The quasi-two-day wave studied using the Northern Hemisphere SuperDARN HF radars

S. B. Malinga, J. M. Ruohoniemi
2007 Annales Geophysicae  
<p><strong>Abstract.</strong> Data from the Super Dual Radar Network (SuperDARN) radars for 2002 were used to study the behaviour of the quasi-two-day wave (QTDW) in the Northern Hemisphere auroral zone. The period of the QTDW is observed to vary in the range of ~42&amp;ndash;56 h, with the most dominant period being ~48 h and secondary peaks at ~42- and ~52-h. The spectral power shows a seasonal variation with a peak power (max~70) in summer. The power shows variations of several days and
more » ... veral days and there is also evidence of changes in wave strength with longitude. The 42-h and the 48-h components tend to be strongly correlated in summer. The onset of enhanced wave activity tends to coincide with the westward acceleration of the zonal mean flow and occurs at a time of strong southward meridional flow. The most frequent instantaneous hourly period is in the 40 to 50 h period band, in line with the simultaneous dominance of the 42-h and the 48-h components. The wave numbers are less variable and are around &amp;minus;2 to &amp;minus;4 during times of strong wave activity. For a period of ~48 h, the zonal wave number is about &amp;minus;3 to &amp;minus;4, using a negative value to indicate westward propagating waves. The 42-h and the 52-h components cover a wider band in the &amp;minus;4 to 1 range. The wide zonal wave number spectrum in our results may account for the observed longitudinal variation in the spectral power of the wave.</p>
doi:10.5194/angeo-25-1767-2007 fatcat:wu7zpdyet5gsviv4adw37jxjiy