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2017

September 2017:

  • CSR, GFZ and JPL have generated and delivered RL05 Level-2 products for June 2017 based on 37 days of data between May 23 and June 28 (CSR) and 38 days of data between May 23 and June 29 (GFZ, JPL). The quality of these products is impacted by the facts that

    • No accelerometer data for GRACE-B are available for this month; therefore, the GRACE-A accelerometer data was used as a “transplant” to derive non-gravitational accelerations acting on GRACE-B (see also news from April 2017).
    • The change of the satellites’ pitch angles (see corresponding bullet below).

  • CSR, GFZ and JPL have generated and delivered RL05 Level-2 products for May 2017 based on 21 days of data between May 2 and May 22. As the GRACE-B accelerometer has been switched on again for the period May 2 till May 24, solely original ACC1B data for GRACE-B and no “transplant” ACC1B data from GRACE-A have been used to generate the May 2017 solutions. However, the quality of these products might be impacted by the fact that the satellites’ pitch angles were changed (see corresponding bullet below).
  • CSR, GFZ and JPL have generated and delivered RL05 Level-2 products for April 2017 based on 28 (CSR) and 29 (GFZ, JPL) days of data between April 10 and May 8. The quality of these products is impacted by the facts that

    • No accelerometer data for GRACE-B are available for this month; therefore, the GRACE-A accelerometer data was used as a “transplant” to derive non-gravitational accelerations acting on GRACE-B (see also news from April 2017).
    • The change of the satellites’ pitch angles (see corresponding bullet below).

  • CSR, GFZ and JPL have generated and delivered RL05 Level-2 products for March 2017 based on 29 days of data between March 17 and April 14. The quality of these products is impacted by the facts that

    • No accelerometer data for GRACE-B are available for this month; therefore, the GRACE-A accelerometer data was used as a “transplant” to derive non-gravitational accelerations acting on GRACE-B (see also news from April 2017).
    • The change of the satellites’ pitch angles (see corresponding bullet below).

  • On March 29, 2017, the pitch angles of both spacecraft were set to 0° in order to improve the quality of the transplanted GRACE-B ACC1B product. However, this also lead to higher noise in the KBR1B data and significantly larger K-band range-rate residuals were observed since then. Note that also the quality of the Level-2 products might be additionally degraded due to this fact.
  • No RL05 Level-2 products could be generated and delivered for February 2017 due to insufficient amount of Level-1B data.
  • GFZ has generated and delivered RL05 Level-2 products for January 2017 based on 27 days of data between January 7 and February 2. CSR and JPL have generated and delivered RL05 Level-2 products for January 2017 based on 28 days of data between January 7 and February 3. The quality of these products is impacted by the fact that no accelerometer data for GRACE-B are available for this month; therefore, the GRACE-A accelerometer data was used as a “transplant” to derive non-gravitational accelerations acting on GRACE-B (see also news from April 2017).

April 2017:

  • CSR, GFZ and JPL have generated and delivered RL05 Level-2 products for December 2017 based on 27 days of data between December 11 and January 6. The quality of these products is impacted by the fact that no accelerometer data for GRACE-B are available for this month (see bullets below).
  • CSR, GFZ and JPL have generated and delivered RL05 Level-2 products for November 2017. The CSR products are based on 28 days of data between November 13 and December 10, the GFZ products are based on 21 days of data between November 14 and December 9 (without November 21, November 22, November 23, November 24, and November 25) and the JPL products are based on 23 days of data from November 14 till December 10 (without November 30, December 1, December 2, and December 3). The quality of these products is impacted by the fact that no accelerometer data for GRACE-B are available for this month (see bullets below).
  • Level-2 products for the mission period after November 2016 are generated using synthetic GRACE-B ACC1B R3 data (see bullet below) and other routine mission data. We believe that users whose analysis domain is smaller than 750 km radius will see considerably more noise than they would have in the mid-mission data (up to 2010); and noticeably more noise than they would have through the years 2015 and 2016. At spatial scales longer than 750 km, the products since November 2016 are slightly degraded relative to the Level-2 products from earlier in 2016. The Level-3 mascon or gridded data products derived from the project Level-2 gravity field models may be more suited for use at smaller spatial scales.
  • Since October 2016, the GRACE-B accelerometer is powered off due to battery limitations within the spacecraft. However, all other science measurements are periodically available - starting from November 2016 - for both spacecraft, resulting in the need to synthesize GRACE-B accelerometer data to allow gravity recovery analysis during this period. Synthetic measurements for GRACE-B accelerometer have been created using the GRACE-A accelerometer measurements, after appropriately accounting for a variable separation between the two satellites, and the small differences in the orientation of the two spacecraft relative to each other. This synthetic ACC measurement is labeled GRACE-B ACC1B R3 dataset, and is delivered together with the other Level-1B datasets (at ISDC: subdirectory ‘Level-1B/JPL/INSTRUMENT/RLR3/’). Older News

December 2016:

  • No RL05 Level-2 products could be generated and delivered for October 2016 due to insufficient amount of Level-1B data.
  • No RL05 Level-2 products could be generated and delivered for September 2016 due to planned switch-offs of the GRACE-A and GRACE-B Microwave Assemblies (MWA) and Instrument Control Units (ICU) on September 3 in order to reduce the load on the batteries.
  • Note that the RL05 Level-2 products for August 2016 generated and delivered by CSR, GFZ and JPL are based on 27 days of data between August 8 and September 3. The quality of these fields is reduced above approximately degree and order 25 compared to previous monthly solutions. The reasons are still under investigation by the SD

June 2016:

  • No RL05 Level-2 products could be generated and delivered for April 2016 due to planned switch-offs of the GRACE-A and GRACE-B Microwave Assemblies (MWA) and Instrument Control Units (ICU) in order to reduce the load on the batteries.
  • Due to a processing bug, the originally published GFZ Level-2 GSM product for February 2016 (labelled ‘GSM-2_2016029-2016060_0032_EIGEN_G---_005a‘) turned out to be erroneous. A correct product has been generated which has replaced the previous wrong one in the GRACE archives ISDC and PO.DAAC. Please make sure that you use the correct version of the GSM product for February 2016. This can be checked by looking at the product generation date (to be found in the record ‘FIRST’ of the Level-2 product file) which should be ‘20160615’. Note that only the GSM files (*.gz and *.txt) are affected; the corresponding GAx products remain unchanged.

May 2016:

  • Note that the RL05 Level-2 products for February 2016 generated and delivered by CSR, GFZ and JPL are based on 32 days of data between January 29 and February 29.

March 2016:

  • Note that the RL05 Level-2 products for January 2016 generated and delivered by CSR, GFZ and JPL are based on 25 days of data between January 4 and January 28.

February 2016:

  • Note that the RL05 Level-2 products for December 2015 generated and delivered by CSR, GFZ and JPL are based on 24 days of data between December 11 and January 3.

January 2016:

  • No RL05 Level-2 products could be generated and delivered for November 2015 due to planned switch-offs of the GRACE-A and GRACE-B Microwave Assemblies (MWA) and Instrument Control Units (ICU) in order to reduce the load on the batteries.

December 2015:

  • No RL05 Level-2 products could be generated and delivered for October 2015 due to planned switch-offs of the GRACE-A and GRACE-B Microwave Assemblies (MWA) and Instrument Control Units (ICU) in order to reduce the load on the batteries.
  • GFZ has generated a new Level-2 correction product 'GAG' which accounts for changes in ECMWF data in May 2015. As already done for GAE and GAF, the GAG product is provided as a GRACE Technical Note (TN-10_GAG-2_2015132-2099001_0000_EIGEN_G---_0005). As a consequence of having a GAG product now, the filename of the GAF product (defined by the period where GAF should be applied) also needed to be changed (now TN-09_GAF-2_2010032-2015131_0000_EIGEN_G---_0005). Additionally, the AOD1B Product Description Document has been updated to include the GAG product (Version 4.4). All files are available in the GRACE archives at GFZ and JPL.

