海南岛气溶胶时空变化及来源追溯

海南岛独特的区域和国家战略位置,使得了解和掌握该地区气溶胶时空格局特征及其大气污染物传输来源是海南大气环境质量监测和污染防治中重要的关注问题。选取MODIS 3 km分辨率气溶胶光学厚度（AOD）产品MOD04_3K,对海南岛2003—2017年AOD时空变化特征进行分析;以海口市为起始点,采用HYSPLIT模式对8次典型大气污染事件在10、500、1000 m 3个相对地面高度上进行48 h后向轨迹计算,以探究该区域大气污染物来源。结果表明：① 海南岛AOD在空间上呈较为明显的三级阶梯状分布,从西北方向向东南递减,2003—2017年在不同阶梯的空间变化趋势差异十分显著;② 2003—2017年海南岛AOD年均值为0.095,各年均值整体呈轻微升高趋势;季节均值差异表现为“春季>秋季>冬季>夏季”,此差异除受区域天气系统与地方风向特征的影响外,本区旅游业发展造成的大气污染物排放也不可忽视;③ 海南岛（海口市）2013—2017年典型大气污染事件发生期间大气污染气流在3个高度上（10、500、1000 m）的后向轨迹基本保持一致,均主要来自于海南岛东北方向。据此,位于该方向毗邻的珠江三角洲地区陆源大气污染物在东北盛行风的影响下被输送至海南岛,在区域天气系统（如大陆冷高压）和局部天气系统（如海风辐合）共同作用下,是促成该地区大气污染事件发生的重要因素。研究结果对深入理解海南岛近十多年来大气环境状况的变化规律、完善该区域大气污染联防联控机制具有重要的意义。     

复杂观测环境下GNSS信号分类及精度评估

基于高度角、信噪比和伪距残差3个指标,采用K均值(Kmeans⁺⁺)、迭代自组织数据分析法(ISODATA)和基于密度带有噪声的空间分类法(DBSCAN)对复杂城市观测环境下的GNSS数据进行分类,并采用伪距单点定位模型(SPP)评估不同算法的分类精度。结果表明,Kmeans⁺⁺算法分类精度最优,在E、N、U 3个方向上的定位精度分别达2.56 m、3.25 m、9.73 m;相较于未采用Kmeans⁺⁺算法的定位精度分别提升57.86%、47.64%、60.98%。为进一步验证算法性能,将Kmeans⁺⁺算法与信噪比、高度角阈值法进行精度对比,结果表明,Kmeans⁺⁺算法的平面和三维定位精度均有显著改善,分别提升24.87%、39.07%（信噪比阈值法）和41.36%、59.91%（高度角阈值法）。     

复杂山区地形条件下ERA5再分析地表气温降尺度方法

高时空分辨率的气温栅格数据是多种地学模型和气候模型的重要输入。山区地形复杂,气温空间异质性强,如何获取高时空分辨率的山区地表气温数据一直是研究热点与难点。本文选择地形复杂的河北省张家口市作为试验区,基于局部薄盘样条函数对ERA5再分析日均近地表气温（2 m高度）进行空间插值,并利用随机森林算法,结合少量气象站观测气温数据、地形地表参数数据构建日均气温订正模型和气温逐时化模型,实现空间分辨率由0.1 °（约11 km）到30 m的逐时气温降尺度,最后将该模型拓展应用于其他时间与区域,检验本文发展的降尺度方法在没有站点观测数据条件下的时空移植性。结果显示,本文降尺度方法得到的高时空分辨率山区气温数据精度较高,1月均方根误差（RMSE）平均值为2.4 ℃,明显优于气象站点插值结果,且气温相对高低的空间分布更为合理、纹理更加丰富;将该方法应用到其他时间与区域的RMSE平均值分别为2.9 ℃与2.5 ℃,均小于再分析资料直接插值所产生的误差。研究结果总体表明,在气象站点较少甚至没有时,可利用本文方法通过ERA5再分析气温准确获取复杂地形条件下的山区高时空分辨率气温数据。     

