Data for: The Annual Cycle of Landfast Ice in the Eastern Bering Sea

Large quantities of data were used for this study. Due to the 10gb file limit of Mendely Data, we can only include instructions on how to acquire the SAR imagery, with R and python scripts to complete the remaining steps. The data is uploaded as a compressed file that unzips into a folder. Within the folder there are two subdirectories: “SAR_Imagery” and “Gradient_Analysis”. The SAR_Imagery subdirectory includes python scripts to initiate downloads of Radarsat-1 imagery covering geographic regions within our study area. The download is accomplished via the Alaska Satellite Facility Data Portal; the creation of an account will be required to download this imagery. The Gradient_Analysis subdirectory includes two folders: “Dates” and “Scripts”. The “Dates” folder includes CSV files listing the three dates used in each “triplet”. These CSV files are needed for the execution of the scripts contained in the “Scripts” folder. To run these scripts, you need R-Studio, a free and open-sourced IDE for the R programming language. Step1_Subfolders.R loops through the dates contained within the CSV files in the “Dates Folders”, and deposits the three SAR images in a new subdirectory. Step2_Gradient.R then loops through these subdirectories and performs the net-gradient-difference analysis needed to procure imagery for identifying landfast ice.本研究采用了海量数据。鉴于门德利数据平台（Mendeley Data）的单文件上传上限为10GB，本次仅提供合成孔径雷达（Synthetic Aperture Radar，SAR）影像的获取指引，以及用于完成后续流程的R语言与Python脚本。本数据集以压缩包形式上传，解压后将得到一个主文件夹，其内包含两个子目录："SAR_Imagery"与"Gradient_Analysis"。 在"SAR_Imagery"子目录中，内置用于批量下载研究区域内指定地理范围的雷达卫星1号（Radarsat-1）影像的Python脚本。该下载流程通过阿拉斯加卫星设施数据门户（Alaska Satellite Facility Data Portal）完成，用户需先注册账号方可获取此类影像。 "Gradient_Analysis"子目录内含两个文件夹："Dates"与"Scripts"。其中"Dates"文件夹包含若干CSV格式文件，每份文件均列有每个"三元组（triplet）"所使用的三个日期信息，此类CSV文件是运行"Scripts"文件夹内脚本的必要前置文件。运行上述脚本需借助R-Studio——一款面向R语言的免费开源集成开发环境（Integrated Development Environment，IDE）。其中Step1_Subfolders.R会遍历"Dates"文件夹内CSV文件中的日期信息，并将对应的三幅SAR影像存入新建子目录；随后Step2_Gradient.R将遍历这些子目录，执行用于获取可识别固定冰（landfast ice）影像所需的净梯度差分析流程。