[Wrf-users] single grid point surface peculiarities in SNOW & TSLB out of real.exe (UNCLASSIFIED)
Mark Stoelinga
mstoelinga at 3tier.com
Mon Mar 15 16:25:35 MDT 2010
Hi Bob,
I have a fix for this precise problem thanks to Michael Duda at NCAR. WRF was producing "eternal lake effect storms" over lakes on the Tibetan Plateau that were being assigned SST values representative of the Indian Ocean...yikes! But Michael's fix has eliminated the really bad LSTs and all works fine now.
Unfortunately it is not a trivial thing...it involves transforming your landuse data set to have a new "inland lakes" index (using code that Michael Duda at NCAR has written) (or just obtaining the transformed data from Michael or myself), making minor changes to GEOGRID.TBL and namelist.wps, and running a new program after metgrid called "tavgsfc.exe", whose output is then used by real.exe to define lake temperatures as the diurnally averaged surface air temperature during the time period of the metgrid analysis.
If you are using multiple resolutions of landuse, you would have to transform all of them with Michael's code. I've only used it on the 30s landuse data set, and so now I use my transformed 30s landuse data with lakes for all WRF grids of ~1km or coarser.
I can give you more details if you're interested. I think I have an old email somewhere that gives a step-by-step to someone else who asked about it.
It would be really great if the NCAR WRF team could incorporate this fix into the standard WPS and WRF systems in a manner that makes it much more transparent to the user. But I don't know if that is in their queue or not.
Mark
--
Mark Stoelinga, PhD
Senior Scientist
3TIER Inc.
2001 6th Avenue, Suite 2100
Seattle, WA 98121
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On Mar 15, 2010, at 1:42 PM, Dumais, Bob (Civ, ARL/CISD) wrote:
> Classification: UNCLASSIFIED
> Caveats: NONE
>
> FYI-
>
> Refer to my recent emails to Dave Gill over at NCAR. It looks
> to me like the problem of these occasional temperature "bullseye"
> patterns arises due to the hi res land use interpolation producing
> single point "islands" in the nest domain that are classified as water.
> These isolated small inland water bodies are not well initialized in
> terms of SST (or I guess SKINTEMP/TSK) values from the external model
> (in the case of my Afghan 1 km nest example, the GFS). Is there a way
> any of you know to improve the initial condition, without doing too much
> effort? Maybe there is a parameter in GEOGRID.TBL or METGRID.TBL that
> can allow for manual setting of SST/SKINTEMP/TSK for any nest inland
> water bodies? Thanks-
>
>
> Bob
>
> -----Original Message-----
> From: Dumais, Bob (Civ, ARL/CISD)
> Sent: Monday, March 15, 2010 2:07 PM
> To: 'gill at ucar.edu'
> Cc: 'Jim Dudhia'
> Subject: RE: single grid point surface peculiarities in SNOW & TSLB out
> of real.exe (UNCLASSIFIED)
>
> Classification: UNCLASSIFIED
> Caveats: NONE
>
> Dave,
>
> Sorry to have bothered you so much on this topic! My
> conclusion after further looking at both the Afghanistan and the
> Washington state/Columbia River Basin hi res cases is this:
>
> (i) it is possible to get very small areas, even singular
> grid point areas, of water classification within a much larger
> surrounding area of land (I suppose vice versa over an open water area
> may also be possible).
>
> (ii) the default value for water temp (SST??) in such an
> instance, such as from GFS 1-degree, may not at all be very
> representative. For example, the Afghanistan "water" grid point where I
> have been finding the bullseye 2 magl temperature value pattern is much
> warmer than it should be for this time of year (~ 296-297 deg K
> initialization). Over the CONUS, the higher res NAM 218 does a decent
> job initializing SST/ Skin Temp for the larger inland lake bodies such
> as Great Salt Lake.
>
> (iii) I find that TSLB and SST fields at t=0 are the same,
> but that TSLB becomes different thereafter. Does TSLB even matter for a
> water point through a WRF simulation? Is it just garbage after t=0 h?
> The T 2 magl does seem to stay fairly consistent with the initial SST
> value throughout the recent Afghan simulation .
