Tropical stratospheric zonal winds in ECMWF ERA-40 reanalysis, rocketsonde data, and rawinsonde data

ECMWF ERA‐40 reanalysis zonal winds are very close to tropical rocketsonde and rawinsonde (radiosonde & radar wind soundings) observations up to 10 hPa. Above 10 hPa differences increase, although the ERA‐40 data provide a good representation of tropical winds up to 2–3 hPa. The amplitudes of the quasi‐biennial oscillation (QBO) and the semi‐annual oscillation (SAO) derived from ERA‐40 data match the rawinsonde and rocketsonde observations up to 2–3 hPa. We conclude that zonal‐mean ERA‐40 equatorial winds could be used, for most purposes, in place of rawinsonde station observations.