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1.
As a result of the 1991 Persian Gulf war, between mid‐January and June 1991, the Persian Gulf was contaminated with an estimated 4 to 6 million barrels of crude oil, released directly into the Gulf from refinement facilities, transhipment terminals, and moored tankers along the coast of Kuwait, and precipitated from oil fire smoke plumes. To assess the environmental impact of the oil, an international team of marine scientists representing 14 nations was assembled under the auspices of the United Nations International Oceanic Commission and the Regional Organization for Protection of the Marine Environment to conduct detailed surveys of the Persian Gulf, the Strait of Hormuz, and the Gulf of Oman, including hydrographic, chemical, and biological measurements. To supplement the field surveys and to serve as an aid in data interpretation, astronauts aboard the Space Shuttle Atlantis photographed water features and coastal habitats in the Persian Gulf during mission STS‐45 (24 March to 02 April 1992). The astronauts collected 111 hand‐held, color photographs of the Gulf (72 70 mm photographs and 39 5‐inch photographs) from an altitude of 296 km (160 n.mi.). The photographs reveal distributions in water turbidity associated with outflow from the Shatt‐al‐Arab and water circulation along the entire coast of Iran and the Strait of Hormuz, coastal wetlands and shallow‐water habitats, and sticks appearing in the sunglint pattern, which appear to be oil.  相似文献   

2.
Spatial autocorrelation analysis was used to identify spatial patterns of 1991 Gulf War (GW) troop locations in relationship to subsequent postwar diagnosis of chronic multisymptom illness (CMI). Criteria for the diagnosis of CMI include reporting from at least two of three symptom clusters: fatigue, musculoskeletal pain, and mood and cognition. A GIS‐based methodology was used to examine associations between potential hazardous exposures or deployment situations and postwar health outcomes using troop location data as a surrogate. GW veterans from the Devens Cohort Study were queried about specific symptoms approximately four years after the 1991 deployment to the Persian Gulf. Global and local statistics were calculated using the Moran's I and G statistics for six selected date periods chosen a priori to mark important GW‐service events or exposure scenarios among 173 members of the cohort. Global Moran's I statistics did not detect global spatial patterns at any of the six specified data periods, thus, indicating there is no significant spatial autocorrelation of locations over the entire Gulf region for veterans meeting criteria for severe postwar CMI. However, when applying local G* and local Moran's I statistics, significant spatial clusters (primarily in the coastal Dammam/Dharhan and the central inland areas of Saudi Arabia) were identified for several of the selected time periods. Further study using GIS techniques, coupled with epidemiological methods, to examine spatial and temporal patterns with larger sample sizes of GW veterans is warranted to ascertain if the observed spatial patterns can be confirmed.  相似文献   

3.
针对北部湾经济区生态文明建设、海洋资源利用和海洋应急救援事件处置等缺乏统一的陆海高程基准等难题,本文首先利用广西北部湾经济区2764项重力数据和8项GNSS水准数据,应用第二类Helmert凝聚法,反演得到广西北部湾海域及沿大陆海岸线向内陆延伸约15 000 km^(2)区域内置信度较高的重力似大地水准面;然后参考重力场选取EIGEN6C4模型,重力似大地水准面对比8项GNSS水准资料,其精度达2.2 cm;最后采用球冠调和分析方法,将2′×2′格网似大地水准面精度提高至1.6 cm,并将陆地高程基准传递到广西北部湾海域及其海岛上,实现该区域陆海高程基准的统一。  相似文献   

4.
The ability of high-resolution imaging systems to resolve small-scale structure on the ocean surface suggests the possibility of using characteristics of Langmuir circulation to map the surface mixed-layer depth and near-surface current. We illustrate this using synthetic aperture radar and infrared imagery that are collected across the edge of the Gulf Stream (GS), which reveals surfactant streaks, or ldquowindrows,rdquo that are induced by Langmuir circulation. Based on changes in the windrow spacing and orientation, the mixed layer is estimated to deepen from 7 to 12 m across the edge of the GS and the current to increase from about 1 to 2 m/s. These spatial changes compare reasonably well with independent data, suggesting that the approach is plausible. It may also be possible to extract additional environmental information from the windrows.  相似文献   

