REMO Multi-Decadal Model Run Description :
The model:
REMO (REgional MOdel) is a grid point model featuring the discretized primitive equations in a
terrain-following hybrid coordinates system. The finite differencing scheme is energy
preserving. The prognostic variables are surface air pressure, horizontal wind components,
temperature, specific humidity and cloud water. A soil model is added to account for soil
temperature and water content. Further details are given by Jacob and Podzun (1997) and Jacob
et al. (1995). For the 40 year run the ECHAM4 physics scheme is used and the model version is
REMO 5.0.
The integration area has a horizontal spherical resolution of 0.5 x 0.5 degrees (~ 47 – 55 km in
zonal direction, ~ 55 km in meridional direction) with a pole at 170 degrees W, 32.5 degrees N,
resulting in 81 x 91 grid points. The grid is rotated so that the equator is located above the
centre of the integration area to achieve a minimum distortion of the grid boxes. The
geographical grid is rotated about “Eularian angles” to form the ‘rotated spherical grid’ (rotated
latitude/longitude grid) . In rotated coordinates, the model extension is from 19.5 degrees West
to 20.5 degrees East and from 25.0 degrees South to 20.0 degrees North. A time step of 5
minutes is adopted. In the vertical, there are 20 hybrid model levels which are adapted to the
orography near the surface. This so-called -system is a combination of the - and the p-system.
The -sytem guarantees an easy and correct way for the formulation of the lower boundary
conditions, but at greater heights the quasi-horizontal structures of the atmosphere get
overlaid by the orography. This can be prevented by using a combined -p-system.
The grid is an Arakawa-C grid, which has good performances for the dispersion of inertia gravity
waves. The zonal wind component u is shifted to the right about /2, the meridional component
v about /2 upwards. The vorticity  is shifted to the upper right about /2, /2. At the
mass point the following variables are defined: ps (surface pressure), h (specific total heat), qDW
(specific total water content), T, qD (specific water vapour content), qW (specific cloud water
content), vertical movement in thesystem)vertical velocity in the pressure system =
dp/dt),(kinetic energy per unit mass),(geopotential),.
The Arakawa-C-grid
Vertical discretization:
The –system includes KE+1 plains and KE layers:
k
½ - - - - - - - - - - - - - - p=0, =0
1 --------u, v, h, qDW ----
1½-------,--|
KE – 1 ½ - - - - -  ,  - - - KE – 1 --------u, v, h, qDW --KE – ½ - - - - - - - - - - - - - KE --------------------------KE + ½ - - - - - - - - - - - - - - p=pS, =1
REMO is forced with NCEP (National Centers for Environmental Prediction) reanalyses (Kalnay et
al., 1996) from 1st of January 1948 to 31 st of December 2003. These observed states are
updated every six hours. In between, values are derived through linear interpolation. The
horizontal resolution of the analyses is 1.875 degrees longitudinally and about the same value
latitudinally (T62 latitudes). Since REMO operates with a rotated spherical grid, its coverage of
NCEP grid-boxes is inhomogeneous. There are many more NCEP grid boxes covered along the
northern margin of the model domain than along the southern margin. The REMO model offers a
resolution enhanced by factor of 1:16, on average. Maximum improvement of resolution is
achieved in the southern part of the integration area.
Lateral boundary conditions:
The aim is to transfer large scale meteorological systems with minimum damping from the global
to the regional model while smaller scale systems and gravity waves shall be free to leave the
regional model domain without reflection at the lateral boundaries. Therefore the modified
technique of Davies (1976) by Kallberg (1977) is used. The sponge zone is 8 grid points wide, in
this zone the REMO values are adapted gradually to the NCEP reanalyses in the direction of the
lateral boundaries.
In addition to the forcing via the lateral boundaries a spectral nudging technique (Von Storch et
al. 2000) was applied for the entire model domain. The method was developed to prevent the
regional model results from differing from the large scale weather phenomena of the global
forcing data. The simulated state is kept close to the driving state at larger scales, while
regional-scale features are free to be generated independent of the global model. The model
solution is spectrally decomposed and so-called nudging terms are added to the model results in
the spectral domain. These terms force the model solution towards the NCEP reanalyses and
they are dependent on height and on wavenumber, having the largest impact on the model
solution for higher model levels and small wavenumbers. This way, the critical regional features
close to the surface are left unchanged.
Model area:
Model orography:
Literature:
Davies, H. C., 1976: A lateral boundary formulation for multi-level prediction models. Quart. J. R.
Meteor. Soc. 102, 405-418.