October 2015:

  • GFZ has generated full variance-covariance matrices for the whole RL05a time series. These so-called CSM-products are provided to users on request. For more information, please read the 'Release Notes for GFZ GRACE Level-2 Products - version RL05' which are available in the GRACE archives at GFZ and JPL.

August 2015:

  • No RL05 Level-2 products could be generated and delivered for June 2015 due to planned switch-offs of the GRACE-A and GRACE-B Microwave Assemblies (MWA) and Instrument Control Units (ICU) in order to reduce the load on the batteries.

July 2015:

  • No RL05 Level-2 products could be generated and delivered for May 2015 due to planned switch-offs of the GRACE-A and GRACE-B Microwave Assemblies (MWA) and Instrument Control Units (ICU) in order to reduce the load on the batteries.
  • The new ECMWF IFS (Integrated Forecast System) cycle 41r1, introduced on 11 May 2015, does not affect dramatically the quality of the AOD1B RL05 products. However, as in January 2006 and January 2010, again jumps at locations with high elevations have been detected since the orography resolution in the new cycle has been increased. In contrast to earlier reported plans to correct these jumps already during AOD1B generation, GFZ has decided to stay with the old procedure within RL05 (a-posteriori correction with Level-2 products) and will modify this approach starting with RL06 which is planned for autumn next year. Therefore GFZ will provide shortly a Level-2 GAG product (similar to GAE and GAF, as described in the current AOD1B Product Description Document V4.3 (will be updated accordingly)) to allow land users to correct this jump a-posteriori.

June 2015:

  • A 2-days orbit repeat cycle caused problems to calculate nominal Level-2 products for March 2015 (see also GRACE ground track plots available at http://www.gfz-potsdam.de/en/grace). The SDS has worked on solution stabilization strategies resulting in the products as described in the following.

  • CSR has generated and delivered following RL05 Level-2 products for March 2015 (please refer to the corresponding notes on the CSR website and to the CSR L2 Release Notes):A standard 60x60 solution where more aggressive than normal post-processing may be required.

    • Additionally, a deviant 60x30 product for experimental use is provided too.
    • No 96x96 solution will be generated and delivered.

  • GFZ has generated and delivered following RL05a Level-2 products for March 2015 (see also GFZ L2 Release Notes):

    • A standard 90x90 solution where more aggressive than normal post-processing may be required.
    • Additionally, a deviant 90x30 product for experimental use is provided too.

  • JPL has generated and delivered following RL05.1 Level-2 products for March 2015 (see also JPL L2 Release Notes):

    • A standard 60x60 solution where more aggressive than normal post-processing may be required.
    • Additionally, a deviant 60x30 product for experimental use is provided too.

  • JPL has additionally generated and delivered deviant 60x30 RL05.1 Level-2 products for January and February 2015 for experimental use.

May 2015:

  • A 2-days orbit repeat cycle caused problems to calculate nominal Level-2 products for February 2015. This problem has and will also affect the January and March 2015 solutions. The SDS has worked on solution stabilization strategies resulting in the products as described in the following.

  • CSR has generated and delivered following RL05 Level-2 products for February 2015 (please refer to the corresponding notes on the CSR website and to the CSR L2 Release Notes):

    • A standard 60x60 solution where more aggressive than normal post-processing may be required.
    • Additionally, a deviant 60x30 product for experimental use is provided too.
    • No 96x96 solution will be generated and delivered.

  • GFZ has generated and delivered following RL05a Level-2 products for February 2015 (see also GFZ L2 Release Notes):

    • A regularized 90x90 solution where more aggressive than normal post-processing may be required.
    • Additionally, a deviant 90x30 product for experimental use is provided too.

