基于引力模型的海洋锋信息提取

海洋锋面是海洋水团特性明显不同的两种或几种水体之间的狭窄过渡带。本文旨在对遥感反演海洋温度场数据(SST),引入引力模型进行海洋锋面的检测。鉴于海洋锋受噪声干扰大,锋面强度小的特点,本文提出了基于引力算法的引力模型。其中,引力算法是将温度数据中的每一个像元点都作为一个独立的天体,其质量对应该像元的温度值,根据引力定律计算3×3区域中,邻域像元对中心点像元的引力和。模型首先对原始数据进行去0处理,为消除对原始数据明暗程度的依赖,对3×3区域数据进行归一化,然后利用函数对归一化后的数据进行增强处理,最后,以引力算法进行锋面检测。验证表明,该模型能有效强化不同区域或水体差异性,并能够有效针对海洋锋信息进行提取,受噪声影响小。     

基于MODIS数据的太湖浮游植物物候变化及其对水表温度的响应

浮游植物物候能够反映浮游植物的生长变化与湖泊生态系统的变化,水温、营养盐浓度等因素对物候有重要影响。太湖富营养化程度较高,水温的影响作用日趋显著,物候与水温关系的研究对理解、控制和改善太湖生态系统具有重要意义。本研究利用2003—2018年MODIS遥感数据计算浮游植物物候指标和湖泊水表温度（Temperature of Water Surface,LSWT）,通过分析太湖浮游植物物候时空变化特点探究了不同区域的物候特征,并结合LSWT揭示了浮游植物物候对LSWT变化的响应关系。结果表明：① 不同浮游植物物候指标具有不同空间分布特点,水华发生次数、峰值叶绿素a（Chla）浓度和水华总持续时间呈现由西部沿岸向湖心区递减的趋势;浮游植物生长开始时间和峰值Chla发生时间分布复杂但在沿岸区域相对较早;② 太湖可被划分为4种具有不同物候特征的区域,Ⅰ类区域主要位于贡湖湾、东部沿岸以及太湖中部开阔水域,该区Chla浓度范围为50~60 μg/L,且波动平缓,水华发生次数最少、开始最晚、持续时间最短;Ⅱ类区域主要分布于太湖西部沿岸,Chla浓度范围为50~90 μg/L且变化剧烈,该区水华发生次数最多、开始最早、持续时间最长;Ⅲ和Ⅳ类属于过渡区域,前者主要分布于梅梁湾、竺山湾及入湾口,后者主要位于南部沿岸以及太湖中部;③ 浮游植物物候对LSWT变化的响应受营养水平影响,当营养水平较高时,浮游植物的生长受LSWT的促进作用显著,LSWT年际变化的升高趋势对浮游植生长物候提前、生物量增加的影响明显,反之,则LSWT变化对浮游植物生长的影响减弱。     

基于DEM修正的MODIS地表温度产品空间插值

地表温度是资源环境、气候变化、陆地生态系统等科学研究的重要参数之一。MODIS LST（Land Surface Temperature, LST）产品是地表温度相关研究的重要数据源。而现有MODIS LST产品均存在云覆盖区域,因此云覆盖区域地表温度估计已成为热红外遥感的前沿性研究难题。为解决MODIS LST产品云遮挡区域地表温度信息缺失,以秦岭地区为研究区,选用2001-2017年的MOD11A2数据,在传统的反距离权重（IDW）、规则样条函数（SPLINE）、普通克里金（OK）、趋势面（TREND）空间插值方法中引入高程因子,通过反复试验形成基于DEM修正的MODIS LST空间插值方法。分析空间插值结果表明： ① 空间插值精度由高到低为：OK>SPLINE>IDW>TREND,基于DEM修正后精度分别提高了约0.38、0.31、0.32和0.78℃; ② 空间插值结果的精度呈现季节差异,夏季6、7、8月的精度较高,1月的精度最低;③ 插值精度与云区的范围存在一定的关系,当云覆盖区域<1.1 km²时,DEM+OK方法的插值误差<0.55 ℃,当云覆盖区域<3.1 km²,插值误差<1 ℃;DEM+SPLINE方法在云覆盖区域<2.7 km²时,插值误差<0.55 ℃,云覆盖区域<10.4 km²,插值误差<1℃;当云覆盖为1.1~2.7 km²时,DEM+SPLINE方法的插值精度高于DEM+OK方法。     

