RO Modeling EXperiment (ROMEX)

The International Radio Occultation Working Group (IROWG) community has recently proposed a collaborative effort to explore the impact of RO observations:

Radio Occultation Modeling Experiment (ROMEX)

ROMEX seeks to quantify the benefit of increasing the quantity of RO observations using additional observations unavailable to weather centers for their real-time operational systems. The IROWG community has gained approval from their respective institutions to perform data assimilation experiments with additional RO measurements over the designated period. 

(Courtesy Christian Marquardt, EUMETSAT and Hui Shao, JCSDA)

Dr. Richard Anthes first introduced the effort concept in May 2022, responding to questions from NOAA for input on future RO needs. The resulting discussion led to a proposal for ROMEX, which the IROWG endorsed in September 2022 (IROWG-9). 

The experiment results will guide the CGMS partners to answer pressing technical and programmatic questions facing the numerical weather prediction (NWP) community.  This will help inform near- and long-term strategies for RO missions and acquisitions by all CGMS partners. 

ROMEX white paper

The full ROMEX white paper (pdf) can be found here.

ROMEX Data Terms and Conditions:

If you want to participate in ROMEX, please sign this document and return it to the steering committee.

We accept signatures by an organization or an individual. If an organization signs the letter, please indicate the POC (point of contact) for this organization. This POC will be responsible for receiving the password for the data FTP later. Also, this person will be contacted if there is a violation of the Terms and Conditions during ROMEXIf no POC is identified explicitly, we’ll get the person who sent in the signature.

Because of the sensitivities that can occur when comparing data sets and model results, it is important to be careful in how we share our results from the ROMEX experiment. It is important to remember that ROMEX is not a contest or a competition; we are all trying to learn from our results to improve our data and modeling products. As a courtesy to our colleagues, we should share potentially sensitive results with them before presenting our results publicly or to a wide audience. This is especially important for publications, presentations at meetings, and publication on web sites. Therefore, please be reminded that all ROMEX participants must adhere to the Terms and Conditions (TnC), particularly regarding the sharing of evaluation results. The ROMEX data use agreement (license) says “The Licensee is authorised to share/redistribute the original ROMEX Data and any ROMEX Derived Data only with ROMEX Participants and EUMETSAT ROM SAF Partners who have signed a “ROMEX Data and ROMEX Derived Data License Agreement”. Redistribution of ROMEX Data and ROMEX Derived Data to any other third party is expressly prohibited.

It’s crucial to ensure that any information shared publicly remains unbiased and objective and accurately reflects the processes applied to the data such as quality control.

ROMEX Data Providers and Users

The list will only include the organizations who have signed the Data License Letter (for data providers only) or Terms and Conditions (for data users. See above). If you want to participate in this effort or have any questions, please get in touch with the steering committee.

Participating organizations or affiliations (representing either an organization or an individual scientist):


Data Providers:

EUMETSAT, GeoOptics, NASA/Spire, NOAA, Tianmu, PlanetIQ, UCAR, Yunyao

ROMEX Data Server 

ROMSAF provides a password-protected service to access the ROMEX data. Once we receive your signed Terms and Conditions (T&C) agreement, you will be notified about accessing the data server. The password for this server has been sent to existing users. If you have signed the T&C but have not received the password, please contact us at

  • Christian Marquardt:

Upcoming ROMEX events/meetings

The ROMEX schedule/planned meetings can be found here.

ROMEX Announcement

ROMEX announcement can be found here.

Contact the ROMEX steering committee (RSC)

Questions or requests for information can be addressed to any RSC members.

The members are:

  • Richard Anthes:
  • Hui Shao:
  • Christian Marquardt:
  • Benjamin Ruston: