Monthly and zonally averaged zonal wind information in the equatorial stratosphere provided by GNSS radio occultation
S. B. Healy, Inna Polichtchouk, Ándrás Horányi
Abstract
Abstract It is demonstrated that a realistic quasi‐biennial oscillation (QBO) of the zonally averaged zonal winds in the tropical stratosphere can be retrieved from a monthly mean GNSS radio occultation (GNSS‐RO) geopotential height climatology via equatorial thermal wind balance. The retrieved GNSS‐RO zonal winds are compared with a zonal wind climatology from radiosonde measurements at Singapore, and the ERA5 atmospheric reanalysis. Simplified low‐resolution reanalysis experiments also show that assimilating just reprocessed GNSS‐RO bending angles and AMSU‐A channel 14 radiances produces a reasonable QBO. Further, it is demonstrated that the ERA5 and ERA‐Interim tropical zonal winds at 30 and 10 hPa are more consistent after the assimilation of COSMIC GNSS‐RO measurements in 2006.