A long-term comparison of wind and tide measurements in the upper mesosphere recorded with an imaging Doppler interferometer and SuperDARN radar at Halley, Antarctica

Data from a near co-located imaging Doppler
interferometer (IDI) and SuperDARN radar recorded since
1996 have been analysed in a consistent manner to compare
the derived mean winds and tides in the upper mesosphere.
By comparing only days when both techniques were recording
good quality meridional wind data it is shown that the
SuperDARN radar winds and tides correlate best with the
IDI height bin 90–95 km. On timescales of one hour the
winds derived from the IDI have a much greater associated
variance and correlate poorly with the SuperDARN winds.
Regression analysis reveals that the observed SuperDARN
daily mean meridional wind strength is approximately 65%
that recorded by the IDI, in good quantitative agreement with
previous studies which have shown contamination to Super-
DARN derived winds due to the significant back lobe of
the radar radiation pattern. Climatologically the two techniques
observe similar monthly mean winds with the Super-
DARN meridional winds suppressed compared to the IDI
which tends to record winds more poleward than those derived
by the SuperDARN radar during the summer months,
and to be slightly more equatorward during the winter. The
12-h tidal amplitude and phase derived from both techniques
are in good agreement, whereas the 24-h tides are seen much
more strongly in the SuperDARN radar, especially in wintertime,
with poor phase agreement. Long term comparison
of the two techniques reveals a tendency for the IDI meridional
winds to be more poleward during solar maximum especially
during summer time; an effect which is not reproduced
in the meridional winds derived from the SuperDARN
radar. These results are discussed in the context of previous
studies to independently determine the veracity of each technique,
and to highlight the circumstances where data derived from these two techniques can be used to draw reliable conclusions
from comparative studies based on geographically
distributed pairs of instruments.