Feser, F., R. Weisse, and H. von Storch, 2001, Multi-decadal atmospheric modeling for Europe
yields multi-purpose data.
EOS Volume 82, Number 28, July 10, 2001
Jacob, D., and R. Podzun, 1997, Sensitivity studies with the regional climate model REMO.
Meteorol. Atmos. Phys. 63, 119-129
Jacob, D., R. Podzun and M. Claussen, 1995, REMO - A model for climate research and weather
prediction. Proceedings of International Workshop on Limited-Area and Variable Resolution
Models, Beijing, China, October 23-27, 1995, 273-278
Kallberg, P., 1977: Test of a lateral boundary relaxation scheme in a barotropic model. ECMWF,
Research Department, Internal Report 3, Bracknell.
Kalnay, E., M. Kanamitsu, R. Kistler, W. Collins, D. Deaven, L. Gandin, M. Iredell, S. Saha, G.
White, J. Woollen, Y. Zhu, M. Chelliah, W. Ebisuzaki, W. Higgins, J. Janowiak, K.C. Mo, C.
Ropelewski, J. Wang, A. Leetmaa, R. Reynolds, R. Jenne, and D. Joseph, 1996, The NCEP/NCAR
40-Year Reanalysis Project. Bull. Amer. Meteor. Soc. 77, 437-471
Von Storch, H., H. Langenberg, and F. Feser, 2000,
A Spectral Nudging Technique for Dynamical Downscaling Purposes
Monthly Weather Review Vol. 128, Nr. 10 (2000), pp 3664-3673
Variable list:
These variables are written out hourly for the REMO model run in REMO-ieee-service format
(highlighted in blue are those codes, that are already extracted from the total model output):
---------------------------------------------------------------type: g=grid, m=mean over output interval (= 1 hour)
code|levels|internal| type | variable
|
| name |
|
129
130
131
132
133
134
135
139
140
141
142
143
144
145
146
147
151
153
156
159
160
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
185
1
20
20
20
20
1
20
1
1
1
1
1
1
1
1
1
1
20
20
1
1
20
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
GEOSP g surface geopotential (orography) [m**2/s**2]
STP
g
temperature
[K] (see notes)(all model levels extracted)
g u-velocity
[m/s]
g v-velocity
[m/s]
Q
g specific humidity [kg/kg] (all model levels extracted)
APS
g Surface pressure [Pa]
g Vertical velocity [Pa/s]
TS
g surface temperature [K] (see also code 169)
WS
g soil wetness
[m]
SN
g snow depth
[m]
APRL
g m large scale precipitation [mm/hour] (snow already included)
APRC
g m convective precipitation [mm/hour] (snow already included)
APRS
g m snow fall
[mm/hour] (142 + 143 = total precipitation)
VDIS
g m boundary layer dissipation [W/m**2]
AHFS
g m surface sensible heat flux [W/m**2]
AHFL
g m surface latent heat flux [W/m**2]
g mean sea level pressure [Pa]
X
g liquid water content
[kg/kg]
g geopotential height
[gpm]
USTAR3 g m ustar**3
[m**3/s**3]
RUNOFF g m surface runoff [m/s]
ACLC
g cloud cover
[fract.] (see also 223)
ACLCV
g total cloud cover [fract.] (see also 164)
ACLCOV g m total cloud cover [fract.]
U10
g m 10m u-velocity [m/s]
V10
g m 10m v-velocity [m/s]
TEMP2 g m 2m temperature [K]
DEW2
g m 2m dew point temperature [K]
TSURF g m surface temperature
[K] (see also 139)
TD
g deep soil temperature [K]
WIND10 g m 10m windspeed
[m/s]
SLM
g land sea mask
[0.: sea, 1.: land]
AZ0
g surface roughness length [m]
ALB
g surface background albedo [fract.]
ALBEDO g surface albedo
[fract.]
