GRACE Tellus Monthly Mass Grids provides monthly gravitational anomalies relative to a 2004-2010 time-mean baseline. The data contained in this dataset are units of "Equivalent Water Thickness" which represent the deviations of mass in terms of vertical extent of water in centimeters. See the provider's Monthly Mass Grids Overview for more details.
The GRACE Tellus (GRCTellus) Monthly Mass Grids Ocean dataset is produced by three centers: CSR (U. Texas / Center for Space Research), GFZ (GeoForschungsZentrum Potsdam), and JPL (NASA Jet Propulsion Laboratory). Each center is a part of the GRACE Ground System and generates Level-2 data (spherical harmonic fields) used in this dataset. The output includes spherical harmonic coefficients of the gravity field and of the dealiasing fields used to compute them. Since each center independently produces the coefficients, the results may be slightly different. It is recommended for most users to use the mean of all three datasets. See the provider's choosing a solution page for more details.
Note
- Land leakage correction: Ocean signals are typically weaker than land signals, by factors of 2 and more, on seasonal and interannual time scales. To minimize leakage from high land signals onto ocean signals, a destriping filter has been applied which may cause cause correlations over much larger distances.
- The GRCTellus Ocean datasets are optimized to examine regional ocean bottom pressure, but NOT intended to be spatially averaged to determine global mean ocean mass.
- A filtered version of the GRCTellus Ocean dataset is also available which uses an alternative filtering method which may reduce leakage errors, and have results which agree better with altimetric sea surface height. NASA/GRACE/MASS_GRIDS/OCEAN_EOFR.
GRACE Tellus月度质量网格提供了相对于2004-2010年时间平均基线的月度引力异常值。该数据集所包含的数据是以 "等水厚度 "为单位，以厘米为单位表示水的垂直范围的质量偏差。更多细节请参见提供者的月度质量网格概述。
GRACE Tellus（GRCTellus）月度质量网格海洋数据集由三个中心制作。CSR（德克萨斯大学/空间研究中心）、GFZ（波茨坦地质研究中心）和JPL（美国航空航天局喷气推进实验室）。每个中心都是GRACE地面系统的一部分，并产生本数据集所使用的二级数据（球面谐波场）。输出包括重力场和用于计算它们的纠偏场的球面谐波系数。由于每个中心独立产生系数，结果可能略有不同。对大多数用户来说，建议使用所有三个数据集的平均值。更多的细节请见供应商的选择解决方案页面。
备注
陆地泄漏校正。在季节性和年际时间尺度上，海洋信号通常比陆地信号弱2倍甚至更多。为了最大限度地减少陆地信号对海洋信号的泄漏，我们应用了一个去带滤波器，这可能会导致更远距离的相关性。
GRCTellus海洋数据集被优化为检查区域性海洋底层压力，但不打算在空间上平均化以确定全球平均海洋质量。
GRCTellus海洋数据集的过滤版本也是可用的，它采用了另一种过滤方法，可以减少泄漏误差，其结果与测高海面高度更一致。nasa/grace/mass_grids/ocean_eofr.
Dataset Availability
2002-07-31T00:00:00 - 2017-01-05T00:00:00
Dataset Provider
NASA Jet Propulsion Laboratory
Collection Snippet
ee.ImageCollection("NASA/GRACE/MASS_GRIDS/OCEAN")
Resolution
111320 meters
Bands Table
Name | Description | Min* | Max* | Units |
lwe_thickness_csr | Equivalent liquid water thickness in centimeters calculated by CSR. | -27 | 36.81 | cm |
lwe_thickness_gfz | Equivalent liquid water thickness in centimeters calculated by GFZ. | -28.87 | 33.02 | cm |
lwe_thickness_jpl | Equivalent liquid water thickness in centimeters calculated by JPL. | -26.03 | 37.36 | cm |
* = Values are estimated
代码：
var dataset = ee.ImageCollection('NASA/GRACE/MASS_GRIDS/OCEAN')
.filter(ee.Filter.date('2016-08-01', '2016-08-30'));
var equivalentWaterThicknessCsr = dataset.select('lwe_thickness_csr');
var equivalentWaterThicknessCsrVis = {
min: -10.0,
max: 10.0,
};
Map.setCenter(6.746, 46.529, 1);
Map.addLayer(
equivalentWaterThicknessCsr, equivalentWaterThicknessCsrVis,
'Equivalent Water Thickness CSR');
数据属性：
Name | Type | Description |
CSR_END_TIME | Double | End date in milliseconds of spherical harmonics solution from CSR. |
CSR_START_TIME | Double | Start date in milliseconds of spherical harmonics solution from CSR. |
GFZ_END_TIME | Double | End date in milliseconds of spherical harmonics solution from GFZ. |
GFZ_START_TIME | Double | Start date in milliseconds of spherical harmonics solution from GFZ. |
JPL_END_TIME | Double | End date in milliseconds of spherical harmonics solution from JPL. |
JPL_START_TIME | Double | Start date in milliseconds of spherical harmonics solution from JPL. |
引用：
D.P. Chambers. 2012. GRACE MONTHLY OCEAN MASS GRIDS NETCDF RELEASE 5.0. Ver. 5.0. PO.DAAC, CA, USA. Dataset accessed [YYYY-MM-DD] at https://doi.org/10.5067/TEOCN-0N005.
Chambers, D.P. and J.A. Bonin: Evaluation of Release 05 time-variable gravity coefficients over the ocean. Ocean Science 8, 859-868, 2012. OS - Evaluation of Release-05 GRACE time-variable gravity coefficients over the ocean.
Chambers D.P. and J. K. Willis: A Global Evaluation of Ocean Bottom Pressure from GRACE, OMCT, and Steric-Corrected Altimetry. J. of Oceanic and Atmosph. Technology, vol 27, pp 1395-1402. doi:10.1175/2010JTECHO738.1, 2010.
