I also did come across the negative precipitation values in CRU data while comparing with model results. And it is more when your region has more hetrogeneous topograohy and landuse. This is very troubling initially - as precipitaion peaks are averaged over the resolution, i.e., 0.5x0.5. You onl;y can over some this problem by assuming/forcing any negative value to zero. This gets more clearer when you run your simulation with subgrid scheme also and compare with no subgrid run and CRU.
Best of luck
Ashok
From: regcnet-request@lists.ictp.it
Reply-To: regcnet@lists.ictp.it
To: regcnet@lists.ictp.it
Subject: Regional Climate Network Digest
Date: Fri, 16 Mar 2007 02:48:06 +0100
>
>
>Content:
>
> 1. negative values in the fields of precipitation (smirnova)
> 2. Re: negative values in the fields of precipitation (Moetasim)
> 3. Re: Problem in running RegCM in IBM machine (Moetasim)
> 4. Re: 10 km run (Moetasim)
> 5. Re: irrigation problem__modify soil moisture (Moetasim)
> 6. Re: negative values in the fields of precipitation
> (gaoxj@cma.gov.cn)
>
>
>----------------------------------------------------------------------
>
>From: "smirnova" <smirnova@meteo.kz>
>Subject: [RegCNET] negative values in the fields of precipitation
>
>Dear All,
>
>I have faced with problem. The fields of precipitation from CRUdata have negative values (-0,000686634) for some regions. What does it mean? And how to avoid them? As I know value -32767 is used for missing data.
>
>Thanks in advance for any help !
>Elena
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>------------------------------
>
>From: Moetasim <mashfaq@purdue.edu>
>Subject: Re: [RegCNET] negative values in the fields of precipitation
>
>you can mask all values below zero. A mask in ferret would be as following:
>
>let masked_rain=if rain[d=1] lt 0.0 then 0.001 else rain[d=1]
>
>This will replace all negative values with 0.001.
>
>Moet
>
>
>
>Quoting smirnova <smirnova@meteo.kz>:
>
> > Dear All,
> >
> > I have faced with problem. The fields of precipitation from CRUdata have
> > negative values (-0,000686634) for some regions. What does it mean? And how
> > to avoid them? As I know value -32767 is used for missing data.
> >
> > Thanks in advance for any help !
> > Elena
> >
>
>
>------------------------------
>
>From: Moetasim <mashfaq@purdue.edu>
>Subject: Re: [RegCNET] Problem in running RegCM in IBM machine
>
>
>Your Terrain didn't run successfully, therefore, it didn't write DOMAIN.INFO
>correctly ( or at all). You should check DOMAIN.INFO file in grads. To diagonse
>the problem, you may send (to RegCNET) what you get after running ./terrain.x
>(for the 2nd time).
>
>Quoting Dilip Ganguly <dganguly@prl.res.in>:
>
> > Dear all,
> >
> > I am facing some problem in trying to run RegCM3 in a new IBM power5+
> > machine of our institute. The specifiactions of this machine are as
> > follows
> > ----------------------------------------------------------
> > -- Four 1.9GHz Power5+ Processors.
> > -- 8 GB RAM
> > -- 73.4 GB * 2 Hard Disk (73.4 GB available for user Data)
> > -- POWER GXT 135P Graphics Accelerator
> > -----------------------------------------------------------
> > I am using the IBM XL FORTRAN V10.1 installed in this machine.
> >
> > Initially, while executing the terrain.x, I was getting the following
> > error message.
> > -------------------------------------------------------------------
> > 1501-510 Compilation successful for file terrain.f.
> > xlf_r -o terrain terrain.o -L../../Commons/env/libibm/ -lnetcdf
> > Target "all" is up to date.
> > exec(): 0509-036 Cannot load program ./terrain because of the following
> > errors:
> > 0509-026 System error: There is not enough memory available now.
> > --------------------------------------------------------------------------
> >
> > Then in order to overcome this problem, I executed the following command
> > in my machine
> >
> > export LDR_CNTRL=MAXDATA=0x80000000@LARGE_PAGE_DATA=Y
> > After using the above coomand, I could execute terrain.x
> > But when I tried to execute the icbc.x, I am etting the following error
> > -----------------------------------------------------------------------
> > IMPROPER DIMENSION SPECIFICATION (ICBC.f)
> > icbc.param: 80 115 18
> > DOMAIN.INFO: 0 0 0
> > Also check ibyte in icbc.param: ibyte= 4
> > STOP Dimensions (subroutine gridml)
> > -------------------------------------------------------------------------
> > Can anyone understand why I am getting this error message. I have checked
> > that after executing the terrain.x, DOMAIN.INFO and DOMAIN.CTL files are
> > properly produced in the RegCM/Input directory. But still I am getting the
> > above error.
