[Ncep.list.emc.nmmb-questions-and-answers] t2m, rh2m, u10m, ... at t=0
Pau
pescribaa at aemet.es
Fri Apr 20 12:31:19 UTC 2018
Hi Jacob.
Many thanks for letting me know the reference values for the DFI filter
parameters you use operationally with you NAM CONUS.
Definitely, we will do some verification, some parallel runs with
different filter parameters. In our case, so far, we are not doing
analysis, so interpolating from global model (10 or more km horizontal
resolution) to NMMB 2.5 km resolution. It can be that the error
introduced by the resolution change jumping needs another kind of filter
parameters, no clear idea, I am not an expert in balancing stuff. In any
case, we now have all the ingredients to tune our DFI and to have the
surface parameters at t=0!
Many thank to all.
Pau
El 20/04/18 a les 14:11, Jacob Carley - NOAA Federal ha escrit:
> Hi Pau,
>
> If you run one of the DFI variants that involves a backward, adiabatic
> integration at such a high resolution you can run into instability
> issues. I suggest keeping the filter window length short and making
> the filter timestep short as well. For reference, here is what we use
> for the operational 3km NAM CONUS Nest at NOAA/NCEP/EMC:
>
> ##########################################
> ##### Fundamental Timestep (seconds) #####
> ##########################################
>
> dt_int: 6 # Integer seconds
> dt_num: 1 # Numerator of fractional second
> dt_den: 4 # Denominator of fractional second
>
> filt_dt_int: 2 # Integer seconds
> filt_dt_num: 0 # Numerator of fractional second
> filt_dt_den: 4 # Denominator of fractional second
>
>
> ###################################
> ##### Digital Filtering options ###
> ###################################
>
> filter_method: 3 # 0--->none ; 1--->DFL ; 2---> DDFI ;
> 3--->TDFI
>
> nsecs_dfl: 1800 # HALF foward filter window (s)
> (DFL)
> nsecs_bckddfi: 1800 # HALF backward integration duration
> (s) (DDFI)
> nsecs_fwdddfi: 3600 # HALF foward filter window (s)
> (DDFI)
> nsecs_bcktdfi: 600 # HALF backward filter window (s)
> (TDFI)
> nsecs_fwdtdfi: 600 # HALF forward filter window (s)
> (TDFI)
>
>
> Hope this helps!
> Jacob
>
>
> On Fri, Apr 20, 2018 at 6:30 AM, Marco Biordi <marco.biordi at gmail.com
> <mailto:marco.biordi at gmail.com>> wrote:
>
> We're using 3600.
>
> Anyway keep this value to be an integer multiple of the time step,
> elsewhere give error.
>
> Marco
>
> 2018-04-20 9:50 GMT+00:00 Pau <pescribaa at aemet.es
> <mailto:pescribaa at aemet.es>>:
>
> Hi Marco,
>
> Thanks very much for the answer, we are going to test it right
> now.
>
> We should see if DFI changes our verification scores but I
> would expect it doesn't, taking into account we are not doing
> analysis cycling with NMMB.
>
> Just a small question, apart from filter_method=3, are using
> the regular values for filtering parameters:
>
> nsecs_bcktdfi: 3600 # HALF backward filter window
> (s) (TDFI)
> nsecs_fwdtdfi: 3600 # HALF forward filter window
> (s) (TDFI)
>
> ?
>
> In our case we are running with around 2.5 km horizontal
> resolution and 5.625 seconds of time step. Probably we should
> make some tunning of this parameters...
>
> Many thanks.
>
> Pau
>
>
> El 20/04/18 a les 10:37, Marco Biordi ha escrit:
>> Hello Pau,
>>
>> you can get t=0 missing parameters when you enable the
>> Digital Filter Initialization.
>>
>> Do that by setting configuration option "filter_method" to
>> value 1 or 2 or 3 (usual one).
>>
>> Regards
>>
>> Marco Biordi
>>
>> San Marino Republic Weather Forecast Center
>> meteo.sm <http://meteo.sm>
>>
>>
>> 2018-04-20 8:26 GMT+00:00 Pau <pescribaa at aemet.es
>> <mailto:pescribaa at aemet.es>>:
>>
>> Hello all,
>>
>> I am a new user of NMMB model. I work at the Spanish Met
>> Agency with
>> several NWP-LAM models. We are running daily NMMB at home
>> and we see
>> that, after UPP processing, we don't get some surface
>> parameters like
>> t2m, rh2m, u10m, v10m or visibility, at t=0, but we do
>> for any lead time
>> t>0. After dedicating some time to look to UPP and NMMB
>> user's guides
>> and namelists, I am quite sure this variables cannot be
>> got in an easy
>> manner for t=0. Could anybody confirm me this? In such a
>> case, we have
>> to do some further final work with vertical
>> interpolations and so.
>>
>> Thanks in advance!
>>
>> Pau Escriba
>>
>> Spanish Met Agency (AEMET)
>>
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