光学仪器实验室绝对辐射定标及现场质量跟踪

为保证现场测量离水辐射率的精度，对现场测量光谱仪进行严格的实验室绝对辐射定标是必不可少的。另外，由于现场试验环境复杂，要在野外长期试验，需要随时监测仪器的工作状态是否稳定。文章以加拿大Satlantic公司的光学仪器航空模拟器（SAS－Ⅱ）为例业阐述实验室绝对辐射定标的方法，类似可推广至同类光学传感器的实验室绝对辐射定标；根据SeaWiFS质量监控器（SQM－Ⅱ）监测剖面仪／表面仪的变化来阐述现场质量跟踪的方法。     

Physical Hydrography and Algal Bloom Transport in Hong Kong Waters

In sub-tropical coastal waters around Hong Kong, algal blooms and red tides are usually first sighted in the Mirs Bay, in the eastern waters of Hong Kong. A calibrated three-dimensional hydrodynamic model for the Pearl River Estuary （Delft3D） has been applied to the study of the physical hydrography of Hong Kong waters and its relationship with algal bloom transport patterns in the dry and wet seasons. The general 3D hydrodynamic circulation and salinity structure in the partially-mixed estuary are presented. Extensive numerical surface drogue tracking experiments are performed for algal blooms that are initiated in the Mirs Bay under different seasonal, wind and tidal conditions. The probability of bloom impact on the Victoria Harbour and nearby urban coastal waters is estimated. The computations show that： i） In the wet season （May - August）, algal blooms initiated in the Mirs Bay will move in a clockwise direction out of the bay, and be transported away from Hong Kong due to SW monsoon winds which drive the SW to NE coastal current; ii） In the dry season （November- April）, algal blooms initiated in the northeast Mirs Bay will move in an anti-clockwise direction and be carried away into southern waters due to the NE to SW coastal current driven by the NE monsoon winds; the bloom typically flows past the east edge of the Victoria Harbeur and nearby waters. Finally, the role of hydrodynamic transport in an important episodic event -- the spring 1998 massive red tide -- is quantitatively examined. It is shown that the strong NE to E wind during late March to early April, coupled with the diurnal tide at the beginning of April, significantly increased the probability of bloom transport into the Port Shelter and East Lamma Channel, resulting in the massive fish kill. The results provide a basis for risk assessment of harmful algal bloom （HAB） impact on urban coastal waters around the Victoria Habour.     

一种基于序列立体观测的非合作目标位姿监测方法

非合作目标的位姿监测,是空间目标态势感知的重要内容之一。本文提出了一种基于立体观测的非合作目标位姿变化监测方法,采用单目观测序列提取Harris角点,运用金字塔稀疏光流法对其进行运动跟踪,利用影像匹配和前方交会获取运动点三维坐标,最后将运动点坐标带入运动方程解算目标位姿变化。半实物仿真试验结果表明:相机距目标距离约为2.5 m时,位置变化检测精度优于2.5 mm,姿态变化检测精度优于0.5°。相比于基于先验信息和特征提取的传统方法,该方法基本满足对非合作目标监测、跟踪、绕飞时位姿测量需求,且在适应性和精度上均有提高。     

Modeling large-scale winter recreation terrain selection with implications for recreation management and wildlife

Winter recreation is a rapidly growing activity, and advances in technology make it possible for increasing numbers of people to access remote backcountry terrain. Increased winter recreation may lead to more frequent conflict between recreationists, as well as greater potential disturbance to wildlife. To better understand the environmental characteristics favored by winter recreationists, and thus predict areas of potential conflict or disturbance, we modeled terrain selection of motorized and non-motorized recreationists, including snowmobile, backcountry ski, and snowmobile-assisted hybrid ski. We used sports recorder Global Positioning System (GPS) devices carried by recreationists at two study areas in Colorado, USA, (Vail Pass and the San Juan Mountains), to record detailed tracks of each recreation type. For each recreation activity, we modeled selection of remotely-sensed environmental characteristics, including topography, vegetation, climate, and road access. We then created spatial maps depicting areas that recreation activities were predicted to select and combined these maps to show areas of potential ecological disturbance or interpersonal conflict between motorized and non-motorized activities. Model results indicate that motorized and non-motorized activities select different environmental characteristics, while still exhibiting some similarities, such as selection for ease of access, reflected in proximity to highways and densities of open forest roads. Areas predicted to have only motorized recreation were more likely to occur further from highways, with greater forest road densities, lower canopy cover, and smoother, less steep terrain, while areas with only non-motorized recreation were closer to highways, with lower forest road densities, more canopy cover and steeper terrain. Our work provides spatially detailed insights into terrain characteristics favored by recreationists, allowing managers to maintain winter recreation opportunities while reducing interpersonal conflict or ecological impacts to sensitive wildlife.     

一次寒潮强风天气过程分析

１９９５年１１月７日出现的寒潮强风天气过程是由于冷空气不断堆积产生强的气压梯度风,地面迅速加压产生强变压风,冷高压脊前高空动量下传产生强的动量下传风所谓三风合一的所造成。影响范围之广,持续时间之长均为历史上所罕见。     

西北太平洋船舶避风暴分析

本文首先对远望二号船避９７０８号强热带风暴航行的情况作了简要回顾,对当时选择航线、悠入航线、徘徊、加速等一系列措施作了详细分析,还探讨了９７０８号强热带风暴的形成和路径预报问题;最后对远洋避风暴方法作了理论探讨。     

海洋中倾废物的声学测量和跟踪

本文较详细地讨论了海洋声学体散射理论和海水中悬浮物扩散理论。对比DFS－2100型声学测量系统和TCL－204型双频探鱼声纳的技术性能之后，对国产TKL－204声学系统作了重大改进，使其适于对海洋倾废物进行测量和跟踪。现场实验结果表明，经过改进后的系统是成功的，同时也证明了文中所用的扩散理论对分析海洋中悬浮物的扩散规律是有用的。     

一种基于道路网络模型减少车辆轨迹数据量的算法

定位及移动通信的发展使我们可以获取和传输车辆在道路网络上的轨迹信息。除实现定位或导航等基本功能外,从车辆轨迹数据中还可以提取大量的交通信息,成为交通规划和管理的一个重要的信息来源。通过建立轨迹数据与道路网络之间的拓扑关系,提取轨迹数据中能代表主要信息的特征点来代替大量的轨迹数据,以达到减少轨迹数据量的目的。特征点通过一个综合了网络关系、速度币口方向的筛选方法进行提取,该方法也同时有利于建立轨迹数据检索结构和定义查询语言,系统的实验和分析验证了所提出方法的有效性。     

Synergistic Effect of the Planetary-scale Disturbance,Typhoon and Meso-β-scale Convective Vortex on the Extremely Intense Rainstorm on 20 July 2021 in Zhengzhou

On 20 July 2021, northern Henan Province in China experienced catastrophic flooding as a result of an extremely intense rainstorm, with a record-breaking hourly rainfall of 201.9 mm during 0800–0900 UTC and daily accumulated rainfall in Zhengzhou City exceeding 600 mm(“Zhengzhou 7.20 rainstorm” for short). The multi-scale dynamical and thermodynamical mechanisms for this rainstorm are investigated based on station-observed and ERA-5 reanalysis datasets.The backward trajectory tracking shows that...