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Abstract:
WIRA is a ground-based microwave Doppler spectroradiometer specifically
designed for the measurement of profiles of horizontal wind in the upper
stratosphere and lower mesosphere region where no other continuously
running measurement technique exists. A proof of principle has been
delivered in a previous publication. A technical upgrade including a new
high-frequency amplifier and sideband filter has improved the signal to
noise ratio by a factor of 2.4. Since this upgrade the full horizontal
wind field comprising zonal and meridional wind profiles is continuously
measured. A completely new retrieval based on optimal estimation has
been set up. Its characteristics are detailed in the present paper.
Since the start of the routine operation of the first prototype in
September 2010, WIRA has been measuring at four different locations at
polar, mid-and tropical latitudes (67 degrees 22' N/26 degrees 38' E, 46
degrees 57' N/7 degrees 26' E, 43 degrees 56' N/5 degrees 43' E and 21
degrees 04' S/55 degrees 23' E) for time periods between 5.5 and 11
months. The data presented in this paper are daily average wind profiles
with typical uncertainties and resolutions of 10 to 20ms(-1) and 10 to
16 km, respectively. A comparison between the data series from WIRA and
European Centre for Medium-Range Weather Forecasts (ECMWF) model data
revealed agreement within 10% in the stratospheric zonal wind. The
meridional wind profiles agree within their error bars over the entire
sensitive altitude range of WIRA. However, significant differences in
the mesospheric zonal wind speed of up to 50% have been found.
