SMAP Radar Twice-Daily SAR and SIR-Enhanced Scatterometer EASE-Grid 2.0 Radar Backscatter, Version 1

This data set contains twice-daily synthetic aperture radar (SAR) and enhanced-resolution scatterometer radar backscatter derived from SMAP radar data. Data are available on the Northern Hemisphere, Southern Hemisphere, Temperate, and Mid-Latitude (sub-set of Global) EASE-Grid 2.0 projections and as either 25 km or 3.125 km resolution grids. This new product uses the drop-in-the bucket gridding (GRD) algorithm and Scatterometer Image Reconstruction (SIR) algorithm to process the individual swath-based data from the input data sets into twice-daily images, producing SAR images (high-resolution), slice and footprint images (both lower-resolution), respectively. Note, that as a companion product, the radiometer form of the SIR algorithm (rSIR) was used to derive brightness temperatures from SMAP radiometer data for the SMAP Radiometer Twice-Daily rSIR-Enhanced EASE-Grid 2.0 Brightness Temperatures, Version 2, data set (NSIDC-0738).

本数据集包含每日两次的合成孔径雷达（synthetic aperture radar，SAR）数据以及源自SMAP雷达数据的增强分辨率散射计雷达后向散射数据。数据覆盖北半球、南半球、温带以及中纬度（全球子集）的EASE-Grid 2.0投影格式，分辨率可选用25千米或3.125千米的格网数据。本新产品采用即插式格网（drop-in-the bucket gridding，GRD）算法与散射计图像重建（Scatterometer Image Reconstruction，SIR）算法，将输入数据集中的单条条带式数据处理为每日两次的影像，分别生成高分辨率SAR影像、低分辨率切片影像与覆盖区影像。需注意，作为配套产品，本数据集使用散射计图像重建辐射计版（rSIR）算法，从SMAP辐射计数据中反演得到亮温，对应数据集为《SMAP辐射计每日两次rSIR增强型EASE-Grid 2.0亮温 版本2》（NSIDC-0738）。