NASA Goddard Space Flight Center Geodesy and Geophysics Laboratory

International Mass Loading Service: Land Water Storage Loading

Introduction

The Earth as a whole responses to external forces as an elastic body. Changes of the continental water contents in soil, snow cover, and canopy exerts variable pressure of water that causes crust deformations. These deformations may reach several centimeters. Land water storage loading should be taken into account in a reduction of astronomical and space geodesy observations when the accuracy better than 2 nrad or 1 cm is required.

Service for the land water storage loading

On 2013.06.01 the service of land water storage loading was established. The service provides

Time series of 3D displacements caused by land water storage loading. The time series are provided in three forms:
1. Precomputed time series for 1272 VLBI, GPS, SLR, and DORIS stations.
2. Precomputed time series at a regular 2′ × 2′ global grid.
3. On-demand online pressure loading computation for an arbitrary point at the Earth.
Two time series of displacements are provided. The first variant is computed using land water storage pressure from the numerical weather model MERRA2 (Reichle et al., 2017) that is available from the GMAO (NASA Global Modeling and Assimilation Office). The second variant is computed land water storage pressure from the numerical weather model GEOS-FPIT also developed by the GMAO.

Model Resolution Date range Latency

MERRA2 0.5 ° × 0.625 ° × 1 hour 1979.01.01 — present 20–50 days

GEOS-FPIT 0.5 ° × 0.625 ° × 1 hour 2000.01.01 — present 6–15 hours

Download pre-computed time series

Time series of 3D displacements at a regualr global grid

3D displacements from MERRA2 (Reichle et al., 2017) model at a regular 2′ × 2′ global grid from 19800101_0000 through 20241002_0000 with time step of 3 hours. NB: Diurnal, semi-diurnal, ter-diurnal and four-times-a-day variations are removed. Last modified on [an error occurred while processing this directive] UTC
Displacements in netCDF format to download. File size: 3.5–5.5 Mb per epoch, 14Gb/year (bzip2 compressed).
Auxiliary 3D displacements of the center mass of the total Earth with respect to the center mass of the solid Earth without atmosphere caused by atmospheric pressure loading. The sum of this displacement and the displacement wrt of the total mass, is the displacement with respect to the center of solid Earth, i.e. center of figure.
Displacements in netCDF format to download. File size: 790 Kb per epoch, 2.3Gb/year.

3D displacements from GEOS-FPIT model at a regular 2′ × 2′ global grid from [an error occurred while processing this directive] through [an error occurred while processing this directive] with time step of 3 hours. NB: Diurnal, semi-diurnal, ter-diurnal and four-times-a-day variations are removed. Last modified on [an error occurred while processing this directive] UTC
Displacements in netCDF format to download. File size: 4–6 Mb per epoch, 17.4Gb/year.
Auxiliary 3D displacements of the center mass of the total Earth with respect to the center mass of the solid Earth without atmosphere caused by atmospheric pressure loading. The sum of this displacement and the displacement wrt of the total mass, is the displacement with respect to the center of solid Earth, i.e. center of figure.
Displacements in netCDF format to download. File size: 790 Kb per epoch, 2.3Gb/year.

Pre-computed series of loading displacements for space geodesy sites

3D displacements from MERRA2 model (Reichle et al., 2017) for 1272 space geodesy stations from 19800101_0000 through 20241002_0000 with time step of 3 hours. NB: Diurnal, semi-diurnal, ter-diurnal and fut-times-a-day variations are removed. Last modified on 20241121_0605 UTC
Displacements in EPHEDISP format to download. File size: 227 Kb per epoch, 0.33Gb/year.
Auxiliary 3D displacements of the center mass of the total Earth with respect to the center mass of the solid Earth without atmosphere caused by atmospheric pressure loading. The sum of this displacement and the displacement wrt of the total mass, is the displacement with respect to the center of solid Earth, i.e. center of figure.
Displacements in netCDF format to download. File size: 227 Kb per epoch, 0.33Gb/year.