化工污染气体无人机遥感监测

无人机大气环境监测虽然处于起步阶段,但已成为环保部门一项重要的工作内容,对于提高突发性大气污染事件的预防及应急监测具有重要意义。本文以化工污染气体排放高危区齐鲁化学工业区为研究区,利用搭载有高分辨率相机和污染气体监测仪的旋翼无人机（“环鹰一号”）系统,结合地面核查验证的方式,设计了一氧化氮（NO）、一氧化碳（CO）和二氧化硫（SO₂）3种污染气体污染遥感监测流程及方法。通过实验区地面验证,以及150、200、250、350 m高度污染气体浓度监测结果分析表明,化工园区污染气体排放具有空间水平差异及垂直扩散特征,联合水平和垂直异常值分析,能为提前排查污染源排放提供有效支撑。本研究是无人机在环保部门大气环境监测中的实际应用,能为后续化工园区及重点企业污染物排放定期监管提供技术支持。     

基于伪纯像元的精度评价策略及其应用

土地覆被是地球科学研究中的重要参量,评价土地覆被数据的制图精度是保障数据合理使用的前提。本文提出了一种基于伪纯像元的精度评价策略（伪纯像元策略）,即当低空间分辨率栅格窗口内对应的高空间分辨率数据中优势类别（面积最大的地类）的占比高于伪纯像元纯度阈值（代表像元纯度,取值范围：35%~100%,步长为5%）时,以此栅格窗口为基准生成土地覆被类型为优势类别的伪纯像元用于精度评价。以澜沧江-湄公河（澜湄）流域为试验区,选择GlobeLand30为参考数据,并基于混淆矩阵精度评价方法对比分析了伪纯像元策略与重采样法（最近邻法和众数法）在CCI-LC（300 m）和MCD12Q1（500 m） 2套全球土地覆被数据精度评价中的差异。结果表明：① 伪纯像元策略在35%~100%纯度阈值下对CCI-LC和MCD12Q1在澜湄流域评价的精度分别为72.76%~55.26%和71.44%~45.41%,比重采样法评价的单一精度（众数法：71.21%和70.54%、最近邻法：71.48和69.87%）能更好地反映像元纯度对土地覆被数据精度的影响;② CCI-LC的总体精度高于MCD12Q1,且2套数据的精度差随纯度阈值的增大而增加,CCI-LC和MCD12Q1在35%、100%纯度阈值下的精度差分别为1.32%和9.85%;③ 2套数据中耕地、有林地、草地和水体的分类精度均相对较高,而灌木林地（精度接近0）和裸地的分类精度均较低;④ 2套数据与GlobeLand30的空间不一致区域多出现在土地覆被类型高度异质化的混合像元区域,且随纯度阈值的增大,评价样本栅格更趋均质,混合像元对评价精度的影响也会递减。伪纯像元精度评价策略适用于跨空间分辨率土地覆被数据的精度对比,为评价全球土地覆被产品在区域尺度的适用性及适用范围提供了新的检验策略。     

不同街景影像微环境提取方法对街面财产犯罪解释的差异分析

作为城市的骨架，街道网络是人们日常活动的重要载体，其也在很大程度上影响着犯罪事件的分布。因此，街道微环境是研究街面犯罪空间格局及其影响机制的重要切入点。已有研究中基于街景影像的街道微环境度量，多采用语义分割单一技术提取各类环境要素在影像中的像素占比，但该方法不适宜提取行人等离散要素。近期有学者结合使用语义分割和目标检测2种技术来提取影像中复杂的环境要素，但2种方法提取的微环境要素对街面犯罪的解释还未有比较研究。为探究这一问题，本文将百度街景影像作为街道层级建成环境数据，采用上述2种做法分别提取并获得街道微观环境特征变量：第1种做法仅使用语义分割技术将所有要素以像素比例度量；第2种做法用语义分割技术将人行道、建筑、墙面、栅栏、树木和草地以像素比例度量，而用目标检测技术将街面行人和路灯以个数度量。在控制了土地利用混合度、集中劣势、街道长度和密度、犯罪吸引器和发生器后，构建零膨胀负二项回归模型以分析街道微环境特征与街面财产犯罪（如街面盗窃、扒窃）间的关系。模型中分别加入通过两种方式提取的街道微环境特征变量，并比较其对街面财产犯罪影响的差异。研究结果表明：(1)与采用语义分割单一技术提取的街道...     

