The Constellation Observing System for Meteorology, Ionosphere, and Climate COSMIC) is 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 accurately measure temperature and moisture at a large number of points in the vertical. These data have improved weather forecasts since they became available. Due to this success, new satellites, called COSMIC-2, are due to be sent into space during the next few years. The first (COSMIC-2A) will be launched next year and will look mainly at the tropics; another set (COSMIC-2B) will look at nearly the entire globe and is currently scheduled for 2020.
This study looks at how much weather forecast models would improve once the observations from COSMIC-2 are available, using a technique known as an Observing System Simulation Experiment (OSSE). Observations that are like the real ones that COSMIC-2 would produce are created and added to a weather forecast model along with the data that are usually available; two forecasts are made, one with the COSMIC-2 data and one without. COSMIC-2A and COSMIC-2B are tested both separately and together because they are to be launched at different times.
Important Conclusions:
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The biggest forecast improvements from COSMIC-2 are in the southern hemisphere.
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COSMIC-2A data improve global weather forecasts, though the largest improvements are from COSMIC-2B data.
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Even more radio-occultation observations around the globe than those provided by COSMIC-2 may give us even better forecasts suggesting the need for more satellites.