Data for CGCAM/GEMINI Coupling
The data comes from the simulation described
here,
which replicates the 21 June DeepWAVE observation. Although the simulation was
run on a fairly complex mesh using stretching in all three directions as well
as zonal de-refinement, the data provided below was resampled on a regular
Cartesian mesh having constant horizontal spacings of 4 km and vertical spacing
of 1 km. The spacing in time is 10 minutes.
Wind Ramping Procedure
The winds were initially damped to zero near the surface and then forced
to the observed wind profile over the first two hours of the run. This
procedure reduces the effect of starting transients and results in a much less
dispersive upward-propagating wave front. Very little (non-acoustic) gravity
wave energy travels into the mesosphere during the ramping phase (first two
hours) so the domain top was placed at 140 km during this initial period. The
simulation was restarted at the two hour mark with five additional zones
stacked on top, each with a factor of 2 de-refinement in the horizontal
directions. These zones extended the top of the simulation to 440 km, with the
last 40 km containing a sponge layer.
Data File Format
Each time instant is written to a separate data file with a name like
vel.011760, where the six digit extension corresponds to the time step when the
data was written. The data files are in pure single precision binary format
and are essentially a dump of the array u(Nx,Ny,Nz,n) where Nx=502, Ny=502,
Nz=321, n=5. The data is ordered with the fortran convention where points in x
are contiguous, points in y have a stride of Nx, etc. The final index, n,
indicates the field, with these being rho', u', v', w', T' (all in SI units)
where primes denote deviations from the horizontally-uniform background state.
The data is centered at 45.8528 degrees South, 173.3738 degrees East and extends
from 80 to 400 km in altitude.
Special Format for the First Two Hours
Since the first two hours of the simulation were run on a smaller domain, data
files from this time period extend only from 80 to 140 km and have Nz=61
points. The data files for this time period are named like vel_short.000480 in
order to distinguish these from the larger data files for later times. The
add_zeros program, to be discussed in more detail below, can be used to produce
Nz=321 files from the Nz=61 files by inserting zeros in the appropriate
locations. The conversion will write a file named like vel.000480, which can
then be used in a unified fashion with the rest of the data files.
Depending on GEMINI's tolerance for transients, you can probably skip at least
a few of the frames before the one hour mark. There may still be some acoustic
transients present in the first frame at 10 minutes, so you may be better off
skipping at least this one. The movies shown
in the web link listed above
start at the two hour mark and thus are not useful for assessing the early-time
behavior.
The add_zeros Program
The add_zeros program will read a file named like
vel_short.000480 and write a full-sized file like vel.000480. The
program will also need to read inputs from the file
cgcam.inp, so make sure this file is present in
the directory where you will be processing the vel_short files (it is
already contained in the tar file referenced in the Data File Download
section below). To run the program simply move into the directory
containing the vel_short and cgcam.inp files and issue
add_zeros [extension]
where extension is the file extension (e.g. 480, leading zeros being
unnecessary). If the extension is not given on the command line, the program
will prompt you for it. The compiled program linked above should run on your
system, but if it does not you can download the
source file and compile it yourself. You
should set the appropriate flag to default to double precision (-r8 for ifort,
-fdefault-real-8 for gfortran, -sreal64 for cray). You may also need to set a
flag to allow Cray-style pointers (--cray-pointer for gfortran).
Background Conditions
The simulation was run with a background state that remained fixed in
the horizontal directions and in time. The resulting profiles in z
can be downloaded below. Note that the background.state
file contains columns for the gas constants gamma and R and these
values were taken from the MSIS database.
File Download
Data for first 2 hours
Data for the remainder of the simulation
Background wind file (ascii)
Background state file (ascii)
Cgcam input file (ascii)
add_zeros program
add_zeros source file