5.
跨比例尺新旧居民地目标变化分析与决策树识别   总被引：1，自引：1，他引：0  
陈利燕  张新长  林鸿  杨敏 《测绘学报》2018,47(3):403-412
变化分析与探测是跨比例尺地图数据更新的核心问题之一。以往研究主要关注时间维上地理实体时空演化引起的地图目标变化,甚至将地图目标变化等同于地理实体真实变化,忽略了尺度维上由地图综合导致的表达变化。本文以居民地数据为例,从表层形式和深层缘由对跨比例尺新旧地图数据间的目标变化进行深入分析。在此基础上,引入机器学习领域的决策树方法构建变化信息识别模型。该模型的目标是判别时态变化和表达变化两种类型,从而提取用于更新小比例尺地图数据的真正变化信息。结合广州市多比例尺地图数据库更新任务及实际数据进行验证,结果显示设计的变化探测模型可以达到90%以上的整体精度。  相似文献   

6.
用Google Earth遥感影像数据作为切入点,以广西北部湾沿海为例,利用RTK进行外业测量,探讨了GE遥感影像应用在海籍调查工作中的可行性,得出在GIS校正配准下的遥感影像是完全可以应用于北部湾海域的海籍调查与测量的要求。  相似文献   

7.
Chlorophyll-a (Chl-a) and Suspended Solid Concentration (SSC) shows the productivity of water and their surrounding environment. These parameters can be effectively estimated through several remote sensing techniques. From the recent reports on the Gulf of Thailand, it is found that Chl-a and SSC are increasing in coastal areas due to changing environment caused by variations in the global carbon cycle, climate change and water pollution linking to anthropogenic conditions such as high population density and rapid urbanization in neighbouring coastal areas deteriorating the coastal and marine environment. Various models are evaluated in this study for estimation of marine Chl-a and SSC by employing Ocean Colour Monitor-2 sensor of Oceansat-2 satellite for Northern Gulf of Thailand. The retrieval of Chl-a and SSC by the atmospheric correction of visible bands from 400 to 700 nm to attain normalized water-leaving radiances and then a suitable algorithm is applied. The In-situ reflectance values of sea waters are measured using the ASD spectroradiometer. The reflectance values of the spectroradiometer are correlated for the same day atmospherically corrected satellite reflectance and the analysis offers high correlation R2 0.73. Satellite derived, Chl-a and SSC are correlated with observed in situ Chl-a and SSC. This analysis offered better correlation of R2 0.86 and 0.85 respectively with the algorithms of Chl-a and SSC.  相似文献   

8.
The mean sea level along the Swedish coast has been recomputed, taking into account the effect of the permanent tide on the height system. The recomputed data show the deviation of mean sea level (1960) from the mean geoid, i.e. the oceanographic deviation of mean sea level, with NAP as zero. On the basis of a conversion between the Finnish and Swedish height systems, mean sea level data from the Finnish coast are reduced to the same system as on the Swedish coast.The geodetically determined mean sea level values are compared with oceanographic model calculations. On the whole, the agreement between geodesy and oceanography is found to be good. Nevertheless, oceanography tends to yield somewhat larger deviations of the mean sea level than geodesy, especially in the extreme parts of both the Gulf of Bothnia and the Gulf of Finland. This might indicate that the oceanographic model has overestimated some effect. However, across the Gulf of Bothnia the oceanographic model predicts slightly smaller mean sea level differences than the geodetic data suggest.  相似文献   

9.
《测量评论》2013,45(45):386-388
Abstract

One of the longest projected loops of triangulation in Canada is the network encircling the Gulf of St Lawrence. This 1200-mile loop involves the triangulation system along the Gaspe coast, across Chaleur Bay, through eastern New Brunswick and Nova Scotia, across Cabot Strait to Newfoundland, northward along the west coast of this island to the Strait of Belle Isle, from the strait of Belle Isle along the north shore of the Gulf of St Lawrence as far as Anticosti Island, and from there southerly to the Gaspe coast.  相似文献   

