ESA Soil Moisture Climate Change Initiative (Soil_Moisture_cci): Version 03.3 data collection

Soil Moisture data (version 03.3) from the European Space Agency's (ESA) Soil Moisture Climate Change Initiative (CCI) project. This dataset collection contains three surface soil moisture datasets, alongside ancilliary data products. The 'Active' and 'Passive' products have been created by fusing scatterometer and radiometer soil moisture products respectively. In the case of the 'Active' product, these have been derived from AMI-WS and ASCAT satellite instruments and for the 'Passive' product from the instruments SMMR, SSM/I, TMI, AMSR-E, WindSat, AMSR2 and SMOS. The 'Combined Product' is then a blended product based on the former two data sets.

The homogenized and merged products present a global coverage of surface soil moisture at a spatial resolution of 0.25 degrees. The products are provided as global daily images, in NetCDF-4 classic file format, the Passive and Combined products covering the period (yyyy-mm-dd) 1978-11-01 to 2016-12-31 and the Active product covering 1991-08-05 to 2016-12-31. The soil moisture data for the Passive and the Combined product are provided in volumetric units [m3 m-3], while the active soil moisture data are expressed in percent of saturation [%]. For information regarding the theoretical and algorithmic base of the datasets, please see the Algorithm Theoretical Baseline Document (ATBD). Other additional documentation and information documentation relating to the datasets can also be found on the CCI Soil Moisture project web site or in the Product Specification Document.

The data set should be cited using all three of the following references:

1. Dorigo, W.A., Wagner, W., Albergel, C., Albrecht, F., Balsamo, G., Brocca, L., Chung, D., Ertl, M., Forkel, M., Gruber, A., Haas, E., Hamer, D. P. Hirschi, M., Ikonen, J., De Jeu, R. Kidd, R. Lahoz, W., Liu, Y.Y., Miralles, D., Lecomte, P. (2017). ESA CCI Soil Moisture for improved Earth system understanding: State-of-the art and future directions. In Remote Sensing of Environment, 2017, ISSN 0034-4257, https://doi.org/10.1016/j.rse.2017.07.001

2. Gruber, A., Dorigo, W. A., Crow, W., Wagner W. (2017). Triple Collocation-Based Merging of Satellite Soil Moisture Retrievals. IEEE Transactions on Geoscience and Remote Sensing. PP. 1-13. 10.1109/TGRS.2017.2734070

3. Liu, Y.Y., Dorigo, W.A., Parinussa, R.M., de Jeu, R.A.M. , Wagner, W., McCabe, M.F., Evans, J.P., van Dijk, A.I.J.M. (2012). Trend-preserving blending of passive and active microwave soil moisture retrievals, Remote Sensing of Environment, 123, 280-297, doi: 10.1016/j.rse.2012.03.014

欧洲空间局（European Space Agency, ESA）土壤湿度气候变化倡议（Soil Moisture Climate Change Initiative, CCI）项目产出的土壤湿度数据集（版本03.3）。
该数据集集合包含三套地表土壤湿度数据集，同时附带辅助数据产品。'主动型'与'被动型'产品分别通过融合散射计土壤湿度产品与辐射计土壤湿度产品生成。其中主动型产品源自AMI-WS与ASCAT卫星传感器，被动型产品则基于SMMR、SSM/I、TMI、AMSR-E、WindSat、AMSR2及SMOS等卫星传感器生成。'组合型产品'则是基于前述两类数据集融合得到的混合产品。

经均一化与融合处理的产品实现了全球范围的地表土壤湿度覆盖，空间分辨率为0.25度。上述产品以全球逐日影像的形式提供，采用NetCDF-4经典文件格式；被动型与组合型产品的时间覆盖范围为1978-11-01至2016-12-31（格式为yyyy-mm-dd），主动型产品的覆盖时段为1991-08-05至2016-12-31。被动型与组合型产品的土壤湿度数据以体积单位[m³·m⁻³]提供，主动型土壤湿度数据则以饱和百分比[%]表示。若需了解数据集的理论与算法基础，请参阅算法理论基准文档（Algorithm Theoretical Baseline Document, ATBD）。其他与数据集相关的补充文档及说明资料，可访问CCI土壤湿度项目官网或查阅《产品规格文档》获取。

引用该数据集时需同时使用以下三篇参考文献：
1. Dorigo, W.A.、Wagner, W.、Albergel, C.、Albrecht, F.、Balsamo, G.、Brocca, L.、Chung, D.、Ertl, M.、Forkel, M.、Gruber, A.、Haas, E.、Hamer, D.P.、Hirschi, M.、Ikonen, J.、De Jeu, R.、Kidd, R.、Lahoz, W.、Liu, Y.Y.、Miralles, D.、Lecomte, P.（2017）。用于提升地球系统认知的ESA CCI土壤湿度数据：研究现状与未来方向。《环境遥感》，2017年，ISSN 0034-4257，https://doi.org/10.1016/j.rse.2017.07.001
2. Gruber, A.、Dorigo, W.A.、Crow, W.、Wagner, W.（2017）。基于三重配对法的卫星土壤湿度反演产品融合。《IEEE地球科学与遥感汇刊》，PP.1-13，DOI:10.1109/TGRS.2017.2734070
3. Liu, Y.Y.、Dorigo, W.A.、Parinussa, R.M.、de Jeu, R.A.M.、Wagner, W.、McCabe, M.F.、Evans, J.P.、van Dijk, A.I.J.M.（2012）。保留趋势的主动与被动微波土壤湿度反演产品融合方法。《环境遥感》，123卷，280-297页，DOI:10.1016/j.rse.2012.03.014