  • JPL has generated and delivered following RL05.1 Level-2 products for February 2015 (see also JPL L2 Release Notes):

    • A standard 60x60 solution where more aggressive than normal post-processing may be required.

April 2015:

  • A 2-days orbit repeat cycle caused problems to calculate nominal Level-2 products for January 2015. This month also suffers from late switch on of GRACE-A and GRACE-B MWAs on 2015-01-13 resulting in only 19 days of useful Level-1B data.
  • The orbit repeat problem will also affect the February and March 2015 solutions. The SDS has worked on solution stabilization strategies resulting in the products as described in the following.

  • CSR has generated and delivered following RL05 Level-2 products for January 2015 (please refer to the corresponding notes on the CSR website and to the CSR L2 Release Notes):

    • A standard 60x60 solution where more aggressive than normal post-processing may be required.
    • Additionally, a deviant 60x30 product for experimental use is provided too.
    • No 96x96 solution will be generated and delivered.

  • GFZ has generated and delivered following RL05a Level-2 products for January 2015 (see also GFZ L2 Release Notes):

    • A regularized 90x90 solution where more aggressive than normal post-processing may be required.
    • Additionally, a deviant 90x30 product for experimental use is provided too.

  • JPL has generated and delivered following RL05.1 Level-2 products for January 2015 (see also JPL L2 Release Notes):

    • A standard 60x60 solution where more aggressive than normal post-processing may be required.

March 2015:

  • GFZ has generated and delivered AOD1B RL05 products for 1979-2000 based on ERA-interim data.

February 2015:

  • No RL05 Level-2 products could be generated and delivered for December 2014 due to planned switch-offs of the GRACE-A and GRACE-B Microwave Assemblies (MWA) and Instrument Control Units (ICU) in order to reduce the load on the batteries.

November 2014:

  • JPL has generated and delivered RL05.1 Level-2 products for the period April 2002 till August 2014. The main differences between RL05.1 and RL05 are the changes to the IERS2010 reference system and use of the 100x100 S1&S2 air tides from Ray/Ponte (2003). RL05.1 also includes the reprocessed AOD RL05 from June 2013 till July 2014 (see below). Further information will be provided in the JPL Level-2 Release Notes and the JPL Level-2 Processing Standards Document.
  • Due to an error in the handling of the input datasets (see news entry from October 2014), the AOD1B de-aliasing fields for the period from June 26, 2013 through July 31, 2014 had to be reprocessed and have been updated in the archives. The nature of the AOD1B error and their impact on GRACE Level-2 gravity fields are detailed at the GFZ AOD1B product website (http://www.gfz-potsdam.de/aod1b) and also in the GSTM2014 presentations of session A.0 (available at http://www.gfz-potsdam.de/grace/gstm/gstm-2014).
  • As a consequence all of the Level-2 data for this duration has been re-processed and the Level-2 fields for the months from June 2013 through July 2014 have been replaced at the PODAAC/ISDC archives. If you downloaded the CSR RL05 Level-2 products GSM, GAC and GAD files for June 2013 through July 2014 solutions prior to October 6, 2014, please download those files again from the GRACE archives. The corresponding reprocessed GFZ products can be recognized by a product generation date ‘20140917’ or later (the date can be found in the record ‘FIRST’ of Level-2 product files). JPL has reprocessed the complete time series April 2002 till August 2014 as RL05.1 (see above).

October 2014:

  • No RL05 Level-2 products could be generated and delivered for July 2014 due to planned switch-offs of the GRACE-A and GRACE-B Microwave Assemblies (MWA) and Instrument Control Units (ICU) in order to reduce the load on the batteries.
  • The AOD1B RL05 products since 25 June 2013 have been reprocessed and replaced in the GRACE archives. On that day the vertical resolution of the ECMWF deterministic forecast model increased from 91 to 137 levels. Wind stress calculation for OMCT atmospheric forcing requires both temperature and humidity from the lowest model level, which is now 137. Specific humidity has been updated correctly, but temperature remained at 91, leading to a cold bias in the boundary layer and therefore a positive bias in the wind stress. Initial investigations have shown that the effect on gravity field modeling is severe and therefore also all Level-2 products since June 2013 have to be reprocessed (already done for CSR and GFZ). More details will be given in the GSTM2014 SDS Status Session and will be published on the website http://www.gfz-potsdam.de/aod1b.