基于栅格的安徽省人居环境人文适宜性评价

新时期新型城镇化建设对适宜的人居人文环境提出了切实要求。运用GIS技术,基于夜间灯光遥感影像、交通矢量、兴趣点（POI）、统计年鉴等多源数据,以500 m×500 m栅格为基础单元,选取经济水平、交通通达、历史文化、公共服务等因子（权重分别为0.36、0.27、0.17、0.20）,采用综合指数法构建人居环境人文适宜性评价模型,定量评价2017年安徽省人居环境人文适宜性。结果表明：① 安徽省人居环境人文适宜性指数介于0.83~87.10之间,划分为高度适宜区、较高适宜区、中度适宜区、一般适宜区及临界适宜区5种类型区,以中度适宜区面积最大,占全省总面积68.72%,高度适宜区面积最小,仅占总面积的1.24%,整体呈现“多核心”、“条带式”空间分异格局;② 交通通达和公共服务是造成全省人居环境人文适宜性分异的主要因子,其指数均值在中度适宜区皆达到了94.18,且贡献率均值在各类型区均在34.00%以上;历史文化对较高及临界适宜区影响明显,贡献率均值分别为10.51%和11.93%;经济水平对高度适宜区的作用最显著,其贡献率均值高达22.02%;③ 全省近90.86%的人口集中分布在人居环境人文适宜性指数43.00~66.00之间,属于中度至较高适宜区的范围,人居环境人文质量与人口分布较为匹配。测评结果较为客观地反映了安徽省人居环境的人文本底。     

结合DSM的机载LiDAR单木树高提取研究

机载LiDAR在提取地形坡度较大区域的冠层高度模型（CHM）时易产生畸变,降低单木树高的提取精度,为此提出一种CHM与数字表面模型（DSM）相结合的树高估算方法。首先基于预处理后的点云生成的CHM,利用局部最大值算法和标记控制分水岭分割算法进行分割,得到单木树冠轮廓多边形;然后结合DSM,采用固定窗口的局部最大值算法探测树顶点并提取其高程,继而与使用狄洛尼三角网和高程内插得到的地面点相减获取树高;最后,以广西兴安县富江村附近地形起伏较大的针叶林为试验区,测试3种不同坡度下,在CHM、CHM结合DSM获得的树高与实测树高分别进行精度分析。结果表明,当树木分别位于平均坡度为32°、27°和15°的试验区时,CHM中提取的树高与实测数据拟合的R²分别为0.84、0.85和0.87,RMSE为1.48、1.41和1.58 m,结合DSM后R²为0.92、0.91和0.93,RMSE为0.93、1.02和1.16 m;在地形坡度较大的区域,本文方法可以有效提高单木树高的估算精度。     

顾及时空邻近的恐怖团伙关系发现方法

现有恐怖团伙关系挖掘方法因其难以顾及恐怖组织特有的结构复杂、行动灵活、生存期长等特点而难以应用于反恐研究中。为此,本文从时空角度出发,通过引入时空邻近与团伙时空同现模式等概念,将多元独立分布的团伙关系发现问题建模为时空同现模式的频繁度评价问题,提出一种点模式分布下的团伙关系挖掘方法。基于此方法构建团伙关系网络,进而提出一种顾及时空邻近的社团关系度量方法。采用该方法对阿富汗与巴基斯坦地区1970—2018年真实GTD数据进行实验分析,结果表明：该研究区域主要恐怖团伙中共存在11种团伙关系（{Taliban,TTP}等）,在团伙关系网络中占据核心地位的恐怖组织为Taliban,其次为TTP、BLA。本文提出的方法能有效地挖掘出恐怖团伙之间潜在的关系,团伙关系的定量表达度量了不同组织在关系网络中的地位,验证分析表明,挖掘结果与相应团伙共同参与事件的时空分布、历史根源高度吻合。本文拓展了时空同现模式挖掘在恐怖团伙关系发现中的应用,研究成果对公安部门在识别某些恐怖事件制造者以及合理分配警力资源方面具有重要意义。     

