[Wrf-users] Re: Wrf-users Digest, Vol 29, Issue 1
WRF Help
wrfhelp at ucar.edu
Wed Jan 3 13:42:20 MST 2007
Best way to do single obs test in WRF-Var is to activate
"pseudo_ob_nl" namelist options.
To do this, set following environment variables in DA_Run_WRF-Var.csh
script.
DA_DA_NUM_PSEUDO 1
DA_PSEUDO_X 25 (X co-ordinate in your grid)
DA_PSEUDO_Y 25 (Y co-ordinate in your grid)
DA_PSEUDO_X 10 (Z co-ordinate in your grid)
DA_PSEUDO_VAL 1.0 (It will set 1.0 K departure from background
tempearture at the desired location)
DA_PSEUDO_ERR 1.0 (It will set observation error as 1.0 K)
DA_PSEUDO_VAR t ( For temperature single obs test)
After successfully running WRF-Var, plot analysis increments
(analysis-background) to see how this single observation changed the
initial background (FG) field at different levels. With this setting
maximum increments is expected at level 10.
Make sure that you switched off the use of all types of observations
like SYNOP, SOUND etc. while running DA_Run_WRF-Var.csh by setting
DA_USE_SYNOP = .FALSE. , DA_USE_SOUND= .FALSE. etc.
wrfhelp
On Jan 2, 2007, at 12:00 PM, wrf-users-request at ucar.edu wrote:
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> Today's Topics:
>
> 1. Seeking WRF-Var Guidance (Don Morton)
> 2. Re: Seeking WRF-Var Guidance (Elif SERTEL)
> 3. Re: Seeking WRF-Var Guidance (Michael Mcatee)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 2 Jan 2007 00:49:02 +0000
> From: "Don Morton" <Don.Morton at umontana.edu>
> Subject: [Wrf-users] Seeking WRF-Var Guidance
> To: wrf-users at ucar.edu
> Message-ID:
> <237e74280701011649j31206e56t1e9185b6cd61e7a7 at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Howdy, now that it's "vacation" time again I'm back to
> trying to muddle my way through WRF-Var. I feel like I
> may have my procedures down correctly, but I don't have
> the practical experience to know if my results are reasonable
> or not.
>
> To date, I have gone through the WRF-Var tutorial successfully
> and understand the basic procedures. In order to gain a better
> understanding of all this, my efforts are now focused on assimilating
> a single surface observation on a 50km x 50km domain centered on
> Deadhorse, Alaska. The domain is 1km resolution with 31 levels.
>
> My intent is to ingest a single surface temperature obs at lat/lon
> 70.20/-148.47 (Deadhorse). I wrote up a Fortran program that
> will take a netCDF wrfout (or wrfinput) filename, lat, and lon as
> arguments, find the four surrounding grid points, then do a bilinear
> interpolation to estimate a "point" value. For this particular
> location
> I find that the initial temperature in my wrfinput_d01 file is -23.8C.
>
> So, I've created a little_r obs file (thank you Mike McAtee and
> Xuanli for
> responding to my post a couple of months ago about how to get my
> surface obs into little_r format) that presents a perturbed
> temperature
> at this point (I've tried several values), then gone through the
> assimilation
> process. In all cases, when I compare the initial temperature in the
> original wrfinput_d01 with the one in the wrfvar output file, they're
> identical out to 7 significant digits. An excerpt of the wrf-var
> output
> from using an obs temperature of 8K higher than the initial
> temperature
> from wrfinput_d01 is:
>
> ----------------------------------------------------------
> Inner iteration stopped after 1 iterations
> Final cost function : 7.76275575D+00 and Gradient: 7.96228229D-14
> ----------------------------------------------------------
>
> Final cost function J = 7.762755752421293
>
> Total number of obs. = 1
> Final 3DVAR value of J = 7.76276
> Final 3DVAR value of Jo = 7.53804
> Final 3DVAR value of Jb = 0.22471
> Final J / total num_obs = 7.76276
> 3DVAR Jb factor used (1)= 1.00000
> 3DVAR Jb factor used (2)= 1.00000
> 3DVAR Jb factor used (3)= 1.00000
> 3DVAR Jb factor used (4)= 1.00000
> 3DVAR Jb factor used (5)= 1.00000
>
> I've also tried perturbations of 4K, 23K, etc. It seems that
> if my perturbed obs is too large (e.g. greater than 12K), the
> obs isn't even used.
>
> Now I'm stuck. I have a number of theories, but I'd like to avoid
> too much blind trial and error. What I'd like to do is introduce an
> observation (or set of observations) that will actually result in my
> wrf-var output showing an initial temperature that's different from
> the one in my original wrfinput_d01.
>
> I'm using the default background error files that came with
> WRF-Var. I do realize that I need to modify these at some
> point, but right now I'm just on an incremental learning curve
> and I'm looking for qualitative differences.