August 2014:

  • The RL02 Level-1B data for several days have been redelivered to the GRACE archives at GFZ and JPL. The reasons for redelivery of these days are:

    • Day was skipped due to amount of work accommodating spacecraft anomalies
    • Day was missing telemetry data due to raw telemetry file corruption
    • Improved missed interrupt detection
    • Improved orbit accuracy
    • Recovery of KBR data previously deemed lost due to an unexplained KBR anomaly

  • The redelivered data are the same as the standard RL02 data and are meant to replace the existing RL02 data for these days. Many of the redelivered files will be the same as before but with new processing time tags. The processing time tag can be found in the header of each file. This will be the only way to distinguish this redelivered data from the original RL02 data. It is also recommended to replace all RL02 Level-1B data products for a given day.

  • The redelivered days fall into two categories:

    • Significant recovery of science data
    • Recovery of mostly housekeeping telemetry or small science data recovery

  • Information about the particular days that have been redelivered can be found in the GRACE SDS newsletter for June 2014 available in the GRACE archives at GFZ and JPL.

June 2014:

  • CSR has generated and delivered calibrated errors for all RL05 Level-2 products (GSM-2_*_UTCSR_0060_0005.txt)
  • CSR has generated and delivered for the whole mission period alternative RL05 Level-2 products up to degree and order 96 (GSM-2_*_UTCSR_0096_0005).
  • GFZ has updated the AOD1B Product Description Document to Version 4.2 which includes editorial changes to chapters 3.6 and 3.7 to better describe the correct usage of various GAA-GAF Level-2 products.

April 2014:

  • No RL05 Level-2 products could be generated and delivered for February 2014 due to planned switch-offs of the GRACE-A and GRACE-B Microwave Assemblies (MWA) in order to reduce the load on the batteries.
  • GFZ has generated and delivered new GAE and GAF Level-2 products in terms of Technical Notes TN08 and TN09. The coefficients may be used to correct discontinuities in atmospheric pressure data on January 29, 2006 and January 26, 2010, respectively. Details are described in chapter 3.7 of the updated AOD1B Product Description Document Version 4.1 which is, as the Technical Notes, available in the GRACE archives at GFZ and JPL.

December 2013:

  • GFZ has generated and delivered a reprocessed RL05 time series called RL05a for January 2003 till July 2013. All RL05a Level-2 products are available at ISDC and PO.DAAC. When making your request at the ISDC retrieval pages, the RL05a GSM products can be found under the same revision number (“5”) as the RL05 GSM products and are distinguishable by the string “_005a” (instead of “_0005”) at the end of the product name. At the PO.DAAC archive, the RL05a GSM products can be found in the directory “allData/grace/L2/GFZ/RL05”. Note that GAx products are not affected and need not to be replaced! Further details are described in the “Release notes for GFZ RL05 GRACE L2 products”, also available at both archives. For the missing months in 2002 (soon to be delivered) and all upcoming months starting with October 2013, only RL05a products will be generated, i.e. the GFZ RL05 time-series will not be continued.

October 2013:

  • Due to the switch-off of GRACE ICUs (Instrument Control Units) and MWA (Microwave Assemblies) between August 5 and September 24 in order to reduce the load on the batteries (see L1B Data Processing Section below) the SDS centers have not generated and delivered RL05 Level-2 products for August and September 2013 as just 5 days of data in August and 7 days of data in September don't allow a meaningful monthly estimate for these two calendar months. Therefore, the SDS has decided to provide the next Level-2 data product for the calendar month of October 2013. The GFZ weekly solutions and the CSR QL solutions are not affected by this unfortunate phasing of the outage. All available Level-1B data will be distributed for the months of August and September.