基于静风期污染物的PM2.5排放清单空间精细化方法

有利气象条件之后的静风期,极大降低了PM_2.5跨区域传输的影响,能够揭示本地源的排放状况。本文尝试性引入了静风期污染物分布揭示本地源排放特征的概念,提出了一种基于遥感数据的PM_2.5排放清单空间精细化方法：首先,利用 MODIS MCD19A2反演的ChinaHighPM_2.5数据,构建高时空分辨率PM_2.5数据融合方法;然后,构建唐山市有利气象条件之后的静风期污染物遴选方法（合理风向和风速：有利气象条件为东风,地面10 m高度风速大于3 m/s,其他风向,持续的较大风力5~10 m/s;静风期风速小于1.5~2.0 m/s）;其次,基于遴选的静风期PM_2.5数据分配MEIC清单中的PM_2.5总排放量,同时对比传统插值方法：基于GDP、人口密度、路网、土地利用类型数据,实现清单各污染源PM_2.5的1 km×1 km空间分配;最后,利用WRF-CMAQ模拟数据和地面台站实测数据进行真实性检验。研究结果表明：① PM_2.5数据填补融合方法能够有效提高PM_2.5监测数据的时空分辨率,且与地面监测值显著相关（R²=0.94,RMSE=4.64 µg/m³,NMB=2%,NME=7%）;② 引入有利气象条件后的静风期概念,提出了静风期污染物的遴选方法,有效降低了PM_2.5跨区域传输的影响,更好地反映了本地源排放的空间分布特征;③ WRF-CMAQ模拟方法的精度验证结果表明,该方法较传统面积插值法NME降低7%,NMB降低10%,RMSE降低1.54 µg/m³,R²提高11%。该方法为排放清单的空间精细化提供了新的研究思路。     

The drift velocity of oil film on the sea

To make surface seawater flow, the shear stress of the wind blowing on the sea must overcome the work of cohesion of seawaterW _c. Oil film on the sea will drift along the wind direction so long as the shear stress of the wind overcomes the work of adhesion between the water and the oilW _a or the work of cohesion of oil W_t,o. Experiments bear out the theory that surface tension of seawater is more than twice that of oils generally, so that the wind influenced drift velocity of the oil film is over two times that of the wind-driven surface current. The wind factor for surface current in Jiaozhou Bay is 0.025, while those for the drift velocities of O-diesel oil film and the used light crude oil film are 0.070 and 0.052 respectively. Generally the primary factors influencing the movement velocity of oil film on the sea are current, wind, and the physicochemical properties of the oil. The drift velocity of oil film is determined from analysis of the work of adhesion between seawater and oil. Experiments and actual observations agree with the theoretical analysis. Contribution No. 1831 from the Institute of Oceanology, Academia Sinica     

Internal wave eigenmodes and their weak nonlinear resonant interaction in a nonlinearly stratified fluid—A preliminary theoretical and experimental study

A preliminary theoretical and experimental study was conducted on internal wave modes and their weak nonlinear resonant interaction in a nonlinearly stratified fluid. An asymptotical solution of the modes and a dispersion relation of internal waves in a stratified fluid with density profile similar to that in our experiment were obtained theoretically. The resonant-interaction mechanism to 2nd order approximation is also discussed. The resonant interaction of the 3rd and 4th mode internal waves excited by the unstable 1st mode wave is analyzed on the basis of data obtained by conductivity probes. The resonant-interaction condition, i.e., ,k ₁+k ₃+k ₄=0, is examined. It is shown that the resonant instability increases with pycnocline thickness and wave maker driving frequency. This work is supported by the National Natural Science Foundation of China.     