>
> (iv) How best to modify in a cold start such initial water
> temp values for points such as these, when it is obvious that the
> initial value provided is out in left field?
>
>
>
> Bob -----Original Message-----
> From: Dumais, Bob (Civ, ARL/CISD)
> Sent: Monday, March 15, 2010 1:23 PM
> To: 'gill at ucar.edu'
> Cc: 'Jim Dudhia'
> Subject: RE: single grid point surface peculiarities in SNOW & TSLB out
> of real.exe (UNCLASSIFIED)
>
> Classification: UNCLASSIFIED
> Caveats: NONE
>
> Hi again Dave,
>
> I looked at this particular case in Afghanistan a little
> more closely this morning, and it seems to actually be related to the
> landuse / landmasking coming out of geogrid.tbl. These are high
> resolution nests (nest 1 is 9 km; nest 2 is 3 km; nest 3 is 1 km) and I
> used 30 arc sec terrain/land use option in geogrid for the
> interpolations of all my nests. I'm finding that for the point I
> identified on the 1 km nest (figures were attached in Friday's email),
> the landmask and xland parameters also produce a bullseye due to a
> "water" classification. This is basically a single "water" point on the
> 1 km nest out all alone amidst the surrounding land. When I plotted
> "xland" using GRADS for the initial "0" output, it bullseyed to a value
> of 1.79. I don't know if this is an artifact of GrADS, but shouln't it
> have gone to 2? Also, plotting landmask produces a bulleseye value of
> just under 0.3 (as opposed to 0 as I would expect). Finally, plotting
> lu_index shows another bullseye pattern with 14 in the center (ie;
> water). All this stuff leads to the behaviors in the SNOW & TSLB field
> that I noted Friday. Any thoughts on this? Is it ok to leave as a 1 km
> bullseye, even if it looks less than "pretty"? Thx-
>
> Bob
>
> -----Original Message-----
> From: Dumais, Bob (Civ, ARL/CISD)
> Sent: Friday, March 12, 2010 5:34 PM
> To: 'gill at ucar.edu'
> Cc: 'Jim Dudhia'
> Subject: single grid point surface peculiarities in SNOW & TSLB out of
> real.exe (UNCLASSIFIED)
>
> Classification: UNCLASSIFIED
> Caveats: NONE
>
> Hi Dave,
>
> I sent this email below off to Jimy a bit back, and he
> suggested forwarding to you since it seems a real.exe issue (perhaps
> with snowcover adjustment if skintemp exceeds 0 deg C??). Enjoy the
> weekend.
>
>
> Bob
>
>
> -----Original Message-----
> From: Dumais, Bob (Civ, ARL/CISD)
> Sent: Friday, March 12, 2010 5:07 PM
> To: 'Jim Dudhia'; wrfhelp
> Cc: 'Mark Stoelinga'; 'Sen Chiao'; 'Don Morton'; 'David Ovens'; 'Andre
> Pattantyus'; 'Min Zhu'; Haines, Patrick (Civ, ARL/CISD); Knapp, Dave
> (Civ, ARL/CISD); Wang, Yansen (Civ, ARL/CISD); Williamson, Chatt (Civ,
> ARL/CISD); Passner, Jeff (Civ, ARL/CISD); 'Dr. Craig A. Mattocks';
> 'Thomas Raab'; 'Hoeth, Brian R. (JSC-WS8)[NOAA]'
> Subject: RE: [Wrf-users] Upper boundary cfl error (UNCLASSIFIED)
>
> Classification: UNCLASSIFIED
> Caveats: NONE
>
> All,
>
> I have captured some examples of the anomalous 2 magl T
> points (alluded to somewhere in our email trail below), which I have
> come across in a few places where I have established high resolution
> grids (such as the Columbia River Basin in WA & Afghanistan). I
> definately used GFS as ICs for my Afghanistan examples attached here,
> but can't recall off the top of my head if it was NAM 218 or GFS for the
> Washington state plots.
>
> The plots above show the evolution of three different fields
> over time (SNOW, T2, & TSLB), the first set for a case over Washington
> state and another for Afghanistan near Kabul. Both are "zoomed in" areas
> of my 1 km domain to isolate the anomaly better. I also show comparative
> temps at sigma level 1 in a few plots, to show that the anomaly is
> basically isolated to the diagnostic 2magl T level and the surface. I do
> realize now that I left out my t=0h TSLB plot for the Washington case
> above.
