Google Earth Engine——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

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发布于 2024-02-02 12:08:22

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发布于 2024-02-02 12:08:22

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.

This dataset is a filtered version of the GRACE Tellus (GRCTellus) Ocean dataset. The 'EOFR' bottom pressure (OBP) grids are obtained by projecting the data from the regular GRC Ocean grids product onto the Empirical Orthogonal Functions (EOFs) of the Ocean Model for Circulation and Tides (OMCT). This effectively filters out signals in the GRACE data that are inconsistent with the physics and OBP variations in the OMCT ocean model.

The EOFR filtered reconstructed OBP fields agree better with radar altimetric sea surface height, reduce leakage around ice sheets and glaciers, and reduce noise in the mid latitudes where OBP variability is lower. (Chambers and Willis, 2010)

Note

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.

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。更多细节见提供者的月度质量网格概述。

该数据集是GRACE Tellus（GRCTellus）海洋数据集的过滤版本。EOFR "底压（OBP）网格是通过将常规GRC海洋网格产品的数据投射到海洋环流和潮汐模型（OMCT）的经验正交函数（EOFs）上获得的。这有效地过滤了GRACE数据中与OMCT海洋模型中的物理学和OBP变化不一致的信号。

EOFR过滤后重建的OBP场与雷达测高的海面高度更加一致，减少了冰原和冰川周围的泄漏，并减少了OBP变化较小的中纬度地区的噪声。(Chambers and Willis, 2010)

注

GRCTellus海洋数据集被优化为检查区域海洋底层压力，但不打算在空间上平均化以确定全球平均海洋质量。

Dataset Availability

2002-12-31T00:00:00 - 2017-01-05T00:00:00

Dataset Provider

NASA Jet Propulsion Laboratory

Collection Snippet

ee.ImageCollection("NASA/GRACE/MASS_GRIDS/OCEAN_EOFR")

Resolution

111320 meters

Bands Table

Name	Description	Min*	Max*	Units
lwe_thickness_csr	Equivalent liquid water thickness in centimeters calculated by CSR.	-18.46	12.29	cm
lwe_thickness_gfz	Equivalent liquid water thickness in centimeters calculated by GFZ.	-15.37	14.56	cm
lwe_thickness_jpl	Equivalent liquid water thickness in centimeters calculated by JPL.	-16.59	11.7	cm

* = Values are estimated

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.

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');