The Use of Spire Radio Occultation Measurements in the GEOS Atmospheric Data Assimilation System

Abstract:

This study evaluates the role of Spire Level 2 bending angle profiles in the context of the Goddard Earth Observing System (GEOS) Atmospheric Data Assimilation System (ADAS) and other RO observing systems. Initial assessment, as part of the NASA Commercial SmallSat Data Acquisition Program (CSDAP) showed that the Spire observations were generally consistent and complementary to existing radio occultation observing systems. In terms of quantity, the Spire observations accounted for ~20-40% of the total RO observing system. Additionally, these new observations were complementary to the other GNSS-RO observing systems in that they filled spatial data voids due to their broad global sampling. Statistically, the observations were found to be comparable to other RO observing systems, though there was a tropospheric bias in those observations derived from the GLONASS GNSS signals. Their forecast impacts were found to be comparable to other RO observing systems. No statistically significant impact on medium range forecast (2+ days) was seen, but there was a quantifiable reduction on short-term (24 hour) forecast error via the FSOI metric. These results, including any additional results in the context of the most recent CSDAP Spire data purchase, will be presented.