A better way to get GPS radio occultation into forecast models published in Monthly Weather Review


The Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) are a set of satellites launched in 2006 that orbit the earth about 500 miles above ground.  They use radio signals from Global Positioning System (GPS) satellites in a process called “radio occultation” to measure temperature and moisture with high accuracy.  These data have proven to improve weather forecasts since they became available.  

This study looks at how much weather forecast models would improve by adding more radio-occultation temperature and moisture data from 12 satellites similar to COSMIC. The work uses a technique known as an Observing System Simulation Experiment (OSSE).  Observations that are like the real ones that this new set of 12 satellites would produce are created and added to a weather forecast model along with the data that are usually available. The simulation of the data from these 12 satellites is based on the original design of the COSMIC-2 mission. Different from earlier OSSEs with COSMIC-2 we used  NOAA’s current data assimilation and forecast system.

The COSMIC satellites produced vertical profiles of the atmosphere by measuring the bend of GPS radio signals as they travel through the atmosphere. Credit: Simmi Sinha, UCAR.

Important Conclusions:

  • The addition of COSMIC-2 observations improves weather forecasts.
  • The impact of the part of the originally planned COSMIC-2 mission that orbits near the Equator has significantly increased as compared to earlier studies, and significant positive impact is now found globally.
  • Earlier findings remain valid, indicating that RO observations around the world are more important to improve weather prediction globally than a denser sampling near the Equator.

For more information, contact aoml.communications@noaa.gov. You can find the full study at https://journals.ametsoc.org/view/journals/mwre/149/1/mwr-d-20-0174.1.xml.

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