y Plot GRACE time-series z
Plot GRACE statistics Statistics Solutions Plot images of GRACE solutions
Hide data
- Select your gravity data
- Choose your geographical area
- Plot time-series
- Export your graph
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About this website
This website allows you to plot time-series of gravity data from the GRACE mission. By monitoring Earth Gravity field's variations, the GRACE mission allows scientists to recover mass transport at the surface of the Earth, such as hydrological cycles, ice-loss and so on. Read more about GRACE...
Examples of use
You can see some examples of use in the left column at the bottom of the page!
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Select your gravity data
Select your data center: CNES/GRGS in Toulouse, France, GFZ in Potsdam, Germany, AIUB in Bern, Switzerland, TUGRAZ in Graz, Austria, CSR in Austin, Texas, JPL in Pasadena, California, TONGJI in Shanghai and HUST in Wuhan, China. Choose your release number and get ready for data analysis! Read more about the data...
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Choose your geographical area
Drag and drop the marker on any point you like. Alternatively, enter its latitude and longitude, or its address! Draw rectangles, triangles and polygons to plot average signal over custom-designed areas, or predefined hydrological basins! Display a background gravity map to see the areas of interest. More info...
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Plot and export your graph!
Plot your graph. Compare series. Zoom in by drawing a rectangle on the graph. Edit the titles. Export your graph in png, jpg or pdf, and reuse it for your scientific presentations!
New features!
You can now save and share your work with a simple link! Use the share icon below. You can also plot individual images of GRACE solutions, as well as various statistics. Click on the "Solutions" or "Statistics" arrows below!
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About the GRACE Mission
Gravity Recovery And Climate Experiment (GRACE) is a joint mission between NASA and DLR (German Space Agency), which was launched in 2002, and is still in orbit as of December 2013. GRACE is made of a pair of satellites, following each other on a polar orbit (89°), at an altitude of approximately 500 km and a distance of 220 km. The main instrument is the K-Band Ranging system, an electromagnetic link in the K/Ka band, which allows to measure the distance variations between both satellites with a precision of the micron level (a tenth of a human hair!).
The KBR instrument, with all other onboard systems, allows to detect variations of Earth's gravity field and thus the movements of mass at the Earth's surface, such as hydrological cycle, ice-loss, earthquakes. By monitoring Earth's gravity field, GRACE is a very unique tool for global climate measurement.
More detailed information about the GRACE mission can be found at the following official links: NASA, CSR, JPL, DLR, GFZ.
Examples
Click on the links to see interesting examples of using the GRACE Plotter:
Sumatra Earthquake: the tsunami of 2005, seen by gravity.
Iceland: geographical extraction, trend, and ice melt.
Predefined hydrological basins: Amazon and Congo.
Spherical harmonics: plot the time series of coefficients.
Periodic regression: adjustement of annual and semiannual signals.
Data centers
Several groups are producing gravity field models from the GRACE data. On this website you will find time series from the following groups:
CNES/GRGS: French National Space Center / Research Group for Space Geodesy, in Toulouse, France. Current release: RL03-v3.
AIUB: Astronomical Institute at the University of Bern, in Switzerland. Current release: RL02.
CSR: Center for Space Research in Austin, Texas. Current release: RL05.
GFZ: German Research Center for Geosciences in Potsdam, Germany. Current release: RL05a.
HUST: Huazhong University of Science Technology, Wuhan, China. Current release: HUST16.
JPL: Jet Propulsion Laboratory, in Pasadena, California. Current release: RL05.
TONGJI: Tongji University, Shanghai, China. Current release: RL02.
TUGRAZ: Technical University of Graz in Austria. Current release: ITSG-2016. -
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Data information
Latest update: February 6th, 2018.
The time series are obtained from the spherical harmonics coefficients provided by the datacenters, and downloaded from the ICGEM.
For equivalent water heights and geoid heights, the mean of the series is removed, and the coefficients are then converted into 1°x1° equivalent water heights grids or geoid grids in order to plot time-series.
Grid conversion
Except for CNES/GRGS, the conversion to grids takes into account spherical harmonic coefficients from degree 2 to degree 90, with C20 replaced by the official TN-07 C20 SLR time-series. For CNES/GRGS, grids takes into account coefficients from degree 2 to 80, without C20 replacement since CNES/GRGS solutions already contain SLR data (Lageos 1&2 / Starlette / Stella up to degree 30). Grid values are computed at the center of pixels, i.e. (89.5°,-179.5°) for the top-left grid point and (-89.5°,179.5°) for the bottom-right.
Background maps
GRACE gravity maps (trend, annual and semiannual amplitude of equivalent water heights) are obtained through a regression on the global series of harmonic coefficients. DDK5 filtered coefficients are used (except for CNES).
Filtering
CNES/GRGS solutions are ready to use and do not need any filtering. For other groups, unfiltered and DDK5 filtered solutions are available (see Kusche et al, 2009 for filtering info).
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Algorithms
Geographical extraction
Single point extraction: barycentric computation from the values at the 4 surrounding grid points. Rectangles and polygons: average over grid points situated inside the contour. Basins: average over grid points from mask file (press "Show data" button for mask info). In every case, grid values are weighted by cos(latitude), in order to obtain per surface unit values (cm/m²).
Note about Google Maps Projection
Google Maps use Mercator Projection, which means that the poles are at the infinity upwards and downwards. Google cuts the map view at around +/- 85.01 degrees. However, one can still enter manually coordinates of points between 85 degrees and 89.5 degrees (+/-) in the form for data extraction.
Regressions
Analytic models are adjusted on time series through a least squares process. The so-called "Periodic model" includes a linear component, an annual component and a semiannual component. The "Advanced model" has a polynomial component instead of linear, and polynomial-modulated annual and semiannual components. In both case, components can be displayed using "Periodic+" and "Advanced+". -
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Credits
The GRACE Plotter, by CNES/GRGS, version 3.7.1.
Concept and developement by Géode & Cie.
This website is an extension of the CNES/GRGS website. See legal notice (in French).
This project has received funding from CNES and the European Union.
Data produced by CNES/GRGS, AIUB, CSR, GFZ, HUST, JPL, TONGJI, TUGRAZ. DDK filtering applied by ICGEM.
Highcharts used under single website License.
jQuery used under MIT License.
All fonts used under SIL OFL License.
Horizon 2020
This project has received funding from the European Union's Horizon 2020 Research and Innovation Programme, under Grant Agreement No. 637010, European Gravity Service for Improved Emergency Management, EGSIEM.
Tips and tricks
Click on the legend of the series to activate/deactivate the series on the graph!
Regressions: use periodic+ and advanced+ to show the components of the adjusted model!
Use bias and scale if you wish to visualize different quantities on the same graph (equivalent water heights and geoid heights).
Save and share your work with a single click! No need to setup an account or mess around with passwords anymore. Just click on the "Share" button, that's it!
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