>
> What I've seen in these forecasts plotted is the following
> behavior:
>
> (i) T2 starts out too warm at an isolated grid
> point, and tend to remain that way
>
> (ii) TSLB starts out too warm at the same
> isolated point (even though that plot is not attached, it does so in the
> Washington case too), but then as the model evolves appears to become a
> local cool spot. The Washington case started at 12z- the Afghanistan
> case at 00 Z.
>
> (iii) SNOW starts out with a local min value
> at the same grid point.
>
> (iv) at the first sigma level and above, this
> seems to have little if any impact on T field.
>
> The WRF version used for the Washington run above was
> 3.0.1.1, and 3.1.1 was used for Afghanistan. To me, this problem seems
> rooted to the initial value of SNOW (and perhaps TSLB) that are
> generated by metgrid.exe in WPS 3.1. I looked at the METGRD.TBL and I am
> using the default interpolation method of four pt + average_4pt. I will
> try a different interpolation method next week to see if it has an
> impact. Have any of you seen this before?
>
>
> Bob
>
>
>
>
>
>
>
> -----Original Message-----
> From: Dumais, Bob (Civ, ARL/CISD)
> Sent: Tuesday, March 09, 2010 10:56 AM
> To: 'Jim Dudhia'
> Cc: Mark Stoelinga; Sen Chiao; Don Morton; David Ovens; Andre
> Pattantyus; Min Zhu; Haines, Patrick (Civ, ARL/CISD); Knapp, Dave (Civ,
> ARL/CISD); Wang, Yansen (Civ, ARL/CISD); Williamson, Chatt (Civ,
> ARL/CISD); Passner, Jeff (Civ, ARL/CISD); Dr. Craig A. Mattocks; Thomas
> Raab; Hoeth, Brian R. (JSC-WS8)[NOAA]
> Subject: RE: [Wrf-users] Upper boundary cfl error (UNCLASSIFIED)
>
> Classification: UNCLASSIFIED
> Caveats: NONE
>
> Jimy,
>
> I was thinking the same thing, and would be glad to!! Very
> exciting I believe. I don't believe I'd be able to provide anything like
> the rigid mathematical treatment you provided in your REPLY for the
> various stability criteria, but I could attempt to provide a little
> better information for users on how to apply epsmm and time step for
> such a complex terrain region as British Columbia if applying a fine
> horizontal resolution nesting scheme. For this, I would probably stick
> initially to the 1 km grid spacing which gave me problems for the past
> few months! Thanks for all your help, as always. You are always a good
> sport about supplying ideas and suggestions, even though I realize you
> are probably swamped by your own research problems and concerns. Have a
> great day!
>
>
> Bob
>
>
> -----Original Message-----
> From: Jim Dudhia [mailto:dudhia at ucar.edu]
> Sent: Tuesday, March 09, 2010 10:46 AM
> To: Dumais, Bob (Civ, ARL/CISD)
> Cc: Jim Dudhia; Mark Stoelinga; Sen Chiao; Don Morton; David Ovens;
> Andre Pattantyus; Min Zhu; Haines, Patrick (Civ, ARL/CISD); Knapp, Dave
> (Civ, ARL/CISD); Wang, Yansen (Civ, ARL/CISD); Williamson, Chatt (Civ,
> ARL/CISD); Passner, Jeff (Civ, ARL/CISD); Dr. Craig A. Mattocks; Thomas
> Raab; Hoeth, Brian R. (JSC-WS8)[NOAA]
> Subject: Re: [Wrf-users] Upper boundary cfl error (UNCLASSIFIED)
>
> Bob,
> Very good to hear. I certainly encourage seeing if you can get
> longer time steps by increasing epssm further. You should look at
> whether other things in the solution are affected, but I think probably
> not, since it is only sound waves we are damping heavily.
> It might be nice to have a grid of various epssm and time-steps to
> see what works and what doesn't, and give a clue how to compromise
> between them. Could make for a nice workshop talk.