10.
本文利用卫星测高、GRACE与温盐数据监测2003-2014年红海海平面变化,并分析了蒸发降水以及亚丁湾-红海质量交换对红海质量变化的影响。红海地区单一的温盐数据存在覆盖不全或质量不佳的问题,综合CORA、SODA与ORAS4温盐数据估算结果得到平均比容海平面变化,以改善比容信号的精度。针对GRACE数据处理过程中截断与空间平滑滤波引起的泄漏误差,提出改进尺度因子纠正泄漏误差,利用卫星测高数据进行模拟实验验证了改进尺度因子的有效性。利用传统尺度因子和改进尺度因子反演的红海质量变化周年振幅分别为16.1±1.3 cm和20.5±1.7 cm,利用卫星测高和温盐数据估算的质量变化周年振幅为20.2±1.0 cm,表明改进尺度因子可有效减小泄漏误差的影响,改善GRACE模型反演红海质量变化的精度。卫星测高、GRACE卫星重力数据以及平均温盐数据具有较好的一致性,联合GRACE和温盐数据估算的红海综合海平面变化周年振幅为16.6±1.7 cm,与卫星测高估算的总海平面变化周年振幅(16.2±0.9 cm)基本一致,表明多源数据可构成完整的红海海平面监测手段。相比于降水-蒸发作用,红海质量变化受红海与亚丁湾的海水质量交换的影响更为显著,其主导了红海质量的季节性变化。  相似文献   

11.
Changes in shoreline, coral reef and seafloor have been mapped using remote sensing satellite data of IRS LISS-III (1998), IRS LISS-II (1988), Survey of India Topographic sheet (1969), Naval Hydrographic Chart (NHO) 1975 and bathymetry data (1999) with ARC-INFO and ARC-VIEW GIS. The analysis of multi-date shoreline maps showed that 4.34 and 23.49 km2 of the mainland coast and 4.14 and 3.31 km2 areas of island coast have been eroded and accreted, respectively, in the Gulf of Mannar. The analysis of multi-date coral reef maps showed that 25.52 km2 of reef area and 2.16 km2 of reef vegetation in Gulf of Mannar have been lost over a period of ten years. The analysis of multi-date bathymetry data indicates that the depth of seafloor has decreased along the coast and around the islands in the study area. The average reduction of depth in seafloor has been estimated as 0.51m over a period of twenty four years. The increased suspended sediment concentration due to coastal and island erosion, and raised reef due to emerging of coast by tectonic movement are responsible for coral reef degradation in the Gulf of Mannar. Validation by ground truth has confirmed these results.  相似文献   

12.
利用基于一维球面快速傅立叶变换的Stokes方法,反演了渤海湾区域重力似大地水准面,并通过少量GPS水准点的拟合实现了GPS水准似大地水准面的建立。  相似文献   

13.
When the ecological effects of the proposed Qattara Hydrosolar Power Project were investigated, a number of submarine ridges were found in Arabs Gulf, Egypt.Those ridges were of unconsolidated oolitic origin, which was of critical importance for the water intake conditions of the Qattara Project. They were scientifically extremely interesting as being the first recent oolites ever found in the Mediterranean. The ridges have been studied concerning the geology, morphology and the water dynamics both in the field and from different satellite sensors‐MSS, TM and SPOT. Satellite mapping of the structure of the ridges, benthic algae and geology has been performed. The identification of the benthic algae has been accomplished by a semi‐manual box‐classifier technique.

A new accurate depth chart of Arabs Gulf has been constructed using TM data calibrated against echosoundings.

By creating a synthetical digital terrain model of the bed‐rock of Arabs Gulf and comparing it with the satellite image the amount of oolitic material of the bay has been estimated.

The character and location of the ridges has been compared with similar oolitic forms in the West Indies.  相似文献   

14.
Landsat TM data was utilised for coastal geomorphic mapping around the Gulf of Khambhat. Various landforms like shoreline, estuaries, mudflats, islands, mangroves, relict aluvium, cliffs, dunes, flood plains, paleochannel, paleomeanders, oxbow lake, etc. were delineated. The estuaries were divided into salt-wedge estuary, fully mixed estuary and partially mixed estuary based on amount of freshwater discharge and nature of tidal currents. The mudflats were classified into high tide flats, intertidal slopes and subtidal zones. These classes were further classified based on their composition. It was concluded that TM data has broughtout many new features and improved the classification of coastal landforms. The presence of coastal features like drowned river valleys, paleomudflats, relict alluvium, dunes, paleomeanders, oxbow lake and terraces clearly indicate the sea-level changes of the Quarternary period.  相似文献   