>
> I'm guessing that maybe introducing a single obs into this domain
> just isn't "enough" for WRF-Var to assimilate it, and the gradient
> I see in the previous example sort of strengthens that theory. So, my
> question is, given my 50x50 1km-resolution domain, is it reasonable
> to expect WRF-Var (with the default background error files) to produce
> some perturbed initial temperatures near Deadhorse, based on a single
> surface temperature obs, or am I asking for too much?
>
> If some kind and patient soul would be willing to help guide me
> through
> this process, I'd be very appreciative, and I'd be very happy to
> write up
> a tutorial - sort of a Dummy's Guide on how - after you've gone
> through
> the WRF-Var Tutorial - you'd go about setting up your own simple
> domain
> with some basic obs for assimilation. In my opinion, the current
> WRF-Var
> tutorial is great for understanding some of the basic procedures,
> but it's
> a huge jump from there to ingesting one's own obs and getting them
> to assimilate effectively into one's own domain. I'd like to think
> that
> this Dummy's Guide would help to bridge that.
>
> I've gone through an AMS paper and Tech Report by Barker, et. al on
> "A Three-Dimensional Variational Data Assimilation System for MM5,"
> but estimate I need to go through these another 758 times before I
> understand most of the details. I have some background in Finite
> Element
> Methods, so the idea of variational methods isn't totally foreign.
> At this
> point, I "think" what I need is access to some practical
> expertise. At this
> point, blindly trying lots of different things doesn't seem very
> productive, and
> I'm not sure where else to turn.
>
> Also, I'm getting the impression that WRF-Var is pretty much an
> extension
> of the MM5 data assimilation code. Does anybody know of "Dummy Guide"
> types of references for MM5 that might help me?
>
> Thanks for your patience and time on reading what I believe may be
> the first wrf-users post of 2007!
>
> Don Morton
>
> --
> Don Morton
> Department of Computer Science
> The University of Montana - Missoula
> http://www.cs.umt.edu/~morton/
>
>
> ------------------------------
>
> Message: 2
> Date: Mon, 1 Jan 2007 20:27:53 -0500 (EST)
> From: "Elif SERTEL" <esertel at envsci.rutgers.edu>
> Subject: Re: [Wrf-users] Seeking WRF-Var Guidance
> To: wrf-users at ucar.edu
> Message-ID:
> <4597.172.23.42.134.1167701273.squirrel at webmail.envsci.rutgers.edu>
> Content-Type: text/plain;charset=iso-8859-1
>
> Dear list,
>
> I am using grads to plot my wrf output results. Is there a time
> number
> limit when converting the wrf output files to grads ctl files using
> wrf to
> grads. I have 6 hourly data for a month. Unfortunately, I could not
> put
> all of them into one ctl file using wrf2grads. What should I do?
>
> Best wishes,
>
> Elif SERTEL.
>
>
>
> ------------------------------
>
> Message: 3
> Date: Tue, 2 Jan 2007 10:59:06 -0600
> From: Michael Mcatee <Michael.Mcatee at aero.org>
> Subject: Re: [Wrf-users] Seeking WRF-Var Guidance
> To: "Don Morton" <Don.Morton at umontana.edu>
> Cc: wrf-users at ucar.edu, wrf-users-bounces at ucar.edu
> Message-ID:
> <OF7F347177.BF148B58-
> ON88257257.005A8C5C-86257257.005D4D2A at notes.aero.org>
>
> Content-Type: text/plain; charset="us-ascii"
>
> Don,
>
> Even thought the observation might be read in it may not be used.
> If the
> observation is 5 standard deviations away from the background (for
> surface
> temperature I believe the error standard deviation is 2 degrees
> C). Also
> if the model terrain is significantly different that the actual
> terrain
> the observation will not be used. One quick way to tell if your ob
> was
> used is to look at the fort.12 file. This file has the fit of the
> background field to the observations (by observation type) and the
> fit of
> the resulting analysis to the observations. If 3DVAR worked then you
> should see a better fit with the analysis than the background.
> Also the
> fort.60 file will tell you which obs were rejected by 3DVAR .
> Hope this helps.
>
> Mike
> ___________________________
> Michael D. McAtee
> The Aerospace Corporation
> 106 Peacekeeper Dr. STE 2N3
> Offutt, AFB, NE 68113-4039
> email: michael.mcatee at aero.org
> Phone: (402) 292-1017
> Fax: (402) 291-3137
>
>
>
> "Don Morton" <Don.Morton at umontana.edu>
> Sent by: wrf-users-bounces at ucar.edu
> 01/01/2007 06:49 PM
>
> To
> wrf-users at ucar.edu
> cc
>
> Subject
> [Wrf-users] Seeking WRF-Var Guidance
>
>
>
>
>
>
> Howdy, now that it's "vacation" time again I'm back to
> trying to muddle my way through WRF-Var. I feel like I
> may have my procedures down correctly, but I don't have
> the practical experience to know if my results are reasonable
> or not.