Influential factors on the exchange rate of dissolved inorganic nutrients at the sediment-water interface in Jiaozhou Bay,China

Incubation experiments are carried out to study the exchange rates of dissolved inorganic nutrients including silicate, phosphate, ammonium, nitrite, and nitrate （^vSiO3-Si,^vPO4-P, ^vNH4-N, ^vNO2-N and ^vNO3-N） at the sediment-water interface in the Jiaozhou Bay. Major factors influencing the exchange rates are discussed in detail, which include the dissolved inorganic nutrient concentrations in porewater （Cpw）, water and clay contents, and grain size of the sediments （CH2O, Cclay and GSsed）. The results may provide insight into the dynamics of nutrient transport and the environmental capacity of nutrients in Jiaozhou Bay, and should be beneficial to solving the problems caused by excessive nutrient input this area.     

A study on the baroclinic structure of the abyssal circulation

In this paper, the linear continuously stratified ntxiel of the abyssal circulation proposed by Pedlosky (1992) was emended to include the second order term - (γθm) in the vertical turbulent mixing pararneterization of - (ω‘θ‘）x = kvθxx- θxxx, in which kv is a vertical diffusion coefficient,and γ is the second order coefficient of turbulent mixing (or simply called γ-term and γ＜0 is only allcmed). The influence of the γ-tema on the baroclinic structure of the abyssal circulation driven by up-welling out of the abyss was investigated, It was found that the γ-term has a noticeable influence on thebaroclinic structure of the upwelling driven abyssal circulation. For uniform upwelling, it favors the baroelinic layering of the abyssal circulation in the eastern part of the basin, but prevents the layering in thewest. In addition, this parameter was found to decrease the vertically averaging meridional velocity of theabyssal circulation frcrn the west to the east on the southern boundary. For upwelling localized near theeastern boundary, the γ - term favors baroclinic layering of the abyssal circulation in the whole basin.Especially, on the southern boundary the γ - term could strengthen the vertically averaging meridional ve-loeity in the west, but gready weaken it in the east. The ntntel presented here might be considered as anextension of the Pedlosky baroclinic ntntel of the abyssal circulation.     

Study on bottom stress under conditions of storm surge and tide

Sea bottom stress is conventionally assumed to be directly proportional to the square of the verticallyaveraged velocity,and the drag coefficient to be dependent on the speed and direction of the wind on the sea surface,the depth and dimension of the sea,the period of the tide and so on. In this paper a three-dimensional numerical model is used to discuss the relation the dragcoefficient and the above-mentioned factors.It can be shown from calculation that the relation, is valid,that the drag coefficient is a constant in a major part of a sea as thought conventionally,andthat there is a small area near the coast where the drag coefficient is far greater.We call it singular area. A number of conclusions on the relation between the drag coefficient and the speed and direction ofthe wind,the sea depth and so on,were obtained.     

Mixing in Shallow Waters： Measurements, Processing, and Applications

Microstructure profiling measurements taken on a shallow Black Sea shelf and in Lake Banyoles and Boadella reservoir (Both in Spain) are analyzed to investigate the influence of boundary-layer-induced turbulence of various sources on mixing in the water interior. The state of turbulence in shallow waters is examined and details of microstructure data processing and error analysis are discussed. The dependence between averaged activity parameter AG and buoyancy Reynolds number Reb for the shelf turbulence indicates that for Reb < 1 the state of turbulence can be described by the fossil turbulence model, which postulates AG-Reb1/2. For Reb> 1, however, the influence of Reb on AG is weak, signifying that the buoyancy Reynolds number can no longer serve as the governing parameter for active turbulent mixing. The generation of turbulence by a one-minute long wind bursts (the Boadella reservoir) increases the averaged dissipation rate (e) of the surface mixed layer by more than 5 times (up to 3×10-6 W kg-1). The influence of the wind bursts was also traced below the ther-mocline, where turbulent patches with     

The extraction of harmonic tidal constants from high and low waters

With the application of electronic computers, the extraction of harmonic constants from high and low waters becomes an extremely simple process as compared with Doods’n’s technique. The phenomenon of aliasing is examined by supposing the samples are taken at intervals of exactly 6 lunar hours. The constituents with frequencies satisfying the relation are inseparable and the coefficient determinant of the normal equations will be singular if the heights only are used. When the values of the first derivatives and the irregularity of the sampling are taken into consideration the condition of the determinant is improved. Large diurnal tides can cause irregularity of sampling and so we are in favour of the separation of the aliased constituents. For tidal current data, if the slack times are available, the results of analysis can be much improved. The results for major constituents derived from the observed high and low waters agree satisfactorily with those from hourly data. This paper was published in Chinese inOcean. Limn. Sinica 17(4):318–328, 1986.     