基于MODIS数据的南极洲冰川变化情况遥感调查与分析

南极洲生态环境是世界各国研究的热点。本文利用2003年和2010年两期MODIS数据对南极洲大陆冰川及其冰架进行遥感调查与分析,获得南极洲2003年和2010年两期冰川及冰架类型、面积等信息,并通过监测初步掌握了南极洲冰川变化情况,进一步对其变化原因及其变化趋势进行初步研究和分析。     

基于MODIS数据的北京气溶胶类型特性与影响因素分析

应用北京城区2001-2007年间的MODIS气溶胶产品及辅助气象数据,分析了北京气溶胶类型特性及其变化趋势,以及风速、降水与气温等气候条件对其的影响。根据AOT550-FM关系模型,将北京气溶胶分成城市/工业型(UI),沙尘型(DD),干净海洋型(CM)和混合型(MT)4种类型,并在此基础上,结合辅助气象数据,分析了气候对总体气溶胶和各类型气溶胶的影响。研究表明,受风向、气温、降水等气候因素影响,北京气溶胶在5月取得最大值,北京气溶胶的主要类型为沙尘型气溶胶(DD)和混合型气溶胶(UI),而主要影响气溶胶为沙尘型气溶胶(DD)和城市/工业型气溶胶(UI)。在2001-2007年间,城市/工业型气溶胶(UI)有较明显的增长,沙尘型气溶胶(DD)则呈现为与地面统计数据相符的下降趋势,总体气溶胶和其他类型气溶胶都处于基本稳定状态,北京大气环境基本稳定。     

基于MODIS数据的气溶胶光学厚度反演

气溶胶在大气污染事件中扮演重要角色。光学厚度作为大气气溶胶的一个重要光学属性,常作为其他相关科学研究的重要参数。本文以ENVI5.0为平台,利用经典的暗像元算法,对2011年8月5日北京地区的MODIS卫星遥感影像数据进行了气溶胶光学厚度(AOD)反演,并对其空间分布进行了分析,为环境监测部门提供了大气污染治理依据。     

2010年中国西南旱情的时空特征分析——基于MODIS数据归一化干旱指数

 近年来,干旱灾害频繁发生,对区域内农业生产和生态环境造成了极大的破坏。为了快速准确地获取大面积地表土壤水分信息用以评估地表受旱程度,本文以2010年年初中国西南大旱为例,运用MODIS可见光-红外波段数据以及像元可信度综合生成了归一化干旱指数(NDDI)。同时,结合研究区内地面气象站点实测的土壤湿度数据验证了NDDI对地表土壤湿度的敏感度。结果表明:相比于植被状态指数(VCI)干旱监测模型,NDDI能更加灵敏地对浅层地表干湿变化做出迅速响应。最后,本文利用NDDI分析了2010年年初中国西南大旱旱情发展的时空演变过程,宏观上重现了此次旱情的发展历程,并使用该指数统计了不同时间节点、不同干旱等级下的贵州省土地受旱面积。结果显示:2010年1月-2010年4月为贵州省旱情最为严重的4个月,平均受旱面积达103 352km²,最大受旱面积达132 257km²,占贵州省总面积的75%以上。同时,旱情等级为重旱的土地面积最大达到88 246 km²,占贵州全境土地面积的50%以上。     

基于MODIS数据定量判识沙尘暴方法的对比研究

利用MODIS数据,结合具体实例,对比研究当前几种利用光谱特征定量判识沙尘暴的方法。从理论上剖析各方法的原理,分析其优劣,并提出一套新的算法的组合方式。研究结果表明,新的组合算法有不小的改进：①大大降低了单一算法在不同时间或地区图像中阈值取值不稳定的影响,减少了图像噪声造成的误判,增强了其通用性和稳定性;②明显减弱了太...     