> >
> > Thanks in advance for your help.
> >
> > Dilip.
> >
> > ---------------------------------------------------------------------
> > Dr. DILIP GANGULY
> > Postdoctoral Fellow
> > Space And Atmospheric Sciences Division
> > Physical Research Laboratory
> > Ahmedabad 380009
> > Gujarat, India
> > Phone: +91 79 26314558 (Laboratory)
> > +91 79 26300505 (Hostel)
> > Fax: +91 79 26314659
> > Alternate Email: ganguly.dilip@gmail.com
> > Visit me at http://www.prl.res.in/~dganguly
> > ---------------------------------------------------------------------
> >
> >
> >
> > _______________________________________________
> > RegCNET mailing list
> > RegCNET@lists.ictp.it
> > https://lists.ictp.it/mailman/listinfo/regcnet
> >
>
>
>------------------------------
>
>From: Moetasim <mashfaq@purdue.edu>
>Subject: Re: [RegCNET] 10 km run
>
>Hi,
>
>1) I agree with gao that a direct run at 10 km using 2.5 degree ICBC data is a
>bit harsh use of RegCM3. The better approach is to run RegCM at intermediate
>resolution (say 25/30 km) and then run a further nested run at 10 km. Also, it
>would be advisable to use better resolution ICBC data (e.g. a high resolution
>ERA40).
>
>2) One reason of RegCM over estimation is your small domain. I expect model
>getting drier if you have a reasonbaly large domain. Small domains/high
>resolutions tend to give over estimation of precpitation. You have to select a
>reasonably large domain. A 50 x 50 domain at 50 km would be a minumum near me-
>this would require you to select a ~250 x 250 domain at 10 km at least.
>
>3) As gao said, CRU data should not be used to compare high resolution run.
>Better choice is station data or high resolution gridded data.
>
>Moet
>
>
>The high precp at 10 km is bit surprising for me. I understand that the domain
>of your simulation is very small (smaller than what a RCM domain should be as a
>minimum).
>
>Quoting gaoxj@cma.gov.cn:
>
> > Hi Csaba,
> >
> > Seems you are doing the highest resolution simulation by RegCM3. I think we
> > do not have such experiences before. I have some suggestions, but do not know
> > whether they will work or not.
> >
> > 1. Generally, people say that the ratio for the driven resolution to RCM
> > resolution is better to be in the range of 3-5, 10 is the maximum. There
> > should be some references on this, but I do not have in hand. Maybe you can
> > try the double-nesting, from 2.5 degrees to say 50 km first, then from 50 to
> > 10?
> >
> > 2. CRU is in the resolution of 0.5 deg. It smoothes the precip peak.
> > Meanwhile, over mountain areas, it tends to under-estimate the real precip
> > because no weather stations there. What about try to evaluate the model by
> > some station data?
> >
> > 3. A critical issue is that RegCM3 is hydro-statistic. Some people say a
> > model like that can go to 10 km, some said not and you need a
> > non-hydro-statistic one. I have no idea about this. Maybe others have?
> >
> > Good luck.
> >
> > Regards,
> >
> > Gao
> >
> > ----- Original Message -----
> > From: "Torma Csaba" <delivitez@nimbus.elte.hu>
> > To: <regcnet@lists.ictp.it>
> > Sent: Wednesday, March 14, 2007 6:20 PM
> > Subject: [RegCNET] 10 km run
> >
> >
> > > Dear RegCM Users,
> > >
> > > We just started to use RegCM3 driven by ERA40 2.5 degree resolution ICBC
> > > data for a European subregion containing the Carpathian Basin and Hungary.
> > >
> > > Our grid resolution is 10 km.
> > >
> > > In the precipitation pattern we found big biases as compared to the CRU
> > > data, especially during summer (convective events cause too much
> > > precipitation). We tried to use both Emanuel and Grell convective schemes,
> > > but the result was quite the same: the precipition was overestimated by
> > > the model with a factor of about 2.
> > >
> > > We suspect that the 10 km resolution causes this overestimation. Using 25
> > > km grid resolution the result is much more realistic, but we would like to
> > > use 10 km grid spacing. Is there any possible solution for this
> > > overestimation? Any suggestion is welcome!