> Jimy
>
> On Mar 9, 2010, at 10:39 AM, Dumais, Bob (Civ, ARL/CISD) wrote:
>
>> Classification: UNCLASSIFIED
>> Caveats: NONE
>>
>> All,
>>
>> Great news to report of my latest Whistler run!! Dr. Dudhia's
>> suspicion seems confirmed, and his suggested solution also seems to be
>
>> spot on!! Last night, with the 90 level version of the model on my 1
>> km domain, I was able to proceed with no issues at all!! This with
>> nonlinear grid stagger per WRF DomainWizard, and a lowest half-level
>> of about 24 magl. Recall that my outer mesh is 9 km (I triple nest-
>> 9/3/1 km).
>>
>> (i) set my course grid advective time step to 6 s from
>
>> my previous value of 9 s (then apply 3:1 ratio onto other nests, so
>> the
>> 1 km nest has an advective time step of about 0.667 s) .
>>
>> (ii) reset the value of the vertical sound wave
>> damping coefficient (epssm) from 0.1 to 0.3
>>
>> Now refer to my new plots above for the 1 km domain: two of them at
>
>> the 5h fcst mark valid 12-23-2010 17Z, and another showing the w
>> vertical profile at the same point and time (50.0565 N; -123.362 W, 30
>
>> s at 12-23-2010 12:00:30 Z)that had the significant low-level vertical
>
>> instability in w yesterday. The differences are amazing! The
>> combination of larger epsmm and smaller timestep completely alleviated
>
>> the problem.
>> The 5 h forecast fields (I have just plotted wind vectors here) look
>> very complex but reasonable. Jimy's earlier worked showed that for
>> greater and greater model slopes, the solution had to be either
>> progressively smaller advective time steps or higher epssm (between 0
>> and 1). I kind of compromised here and did a little of both, and the
>> results are very promising. I trust from Jimy's paper that this
>> damping coeefficient has been shown to have limited to no impacts on
>> the important flow/meteorological modes other than acoustical.
>>
>> My next step is to do the same model run again, except with a
>> larger time step (9 s for 9 km grid). If this fails, I'll keep that
>> time step and go to a higher epssm. Finally, if one or the other
>> works, I'll try a final experiment with a time step of 27 s for 9 km
>> (a 3;1 ratio for grid space/time step). Many thanks need to go out to
>> Dr. Dudhia for his suggestion over the past week- someone should buy
>> him a beer this weekend!! We have plenty we can experiment with
>> seemingly. Cheers-
>>
>>
>>
>> Bob
>>
>> -----Original Message-----
>> From: Dumais, Bob (Civ, ARL/CISD)
>> Sent: Monday, March 08, 2010 10:44 AM
>> To: 'Jim Dudhia'; 'Mark Stoelinga'; 'Sen Chiao'; 'Don Morton'; 'David
>> Ovens'; 'Andre Pattantyus'; 'Min Zhu'; Haines, Patrick (Civ, ARL/
>> CISD); Knapp, Dave (Civ, ARL/CISD); Wang, Yansen (Civ, ARL/CISD);
>> Williamson, Chatt (Civ, ARL/CISD); Passner, Jeff (Civ, ARL/CISD); 'Dr.
>> Craig A.
>> Mattocks'
>> Subject: RE: Re: [Wrf-users] Upper boundary cfl error (UNCLASSIFIED)
>>
>> Classification: UNCLASSIFIED
>> Caveats: NONE
>>
>> Greetings!
>>
>> For all of you who enjoyed last week's message trail regarding
>> the single point "blow-up" on my Whistler, BC 1 km domain- I have more
>> :)
>>
>> As noted in my earlier email from this morning, I did move my
>> nest
>> 3 (1 km) domain center slightly to the east by 0.25 deg longitude in
>> order to avoid that troublesome point in my initial domain (~
>> 50.1286 N;
>> -123.6265 W). The plots I emailed Thursday were from that domain and
>> showing that particular grid point location.
>>
>> I let the new domain with the shift run over the weekend, and
>> when I looked at the results this morning I discovered it blew up
>> again but at a new location!! At first glance it appeared to be
>> possibly at the same I,J location on the new grid as in the initial
>> domain. I have confirmed to myself this is not the case, so we can put
>
>> that concern to bed. This is back to purely a slope discussion again I
>
>> think.
