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<p>
Dear All,
</p>
<p>
These days I am about to set up a
<span class="caps">
CCLM
</span>
simulation over some mountaineous domain at 0.1° horizontal resolution. Doing so I started to wonder about the orography filtering. Reading
<span class="caps">
COSMO
</span>
Newsletter 1 (2001) by Almut Grassmann I understood that the latter is useful if not even mandatory. Yet I am still puzzled about the meaning of the different namelist parameters and the effects different values would have on the simulated climate.
</p>
<p>
I checked http://cosmo-model.org/content/tasks/operational/ and tried the INT2LM namelist setups
<span class="caps">
DWD
</span>
uses for
<span class="caps">
COSMO
</span>
-EU with
</p>
lfilter_oro T
lxso_first F
l_topo_z F
norder_filter 5
eps_filter 0.1000
ilow_pass_oro 1
numfilt_oro 1
ilow_pass_xso 0
numfilt_xso 1
rxso_mask 0.0000
rfill_valley 0.0000
ifill_valley 0
<p>
and the setup Meteo Swiss uses for
<span class="caps">
COSMO
</span>
-7 and
<span class="caps">
COSMO
</span>
-2 with
</p>
lfilter_oro T
lxso_first F
l_topo_z F
norder_filter 5
eps_filter 0.1000
ilow_pass_oro 4
numfilt_oro 1
ilow_pass_xso 5
numfilt_xso 1
rxso_mask 750.0000
rfill_valley 0.0000
ifill_valley 7
<p>
The orography produced with the latter setup is much smoother than that produced with the former.
</p>
<p>
I also saw that the
<span class="caps">
COSMO
</span>
-DE setup equals that of
<span class="caps">
COSMO
</span>
-7 and
<span class="caps">
COSMO
</span>
-2 except rxso_mask = 625.0000 and ifill_valley = 0. As my resolution is slightly coarser than those of
<span class="caps">
COSMO
</span>
-EU and
<span class="caps">
COSMO
</span>
-7 I thought I should choose between the two setups listed above but since the respective resulting orographies differ so much I don’t know what to do. Any suggestions?
</p>
<p>
I’d like to know why there are all those different filtering setups in use and what kind of differences I can expect between the simulated weathers/climates with differently smoothed orographies. Also I wondered if one should filter differently for climate simulations than for weather forecasts…
</p>
<p>
With many thanks in advance,
<br/>
Stefan
</p>
<p>
Dear All,
</p>
<p>
These days I am about to set up a
<span class="caps">
CCLM
</span>
simulation over some mountaineous domain at 0.1° horizontal resolution. Doing so I started to wonder about the orography filtering. Reading
<span class="caps">
COSMO
</span>
Newsletter 1 (2001) by Almut Grassmann I understood that the latter is useful if not even mandatory. Yet I am still puzzled about the meaning of the different namelist parameters and the effects different values would have on the simulated climate.
</p>
<p>
I checked http://cosmo-model.org/content/tasks/operational/ and tried the INT2LM namelist setups
<span class="caps">
DWD
</span>
uses for
<span class="caps">
COSMO
</span>
-EU with
</p>
lfilter_oro T
lxso_first F
l_topo_z F
norder_filter 5
eps_filter 0.1000
ilow_pass_oro 1
numfilt_oro 1
ilow_pass_xso 0
numfilt_xso 1
rxso_mask 0.0000
rfill_valley 0.0000
ifill_valley 0
<p>
and the setup Meteo Swiss uses for
<span class="caps">
COSMO
</span>
-7 and
<span class="caps">
COSMO
</span>
-2 with
</p>
lfilter_oro T
lxso_first F
l_topo_z F
norder_filter 5
eps_filter 0.1000
ilow_pass_oro 4
numfilt_oro 1
ilow_pass_xso 5
numfilt_xso 1
rxso_mask 750.0000
rfill_valley 0.0000
ifill_valley 7
<p>
The orography produced with the latter setup is much smoother than that produced with the former.
</p>
<p>
I also saw that the
<span class="caps">
COSMO
</span>
-DE setup equals that of
<span class="caps">
COSMO
</span>
-7 and
<span class="caps">
COSMO
</span>
-2 except rxso_mask = 625.0000 and ifill_valley = 0. As my resolution is slightly coarser than those of
<span class="caps">
COSMO
</span>
-EU and
<span class="caps">
COSMO
</span>
-7 I thought I should choose between the two setups listed above but since the respective resulting orographies differ so much I don’t know what to do. Any suggestions?