> > >
> > > Thanks in advance.
> > >
> > > Kind regards,
> > > Csaba TORMA
> > > _______________________________________________
> > > RegCNET mailing list
> > > RegCNET@lists.ictp.it
> > > https://lists.ictp.it/mailman/listinfo/regcnet
> > >
> > _______________________________________________
> > RegCNET mailing list
> > RegCNET@lists.ictp.it
> > https://lists.ictp.it/mailman/listinfo/regcnet
> >
>reasonablyk we
> > do not have such experiences before. I have some suggestions, but do not know
> > whether they will work or not.
> >
> > 1. Generally, people say that the ratio for the driven resolution to RCM
> > resolution is better to be in the range of 3-5, 10 is the maximum. There
> > should be some references on this, but I do not have in hand. Maybe you can
> > try the double-nesting, from 2.5 degrees to say 50 km first, then from 50 to
> > 10?
> >
> > 2. CRU is in the resolution of 0.5 deg. It smoothes the precip peak.
> > Meanwhile, over mountain areas, it tends to under-estimate the real precip
> > because no weather stations there. What about try to evaluate the model by
> > some station data?
> >
> > 3. A critical issue is that RegCM3 is hydro-statistic. Some people say a
> > model like that can go to 10 km, some said not and you need a
> > non-hydro-statistic one. I have no idea about this. Maybe others have?
> >
> > Good luck.
> >
> > Regards,
> >
> > Gao
> >
> > ----- Original Message -----
> > From: "Torma Csaba" <delivitez@nimbus.elte.hu>
> > To: <regcnet@lists.ictp.it>
> > Sent: Wednesday, March 14, 2007 6:20 PM
> > Subject: [RegCNET] 10 km run
> >
> >
> > > Dear RegCM Users,
> > >
> > > We just started to use RegCM3 driven by ERA40 2.5 degree resolution ICBC
> > > data for a European subregion containing the Carpathian Basin and Hungary.
> > >
> > > Our grid resolution is 10 km.
> > >
> > > In the precipitation pattern we found big biases as compared to the CRU
> > > data, especially during summer (convective events cause too much
> > > precipitation). We tried to use both Emanuel and Grell convective schemes,
> > > but the result was quite the same: the precipition was overestimated by
> > > the model with a factor of about 2.
> > >
> > > We suspect that the 10 km resolution causes this overestimation. Using 25
> > > km grid resolution the result is much more realistic, but we would like to
> > > use 10 km grid spacing. Is there any possible solution for this
> > > overestimation? Any suggestion is welcome!
> > >
> > > Thanks in advance.
> > >
> > > Kind regards,
> > > Csaba TORMA
> > > _______________________________________________
> > > RegCNET mailing list
> > > RegCNET@lists.ictp.it
> > > https://lists.ictp.it/mailman/listinfo/regcnet
> > >
> > _______________________________________________
> > RegCNET mailing list
> > RegCNET@lists.ictp.it
> > https://lists.ictp.it/mailman/listinfo/regcnet
> >
>precipitationwe
> > do not have such experiences before. I have some suggestions, but do not know
> > whether they will work or not.
> >
> > 1. Generally, people say that the ratio for the driven resolution to RCM
> > resolution is better to be in the range of 3-5, 10 is the maximum. There
> > should be some references on this, but I do not have in hand. Maybe you can
> > try the double-nesting, from 2.5 degrees to say 50 km first, then from 50 to
> > 10?
> >
> > 2. CRU is in the resolution of 0.5 deg. It smoothes the precip peak.
> > Meanwhile, over mountain areas, it tends to under-estimate the real precip
> > because no weather stations there. What about try to evaluate the model by
> > some station data?
> >
> > 3. A critical issue is that RegCM3 is hydro-statistic. Some people say a
> > model like that can go to 10 km, some said not and you need a
> > non-hydro-statistic one. I have no idea about this. Maybe others have?
> >
> > Good luck.
> >
> > Regards,
> >
> > Gao
> >
> > ----- Original Message -----
> > From: "Torma Csaba" <delivitez@nimbus.elte.hu>
> > To: <regcnet@lists.ictp.it>
> > Sent: Wednesday, March 14, 2007 6:20 PM
> > Subject: [RegCNET] 10 km run
> >
> >
> > > Dear RegCM Users,
> > >
> > > We just started to use RegCM3 driven by ERA40 2.5 degree resolution ICBC
> > > data for a European subregion containing the Carpathian Basin and Hungary.
