Two-Dimensional Horizontal Correlation Functions in the MLT Region
Estimated Using Multistatic Specular Meteor Radar Observations
Abstract
The study of the mesosphere and lower thermosphere (MLT) dynamics
presents great challenges. One of them is trying to find a dominant
theory that explains mesoscales variations. Recently, Vierinen et al.
(2019) introduced the Wind field Correlation Function Inversion (WCFI)
technique that estimates spatial correlation functions (among other
products) of the wind velocity field in the MLT from multistatic
specular meteor radar observations. The correlations can be determined
for lags in two dimensions (East-West and North-South directions), from
which the frequently used hypothesis of horizontal isotropy on
correlation functions of the fluctuating wind can be examined. Moreover,
using the two dimensional correlation functions of the fluctuating wind,
we investigate the two-point correlations of vertical vorticity (Qzz)
and horizontal divergence (P) (Lindborg, 2007). Assuming that the
velocity field is statistically homogeneous in horizontal planes of
certain thickness, these functions can be expanded to get similar,
compact forms. Qzz and P are of great significance since they can
provide information on the relative importance of stratified turbulence
and internal gravity waves to explain the mesoscale dynamics in the
middle atmosphere.