822 Recent and New GNSSRO Missions: Quality Assessment and Comparative Data Assimilation Study

Tuesday, 14 January 2020
Hall B (Boston Convention and Exhibition Center)
F. vandenberghe, Joint Center for Satellite Data Assimilation, Boulder, CO; and S. Dutta, H. Zhang, S. Albergel, H. Shao, and J. G. Yoe

The Joint Center for Satellite Data Assimilation (JCSDA) supports its partner agencies in the effort to assimilate Radio-Occultation (RO) observation from Global Navigation Satellite Systems (GNSS). The objectives are twofold:

1) Adding into operations, observations from new platforms as they become available, and

2) Developing and transitioning advanced assimilation capabilities.

JCSDA’s efforts toward 2) are described in a companion talk (Zhang et al.). This talk focuses on 1) and reports on the evaluation of the data from the PAZ and MetOp-C missions. We use the PAZ data processed by CDAAC for which the two polarized signals have been combined to produce bending angles, similar to other existing missions. The MetOp-C observations were provided by Eumetsat. For each platform, we computed the mean bias and root mean square errors of the observations minus background (OmB) using the operational NOAA global 6-hour forecast over the month of January 2019. We compared those statistics against the ones obtained from the currently operational GNSSRO platforms (COSMIC-1, MetOp-A&B, Tandem-X, Terra-X and Kompsat-5). The results show that PAZ data have a very low bias with performances comparable to those of Kompsat-5. The MetOp-C statistics are very similar to those of MetOp-A, with a significant bias in the lowest troposphere. For both platforms, we conducted a month long of 6-hourly cycling assimilations/forecasts and generated score cards, a measure of the benefit of the assimilation relative to the current operational forecast. The PAZ score card shows an improvement of the geopotential height anomaly correlation for days 1-3 forecast in the Southern hemisphere. The assimilation of MetOp-C data results in a temperature bias reduction above 10hPa in the Northern hemisphere for all forecasts. We intend to repeat similar studies with the coming COSMIC-2 mission.

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