CSR Release-06 GRACE Level-2 Data Products
Updated: 2018-04-26

Thank you for your interest in the latest, Release-06 GRACE Level-2 data products. Users looking for our mean (static) Earth gravity field model may visit the GGM05 web page (http://www2.csr.utexas.edu/grace/gravity/); or visit the ICGEM website (http://icgem.gfz-potsdam.de/home) for our latest model GGM05C, as well as a variety of other mean field models.

This page describes the RL06 time-series of monthly time-variable gravity field estimates. The description on this page is presently intended for users already familiar with the nomenclature and use of GRACE Level-2 data products. Viewers not familiar with these may choose to start instead at http://www2.csr.utexas.edu/grace/asdp.html.

As of today (Apr 26, 2018) the CSR RL06 Level-2 data products are available for the span Jan 2003 through Aug 2016. The RL06 products for the 2002 months will be delivered as they are produced within the next few weeks. The RL06 data products for month with single accelerometer data will be produced and released over the next month. The RL06 data products include new GSM, GAC and GAD data products.

Data Access:

As before, users may access all GRACE data products and documents through PO.DAAC (ftp://podaac.jpl.nasa.gov/allData/grace/L2/CSR/RL06/) or through ISDC (http://isdc.gfz-potsdam.de/grace).

Information Content in RL06 GSM Files:

The information content in RL06 GSM files is the same as in the previous (RL05) GSM files. That is, the RL06 GSM files continue to represent the total gravity variability due to land surface hydrology, cryospheric changes, episodic (earthquake) processes, glacial isostatic adjustment (GIA), and corrections to the background models for atmospheric and oceanic processes. The RL06 GSM products can continue to be used in the same way as RL05 GSM products.

Changes to the GSM Filename:

The definition of certain fields in the Level-2 filenames have changed in order to comply with GRACE-FO filename conventions. Please refer to the Level-2 handbook for more details (ftp://podaac-ftp.jpl.nasa.gov/allData/grace/docs/L2-UserHandbook_v3.0.pdf).

A GRACE Level-2 gravity field product is a set of spherical harmonic coefficients of the exterior geopotential. A product name is specified as

PID-2_YYYYDOY-YYYYDOY_dddd_sssss_mmmm_rrvv

Where

PID is 3-character product identification mnemonic -2 denotes a GRACE Level-2 product
YYYYDOY-YYYYDOY specifies the date range (in year and day-of-year format) of the data used in creating this product
dddd specifies the gravity mission
sssss is an institution specific string
mmmm is a 4-character mnemonic used to identify the characteristics of the gravity solution
rrvv is a 2-digit (leading-zero-padded) release number and 2-digit (leading zero-padded) version number

The Product Identifier mnemonic (PID) is made up of one of the following values for each of its 3 characters:

1st Character

= G: Geopotential coefficients

2nd Character

= S: Estimate made from only GRACE data
= C: Combination estimate from GRACE and terrestrial gravity information
= A: Average of any background model over a time period

3rd Character

= M: Estimate of the Static field.
= U: Geopotential estimate relative to the background gravity model
= A: non-tidal atmosphere (see AOD1B Description Doc)
= B: non-tidal Oceans (see AOD1B Description Doc)
= C: combination of non-tidal atmosphere and ocean - for details of combination see AOD1B Description Doc
= D: bottom-pressure over oceans, zero over land – for details of combination, see AOD1B Description Doc

The ‘dddd’ string specifies the gravity mission:

= GRAC:  Gravity Recovery and Climate Experiment

The ‘sssss’ string specifies the institute where the data were processed:

= UTCSR:  The University of Texas at Austin Center for Space Research
= JPLEM:  NASA Jet Propulsion Laboratory
= GFZOP:  GFZ German Research Center for Geosciences

The ‘mmmm’ string is a 4-character mnemonic used to characterize the gravity solution. The first character is used to identify the primary observation type used in the gravity solution (Note: MWI = Microwave Instrument). The second character defines the size of the spherical harmonic expansion in the file. The third and fourth characters are used to represent other characteristics of the gravity solution, including the type of basis function used, whether it is an unconstrained or constrained solution, and the type of windowing function used. For any files that describe the average of a background model (where ‘A’ is the 2nd character in the PID), only the 2nd character in the ‘mmmm’ string is defined/applicable. The 1st, 3rd, and 4th characters are set to be equivalent to the corresponding gravity solution.

1st Character

= A: MWI range data
= B: MWI range-rate data
= C: MWI range-acceleration data

2nd Character

= A: 60 x 60 spherical harmonic expansion
= B: 96 x 96 spherical harmonic expansion
= C: 180 x 180 spherical harmonic expansion
= D: 60 x 30 spherical harmonic expansion

3rd and 4th Characters

= 01: unconstrained spherical harmonic solution with a boxcar windowing function

The ‘rrvv’ string indicates the release (rr) and version (vv) of the solution. The release number is tied to a specific set of background force models, and indicates consistency between solutions across different missions. All quicklook solutions will be given a release number of ‘QL’. The version number indicates the version of the solution under a specific release.

Ancillary Data Products:

For the replacement SLR-derived C20 values, please visit the "Further Details" link below.

Additional regularized RL06 GSM product time-series and RL06 mascon solutions should be available shortly.

Further Details on RL06 Reprocessing

Please revisit these pages for further information.