The yearly wave in pressure and zonal geostrophic wind at sea level on the southern hemisphere and its interannual variability

Article English OPEN
Van Loon, H. ; Rogers, Jeffery C. (2011)

The yearly wave (first harmonic) in the sea level mean pressure on the southern hemisphere is largest at 30° S over and near the three continents, where it also explains most of the mean annual variance. In middle and high latitudes, the half-yearly wave dominates so that even in the Antarctic the yearly wave is mostly secondary. In single years, the amplitude of the yearly wave south of 40° S may be large, but as the phase varies widely from one year to another, the mean wave becomes small. The yearly wave in the mean zonal geostrophic wind at sea level is largest in the tropics and subtropics. Like the pressure wave, it is second to the half-yearly wave over most of middle and high southern latitudes. The phase of the yearly wave appears in four concentric belts as follows: maximum westerlies/minimum easterlies in summer in the tropics outside the eastern Pacific Ocean; maximum westerlies/minimum easterlies in winter in the subtropics; maximum westerlies in summer in the latitudes round 50° S (unlike the northern hemisphere); and maximum westerlies/minimum easterlies in winter over most of the area covered by sea ice. Just as the pressure wave, the yearly wave in the zonal wind has a large interannual variation.DOI: 10.1111/j.1600-0870.1984.tb00253.x
  • References (8)

    Hofmeyr, W. L. 1957. Atmospheric sea-level pressure over the Antarctic. I n Mefeoro/ogv OJ (he Anfarcfic (M.P. van Rooy, ed.), Pretoria, Weather Bureau, 5 1-70.

    Schwerdtfeger, W. and Prohaska, F. 1966. Der Jahresgang des Luftdrucks auf der Erde und seine halbjahrigeKomponente. Mefeo. Rundsch. 9.33-43.

    Spitaler, R. 1901. Die periodischen Lufmassenverschiebungen. Pefermanns Miff. 137.5 I pp.

    van Loon, H. 1966. On the annual temperature range over the southern oceans. Geogr. Rec. 56,497-5 I S .

    van Loon, H. 1972. Pressure in the southern hemisphere. Mefeo. Monogr. 13. no. 35.59-86.

    van Loon, H. and Rogers, J. C. 1981. Remarks on the circulation over the southern hemisphere in FGGE and on its relation to the phases of the Southern Oscillation. Mon. Wea. Rev. 109,2255-2259.

    van Loon, H. and Rogers, J. C. 1984. Interannual variations in the half-yearly cycle of pressure gradients and zonal wind at sea level on the southern hemisphere. Tellus 36A. 76-86.

    Wahl, E. 1942. Untersuchungen iiber den jahrlichen Luftdruckgang. Verog. Mefeorol. Insf. Univ. Berlin 4. 3-71.

  • Metrics
    No metrics available
Share - Bookmark