基于长时间序列MODIS数据的鄱阳湖湖面面积变化分析

湖泊是气候、水和生物地球化学循环的关键组分,遥感观测有助于获得湖泊面积变化及对环境的响应信息。本文基于长时间序列遥感观测提出了一种利用像元水淹没/陆地出露比例的湖面变化分析算法,并应用于鄱阳湖的湖面提取及变化分析。首先,用全年遥感数据合成获得当年最大湖面;然后,在此最大湖面范围内,识别出每景数据的水体和陆地状态;最后,统计一定时期内每个像元的水淹没比例,并据此分析湖泊的年际和季节变化特征。该算法的最大优势是克服了云的干扰,以及湖面快速变化造成的年际变化对比分析困难问题。算法应用于2000-2010年MODIS观测,分析结果表明,本算法检测出的湖面面积与鄱阳湖水文站水位观测资料非常一致;算法可以获得鄱阳湖湖面面积的显著季节变化信息;2000-2010年间,鄱阳湖湖面面积在丰水期未发现有规律的变化;在枯水期,2003年后湖面面积急剧减小。     

基于MODIS的光合有效辐射估算系统设计与实现

本文采用PARcalc算法,并以C#和ENVI/IDL二次开发语言,设计了主要以MODIS产品为驱动的光合有效辐射估算系统。鉴此,比较了IDL和ArcGIS Engine两者的技术特点,设计了IDL与ArcGIS Engine共存、多种开发环境相结合的技术方案。同时,对模型参数置备、光合有效辐射估算、模型分析等模块的功能,以及多种语言混合编程、数据分块处理、瞬时及日光合有效辐射批量计算等关键技术进行了分析。最后,以内蒙古地区作为研究区,估算了该区2007全年和四季的总光合有效辐射及日均光合有效辐射,并对其特征值作了对比分析。结果表明,对研究区域尺度光合有效辐射的定量化计算具有一定的参考价值。     

The effect of the East China Sea Kuroshio Front on the marine atmospheric boundary layer

Various satellite data, JRA-25 (Japan reanalysis of 25 years) reanalyzed data and WRF (Weather Research Forecast) model are used to investigate the in situ effect of the ESKF (East China Sea Kuroshio Front) on the MABL (marine atmospheric boundary layer). The intensity of the ESKF is most robust from January to April in its annual cycle. The local strong surface northerly/northeasterly winds are observed right over the ESKF in January and in April and the wind speeds decrease upward in the MABL. The thermal wind effect that is derived from the baroclinic MABL forced by the strong SST gradient contributes to the strong surface winds to a large degree. The convergence zone existing along the warm flank of the ESKF is stronger in April than in January corresponding to the steeper SST (sea surface temperature) gradient. The collocations of the cloud cover maximum and precipitation maximum are basically consistent with the convergence zone of the wind field. The clouds develop higher (lower) in the warm (cold) flank of the ESKF due to the less (more) stable stratification in the MABL. The lowest clouds are observed in April on the cold flank of the ESKF and over the Yellow Sea due to the existence of the pronounced temperature inversion. The numerical experiments with smoothed SST are consistent with the results from the ovservations.     

A PRELIMINARY ANALYSIS ON THE CHARACTERISTICS OF THE KUROSHIO FRONTAL EDDY IN THE EAST CHINA SEA IN SPRING

The Kuroshi'o front eddy's surface and sectional isothermal distribution characteristics were analyzed on the basis of observation data obtained in April 13-16 of 1989 in the East China Sea. It was found from the similarity between these isothermal distributions with those in January and beginning of June for the years 1986-1990 that the Kuroshio front eddy often occurred from March to the beginning of June. The Kuroshio front eddy movement in the East China Sea in spring was along two routes: the Okinawa Trough route, and the continental shelf slope route. The two moving routes both in the surface layer and in the section are described, their causes are discussed, and differences are compared.     

The formation of wind curl in the marine atmosphere boundary layer over the East China Sea Kuroshio in spring