SRADS g m net surface solar radiation [W/m**2]
TRADS g m net surface thermal radiation [W/m**2]
SRAD0 g m net top solar radiation
[W/m**2]
TRAD0 g m top thermal radiation (OLR) [W/m**2]
USTR
g m surface u-stress
[Pa]
VSTR
g m surface v-stress
[Pa]
EVAP
g m surface evaporation
[m/s]
TDCL
g soil temperature [K] (see description below)
SRAFS
g m net surf. solar radiation (clear sky) [W/m**2]
186 1 TRAFS
187 1 SRAF0
188 1 TRAF0
189 1 SCLFS
190 1 TCLFS
191 1 SCLF0
192 1 TCLF0
194 1 WLM1
195 1 USTRGW
196 1 VSTRGW
197 1 VDISGW
198 1 VGRAT
199 1 VAROR
200 1 VLT
201 1 T2MAX
202 1 T2MIN
203 1 SRAD0U
204 1 SRADSU
205 1 TRADSU
206 1 TSN
207 1 TD3
208 1 TD4
209 1 TD5
210 1 SEAICE
211 1 SICED
212 1 FOREST
213 1 TEFF
214 1 TSMAX
215 1 TSMIN
216 1 WIMAX
217 1 TOPMAX
218 1 SNMEL
220 1 TSLIN
g m net surf. thermal radiation (clear sky) [W/m**2]
g m net top solar radiation (clear sky) [W/m**2]
g m net top thermal radiation (clear sky) [W/m**2]
g m surface solar cloud forcing
[W/m**2]
g m surface thermal cloud forcing
[W/m**2]
g m top solar cloud forcing
[W/m**2]
g m top thermal cloud forcing
[W/m**2]
g skin reservoir content (t-1) [m]
g m u-gravity wave stress
[Pa]
g m v-gravity wave stress
[Pa]
g m gravity wave dissipation
[W/m**2]
g vegetation ratio
g orographic variance (for surface runoff)
g leaf area index
g maximum 2m-temperature
[K]
g minimum 2m-temperature
[K]
g m top solar radiation upward
[W/m**2]
g m surface solar radiation upward [W/m**2]
g m surface thermal radiation upward [W/m**2]
g snow temperature [K] (see description below)
g soil temperature [K]
"
g
"
[K]
"
g
"
[K]
"
g sea ice cover [fract.]
g sea ice depth [m]
g vegetation type
g m (effective) sea-ice skin temperature [K]
g maximum surface temperature
[K]
g minimum surface temperature
[K]
g maximum 10m-wind speed
[m/s]
g maximum height of convective cloud tops [Pa]
g m snow melt
[m/s]
gm
land: residual surface heat budget [W/m**2]
sea-ice: conductive heat flux
[W/m**2]
221 1 DSNAC
g m snow depth change
[m/s]
223 20 ACLCAC g m cloud cover
[fract.]
224 20 TKE
g turbulent kinetic energy
226 1 FAO
g FAO data set (soil data flags)
[0...5.]
227 1 RGCGN
g heat capacity of soil
228 1 SODIF
g soil diffusivity
229 1 WSMX
g field capacity of soil
230 1 QVI
g m vertically integrated specific humidity [kg/m**2]
231 1 ALWCVI g m vertically integrated liquid water cont. [kg/m**2]
232 1 GLAC
g glacier mask
[0.: no, 1.: yes]
-----------------------------------------------------------------------------Description of soil temperatures:
|---------|-----------------------------------| TS
| surface temperature (=interface to atmosphere)
|---------|-----------------------------------| TSN
| snow temperature
|---------|-----------------------------------| TD3
|
|---------|
| TD4
|
|---------| soil temperatures
| TD5
|
|---------|
| TD
|
|---------|
| TDCL |
|---------|------------------------------------Note: The surface temperature TS is always the interface temperature
to atmosphere even in snow covered areas!
---------------------------------------------------------------------------The extracted files are saved at archive.dkrz.de at DKRZ in the directory:
/ut/5/g262012/remo000/remo5.0/output/19YY/...
remo000xe.....130.srv Temperature at all model levels
133
Spec. Humidity at all model levels
134
Surface Pressure
139
Surface Temperature
142
Large scale Precipitation
143
Convective Precipitation
144
Snow
151
MSLP
156
Geopotential Height
163
Total Cloud Cover instantaneously
164
Total Cloud Cover hourly mean value
165
U 10m Wind Component
166
V 10m Wind Component
167
2m Temperature
168
2m Dew Point Temperature
173
Surface Roughness Length
176
Net Surface Radiation
177
Net surface thermal radiation
180
Surface U-Stress
181
Surface V-Stress
182
Surface Evaporation
204
surface solar radiation upward
205
surface thermal radiation upward
The format of the extracted variables is ieee-service format. It can be read with these
FORTRAN commands:
READ(10) ICODE, ILEVEL, IDATE, ITIME, NLON, NLAT, IDISP1, IDISP2
READ(10) ((FIELD(ILON,ILAT), ILON=1,NLON), ILAT=1,NLAT)
[ With the integer header variables:
IDATE=YYYYMMDD, ITIME=HHMM, ICODE=see above, ILEVEL=level, NLON=number of
longitudes, NLAT=number of latitudes, IDISP1, IDISP2=for user diposal (is set to 0). ]