SMAP L4 Global 3-hourly 9 km EASE-Grid Surface and Root Zone Soil Moisture Analysis Update, Version 6

This data set is retired and no longer available for download. We recommend using the newest version of SMAP L4 Global 3-hourly 9 km EASE-Grid Surface and Root Zone Soil Moisture Analysis Update (SPL4SMAU) data set as an alternative.

SMAP Level-4 (L4) surface and root zone soil moisture data are provided in three products:
* SMAP L4 Global 3-hourly 9 km EASE-Grid Surface and Root Zone Soil Moisture Geophysical Data (SPL4SMGP, DOI: 10.5067/9LNYIYOBNBR5)
* SMAP L4 Global 3-hourly 9 km EASE-Grid Surface and Root Zone Soil Moisture Analysis Update (SPL4SMAU, DOI: 10.5067/0D8JT6S27BS9)
* SMAP L4 Global 9 km EASE-Grid Surface and Root Zone Soil Moisture Land Model Constants (SPL4SMLM, DOI: 10.5067/5C36BVQZW28K).
For each product, SMAP L-band brightness temperature data from descending and ascending half-orbit satellite passes (approximately 6:00 a.m. and 6:00 p.m. local solar time, respectively) are assimilated into a land surface model that is gridded using an Earth-fixed, global cylindrical 9 km Equal-Area Scalable Earth Grid, Version 2.0 (EASE-Grid 2.0) projection.

本数据集已退役，不再提供下载服务。我们推荐使用最新版SMAP L4全球3小时9千米EASE-Grid地表与根区土壤湿度分析更新数据集（SPL4SMAU）作为替代方案。

SMAP四级（L4）地表与根区土壤湿度数据包含三款产品：
* SMAP L4全球3小时9千米EASE-Grid地表与根区土壤湿度地球物理数据集（SPL4SMGP，DOI: 10.5067/9LNYIYOBNBR5）
* SMAP L4全球3小时9千米EASE-Grid地表与根区土壤湿度分析更新数据集（SPL4SMAU，DOI: 10.5067/0D8JT6S27BS9）
* SMAP L4全球9千米EASE-Grid地表与根区土壤湿度陆面模式常数数据集（SPL4SMLM，DOI: 10.5067/5C36BVQZW28K）。

针对每一款产品，研究团队将SMAP L波段亮温数据（对应降轨与升轨半圈卫星过境，当地太阳时分别约为清晨6:00与傍晚6:00）同化至采用地球固定全球圆柱等面积可缩放网格2.0版（EASE-Grid 2.0）投影、分辨率为9千米的陆面模式中。