Esrange Sweden Simulation - Summer Conditions
This page describes a numerical simulation of gravity waves due to summertime
winds blowing over the Scandinavian Mountain ranges in Norway and Sweden.
Computational Domain
The layout of the of the simulation is shown in the figure below. Note that
the boundaries of the computation domain (shown by the thin white line) has
been rotated by 26 degrees with respect to lines of constant latitude.
Just the computational domain is shown in the figure below. In this plot, the surface has been interpolated to rectangular coordinates.
The mesh is uniform at 500 m spacing from the Norwegian coastline to a point 50 km east-southeast of Esrange, Sweden. Gentle stretching is used upstream and downstream of these points. The mesh is also uniformly spaced at 500 m in the lateral direction over the central regon +/- 50 km N-NE and S-SW of Esrange. Gentle stretching is once again used from this region to the outer boundaries. The mesh is uniformly spaced at 125 m for all altitudes in the z direction. In total the mesh contains 650 x 274 x 256 points and sponge layers are used on all external boundaries in order to absorb outgoing waves.
Wind and Thermodynamic Profiles
The wind and temperature profiles were taken from radiosonde mesurements
taken over Barrow Alaska on August 18 2016 at 0:00 UTC. The radiosonde
measurements were smoothed somewhat and the data was extended above 30 km.
The measured winds were cose to zero at at 30 km, so they were simply held
fixed at zero above 30 km. The temperature profile was extrapolated along
the linear rate found in the measurements near 30 km.
Initial Wind Condition
Here the winds are initially set to zero from the surface to an altitude of
about 20 km. At this point the wind transitions to the profiles shown in the
plots above. Forcing terms then gradually introduce winds near the surface
with the
objective of achieving the profile shown above within a two hour period.
A hyperbolic tangent function is used in order to produce gentle
acceleration of the wind near the beginning and end of the forcing period.
The maximum forcing rate is equivalent to that of a linear ramp with a
duration of 45 minutes.
Computational Domain
The layout of the of the simulation is shown in the figure below. Note that
the boundaries of the computation domain (shown by the thin white line) has
been rotated by 26 degrees with respect to lines of constant latitude. Just the computational domain is shown in the figure below. In this plot, the surface has been interpolated to rectangular coordinates.
The mesh is uniform at 500 m spacing from the Norwegian coastline to a point 50 km east-southeast of Esrange, Sweden. Gentle stretching is used upstream and downstream of these points. The mesh is also uniformly spaced at 500 m in the lateral direction over the central regon +/- 50 km N-NE and S-SW of Esrange. Gentle stretching is once again used from this region to the outer boundaries. The mesh is uniformly spaced at 125 m for all altitudes in the z direction. In total the mesh contains 650 x 274 x 256 points and sponge layers are used on all external boundaries in order to absorb outgoing waves.
Wind and Thermodynamic Profiles
The wind and temperature profiles were taken from radiosonde mesurements
taken over Barrow Alaska on August 18 2016 at 0:00 UTC. The radiosonde
measurements were smoothed somewhat and the data was extended above 30 km.
The measured winds were cose to zero at at 30 km, so they were simply held
fixed at zero above 30 km. The temperature profile was extrapolated along
the linear rate found in the measurements near 30 km.