Sammendrag
The Meinel bands of OH in the night airglow have been monitored from the Northern Lights Station near Longyearbyen, Svalbard (15degreesE, 78degreesN) for the past 20 years. The rotational lines of the (6-2) and (8-3) bands yield a trustworthy measure of the neutral temperature in the upper mesosphere. There is a seasonal winter maximum, but wide variations predominate throughout the winter months. The variations of less than one day have been shown to be due to direct gravity wave forcing and those greater than one day are correlated with warmings in the polar stratosphere. Our analysis shows that the polar upper mesospheric temperature variations correlate best overall with the zonal stratospheric wind at 45degreesN and 30 hPa, indicating gravity wave filtering at that height and gravity wave forcing from that latitude region. The trend of the timeseries calculated from weekly averages of the rotational temperatures is -0.6 K/year. If the stratospheric wind at 45degreesN is included in a multiple regression the trend becomes -0.3 K/year. (C) 2002 Elsevier Science Ltd. All rights reserved.
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