[RegCNET] tmax and tmin

[Lara Kueppers]

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
>
> Tomáš 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
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>>>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                        ~
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>>
>
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-- 
~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
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