Nonlinear ocean internal waves observed by multifrequency synthetic aperture radar

A numerical model which consists of the Korteweg-de Vries (KdV) equation, the action balance equation and the radar backscat- tering model is developed to simulate the frequency dependence of synthetic aperture radar (SAR) remote sensing of nonlinear o- cean internal waves. Muhifrequency data collected by NASA SIR - C SAR and NASA JPL AIRSAR are used as comparison. Case studies show that the results of simulation agree well with the results of SAR data.     

SAR图像复合分布船只检测模型

提出了一种基于复合参数分布的SAR图像船只检测模型。模型使用Pearson分布系统模拟SAR图像海洋背景散射分布, Pearson分布系统由4种参数分布组成, 包括Pearson I分布(g)、Ⅲ分布、Ⅳ分布(反g)和Ⅵ分布。模型采用基于β平面的分布选择器确定采用哪种分布来拟合SAR图像海面后向散射分布, 同时利用4种分布, 结合CFAR技术, 建立CFAR方程, 通过解算方程得到检测阈值, 利用阈值进行SAR图像船只检测。通过图像试验验证表明, 该模型检测效果良好, 具有一定的实用价值。     

沿海丘陵地区面雨量估算插值方法试验比较

本文以温州地区为代表,对各种插值方法进行试验得出华东沿海丘陵地区最优的面雨量估算插值方法。根据影响的天气系统,将温州地区的降水性质分为冷空气、倒槽、西南低涡、静止锋、台风、副高边缘对流等典型降水类型。通过对近10a历史天气图和温州地区90个雨量观测站日降水量资料分析,选定该地区的各类天气过程的典型代表过程,再以各个过程中最具代表性的日降水作为试验资料。以目前研究应用得最多的反距离法、克里格法、样条插值法对各日降水在不同站密度等级条件下分别插值。根据制定的评价标准分析各插值方法对面雨量估算的适用性,从而系统、客观地得出华东沿海丘陵地区面雨量估算的最优插值方法及其对测站密度的要求。     

山西省堡子湾金矿地质特征

目前在晋北及晋蒙交界地区已发现数十个规模不等的类似角砾岩筒，均含金、银多金属矿化，已探明的有大型银矿、中型金或金银矿。研究表明，堡子湾金矿是一个与海西晚期中酸性次火山岩有成因联系的隐爆角砾岩筒型热液金矿，成矿母岩为二长花岗斑岩     

山西省堡子湾金矿地球化学特征

从微量元素、稳定同位素、流体包裹、稀土元素等阐述了该矿床地球化学特征,并建立了地球化学异常模式。     

不同水分处理下南京地区冬小麦耗水量特征及其模拟

通过对冬小麦设定的5个生育期分别进行不同程度的水分肋迫试验。结果表明，全生育期内，冬小麦耗水量呈双峰型，且随土壤湿度的增加而增大。本文利用了气象和作物观测资料对不同水分条件下的冬小麦耗水量进行了模拟，并用实测资料进行验证，效果令人满意。     

Numerical investigation of wake-collapse internal waves generated by a submerged moving body

The state-of-the-art OpenFOAM technology is used to develop a numerical model that can be devoted to numerically investigating wake-collapse internal waves generated by a submerged moving body.The model incorporates body geometry,propeller forcing,and stratification magnitude of seawater.The generation mechanism and wave properties are discussed based on model results.It was found that the generation of the wave and its properties depend greatly on the body speed.Only when that speed exceeds some critical value,between 1.5 and 4.5 m/s,can the moving body generate wake-collapse internal waves,and with increases of this speed,the time of generation advances and wave amplitude increases.The generated wake-collapse internal waves are confirmed to have characteristics of the second baroclinic mode.As the body speed increases,wave amplitude and length increase and its waveform tends to take on a regular sinusoidal shape.For three linearly temperature-stratified profiles examined,the weaker the stratification,the stronger the wake-collapse internal wave.     

