[RegCNET] tmax and tmin
Wm. J. Gutowski
gutowski at iastate.edu
Thu Nov 17 05:55:52 CET 2005
Lara:
I'm not sure that using the lowest ATM
level is the best choice, although we do want an
air temperature. What most models that I know
about typically do is use the near-surface air
temperature that the land-surface model
determines, perhaps in conjunction with the PBL
model This is the temperature that corresponds
to what the observing stations are measuring.
The lowest ATM level may be many meters above the
surface. For example, RegCM's lowest layer's
delta sigma = 0.05 implies a lowest-layer
thickness of about 500 m, that the nominal middle
of the layer is at about 250 m.
There may be a further issue here though
(and I need help from the ICTP people on this!):
is the near-surface air temperature computed in
RegCM3 at 2 m? I thought some observation
stations used
other heights above the surface.
Also, how well do we know that Tmin/Tmax
stations adhere to WMO standards? I know if the
U.S. they don't, simply because of the disparate
reset times used. If that is the case elsewhere,
then I suggest doing the reset at a default time
of 00 UTC (so that the values are for the
calendar day ending at that time). This could be
a parameter that the user can change in the input
files, though that might cause confusion about
what day to associate the values with.
(Arguably, that potential for confusion will
always be there relative to the local clock.)
Bill
At 11:02 AM -0800 05.11.16, Lara Kueppers wrote:
>Jeremy-
>A couple of things:
>* Mark and I were discussing that it would be
>best if Tmin and Tmax were calculated from air
>temperature (lowest ATM level) so that they are
>consistent with the average T values. If you
>output this in the SRF file, that's fine, just
>so it's clear we're talking atmospheric min and
>max.
>* Also, calculating min and max from 00 to 00
>UTC seems the most workable option. Unless there
>is some argument for having sub-daily min and
>max (as opposed to average) temperature, we'd
>say limit the file size!
>
>One other thought... Would anyone else find it
>useful to have the combined surface albedo
>values available from BATS? (i.e. the total vis
>and ir albedos calculated from veg, soil, snow
>etc.) This would be helpful for interpreting
>seasonal cycle results from land cover change
>experiments. Of course this would increase the
>file size...
>
>Lara
>
>Jeremy Pal wrote:
>
>>Hi,
>>Having it done based on local time may be a bit
>>tricky to code up. As an alternative, we could
>>consider storing the max/min temperature and
>>wind for every output interval (e.g. 3 hours).
>>This way, the user can decide the reset time at
>>the postproc stage... Of course, this increases
>>the SRF output file size by about 15% as
>>opposed to just a couple percent.
>>What do you think of this idea?
>>Jeremy
>>
>>Tomá” Halenka wrote:
>>
>>>Dear All,
>>>
>>>Not bad hearing Tmax and Tmin will be included properly in new edition
>>>of RegCM. But I would recommend to use WMO definition and reset time,
>>>moreover, keep in mind it has to be done in local time as my opinion.
>>>
>>>Best regards,
>>>
>>>Tomas
>>>
>>>*************************************************
>>>RNDr. Tomas Halenka, CSc.
>>>Charles University in Prague,
>>>Faculty of Mathematics and Physics,
>>>Department of Meteorology and Environment Protection,
>>>V Holesovickach 2, 180 00 Prague 8,
>>>Prague, Czech Republic,
>>>Phone: +420 2 21912514
>>>Fax: +420 2 21912533
>>>E-mail: tomas.halenka at mff.cuni.cz
>>>*************************************************
>>>
>>>-----Original Message-----
>>>From: regcnet-bounces at lists.ictp.it
>>>[mailto:regcnet-bounces at lists.ictp.it] On Behalf Of BI XUNQIANG
>>>Sent: Wednesday, November 16, 2005 9:48 AM
>>>To: Wm. J. Gutowski
>>>Cc: Gao Xuejie; regcnet at lists.ictp.it
>>>Subject: Re: [RegCNET] tmax and tmin
>>>
>>>
>>>Dear Bill, Lara, and Gao:
>>>
>>>In the next public released RegCM3 version, we will add Tmax, Tmin
>>>and vertital velocity (for pressure level) as the standard output.
>>>
>>>We will calculated Tmax and Tmin as the way Bill suggested (for
>>>every land surface step, and reset at 00 UTC).
>>>
>>>Any other fields are also necessary to be included ?
>>>
>>>Thanks and best regards,
>>>
>>>On Tue, 15 Nov 2005, Wm. J. Gutowski wrote:
>>>
>>>
>>>>Dear Lara:
>>>> I am not the expert on this, but I am pretty sure that observed
>>>>
>>>>
>>>Tmin
>>>>and Tmax are obtained primarily from min/max thermometers, which
>>>>
>>>>
>>>record the
>>>>highest and lowest temperature attained since the last time they were
>>>>
>>>>
>>>reset.
>>>>They are almost always reset every 24 hours, though they don't all get
>>>>
>>>>
>>>reset
>>>>at the same time. That is, different stations, even in the same
>>>>
>>>>
>>>country (or
>>>>in the US, the same state) may reset their thermometers at different
>>>>
>>>>
>>>times of
>>>>the day. This can induce a small bias in one station's climatological
>>>>
>>>>
>>>
>>>
>>>>averages compared to what it would get if it reset at another time.
>>>>
>>>>
>>>This is
>>>>documented in the literature somewhere, though I don't have the
>>>>
>>>>
>>>reference
>>>>myself.
