATCOR, and 6SV methods. The images classified by the algorithms of machine learning, Random Forest, Multilayer Perceptron and Naive Bayes were tested 30 times in random sampling. Given the overall accuracy of each test, the algorithms were evaluated using the Friedman and Nemenyi tests to identify the statistical difference in the treatments. The obtained results indicated that the overall accuracy and the balanced accuracy index were on an average around 0.55 and 0.45, respectively, for the Naive Bayes and Multilayer Perceptron algorithms in the ATCOR atmospheric correction. According to the Friedman and Nemenyi tests, both algorithms were defined as the best classifiers. These results demonstrate that Landsat 8 OLI images were able to identify an incidence of the coffee berry necrosis by means of machine learning techniques, a fact that cannot be observed by the Pearson correlation.     

复杂地形景区三维导览图的设计与实现

为满足复杂地形景区对三维地图导览的需求,构建更为清晰的三维地图模型,提供良好的三维导览地图设计方案显得尤为重要。为了更好地与卫星影像进行贴合,DEM数据的采样密度要与卫星影像的分辨率一致。本文通过对比当下常用的四种空间插值方法的适用范围与运用特点,设置相关阈值及权重,直观比较了四种插值方法产生的插值结果,选择更适合复杂景区DEM插值的插值方法并对其进行精度提升,以此得到符合精度要求的DEM数据。最后利用相应地区的卫星影像进行地图投影及影像贴图,两种数据结合构建复杂景区的三维地图模型,给游客带来更为精确直观的定位信息和空间要素信息。