Various data are used to investigate the characteristics of the surface wind field and rainfall on the East China Sea Kuroshio (ESK) in March and April, 2011. In March, the wind speed maximum shows over the ESK front (ESKF) in the 10 meter wind field, which agrees with the thermal wind effect. A wind curl center is generated on the warm flank of the ESKF. The winds are much weaker in April, so is the wind curl. A rainband exists over the ESKF in both the months. The Weather Research and Forecasting (WRF) model is used for further researches. The winds on the top of the marine atmosphere boundary layer (MABL) indicate that in March, a positive wind curl is generated in the whole MABL over the warm flank of the ESKF. The thermal wind effect forced by the strong SST gradient overlying the background wind leads to strong surface northeasterly winds on the ESKF, and a positive shearing vorticity is created over the warm flank of the ESKF to generate wind curl. In the smoothed sea surface temperature experiment, the presence of the ESKF is responsible for the strong northeast winds in the ESKF, and essential for the distribution of the rainfall centers in March, which confirms the mechanism above. The same simulation is made for April, 2011, and the responses from the MABL become weak. The low background wind speed weakens the effect of the thermal wind, thus no strong Ekman pumping is helpful for precipitation. There is no big difference in rainfall between the control run and the smooth SST run. Decomposition of the wind vector shows that local wind acceleration induced by the thermal wind effect along with the variations in wind direction is responsible for the pronounced wind curl/divergence over the ESKF.     

ANALYSIS OF Cu, Cd, Co AND Ni IN SURFACE WATER OF THE KUROSHIO AREA IN THE EAST CHINA SEA

Study of 1986 and 1987 heavy metal distribution in surface water of the Kuroshio area in the East China Sea showed regional and slight seasonal variations in distribution and concentration . Heavy metal levels in Taiwan Strait, the sea area north of Taiwan and the continental shelf are higher than those in the main axis of the Kuroshio . Dissolved Cu in summer and winter decreases with the increase of salinity , but dissolved Cd has no obvious change with salinity .     

Analysis of seasonal variation of water masses in East China Sea

Seasonal variations of water masses in the East China Sea （ECS） and adjacent areas are investigated, based on historical data of temperature and salinity （T-S）. Dynamic and thermodynamic mechanisms that affect seasonal variations of some dominant water masses are discussed, with reference to meteorological data. In the ECS above depth 600 m, there are eight water masses in summer but only five in winter. Among these, Kuroshio Surface Water （KSW）, Kuroshio Intermediate Water （KIW）, ECS Surface Water （ECSSW）, Continental Coastal Water （CCW）, and Yellow Sea Surface Water （YSSW） exist throughout the year. Kuroshio Subsurface Water （KSSW）, ECS Deep Water （ECSDW）, and Yellow Sea Bottom Water （YSBW） are all seasonal water masses, occurring from May through October. The CCW, ECSSW and KSW all have significant seasonal variations, both in their horizontal and vertical extents and their T-S properties. Wind stress, the Kuroshio and its branch currents, and coastal currents are dynamic factors for seasonal variation in spatial extent of the CCW, KSW, and ECSSW, whereas sea surface heat and freshwater fluxes are thermodynamic factors for seasonal variations of T-S properties and thickness of these water masses. In addition, the CCW is affected by river runoff and ECSSW by the CCW and KSW.     

THERMOHALINE FINESTRUCTURE AND ITS RELATION WITH THE WATER MASSES AND CURRENTS SYSTEM IN THE NORTHERN EAST CHINA SEA

Eighy-one CTD profiles gathered in springtime were used for northem East China Sea tbermohalinefinestructure studies indicating that the finestructure properties vaned with region and depth, as shown infinesructure specra, distribution of Cox numbers etc..Some results closely wiated to distribution of watermasses and Analysis of two typical profiles revealed differenes in autospectra of temperature,salihity and potential density gradients, probobility distribution of temperature finestructure gradient,Cox numberc.etc. The probability density function of vertical temperature gradients, which varied withsample interval, is given. The variances of temperatare finestructare gradient are used to estimate the lat-eral diffusivity and lateral temperatare flux, which were 10.3 (m~2/s) and 5.5×10~(-4) (℃ m/s),respectivly.     

The Kuroshio transport east of taiwan and the Sea Surface Height Anomaly from the interior ocean

1　Introduction　TheKuroshioflowsthroughtheEastTaiwanChan nel (ETC)betweenthenortheastcoastofTaiwanandtheJapaneseRyukyuIslandbeforeenteringintotheEastChinaSea (ECS)astheextendingflowoftheNorthEquatorialCurrent (NEC)whichbifurcatestotheeastofthePhilippines…     

Formation and evolution of the modem warm current system in the East China Sea and the Yellow Sea since the last deglaciation

