The use of GPS radio occultation measurements at ECMWF
Sean Healy
ECMWF
4 Sept, 10 am, in 2890
Abstract:
ECMWF has assimilated GPS radio occultation (GPS-RO) measurements
operationally since December 2006, and they are now considered to be a
key component of the global observing system. Importantly, these
measurements complement the information provided by satellite
radiances, because they have good vertical resolution and they can be
assimilated without bias correction to the background model. This talk
will review how the assimilation of the GPS-RO data at ECMWF has
evolved since 2006, and summaries the current impact of this data in
the numerical weather prediction system. Current efforts to improve the
forward modelling of the GPS-RO data will be described, and areas which
require further improvement, such as improved observation error
statistics, will be highlighted. Recent wave optics simulation results
estimating the size of both the instrument errors and forward
model/retrieval errors in the troposphere will be presented.
The importance of GPS-RO measurements for climate reanalyses will be
demonstrated. It will be shown that the consistency of ERA5, JRA55 and
MERRA-2 temperature estimates in the lower/middle stratosphere has
improved since the active assimilation of COSMIC data in 2006.