Abstract
Abstract. Ground-based remote sensing of atmospheric parameters is often limited to single station observations by vertical profiles at a certain geographic location. This is a limiting factor for investigating gravity wave dynamics as the spatial information is often missing, e.g., horizontal wavelength, propagation direction or intrinsic frequency. In this study, we present a new retrieval algorithm for multistatic meteor radar networks to obtain tomographic 3-D wind fields within a pre-defined domain area. The algorithm is part of the Agile Software for Gravity wAve Regional Dynamics (ASGARD) and called 3D-Var, and based on the optimal estimation technique and Bayesian statistics. The performance of the 3D-Var retrieval is demonstrated using two meteor radar networks: the Nordic Meteor Radar Cluster and the Chilean Observation Network De Meteor Radars (CONDOR). The optimal estimation implementation provide statistically sound solutions and diagnostics from the averaging kernels and measurement response. We present initial scientific results such as body forces of breaking gravity waves leading to two counter-rotating vortices and horizontal wavelength spectra indicating a transition between the rotational k−3 and divergent k-5/3 mode at scales of 80–120 km. In addition, we performed a keogram analysis over extended periods to reflect the latitudinal and temporal impact of a minor sudden stratospheric warming in December 2019. Finally, we demonstrate the applicability of the 3D-Var algorithm to perform large-scale retrievals to derive meteorological wind maps covering a latitude region from Svalbard, north of the European Arctic mainland, to central Norway.
Highlights
The mesosphere/lower thermosphere (MLT) is of crucial interest to understand the vertical coupling between the middle and upper atmosphere
Chau et al (2021) presented some results from a Peruvian meteor radar network using a mean curvature as a constraint for the solution, which in principle is almost identical to the volume velocity processing (VVP) method (Waldteufel and Corbin, 1979), whereas Stober et al (2018a) only assumed local correlation and retrieved arbitrary wind fields
We present a new 3D-Var retrieval algorithm of the Agile Software for Gravity wAve Regional Dynamics (ASGARD) software, which is designed to infer 3-D tomographic winds from multistatic observations
Summary
The mesosphere/lower thermosphere (MLT) is of crucial interest to understand the vertical coupling between the middle and upper atmosphere. There are some resonance lidars with day- and nighttime capabilities to simultaneously observe horizontal winds and temperatures at the MLT (Krueger et al, 2015; Wörl et al, 2019) These measurements permit us to determine the intrinsic gravity wave properties through a hodograph analysis, modeling or polarization relations (Fritts et al, 2002). The second meteor radar network is called Chilean Observation Network De Meteor Radars (CONDOR) and employs a monostatic radar at the Andes Lidar Observatory (ALO), a passive receiver at the Southern Cross Observatory (SCO) and another passive receiver at Las Campanas Observatory (LCO) Based on these data sets, we demonstrate the utility of the technique with a series of case studies of body forces, vortices and other spatial features that are not observable by other techniques so far.
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