Welcome to COST-G

The International Combination Service for Time-variable Gravity Fields (COST-G) is a product center of the International Gravity Field Service (IGFS) and is dedicated to the combination of monthly global gravity field models. COST-G stems from the activities of the former H2020 project European Gravity Service for Improved Emergency Management (EGSIEM) and is further developed within the follow-up project Global Gravity-Based Groundwater Product (G3P), which is funded from the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement no. 870353 (funding period 2020-2022).

Please use the top menu to visit the various parts of our website!

Best regards,
Your COST-G Team.


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Latest GRACE-FO combination results


Weights (RL02)


Weights (RL01)


Noise over the oceans (RL02)


Noise over the oceans (RL01)

Latest News

July 20th 2023

Starting on 18th July, the Copernicus POD Service deployed a new version of the system (3.3.0) which uses the COST-G FSM for gravity field modeling in all the operational chains.

July 10th 2023

COST-G has a new flyer! Check it here!

June 26th 2023

COST-G is kicking off its annual meeting in Bern this week!

April 18th 2023

COST-G GRACE-FO RL02 is now available at ICGEM.

New input time-series of RL02 are: GFZ-, JPL-, CSR-RL06.1, which apply the new JPL accelerometer transplant product, and AIUB-GRACE-FO-RL03, which makes use of empirical noise modelling strategies. All non-SDS analysis centers apply IfG's alternative accelerometer transplant product. As a consequence C30 is significantly improved in the combination and it is not necessary anymore, to replace it by SLR-derived values. Furthermore the weighting scheme was adapted: the high-order gravity field coefficients that are poorly defined due to the near polar orbits and along-track observation geometry are excluded when deriving the relative weights by variance component estimation. As a consequence the relative weights reflect much better the noise in the low- to medium-degree coefficients, which are the most relevant for the users.

April 14th 2022

We have a new publication online: COST-G gravity field models for precise orbit determination of Low Earth Orbiting Satellites.

December 17th 2021

Precise orbit determination (POD) of Low Earth Orbiters (LEOs) depends on the precise knowledge of the Earth's gravity field and its time-variations. But the latency of 2-3 months of the GRACE-FO monthly gravity fields prevents their application in operational LEO POD. To bridge this gap, starting from September 2021 COST-G is providing a deterministic signal model (DSM) as a new Level-2 product to enable POD that is always based on the newest GRACE-FO gravity field observations. The DSM consists of secular, seasonal and semi-annual variations that are fitted to the monthly GRACE-FO combined models. It is foreseen to quarterly update the DSM applying a sliding window approach of flexible window length that allows to timely react to singular events like the massive ice melt in Greenland in 2019 or, e.g., major earthquakes.

The new product is available in the gfc-format (extended by time-variable constituents) from ICGEM: Click here.

January 11th 2021

COST-G is having its annual start of the year meeting from 11th to 15th of January!

November 23rd 2020

COST-G GRACE-FO monthly models are now available!

November 4th 2020

Benchmark data for verifying background model implementations in orbit and gravity field determination software available here (Martin Lasser et al. 2020)

June 16th 2020

COST-G RL01 Level 2B and Level-3 products are available and the GravIS portal has been updated!

May 19th 2020

New article published in the International Association of Geodesy Symposia.

May 7th 2020

COST-G had its virtual meeting at the EGU 2020!

March 18th 2020

COST-G standards and RL01 release notes are now available here!