What is the difference between MAPS and RUC?
MAPS is the development version of the RUC, run in real time
at FSL. RUC is the operational version, run at NCEP.
So, MAPS is an experimental version of the RUC.
Only the RUC runs in the fully operational sense at NCEP.
(However, an official backup RUC does run at FSL.)
Both MAPS and RUC are high-frequency data assimilation
and mesoscale numerical weather prediction systems.
What do you mean by "40km MAPS"?
We use this term to designate our real-time cycle that
runs on the identical domain as the RUC-2 at NCEP
and produces the real-time products available from
the MAPS home page. This is partly a
convenience to help us distinguish this particular cycle
from parallel test cycles we are making using different
domains and resolutions (e.g., the 60km-resolution,
smaller domain of the old RUC-1).
What is the wind direction shown in RUC/MAPS weather maps?
The wind flags for these maps are the usual convention for
weather maps, showing the direction from which the wind is coming.
If the wind flag is toward the west, that means that the wind
direction is from the west toward the east.
Why do I get forecasts from different runs when
clicking the "All Times" button for MAPS or RUC products?
This can sometimes happen because early output times from
new runs are processed into products while the run is still
continuing in order to make available the latest
products. Also, sometimes runs may be missing or products
may be missing because of computer/disk outages.
Could you please run the MAPS model out past 12 hours?
There are now runs of the experimental 40km MAPS model out to 36 hours
run updated every 6 hours. You can get these by clicking
on "40km MAPS" under "Current and forecast weather" in the index.
At NCEP, the niche of the RUC is the frequently updated
analyses and short-range (out to 12 h) forecasts, so
don't expect 36 h forecasts from the RUC at NCEP.
There is, however, some chance that a version of the RUC model
will run out to 36-48 h at NCEP as part of a regional model
ensemble.
How can I make bookmarks with the new MAPS/RUC homepage
(issued 10/24/98)?
Push the
right mouse button in either Netscape or Microsoft Explorer
and make a link directly to the frame you are viewing.
Also, you can see the actual URL at the bottom of the display
in either Netscape or Explorer.
Is the 40-km MAPS generally of better quality than the RUC?
The 40km MAPS usually includes improvements more quickly than
the RUC. The RUC runs slightly more reliably than the MAPS.
So I would give MAPS a slight edge, but this may not be true
in a given case. At NCEP, the RUC may get some observations
not assimilated into the MAPS. The 40km MAPS link in the index
gives some more information, as well as a change log for the 40km
MAPS, so you can see what changes have been made recently.
Are the mass and velocity values calculated at the same grid point location,
those points defined in RUC-2 file 40kmlatlon.asc?
(unlike Eta where mass and velocity are at different locations - i.e. semistaggered
Arakawa E grid)?
The answer is yes.
The native RUC model horizontal grid is an Arakawa C grid, in
which there is staggering. This is in the model itself. However,
all RUC wind output, even in the hybrid-b native vertical
coordinate, is unstaggered back onto the mass points. So that
is what you are seeing in any output file, unstaggered winds.
Do you have FORTRAN code for converting the u and v wind components aligned to the RUC-2
grid to components with respect to true north (meteorological standard)?
Here is a code snippet that should do the job.
PARAMETER ( ROTCON_P = 0.422618 )
PARAMETER ( LON_XX_P = -95.0 )
C** ROTCON_P R WIND ROTATION CONSTANT, = 1 FOR POLAR STEREO
C** AND SIN(LAT_TAN_P) FOR LAMBERT CONFORMAL
C** LON_XX_P R MERIDIAN ALIGNED WITH CARTESIAN X-AXIS(DEG)
C** LAT_TAN_P R LATITUDE AT LAMBERT CONFORMAL PROJECTION
C** IS TRUE (DEG)
PARAMETER ( LAT_TAN_P = 25.0 )
do j=1,ny_p
do i=1,nx_p
angle2 = rotcon_p*(olon(i,j)-lon_xx_p)*0.017453
sinx2 = sin(angle2)
cosx2 = cos(angle2)
do k=1,nzp_p
ut = u(i,j,k)
vt = v(i,j,k)
un(i,j,k) = cosx2*ut+sinx2*vt
vn(i,j,k) =-sinx2*ut+cosx2*vt
end if
end do
end do