May 2013:

  • No RL05 Level-2 products could be generated and delivered for March 2013 due to planned switch-offs of the GRACE-A and GRACE-B Instrument Control Units and Microwave Assemblies in order to reduce the load on the batteries.

February 2013:

  • Ongoing updates on CSR RL05 are provided at http://www.csr.utexas.edu/grace/RL05.html.

  • Additionally to the standard monthly solutions, GFZ now also provides weekly RL05 solutions (aligned to GPS weeks) which contain spherical harmonic coefficients complete up to degree and order 30. Currently, available weekly solutions cover the time span from 2003/01/05 till 2012/09/22. The weekly Level-2 products (GSM + GAx files) can be downloaded at GFZ's ISDC archive.

August 2012:

  • CSR has generated and delivered RL05 Level-2 products for February 2011 till June 2012, except June 2011 and May 2012 (due to missing accelerometer data).
  • JPL has generated and delivered RL05 Level-2 products for February 2011 till April 2012, except June 2011 (due to missing accelerometer data).
  • GFZ has generated and delivered RL05 Level-2 products for January till June 2012 (except May 2012 due to missing accelerometer data), February till December 2011 (except June 2011 due to missing accelerometer data) and February till December 2004. Note that due to sparse ground track coverage caused by short-interval repeat orbit patterns some of the new solutions are stabilized by applying a modified version of the regularization method used for previous releases, which is based on Kaula’s power law. The stabilized solutions can be identified by the string ‘GK2-‘ instead of ‘G---‘ in the GFZ GSM-product name. For further details please refer to the ‘Release Notes for GFZ GRACE Level-2 Products - version RL05’ which can be downloaded at the archives.

July 2012:

  • RL05 will substitute RL04 Level-2 and RL02 will substitute RL01 Level-1B data starting from May 2012.

May 2012:

  • All three centers have generated and delivered RL05 Level-2 products (CSR up to degree 60 for period 2004-2010, GFZ up to degree 90 for period 2005-2010, JPL up to degree 90 for period 2004-2010) based on reprocessed L1B data (RL02), updated processing standards and background models. Updated RL02/RL05 documentation (e.g. Release Notes, Processing Standards Documents) is partly also already available at the archives and will be completed along with still missing monthly products during the next few weeks. The new L1/L2 products are already publicly available.
  • RL05 will substitute RL04 within the next months. Please refer to the upcoming newsletters.

March 2012:

  • At 10:46:50.875 UTC, the orbiting phase of the twin GRACE satellites has completed 10 years in orbit. In recognition of this anniversary, the project will release over the next few weeks a new gravity solution based on a complete and detailed reanalysis of the GRACE mission data set. The solution, designated the GRACE RL05 Solution, is the result of reprocessing the 10 year data set, taking advantage of improvements in modeling and data quality and adding additional data from the extended mission. The improved accuracy and extended data length on which the solution is based will allow more complete studies of seasonal and decadal signals involved in climate change processes. In addition to the improvements associated with an additional iteration of the mission data, the RL05 solution benefits from a significantly improved AOD1B background model for the correction of high frequency atmosphere and ocean mass variations, improved ocean tide models and improvements in the Level 1B data. To accommodate investigations that will be presented at the EGU in April 2012, an initial release, covering a six year span (2005 till 2010) from the GRACE GFZ RL05 Level 2 Solution, has been placed in the archive by the anniversary epoch including the AOD1B RL05 Model, covering the period from July 2002 through December 2011. The Level- 1B RL02 data and remaining Level-2 gravity solutions, along with updated documentation, will be placed in the archives during the following weeks. Further details on the RL05 release will be found in the monthly newsletters as they develop.

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