Search Results

You are looking at 1 - 2 of 2 items for :

  • Author or Editor: VOLKER WAGNER x
  • Monthly Weather Review x
  • Refine by Access: Content accessible to me x
Clear All Modify Search
LUTZ HASSE and VOLKER WAGNER

Abstract

The ratio between observed surface and geostrophic wind speed has been investigated from observations at the German Bight, taking geostrophic wind and the air-sea temperature difference as parameters. The ratio decreases with increasing geostrophic wind and increasing stability. While stability is an important parameter for light to moderate winds, variation of the ratio with geostrophic wind speed cannot be neglected, taking the full range of geostrophic wind speeds into consideration. From the Navier-Stokes equations, such a variation is to be expected. For light winds, the (local) surface wind may exceed the (mesoscale) geostrophic wind. Both effects together can be described approximately by a linear relation between the surface wind and geostrophic wind, with a slope of 0.56 and a constant term b>0 varying with stability. The residual error was 2 m/s. Variation with latitude is inferred from the Navier-Stokes equations.

Full access
ERNST AUGSTEIN, HERBERT RIEHL, FEODOR OSTAPOFF, and VOLKER WAGNER

Abstract

The vertical and horizontal mass and energy transports for the layer between the sea surface and 700 mb are calculated for the first (undisturbed) period of the Atlantic Trade-Wind Experiment 1969. The trade-wind inversion represents a layer with a strong downward mass flux due to the mean motion. The height of the inversion and its thermodynamic properties seem to depend on the balance between the mean atmospheric sinking and the turbulent mixing.

Because of the vertical transport from the sea surface into the atmosphere, this process assures that water vapor is totally accumulated in the layer below the inversion and transported downstream into the equatorial trough region. Thus the effectiveness of the atmospheric heat absorption in the trades as a force for driving the large-scale circulation is closely related to the vertical static structure as well as to the kinematic field of the low-level trade-wind region.

Full access