>>>> Using the 3-hourly output will tend to reduce the diurnal
>>>>
>>>>
>>>temperature
>>>>range you get because that is probably not sampling the extremes of
>>>>
>>>>
>>>the day,
>>>>though I have not seen this reduction tabulated by anyone, and it
>>>>
>>>>
>>>probably
>>>>depends on location and season. Including a computation of the true
>>>>
>>>>
>>>daily
>>>>min/max temperature would be just a few lines
>>>>of code, and some of us RegCNETers have
>>>>undoubtedly done it for their version of the
>>>>code - we
>>>>
>>>>
>>>really
>>>>should have it as part of the standard model, I think. There would
>>>>
>>>>
>>>still be
>>>>the question of what time of day to "reset the thermometer", but in
>>>>
>>>>
>>>model
>>>>intercomparisons I've been part of, we typically agree to go from 00
>>>>
>>>>
>>>UTC - 00
>>>>UTC.
>>>>
>>>>Bill
>>>>
>>>>At 11:32 AM -0800 05.11.14, Lara Kueppers wrote:
>>>>
>>>>
>>>>>Hi-
>>>>>Awhile back I asked how Tmin and Tmax in the
>>>>>SRF output file were calculated. Here is
>>>>>Nellie's recent reply, in case anyone else
>>>>>is interested.:
>>>>>
>>>>>"Hi Lara,
>>>>>
>>>>>I just verified this with Bi...Tmin and Tmax are calculated from the
>>>>>
>>>>>
>>>BATS
>>>>>output, so if you have the model output to the SRF file every 3
>>>>>
>>>>>
>>>hours, then
>>>>>that is what the min and max are calculated from. Bi thinks this is
>>>>>
>>>>>
>>>a
>>>>>better way to do it since min and max temp observations are generally
>>>>>
>>>>>
>>>taken
>>>>>from 3 or 6 hourly obs. You can increase the frequency of the srf
>>>>>
>>>>>
>>>output
>>>>>variables (in the regcm.in file) to see how much of difference it
>>>>>
>>>>>
>>>would
>>>>>make in the diurnal temp range. "
>>>>>
>>>>>--
>>>>>~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
>>>>>Lara M. Kueppers, PhD
>>>>>Postgraduate Researcher
>>>>>Department of Earth Sciences
>>>>>University of California, Santa Cruz
>>>>>1156 High Street
>>>>>Santa Cruz, CA 95064
>>>>>USA
>>>>>
>>>>>831.459.3504 ph
>>>>>831.459.3074 fax
>>>>>kueppers at pmc.ucsc.edu
>>>>>
>>>>>_______________________________________________
>>>>>RegCNET mailing list
>>>>>RegCNET at lists.ictp.it
>>>>>https://lists.ictp.it/mailman/listinfo/regcnet
>>>>>
>>>>>
>>>>--
>>>>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>>William J. Gutowski, Jr.
>>>>3021 Agronomy Hall
>>>>Dept. of Geological and
>>>> Atmospheric Sciences
>>>>Iowa State University
>>>>Dept. of Agronomy
>>>>Ames, Iowa 50011-1010
>>>>
>>>>gutowski at iastate.edu
>>>>Tel:1-515-294-5632
>>>>Fax:1-515-294-2619
>>>>http://www.ge-at.iastate.edu/
>>>>http://rcmlab.agron.iastate.edu/
>>>>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>>
>>>>_______________________________________________
>>>>RegCNET mailing list
>>>>RegCNET at lists.ictp.it
>>>>https://lists.ictp.it/mailman/listinfo/regcnet
>>>>
>>>>
>>>>
>>>
>>>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>~ Dr. Xunqiang Bi email:bixq at ictp.it
>>>~ ~ Physics of Weather and Climate Group
>>>~
>>>~ The Abdus Salam ICTP ~
>>>~ Strada Costiera, 11 ~
>>>~ P.O. BOX 586, 34100 Trieste, ITALY ~
>>>~ Tel: +39-040-2240302 Fax: +39-040-2240449 ~
>>>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>_______________________________________________
>>>RegCNET mailing list
>>>RegCNET at lists.ictp.it
>>>https://lists.ictp.it/mailman/listinfo/regcnet
>>>
>>>
>>>_______________________________________________
>>>RegCNET mailing list
>>>RegCNET at lists.ictp.it
>>>https://lists.ictp.it/mailman/listinfo/regcnet
>>>
>>
>>--
>>The Abdus Salam International Centre for Theoretical Physics
>>Strada Costiera 11; 34100 Trieste, ITALY
>>Phone: +39 040 2240579; Fax: +39 040 2240449
>>
>>------------------------------------------------------------------------
>>
>>_______________________________________________
>>RegCNET mailing list
>>RegCNET at lists.ictp.it
>>https://lists.ictp.it/mailman/listinfo/regcnet
>>
>
>--
>~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
>Lara M. Kueppers, PhD
>Postgraduate Researcher
>Department of Earth Sciences
>University of California, Santa Cruz
>1156 High Street
>Santa Cruz, CA 95064
>USA
>
>831.459.3504 ph
>831.459.3074 fax
>kueppers at pmc.ucsc.edu
>
>_______________________________________________
>RegCNET mailing list
>RegCNET at lists.ictp.it
>https://lists.ictp.it/mailman/listinfo/regcnet
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
William J. Gutowski, Jr.
3021 Agronomy Hall
Dept. of Geological and
Atmospheric Sciences
Iowa State University
Dept. of Agronomy
Ames, Iowa 50011-1010
gutowski at iastate.edu
Tel:1-515-294-5632
Fax:1-515-294-2619
http://www.ge-at.iastate.edu/
http://rcmlab.agron.iastate.edu/
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.ictp.it/pipermail/regcnet/attachments/20051116/a9da4688/attachment-0002.html>
More information about the RegCNET
mailing list