一直有粉丝询问我数据下载的问题，这里我将汇总三大GRACE Mascon数据的下载链接，以及基础的数据处理方法。

(资料图)

首先，GRACE Mascon数据包含有三大机构，分别是CSR、JPL和GSFC（注意不是GFZ）。

1.CSR mascon

下载网址：https://www2.csr.utexas.edu/grace/RL06_mascons.html

数据的基本信息：①The solutions with all the appropriate corrections applied (GAD, GIA, C20, C30, degree1, etc) in equi-angular grids.【前期数据预处理已经完成】

②The mass anomaly grids in CSR RL06 v02 mascons for the GRACE/GRACE-FO time variable gravity are represented on the ellipsoidal earth of semi-major axis of 6378.1363 km

③已经完成的预处理：C20 replacement ，C30 replacement ，Degree 1 Corrections，GIA Correction ，GAD Correction

④Please note that all the grids provided (including the corrected grids) are anomalies relative to 2004.0000 - 2009.999 mean baseline. If any user decides to undo any correction and apply their own corrections, they should compute the anomaliesrelative to the same mean baselinefor their corrections before applying their corrections.

⑤No additional smoothing or empirical de-striping or filtering applied to this data. The users should not apply any additional filtering or scaling factors to these solutions. These global solutions are not tailored towards a particular application and hence the solution set is applicable to all science areas of interest ie., oceanography, land surface hydrology, cryosphere, etc.

2.JPL Mascon

下载网址：https://grace.jpl.nasa.gov/data/get-data/jpl_global_mascons/

数据的基本信息：①基于Level-1 GRACE/GRACE-FO observations数据解算

②进行了一阶项补充、二阶项替换、GIA改正【ICE6G-D model from Peltier et al. (2017)】

③No additional empirical destriping filter has been applied to the data. This results in better S/N ratios of the mascon fields compared to the conventional spherical-harmonic solutions.【未进行前期的滤波处理，采用先验的质量划分，得到比GRACE球谐数据更高的信噪比】

④All reported data are anomalies relative to the 2004.0-2009.999 time-mean baseline. Note that this baseline needs to be consistent when comparing GRACE/GRACE-FO data to other anomaly data (e.g., groundwater or sea level). 

⑤Note that the land-grid-scaling (described below) has notyetbeen applied to the GRACE/GRACE-FO data fields; users must apply these optional gain factors. 【需要进行尺度因子恢复原始信号】

⑥Please note: the gain factors can be used for hydrology-related signals, but should not be used for mountain glaciers or ice sheets【不用于山地冰川冰盖的质量信号恢复，as these components are not in the CLM data that is underlying（水文模型的低估） the gain factors】，尺度因子计算：g'(x,y,t) = g(x,y,t) * s(x,y)

3.GSFC Mascon

下载网址：https://earth.gsfc.nasa.gov/geo/data/grace-mascons

数据基本信息：①GSFC.glb.200204_202211_RL06v2.0_OBP-ICE6GD，Global mascon solution where the GAD product has been restored, meaning the ocean mascons describe ocean bottom pressure (OBP). This product is comparable to the JPL and CSR mascon products.

②GSFC.glb.200204_202211_RL06v2.0_OBP-ICE6GD_HALFDEGREE.nc，Global mascon solution where the GAD product has been restored, meaning the ocean mascons describe ocean bottom pressure (OBP). This product is comparable to the JPL and CSR mascon products. The 1-arc-degree equal area values have been placed on an equal angle 0.5x0.5 degree grid. Land values are determined with a least squares estimator that conserves mass over each region, while ocean values have been interpolated/extrapolated.【建议下载这个】

③Mean removed: 2004.0 – 2010.0，与CSR和JPL的时间段一致

④同样进行了一阶项补充、二阶项替换、C30替换、GIA改正

关于读取时间序列，可以去我的CSDN下载一个程序包：https://download.csdn.net/download/weixin_43047707/85401807?spm=1001.2014.3001.5503，里面包含读取格网数据的程序，其对于三大机构的数据都适用

另外，我还发现一个很有用的网站，可以在线分析全球流域的水储量变化【看来用GRACE单纯做流域水储量变化已经做烂了，没意义。。。】

网址：https://ccar.colorado.edu/grace/index.html，如下的界面，可以选择GSFC和JPL的mascon的数据。

选择GSFC数据，进入界面，可以选择大洲和流域，以及全球的趋势。我们这里选择流域

选择长江流域，点击界面，即可以看到长江流域的所有的质量变化时间序列，还可以选择质量变化（Gt）和等效水高变化（cm），同时可以选择导出数据。【但是本人觉得用于计算结果的参考还行，用于论文数据结果欠妥】

下面是全球的质量变化速率图

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