CMAP全球降水观测资料

全球降水的逐月、逐候数据，包括标准版和加强版，空间分辨率为2.5°×2.5°。该数据将雨量计观测数据和卫星降水估计（GPI，OPI, SSM/I scattering，SSM/I emission，MSU）融合在一起。加强版数据还包括了混合的NCEP/NCAR再分析降水数据。月降水资料涉及变量为降水率（mm/d），数值范围基本集中在0～70 mm/d，候降水资料包括了每年73候的数据。与GPCP降水资料比较，存在一些不同（不矛盾）。
需要注意，本数据集的资料源并不连续，如SSM/I（passive microwave-scattering and emission）从1987年6月开始获取。在此之前，仅可获取MSU反演（Spencer，1993）的微波衍生估计（microwave-derived estimates）。这是一种基于排放的模型，因此仅可获取海洋区域的降水。另外，高时间分辨率的对地同步卫星（每3 hr）IR数据在1986年可获取。在此之前，在绕极卫星OLR数据的基础上，OPI（Xie and Arkin, 1997）估计已使用。混合技术（the merging technique）在文献Xie and Arkin（1997）中做了详细描述。
时段 逐月：1979.1—2009.9
逐候：1979.1—2009.9.23
气候月平均：1979—2000平均

This dataset provides monthly and pentad global precipitation data, including Standard Edition and Enhanced Edition, with a spatial resolution of 2.5°×2.5°. This dataset merges in-situ rain gauge observations with satellite precipitation estimates (GPI, OPI, SSM/I scattering, SSM/I emission, MSU). The Enhanced Edition additionally incorporates merged NCEP/NCAR reanalysis precipitation data. Variables included in the monthly precipitation dataset are precipitation rate (mm/d), with values generally ranging from 0 to 70 mm/d. The pentad precipitation data covers 73 pentads per year. There are some non-contradictory differences when compared with GPCP precipitation datasets.

It should be noted that the data sources of this dataset are not continuous. For example, SSM/I (passive microwave-scattering and emission) data is available from June 1987 onwards. Prior to this, only microwave-derived estimates from MSU retrievals (Spencer, 1993) were accessible. This is an emission-based model, so it only retrieves precipitation over oceanic regions. In addition, 3-hourly high-temporal-resolution geostationary satellite IR data was available in 1986. Prior to 1986, the OPI estimation method (Xie and Arkin, 1997) was adopted based on polar-orbiting satellite OLR data. The merging technique is described in detail in Xie and Arkin (1997).

Time periods: Monthly: 1979.1–2009.9; Pentad: 1979.1–2009.9.23; Climatological monthly mean: 1979–2000 average.