>>
>> The plots I have now show the blow up for the new domain, at/near
>
>> the grid point location (50.0565 N and -123.362 W). The first set of
>> slides show the w, horizontal vector sfc wind, and terrain fields for
>
>> this area/point. Notice the same exact behaviors as noted for the
>> other location in my original configuration!! Since this new grid
>> point location also happened to be contained in my original nest
>> configuration, the last few plots attached here will show some of
>> these same plots for the new location in the old configuration. Notice
>
>> the vertical profile of W in the last plot and how similar it appears!
>> Just
>> not enough apparently to cause a CFL violation at this point in the
>> original configuration. Interesting.
>>
>> The only other comment I have to make about hi res complex model
>
>> topography and strange behaviors is this. In certain places (such as
>> my Columbia River Basin runs in Washington at 1 km), I do not see such
>
>> blow ups but another phenomena. In or near the narrow river basin
>> locations (which may be just a few grid points across), I'll
>> occasionally find single points where there appear to be "bullseyes"
>> in the surface T/TD fields along with stronger wind values. These
>> bullseyes appear almost immediately at the start of the simulations,
>> and can cause differences of up to several deg C between that point
>> and its surroundings. I do not know if there is some kind of relation
>> to the things we are seeing with the slope, or if it some kind of
>> Bernoulli flow kind of thing. I'll try to capture and example for you
>> all later.
>>
>> Bob
>>
>> PS: You can open all these gif attachments with MS Picture Manager or
>> similar. Note that in my original configuration I sent Thur, the blow
>> up really took off at about 1m 45s (even though my plots may have
>> erroneously said 90s ). In my new configuration at the new "blow up"
>> location, the blow ups and CFLs appear to be even earlier at 30s.
>> Plots
>> 1-6 attached show fields for this new point location. Plots 7 and 8
>> show fields for this same location within the old configuration at 1m
>> 45s of that run. Notice it has some of that strange low-level w
>> behavior but not enough to cause a blow up or CFL violations!!
>> Disregard the wording on my plot title in Figs 7-8 - it should read
>> the opposite of what it does!
>>
>>
>> -----Original Message-----
>> From: Dumais, Bob (Civ, ARL/CISD)
>> Sent: Thursday, March 04, 2010 5:22 PM
>> To: 'Jim Dudhia'; 'Mark Stoelinga'; 'Sen Chiao'; 'Don Morton'; David
>> Ovens; 'Andre Pattantyus'; 'Min Zhu'; Haines, Patrick (Civ, ARL/CISD);
>
>> Knapp, Dave (Civ, ARL/CISD); Wang, Yansen (Civ, ARL/CISD); Williamson,
>
>> Chatt (Civ, ARL/CISD); Passner, Jeff (Civ, ARL/CISD)
>> Subject: Re: [Wrf-users] Upper boundary cfl error (UNCLASSIFIED)
>>
>> Classification: UNCLASSIFIED
>> Caveats: NONE
>>
>> All-
>>
>> For anyone interested, here are a few GRADS plots along
>> with my configuration namelists (using my triple nest configuration)
>> for that problematic domain near Whistler, BC (where the blow-ups
>> happen after a few minutes). I've tried several cases in Feb, such as
>> Feb 23 12Z - Feb 24 12Z (using 06UTC Feb 23 GFS datasets), and this
>> happens all the time in this configuration. I also have a double nest
>> configuration (basically, nests 2 and 3 shown here without outer nest,
>
>> using
>> NAM-218)
>> where this happens also. My GEOGRID.TBL shows I am using just a
>> single pass smoothing in all my previous attempts. Perhaps this is a
>> good domain for others to focus upon for investigating this problem?
>> Thanks,
>> and all have a good evening!
>>
>> Bob
>> Classification: UNCLASSIFIED
>> Caveats: NONE
>>
>>
>> Classification: UNCLASSIFIED
>> Caveats: NONE
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>>
>> Classification: UNCLASSIFIED
>> Caveats: NONE
>>
>>
>> <03fixw.gif><02fixw.gif><01fixw.gif>
>
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