Sand Areas for the Undeveloped Areas of New Jersey's Barrier Islands, Extracted from Orthoimagery, March 9, 1991, to July 30, 2013

Assessing the physical change to shorelines and wetlands is critical in determining the resiliency of wetland systems that protect adjacent habitat and communities. The wetland and back-barrier shorelines of New Jersey changed as a result of wave action and storm surge that occurred during Hurricane Sandy, which made landfall on October 29, 2012. The impact of Hurricane Sandy will be assessed and placed in its historical context to understand the future vulnerability of wetland systems. Making these assessments will rely on data extracted from current and historical resources such as maps, aerial photographs, satellite imagery, and lidar elevation data, which document physical changes over time. This USGS Data Series publication includes several open-ocean shorelines, back-island shorelines, back-island shoreline points, sand area polygons, and sand lines for the undeveloped areas of New Jersey's barrier islands that were extracted from orthoimagery (ortho aerial photography) dated from March 9, 1991 to July 30, 2013. This data-set consists of polygons that represent the sand areas found in orthoimagery taken on the date specified in the filename and in the "Date_" field in the feature attribute table. Orthoimagery of New Jersey were acquired in digital format from U.S. Department of Agriculture (USDA), U.S. Geological Survey (USGS), National Oceanic and Atmospheric Administration (NOAA), and New Jersey Geographic Information Network (NJGIN). Prior to processing, the images were trimmed to remove the bulk of the areas that were not going to be analyzed. Using ERDAS Imagine 9.3, the images were classified into 40 classes that were coded as either sand or not sand. Due to varying conditions within the imagery, the coding occasionally varied from one area to another. Using ArcGIS 10.2, the resulting coded raster data-sets were converted to polygons and edited. The following list provides additional details about the orthoimagery used. The sand areas for each date and area is in a separate data-set (shapefile) named nj_sandpo_<range of dates>_<area name>.shp. The orthoimage date for each polygon is included in the shapefile attribute table's "Date_" field. Date Type Source Resolution 19910309-19910313 Pan USGS, DOQQ 1 m (meter) 19950325-19950407 CIR USGS, DOQQ 1 m 20020218-20020411 CIR NJGIN 1 m* 20060805-20060613 Natural USDA, NAIP 1 m 20070318-20070415 Natural NJGIN 1 m* 20080808-20080826 Natural USDA, NAIP 1 m 20100703-20100726 Natural USDA, NAIP 1 m 20120314-20120416 RGBI NJGIN 1 m* 20130707-20130730 Natural USDA, NAIP 1 m Pan - Panchromatic (1 band, gray scale) CIR - Color Infrared (infrared, red, green) Natural - Natural Color (red, green, blue) RGBI - Natural Color and Infrared (red, green, blue, and infrared) DOQQ - Digital Orthophoto Quarter Quads NAIP - National Agriculture Imagery Program *Resampled from 1-foot resolution imagery then smoothed using a 3 pixel by 3 pixel focal mean.评估海岸线与湿地的物理变化，对于明确湿地系统的韧性至关重要——此类系统可庇护邻近生境与社区。新泽西州的湿地及障后海岸线，因2012年10月29日登陆的飓风“桑迪”引发的波浪作用与风暴潮发生了改变。本次研究将评估飓风“桑迪”的影响，并结合历史背景展开分析，以明晰湿地系统未来的脆弱性。 开展此类评估所需的数据，将提取自各类当前与历史资料，包括地图、航空摄影、卫星影像以及激光雷达（lidar）高程数据，这些资料可记录随时间推移发生的物理变化。 本美国地质调查局（U.S. Geological Survey, USGS）数据系列出版物，包含新泽西州障壁岛未开发区域的多组开放海洋海岸线、障后岛海岸线、障后岛海岸线点位、沙区多边形及沙线数据，这些数据提取自1991年3月9日至2013年7月30日期间的正射影像（orthoimagery，正射航空摄影）。 本数据集由多边形构成，这些多边形代表从对应文件名及要素属性表"Date_"字段指定日期拍摄的正射影像中识别出的沙区。 新泽西州的正射影像以数字格式从美国农业部（U.S. Department of Agriculture, USDA）、美国地质调查局（USGS）、美国国家海洋和大气管理局（National Oceanic and Atmospheric Administration, NOAA）以及新泽西州地理信息网络（New Jersey Geographic Information Network, NJGIN）获取。处理前，先对影像进行裁切，移除绝大多数无需分析的区域。借助ERDAS Imagine 9.3软件，将影像划分为40个类别，其中编码为沙或非沙。由于影像内部条件存在差异，部分区域的编码偶尔会出现不一致。随后使用ArcGIS 10.2软件，将生成的编码栅格数据集转换为多边形并进行编辑。 以下列表提供了所用正射影像的更多细节。各日期与区域对应的沙区存储在独立的形状文件（shapefile）中，文件名为nj_sandpo_<日期范围>_<区域名称>.shp。每个多边形对应的正射影像日期包含在形状文件属性表的"Date_"字段中。 日期 影像类型 来源 分辨率 19910309-19910313 全色（Pan） USGS、DOQQ 1米 19950325-19950407 彩色红外（CIR） USGS、DOQQ 1米 20020218-20020411 彩色红外（CIR） NJGIN 1米* 20060805-20060613 自然色（Natural） USDA、NAIP 1米 20070318-20070415 自然色（Natural） NJGIN 1米* 20080808-20080826 自然色（Natural） USDA、NAIP 1米 20100703-20100726 自然色（Natural） USDA、NAIP 1米 20120314-20120416 RGBI NJGIN 1米* 20130707-20130730 自然色（Natural） USDA、NAIP 1米 全色（Pan）：全色影像（单波段灰度影像） 彩色红外（CIR）：彩色红外影像（红外、红、绿波段） 自然色（Natural）：自然色影像（红、绿、蓝波段） RGBI：自然色+红外影像（红、绿、蓝及红外波段） DOQQ：数字正射影像四分之一幅（Digital Orthophoto Quarter Quads） NAIP：国家农业影像计划（National Agriculture Imagery Program） *：从1英尺分辨率影像重采样后，使用3×3像素焦点均值进行平滑处理。