>
> To date, I have gone through the WRF-Var tutorial successfully
> and understand the basic procedures. In order to gain a better
> understanding of all this, my efforts are now focused on assimilating
> a single surface observation on a 50km x 50km domain centered on
> Deadhorse, Alaska. The domain is 1km resolution with 31 levels.
>
> My intent is to ingest a single surface temperature obs at lat/lon
> 70.20/-148.47 (Deadhorse). I wrote up a Fortran program that
> will take a netCDF wrfout (or wrfinput) filename, lat, and lon as
> arguments, find the four surrounding grid points, then do a bilinear
> interpolation to estimate a "point" value. For this particular
> location
> I find that the initial temperature in my wrfinput_d01 file is -23.8C.
>
> So, I've created a little_r obs file (thank you Mike McAtee and
> Xuanli for
> responding to my post a couple of months ago about how to get my
> surface obs into little_r format) that presents a perturbed
> temperature
> at this point (I've tried several values), then gone through the
> assimilation
> process. In all cases, when I compare the initial temperature in the
> original wrfinput_d01 with the one in the wrfvar output file, they're
> identical out to 7 significant digits. An excerpt of the wrf-var
> output
> from using an obs temperature of 8K higher than the initial
> temperature
> from wrfinput_d01 is:
>
> ----------------------------------------------------------
> Inner iteration stopped after 1 iterations
> Final cost function : 7.76275575D+00 and Gradient: 7.96228229D-14
> ----------------------------------------------------------
>
> Final cost function J = 7.762755752421293
>
> Total number of obs. = 1
> Final 3DVAR value of J = 7.76276
> Final 3DVAR value of Jo = 7.53804
> Final 3DVAR value of Jb = 0.22471
> Final J / total num_obs = 7.76276
> 3DVAR Jb factor used (1)= 1.00000
> 3DVAR Jb factor used (2)= 1.00000
> 3DVAR Jb factor used (3)= 1.00000
> 3DVAR Jb factor used (4)= 1.00000
> 3DVAR Jb factor used (5)= 1.00000
>
> I've also tried perturbations of 4K, 23K, etc. It seems that
> if my perturbed obs is too large (e.g. greater than 12K), the
> obs isn't even used.
>
> Now I'm stuck. I have a number of theories, but I'd like to avoid
> too much blind trial and error. What I'd like to do is introduce an
> observation (or set of observations) that will actually result in my
> wrf-var output showing an initial temperature that's different from
> the one in my original wrfinput_d01.
>
> I'm using the default background error files that came with
> WRF-Var. I do realize that I need to modify these at some
> point, but right now I'm just on an incremental learning curve
> and I'm looking for qualitative differences.
>
> I'm guessing that maybe introducing a single obs into this domain
> just isn't "enough" for WRF-Var to assimilate it, and the gradient
> I see in the previous example sort of strengthens that theory. So, my
> question is, given my 50x50 1km-resolution domain, is it reasonable
> to expect WRF-Var (with the default background error files) to produce
> some perturbed initial temperatures near Deadhorse, based on a single
> surface temperature obs, or am I asking for too much?
>
> If some kind and patient soul would be willing to help guide me
> through
> this process, I'd be very appreciative, and I'd be very happy to
> write up
> a tutorial - sort of a Dummy's Guide on how - after you've gone
> through
> the WRF-Var Tutorial - you'd go about setting up your own simple
> domain
> with some basic obs for assimilation. In my opinion, the current
> WRF-Var
> tutorial is great for understanding some of the basic procedures,
> but it's
> a huge jump from there to ingesting one's own obs and getting them
> to assimilate effectively into one's own domain. I'd like to think
> that
> this Dummy's Guide would help to bridge that.
>
> I've gone through an AMS paper and Tech Report by Barker, et. al on
> "A Three-Dimensional Variational Data Assimilation System for MM5,"
> but estimate I need to go through these another 758 times before I
> understand most of the details. I have some background in Finite
> Element
> Methods, so the idea of variational methods isn't totally foreign. At
> this
> point, I "think" what I need is access to some practical
> expertise. At
> this
> point, blindly trying lots of different things doesn't seem very
> productive, and
> I'm not sure where else to turn.
>
> Also, I'm getting the impression that WRF-Var is pretty much an
> extension
> of the MM5 data assimilation code. Does anybody know of "Dummy Guide"
> types of references for MM5 that might help me?
>
> Thanks for your patience and time on reading what I believe may be
> the first wrf-users post of 2007!
>
> Don Morton
>
> --
> Don Morton
> Department of Computer Science
> The University of Montana - Missoula
> http://www.cs.umt.edu/~morton/
> _______________________________________________
> Wrf-users mailing list
> Wrf-users at ucar.edu
> http://mailman.ucar.edu/mailman/listinfo/wrf-users
>
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