To reconstruct the formation and evolution process of the warm current system within the East China Sea (ECS) and the Yellow Sea (YS) since the last deglaciation, the paleoceangraphic records in core DGKS9603, core CSH1 and core YSDPI02, which were retrieved from the mainstream of the Kuroshio Current (KC), the edge of the modem Tsushima Warm Current (TWC) and muddy region under cold waters accreted with the Yellow Sea Warm Current (YSWC) respectively, were synthetically analyzed. The results indicate that the formation and evolution of the modem warm current system in the ECS and the YS has been accompanied by the development of the KC and impulse rising of the sea level since the last deglaciation. The influence of the KC on the Okinawa Trough had enhanced since 16 cal kyr BE and synchronously the modem TWC began to develop with the rising of sea level and finally formed at about 8.5 cal kyr BP. The KC had experienced two weakening process during the Heinrich event 1 and the Younger Drays event from 16 to 8.5 cal kyr BP. The period of 7-6 cal kyr BP was the strongest stage of the KC and the TWC since the last deglaciation. The YSWC has appeared at about 6.4 cal kyr BP. Thus,the warm current system of the ECS and the YS has ultimately formed. The weakness of the KC,indicated by the occurrence of Pulleniatina minimum event (PME) during the period from 5.3 to 2.8 cal kyr BE caused the main stream of the TWC to shift eastward to the Pacific Ocean around about 3 cal kyr BP. The process resulted in the intruding of continent shelf cold water mass with rich nutrients. Synchronously, the strength of the YSWC was relatively weak and the related cold water body was active at the early-mid stage of its appearance against the PME background, which resulted in the quick formation of muddy deposit system in the southeastern YS. The strength of the warm current system in the ECS and the YS has enhanced evidently, and approached to the modern condition gradually since 3 cal kyr BP.     

STUDY OF WATER—TRANSPORT THROUGH SOME MAIN STRAITS IN THE EAST CHINA SEA AND SOUTH CHINA SEA

OCCAM global ocean model results were applied to calculate the monthly water transport through 7 straits around the East China Sea(ECS)and the South china Sea(SCS).Analysis of the features of velocity profiles and their variations in the Togara Strait,Luzon Strait and Eastern Taiwan Strait showed that;1)the velocity profiles had striped pattern in the Eastern Taiwan Strait,where monthly flux varied from 22.4 to 28.1 Sv and annual mean was about 25.8 Sv;2)the profiles of velocity in the Togara Strait were characterized by core structure,and monthly flux varied from 23.3 to 31.4 Sv,with annual mean of about 27.9 Sv;3)water flowed from the SCS to the ECS in the Taiwan Strait,with maximum flux of 3.1 Sv in July and minimum of 0.9 Sv in November;4)the flux in the Tsushima Strait varied by only about 0.4 Sv by season and its annual mean was about 2.3 Sv;5)Kuroshio water flowed into the SCS in the Luzon Strait throughout the year and the velocity profiles were characterized by multi-core structure.The flux in the Luzon Strait was minimun in June(about 2.4 Sv)and maximum in February(about 9.0 Sv),and its annual mean was 4.8 Sv;6)the monthly flux in the Mindoro Strait was maximum in December(3.0 Sv)and minimum in June(Only 0.1 Sv),and its annual mean was 1.3 Sv;7)Karimata Strait water flowed into the SCS from May to August,with maximum in-flow flux of about 0.75 Sv in June and flowed out from September to April at maximum outflow flux of 3.9 Sv in January.The annual mean flux was about 1.35 Sv.     

东海区鲳鱼资源利用现状分析

通过对东海区鲳鱼近年群体组成变化及银鲳生物学特性变化来分析目前鲳鱼资源利用状况,结果表明：一方面,虽然近年鲳鱼产量大幅增加,但其平均体重、优势叉长组成及年龄组成均出现明显下降,资源状况日益恶化;另一方面,1龄鱼已占渔获的93．68％,目前捕捞现行点开捕年龄tc=1和捕捞死亡系数F＝2．51,单位补充量繁殖力相对百分比P＜1．9％,单位补充量渔获量(Yw／R)为70g／尾,均显示已处于严重的生物学型捕捞过度．建议渔业管理部门大力削减作业渔船约50％,严格控制捕捞强度,逐步推迟开捕年龄至3龄以上,使鲳鱼资源真正能够永续利用。