[Ncep.list.emc.nmmb-questions-and-answers] t2m, rh2m, u10m, ... at t=0

[Jacob Carley - NOAA Federal]

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>
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>:
>
>> 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
>>
>>
>> 2018-04-20 8:26 GMT+00:00 Pau <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)
>>>
>>> _______________________________________________
>>> Ncep.list.emc.nmmb-questions-and-answers mailing list
>>> Ncep.list.emc.nmmb-questions-and-answers at lstsrv.ncep.noaa.gov
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>>>
>>
>>
>>
>
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