Horizontal wavelength of gravity waves in the lower atmosphere measured by the SOUSY Svalbard Radar

Height profiles of the vertical atmospheric motion are analyzed to obtain the vertical phase and group velocities of the atmospheric gravity wave motion by the technique of phase and group velocity tracing. Then the horizontal wave vector component along the direction of the mean wind is obtained by the gravity wave dispersion relation, and the angle 101 between the horizontal wave vector and the mean wind velocity is obtained by the polarization relation. The data were taken during the period between March 30 and April 24 in 2000 using the SOUSY Svalbard Radar. The altitude range of measurement is between 2.4 km and 14.25 km. Most of the wave packets (about 75%) in the Range-Time-Intensity (RTI) plots of velocity show that the vertical phase and group velocities are in the opposite direction (Type 1 wave packets). The rest (about 25%) are shorter lasting wave packets showing that the vertical phase and group velocities are in the same direction (Type 2 wave packets). By horizontal wave vector analysis we have found no wave packet moving against the background wind. Statistical analysis of the angle vertical bar theta vertical bar, which is the angle between the horizontal wave vector and the background wind velocity vector, reveals a trend, namely that the percentage of wave packets monotonically decreases with the angle vertical bar theta vertical bar.