15.
利用广西北部湾经济区2004-2008年的土地利用变更数据,采用改进的TOPSIS方法对广西北部湾经济区的土地利用结构合理性、土地利用动态,以及土地利用类型相关性进行了分析.  相似文献   

16.
基于神经网络技术的多因子遥感水深反演模型   总被引：1，自引：0，他引：1  
采用动量BP人工神经网络方法,研究影响多光谱遥感水深反演的各种因素,概括出主要的影响因素,即:泥沙与叶绿素,通过在网络输入端加入泥沙参数因子与叶绿素参数因子,对神经网络进行训练,对大连湾的水深进行反演,取得较好的效果。  相似文献   

17.
基于CORS系统,结合网络RTK技术在北部湾测区（东区）1：10 000航测外业控制测量项目中的应用情况,分析了CORS系统在航测控制中的应用优势,与常规方法相比此方法明显提高了工作效率,且精度更高。  相似文献   

18.
When Hurricane Katrina passed over southern Florida, Florida Bay and the West Florida Shelf, and into the Gulf of Mexico, empirically derived chl a increases were observed in the Tortugas Gyre circulation feature, and in adjacent waters. Analysis of the empirically derived chl a increase within the gyre has been primarily attributed to initiation of a phytoplankton bloom promoted by nutrients upwelled by Katrina's winds. Detailed analysis of inherent optical properties derived from remotely sensed radiances, however, indicated the interaction of Katrina with shallow coastal and shelf waters likely entrained waters with higher concentrations of chromophoric dissolved organic matter (CDOM) into the gyre circulation, augmenting the chl a signal. Storm-induced upwelling would also transport optically active CDOM to the surface. Increases in empirically derived chl a in the Florida coastal waters influenced by Katrina's winds were therefore partly due to increased absorption by CDOM. This analysis indicates that elevated empirically derived chl a in hurricane-influenced waters should not be unambiguously attributed to increased phytoplankton productivity, particularly in an optically complex coastal environment.  相似文献   

19.
The critical angle is the angle at which the contrast of oil slicks reverse their contrasts against the surrounding oil-free seawater under sunglint. Accurate determination of the critical angle can help estimate surface roughness and refractive index of the oil slicks. Although it’s difficult to determine a certain critical angle, the potential critical angle range help to improve the estimation accuracy. In this study, the angle between the viewing direction and the direction of mirror reflection is used as an indicator for quantifying the critical angle and could be calculated from the solar/viewing geometry from observations of the Moderate Resolution Imaging Spectroradiometer (MODIS). The natural seep oil slicks in the Gulf of Mexico were first delineated using a customized segmentation approach to remove noise and apply a morphological filter. On the basis of the histograms of the brightness values of the delineated oil slicks, the potential range of the critical angle was determined, and then an optimal critical angle between oil slicks and seawater was then determined from statistical and regression analyses in this range. This critical angle corresponds to the best fitting between the modeled and observed surface roughness of seep oil slicks and seawater.  相似文献   

20.
This study investigates the changes in simulated watershed runoff from the Agricultural NonPoint Source (AGNPS) pollution model as a function of model input cell size resolution for eight different cell sizes (30 m, 60 m, 120 m, 210 m, 240 m, 480 m, 960 m, and 1920 m) for the Little River Watershed (Georgia, USA). Overland cell runoff (area-weighted cell runoff), total runoff volume, clustering statistics, and hot spot patterns were examined for the different cell sizes and trends identified. Total runoff volumes decreased with increasing cell size. Using data sets of 210-m cell size or smaller in conjunction with a representative watershed boundary allows one to model the runoff volumes within 0.2 percent accuracy. The runoff clustering statistics decrease with increasing cell size; a cell size of 960 m or smaller is necessary to indicate significant high-runoff clustering. Runoff hot spot areas have a decreasing trend with increasing cell size; a cell size of 240 m or smaller is required to detect important hot spots. Conclusions regarding cell size effects on runoff estimation cannot be applied to local watershed areas due to the inconsistent changes of runoff volume with cell size; but, optimal cells sizes for clustering and hot spot analyses are applicable to local watershed areas due to the consistent trends.  相似文献   

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