MODIS/TERRA MOD44W Land Water Mask Derived from MODIS and SRTM L3 Global 250m SIN Grid

Land Water Mask Derived from MODIS and SRTM L3 Global 250m SIN Grid MOD44W The new MODIS 250 m land-water mask (Short Name: MOD44W) is an improvement over the existing MODIS Nadir Bidirectional Reflectance Distribution Function (BRDF)-Adjusted Reflectance (NBAR) and MODIS land cover-based global land-water mask (Salomon et al., 2004). The MODIS NBAR and land cover based mask was itself an improved version of the EOS DEM-based land-water mask (Logan et al., 1999). The new MODIS 250 m mask is primarily created with three different data inputs: The Shuttle Radar Topography Mission's (SRTM) Water Body Dataset (SWBD) (Areas between 60? S to 60 N); The MOD44C, a non-public, 250 m global 16-day composite collection based on 8+ years of Terra MODIS data, and 6+ years of Aqua MODIS data. This data set originally provided the input to produce the Vegetative Cover Conversion, and Vegetative Continuous Fields products (Areas between 60 N to 90 N); and the MODIS based Mosaic of Antarctica (MOA), which is a 250 m MODIS level-1b mosaic for Antarctica (Areas within Antarctica between 60 S and 90 S). Other appropriate and publicly available data sets were also used to supplement the production of the MODIS 250 m land water mask. Additional details regarding the methodology are available in the User Guide. This marks the first time that such a global MODIS-SRTM land-water mask is offered publicly to end-users. This data set is provided in the same gridded tile structure that is common to several higher-level MODIS land products.基于MODIS与SRTM的L3级全球250米SIN格网陆地水体掩膜（MOD44W） 这款全新的250米中分辨率成像光谱仪（Moderate-resolution Imaging Spectroradiometer，简称MODIS）陆地水体掩膜（短名称：MOD44W），相较于此前基于MODIS天底视角双向反射分布函数（Bidirectional Reflectance Distribution Function，BRDF）校正反射率（Nadir BRDF-Adjusted Reflectance，NBAR）与MODIS土地覆盖数据生成的全球陆地水体掩膜（Salomon等，2004），性能更优。而此前基于MODIS NBAR与土地覆盖数据的掩膜产品，本身也是基于EOS数字高程模型（Digital Elevation Model，DEM）的陆地水体掩膜（Logan等，1999）的升级版。该新型250米MODIS陆地水体掩膜主要由三类数据源生成：一是航天飞机雷达地形测绘任务（Shuttle Radar Topography Mission，SRTM）水体数据集（Shuttle Radar Topography Mission Water Body Dataset，SWBD），覆盖范围为南纬60°至北纬60°区域；二是非公开数据集MOD44C：该数据集基于8年以上的Terra MODIS数据与6年以上的Aqua MODIS数据生成，为全球250米分辨率16天合成数据集，曾作为植被覆盖转换与植被连续场产品的输入数据源，覆盖范围为北纬60°至北纬90°区域；三是基于MODIS的南极镶嵌图（Mosaic of Antarctica，MOA）：该数据集为南极地区250米分辨率MODIS 1b级镶嵌数据，覆盖范围为南纬60°至南纬90°的南极区域。此外，研究团队还采用了其他合适的公开数据集辅助生成该250米MODIS陆地水体掩膜。关于制作方法的更多细节可查阅用户指南。 本次发布的全球MODIS-SRTM陆地水体掩膜为首次面向终端用户公开的同类产品。该数据集采用与多款高级MODIS陆地产品一致的格网瓦片结构进行组织。