Plateau typeE(%)- pH curves of interfacial exchange between liquid and solid in seawater

A study on the curves of the exchange ratioE(%)- pH on the liquid-solid interface of the systems Zn (II) with clay minerals, (Kaolinite, illite and montmorillonite), Zn (II) with hydrous ferric oxides (amorphous ferric oxide, geothite and hematite), Zn (II) with hydrous manganese oxide (γ-MnOOH, manganite and δ-MnO₂) etc. in seawater resulted in the discovery of new plateau type exchange ratioE(%)-pH curves not yet reported in literature. The two factors that decide the growth, decline and the change of the “plateau type” curve are: (1) the inherent characteristics of systems, which can be explained by the exchange constants (i=1, 2, 3, etc.) of interfacial stepwise ion/coordination particle exchange between liquid and solid; and (2) . The theory of interfacial stepwise ion/coordination particle exchange in seawater was applied to explain the experimental results of the above study and a general formula was derived for the plateau type exchange ratioE(%)-pH curves. The theoretically simulated and calculated curves coincided well with the experimental results. This paper provides new and powerful experimental basis to support the theory of interfacial stepwise ion/coordination particle exchange in seawater. The project was supported by the National Natural Science Foundation of China.     

Micro-site conditions of epiphytic orchids in a human impact gradient in Kathmandu valley, Nepal

We studied distribution and site conditions of epiphytic orchids in a gradient of human interference in Kathmandu valley, central Nepal. The aim was to understand the recent distribution pattern of epiphytic orchids, with respect to (i) the micro-site conditions and (ii) the type and intensity of land use. The occurrence of epiphytic orchids was recorded for a grid with 1.5 km cell size. The cells represent different types and intensities of human impact. Site factors such as bark rugosity, bark pH, diameter at breast height (dbh; 1.3 m) of host trees, exposure to wind and sunlight intensity were recorded. With regard to the species richness and abundance of epiphytic orchids, we compared different human impact categories from very strong human impact (settlement area) to very low human impact (national park). Remote sensing was used for a supervised classification of land cover. Ficus religiosa turned out to be the most important host species for orchids in urban areas, while Schima wallichii and Alnus nepalensis significantly host orchids in the other categories. Both species richness and abundance of epiphytic orchids were significantly higher under very low human impact (forest in national park) and also some remaining patches of primary forest than the other regions. Micro-climate is crucial for orchid populations. Host bark pH, bark rugosity, sunlight intensity and host exposure were significantly different for all human impact categories in order to harbour epiphytic orchid species. Habitats with a mixture of mature trees are suitable and essential for the conservation of viable populations of epiphytic orchids in settled areas. The study reveals that to improve the population size of orchids it is essential for future urban forestry to: (i) Protect old trees as carriers of existing epiphytic orchid diversity, (ii) protect medium old trees to ensure that they may become old trees, (iii) plant new host trees for the future, (iv) plant in groups instead of single isolate trees. Trees should especially be planted in areas where orchids still exist to provide more trees for orchid population enlargement (e.g. along riparian system). Native species should be favoured; the pool of such native host species is wide.     

武汉市中心城区住宅价格空间分布格局及其影响因素研究

利用网页爬虫技术从安居客网站抓取了武汉市中心城区2016年7月共3 188个小区的平均房价数据。运用GIS空间分析方法和GWR模型对武汉市中心城区房价空间分布模式及其影响因素进行探讨。研究发现武汉市中心城区的房价具有聚类分布特征;新盘房价与片区位置(汉口、武昌、汉阳)、环线位置(内环、二环、中环)、距湖泊距离、距商圈距离、小区附近学校个数显著相关;楚河汉街商圈对二手房房价的影响力度高于其他商圈,东湖和沙湖对二手房房价的影响效应也很显著。