</p>
<p>
I’d like to know why there are all those different filtering setups in use and what kind of differences I can expect between the simulated weathers/climates with differently smoothed orographies. Also I wondered if one should filter differently for climate simulations than for weather forecasts…
</p>
<p>
With many thanks in advance,
<br/>
Stefan
</p>
These days I am about to set up a
CCLM
simulation over some mountaineous domain at 0.1° horizontal resolution. Doing so I started to wonder about the orography filtering. Reading
COSMO
Newsletter 1 (2001) by Almut Grassmann I understood that the latter is useful if not even mandatory. Yet I am still puzzled about the meaning of the different namelist parameters and the effects different values would have on the simulated climate.
I checked http://cosmo-model.org/content/tasks/operational/ and tried the INT2LM namelist setups
DWD
uses for
COSMO
-EU with
lfilter_oro T
lxso_first F
l_topo_z F
norder_filter 5
eps_filter 0.1000
ilow_pass_oro 1
numfilt_oro 1
ilow_pass_xso 0
numfilt_xso 1
rxso_mask 0.0000
rfill_valley 0.0000
ifill_valley 0
and the setup Meteo Swiss uses for
COSMO
-7 and
COSMO
-2 with
lfilter_oro T
lxso_first F
l_topo_z F
norder_filter 5
eps_filter 0.1000
ilow_pass_oro 4
numfilt_oro 1
ilow_pass_xso 5
numfilt_xso 1
rxso_mask 750.0000
rfill_valley 0.0000
ifill_valley 7
The orography produced with the latter setup is much smoother than that produced with the former.
I also saw that the
COSMO
-DE setup equals that of
COSMO
-7 and
COSMO
-2 except rxso_mask = 625.0000 and ifill_valley = 0. As my resolution is slightly coarser than those of
COSMO
-EU and
COSMO
-7 I thought I should choose between the two setups listed above but since the respective resulting orographies differ so much I don’t know what to do. Any suggestions?
I’d like to know why there are all those different filtering setups in use and what kind of differences I can expect between the simulated weathers/climates with differently smoothed orographies. Also I wondered if one should filter differently for climate simulations than for weather forecasts…
Orography filtering
Dear All,
These days I am about to set up a CCLM simulation over some mountaineous domain at 0.1° horizontal resolution. Doing so I started to wonder about the orography filtering. Reading COSMO Newsletter 1 (2001) by Almut Grassmann I understood that the latter is useful if not even mandatory. Yet I am still puzzled about the meaning of the different namelist parameters and the effects different values would have on the simulated climate.
I checked http://cosmo-model.org/content/tasks/operational/ and tried the INT2LM namelist setups DWD uses for COSMO -EU with
lfilter_oro T lxso_first F l_topo_z F norder_filter 5 eps_filter 0.1000 ilow_pass_oro 1 numfilt_oro 1 ilow_pass_xso 0 numfilt_xso 1 rxso_mask 0.0000 rfill_valley 0.0000 ifill_valley 0and the setup Meteo Swiss uses for COSMO -7 and COSMO -2 with
lfilter_oro T lxso_first F l_topo_z F norder_filter 5 eps_filter 0.1000 ilow_pass_oro 4 numfilt_oro 1 ilow_pass_xso 5 numfilt_xso 1 rxso_mask 750.0000 rfill_valley 0.0000 ifill_valley 7The orography produced with the latter setup is much smoother than that produced with the former.
I also saw that the COSMO -DE setup equals that of COSMO -7 and COSMO -2 except rxso_mask = 625.0000 and ifill_valley = 0. As my resolution is slightly coarser than those of COSMO -EU and COSMO -7 I thought I should choose between the two setups listed above but since the respective resulting orographies differ so much I don’t know what to do. Any suggestions?
I’d like to know why there are all those different filtering setups in use and what kind of differences I can expect between the simulated weathers/climates with differently smoothed orographies. Also I wondered if one should filter differently for climate simulations than for weather forecasts…
With many thanks in advance,
Stefan