祁连山综合观测网：黑河流域地表过程综合观测网（阿柔超级站物候相机观测数据集-2021）

该数据集包含2021年1月1日至12月31日黑河流域地表过程综合观测网中游阿柔超级站的物候相机观测数据，该仪器由北京师范大学自主研发并进行处理。物候相机集成数据获取与数据传输功能。该物候相机采用垂直向下的方式采集数据，拍摄数据分辨率为1280*720，可指定拍摄时间频率。对于绿度指数物候期计算，需要根据感兴趣区域计算相对绿度指数（GCC, Green Chromatic Coordinate公式为GCC=G/(R+G+B), R、G、B为图像红、绿、蓝三通道像元值），然后进行无效值填充和滤波平滑，最后根据生长曲线拟合确定关键物候期参数，如生长季起始日、顶峰、生长季结束日等；对于覆盖度，首先进行数据预处理，选择光照不太强的图像，然后将图像分割为植被和土壤，计算每张图像的植被像素占计算区域内的比例作为该图像对应的覆盖度，在时间序列数据提取完成以后，再按用户指定的时间窗口对原始覆盖度数据进行平滑滤波，滤波后的得结果为最终的时间序列覆盖度。本数据集包括相对绿度指数（Gcc）。
黑河流域地表过程综合观测网或站点信息请参考Liu et al. (2018)。

This dataset contains phenological camera observation data collected at the Arou Super Station in the middle reaches of the Heihe River Basin Surface Process Comprehensive Observation Network from January 1 to December 31, 2021. The instrument was independently developed and processed by Beijing Normal University, and integrates both data acquisition and data transmission functions. It collects data in a vertically downward orientation, with a shooting resolution of 1280×720, and the shooting time interval can be specified as required.

For the calculation of phenological phases based on the greenness index, the relative green chromatic coordinate (GCC, Green Chromatic Coordinate, with the formula GCC = G/(R+G+B), where R, G, and B represent the pixel values of the red, green, and blue channels of the image, respectively) shall be calculated based on the region of interest. Subsequently, invalid value filling and filtering smoothing are conducted, and finally key phenological parameters including the start date of the growing season, peak value, and end date of the growing season are determined via growth curve fitting.

For vegetation coverage calculation, data preprocessing is first performed by selecting images with moderate lighting conditions. Then, the images are segmented into vegetation and soil components, and the proportion of vegetation pixels within the target region of each image is calculated as the coverage value corresponding to that image. After the extraction of time-series data is completed, smooth filtering is applied to the original coverage data using the user-specified time window, and the filtered result serves as the final time-series coverage product.

This dataset includes the relative green chromatic coordinate (GCC). For information about the Heihe River Basin Surface Process Comprehensive Observation Network and its stations, please refer to Liu et al. (2018).