Oceanic pycnocline depth retrieval from SAR imagery in the existence of solitary internal waves

Oceanic pycnocline depth is usually inferred from in situ measurements. It is attempted to estimate the depth remotely. As solitary internal waves occur on oceanic pycnocline and propagate along it, it is possible to retrieve the depth indirectly in virtue of the solitary internal waves. A numerical model is presented for retrieving the pycnocline depth from synthetic aperture radar （SAR） images where the solitary internal waves are visible and when ocean waters are fully stratified. This numerical model is constructed by combining the solitary internal wave model and a two-layer ocean model. It is also assumed that the observed groups of solitary internal wave packets on the SAR imagery are generated by local semidiurnal tides. A case study in the East China Sea shows a good agreement with in situ CTD （conductivity-temperature-depth） data.     

Study of the propagation direction of the internal waves in the South China Sea using satellite images

Internal wave propagation carries considerable vertical shear which can lead to turbulence and mixing. Based on the analysis of more than 2 500 synthetic aperture radar (SAR) and optical satellite images, the internal wave propagation in the whole South China Sea was investigated systematically. The results show that (1) in the northeastern South China Sea, most internal waves propagate westward from the Luzon Strait and are diffracted by coral reefs near the Dongsha Islands. Some impinge onto the shelf and a few are reflected; (2) in the northwestern South China Sea, most internal waves are generated at the shelf and propagate northwestward or westward to the coast; (3) in the western South China Sea, most internal waves propagate westward to the Vietnamese coast, except a few propagate southward to the deep sea; and (4) in the southern South China Sea, most internal waves propagate southwestward to the coast. Some propagate southeastward to the coast of Kalimantan Island, and a few propagate southeastward because of the influence of the Mekong River.     

淮北平原中小型湖泊鸟类多维度多样性

湿地介于陆地和水生生态系统之间,具有丰富的生态价值,湿地公园在维持生态平衡,提高鸟类多样性等方面具有重要作用。2022年3月-2023年2月,采用样点法和样线法对淮北平原地区颍州西湖国家湿地公园进行鸟类调查,通过对鸟类群落的物种多样性、分类学多样性、功能多样性和系统发育多样性4个维度多样性指数以及鸟类生态类群的分析探究湿地公园鸟类群落的时空分布格局。本轮调查共记录鸟类153种共26107只次,其中国家Ⅰ级重点保护野生动物1种,国家Ⅱ级重点保护野生动物16种;IUCN红色名录极危物种1种,易危物种2种。结果表明:春季功能丰富度、物种丰富度和香农-威纳指数在湖泊、防护林和绿化带3种生境之间差异显著,夏季湖泊生境中物种丰富度(24.67±0.94)和系统发育多样性(985.14±52.57)显著高于绿化带和防护林,秋季功能丰富度(8.24±0.90)和系统发育多样性(935.34±37.12)在湖泊中均最高,冬季湖泊香农-威纳指数(2.31±0.03)、功能丰富度(3.73±0.77)显著高于绿化带和防护林2种生境;绿化带生境中,多个多样性指数在春季最高,在冬季均达到最低水平,湖泊生境冬季的物种丰富度(25.00±0.82)、香农-威纳指数和辛普森指数(0.84±0.01)在冬季最高,夏季系统发育多样性最高;防护林生境中物种丰富度(22.67±2.87)在秋季显著高于其他3个季节。单次调查中发现并记录青头潜鸭(Aythya baeri)15只,超过东亚-澳大利西亚候鸟迁徙路线该物种种群数量的1%,达到国际重要湿地标准。结果显示秋季为该湿地公园鸟类多样性保护的重点季节,湖泊生境为该湿地公园的重点保护区域,颍州西湖国家湿地公园对迁徙及越冬水鸟具有重要生态价值,应进一步加强鸟类监测,提升其生态功能。