3D displacements from GEOS-FPIT model for 1272 space geodesy stations from 20000101_0030 through 20241120_1830 with time step of 3 hours. NB: Diurnal, semi-diurnal, ter-diurnal and for-times-a-day variations are removed. Last modified on 20241121_0221 UTC.
Displacements in EPHEDISP format to download. File size: 227 Kb per epoch, 0.66Gb/year.
Auxiliary 3D displacements of the center mass of the total Earth with respect to the center mass of the solid Earth without atmosphere caused by atmospheric pressure loading. The sum of this displacement and the displacement wrt of the total mass, is the displacement with respect to the center of solid Earth, i.e. center of figure.
Displacements in netCDF format to download. File size: 227 Kb per epoch, 0.66Gb/year.

Download pre-computed harmonic variations of displacements

Harmonic variations of 3D displacements at a regular global grid

3D harmonic displacement variations from MERRA2 model at a regular 2′ × 2′ global grid Computed over the range of 37 years [1980.01.01, 2017.02.20] They include displacements at 8 diurnal and semi-diurnal frequencies
Displacements in NetCDF format are available for downloading.
Displacements in HEB format are available for downloading as well.

Auxiliary 3D land water storae displacements of the center mass of the total Earth with respect to the center mass of the solid Earth without land water. The sum of this displacement and the displacement wrt of the total mass, is the displacement with respect to the center of solid Earth, i.e. center of figure.
Displacements in NetCDF format are available for downloading.
Displacements in HEB format are available for downloading as well.

3D harmonic displacement variations from GEOS-FPIT model at a regular 2′ × 2′ global grid. Computed over the range of 17 years [2000.01.01, 2017.02.20] They include displacements at 18 diurnal, semi-diurnal, ter-diurnal, and four-times-a-day frequencies.
Displacements in NetCDF format are available for downloading.
Displacements in HEB format are available for downloading as well.

Auxiliary 3D land water storae displacements of the center mass of the total Earth with respect to the center mass of the solid Earth without land water. The sum of this displacement and the displacement wrt of the total mass, is the displacement with respect to the center of solid Earth, i.e. center of figure.
Displacements in NetCDF format are available for downloading.
Displacements in HEB format are available for downloading as well.

Pre-computed harmonic variations of loading displacements for space geodesy sites

3D harmonic displacement variations from MERRA2 model for 1272 space geodesy sites. The variations were computed over the range of 36 years [1979.09.01, 2015.01.01]. They include displacements at 8 diurnal and semi-diurnal frequencies.
Displacements in format are available for downloading.

Auxiliary 3D land water storae displacements of the center mass of the total Earth with respect to the center mass of the solid Earth without land water. The sum of this displacement and the displacement wrt of the total mass, is the displacement with respect to the center of solid Earth, i.e. center of figure.
Displacements in NetCDF format are available for downloading.

3D harmonic displacement variations from GEOS-FPIT model for 1272 space geodesy sites. The variations were computed over the range of 18 months [2000.01.01, 2017.02.20]. They include displacements at 18 diurnal, semi-diurnal, ter-diurnal, and four-times-a-day frequencies.

Auxiliary 3D land water storae displacements of the center mass of the total Earth with respect to the center mass of the solid Earth without land water. The sum of this displacement and the displacement wrt of the total mass, is the displacement with respect to the center of solid Earth, i.e. center of figure. Displacements in format are available for downloading.

Compute time series of land water storage loading on-demand

You can order computation of the time series for the stations of your interest. You need to prepare a station file in plain ascii that has four columns separated by one or more blanks:

Station_name X-coordinate Y-coordinate Z-coordinate

Station name should have no more than 8 characters. X,Y,Z are carthesian coordinates of the station of interest in a crust-fixed coordinates system. Units are meters. Here is an example.

Model:

MERRA2	from 19800101_0000 through 20241002_0000
GEOSFPIT	from 20000101_0030 through 20241120_1830

Mode:

Time series

harmonics coefficients

Frame:

Center of mass

Center of figure

Start date:

Format: YYYY.MM.DD_hh:mm:ss

Stop date:

Format: YYYY.MM.DD_hh:mm:ss

Station file:

E-mail address:

Optional

Results of on-demand computations are accessible from here.

Acknowledgment

This work was supported by NASA Earth Surface & Interior program, grant NNX12AQ29G.

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Last update: 2023.08.31_18:58:02

Model	Resolution	Date range	Latency
MERRA2	0.5 ° × 0.625 ° × 1 hour	1979.01.01 — present	20–50 days
GEOS-FPIT	0.5 ° × 0.625 ° × 1 hour	2000.01.01 — present	6–15 hours