> > >
> > > Our grid resolution is 10 km.
> > >
> > > In the precipitation pattern we found big biases as compared to the CRU
> > > data, especially during summer (convective events cause too much
> > > precipitation). We tried to use both Emanuel and Grell convective schemes,
> > > but the result was quite the same: the precipition was overestimated by
> > > the model with a factor of about 2.
> > >
> > > We suspect that the 10 km resolution causes this overestimation. Using 25
> > > km grid resolution the result is much more realistic, but we would like to
> > > use 10 km grid spacing. Is there any possible solution for this
> > > overestimation? Any suggestion is welcome!
> > >
> > > Thanks in advance.
> > >
> > > Kind regards,
> > > Csaba TORMA
> > > _______________________________________________
> > > RegCNET mailing list
> > > RegCNET@lists.ictp.it
> > > https://lists.ictp.it/mailman/listinfo/regcnet
> > >
> > _______________________________________________
> > RegCNET mailing list
> > RegCNET@lists.ictp.it
> > https://lists.ictp.it/mailman/listinfo/regcnet
> >
>reasonablyk we
> > do not have such experiences before. I have some suggestions, but do not know
> > whether they will work or not.
> >
> > 1. Generally, people say that the ratio for the driven resolution to RCM
> > resolution is better to be in the range of 3-5, 10 is the maximum. There
> > should be some references on this, but I do not have in hand. Maybe you can
> > try the double-nesting, from 2.5 degrees to say 50 km first, then from 50 to
> > 10?
> >
> > 2. CRU is in the resolution of 0.5 deg. It smoothes the precip peak.
> > Meanwhile, over mountain areas, it tends to under-estimate the real precip
> > because no weather stations there. What about try to evaluate the model by
> > some station data?
> >
> > 3. A critical issue is that RegCM3 is hydro-statistic. Some people say a
> > model like that can go to 10 km, some said not and you need a
> > non-hydro-statistic one. I have no idea about this. Maybe others have?
> >
> > Good luck.
> >
> > Regards,
> >
> > Gao
> >
> > ----- Original Message -----
> > From: "Torma Csaba" <delivitez@nimbus.elte.hu>
> > To: <regcnet@lists.ictp.it>
> > Sent: Wednesday, March 14, 2007 6:20 PM
> > Subject: [RegCNET] 10 km run
> >
> >
> > > Dear RegCM Users,
> > >
> > > We just started to use RegCM3 driven by ERA40 2.5 degree resolution ICBC
> > > data for a European subregion containing the Carpathian Basin and Hungary.
> > >
> > > Our grid resolution is 10 km.
> > >
> > > In the precipitation pattern we found big biases as compared to the CRU
> > > data, especially during summer (convective events cause too much
> > > precipitation). We tried to use both Emanuel and Grell convective schemes,
> > > but the result was quite the same: the precipition was overestimated by
> > > the model with a factor of about 2.
> > >
> > > We suspect that the 10 km resolution causes this overestimation. Using 25
> > > km grid resolution the result is much more realistic, but we would like to
> > > use 10 km grid spacing. Is there any possible solution for this
> > > overestimation? Any suggestion is welcome!
> > >
> > > Thanks in advance.
> > >
> > > Kind regards,
> > > Csaba TORMA
> > > _______________________________________________
> > > RegCNET mailing list
> > > RegCNET@lists.ictp.it
> > > https://lists.ictp.it/mailman/listinfo/regcnet
> > >
> > _______________________________________________
> > RegCNET mailing list
> > RegCNET@lists.ictp.it
> > https://lists.ictp.it/mailman/listinfo/regcnet
> >
>
>
>------------------------------
>
>From: Moetasim <mashfaq@purdue.edu>
>Subject: Re: [RegCNET] irrigation problem__modify soil moisture
>
>Water.f is a part of BATS land surface model's subroutines. You may search for
>BATS (Biosphere Atmosphere Transfer Scheme) manual, which is available online.
>If you intend to update soil moisture at each time step in the model then you
>have to understand the BATS structure.
>
>Moet
>
>Quoting ljy_926@126.com:
>
> >
> >
> >
> > dear regcnet:
> > Hello! I'm a new user of RegCM3. Now I want to update soil moisture by
> > using some
> > methods such as drop irrigation, et al. I find it can be carried out by
> > modifying program
> > of 'water.f'. But the meanings of many variables in 'water.f' are not clear.
> > So I have
> > three questions about this problem:
> > (1) if I do so, is it right ?
> > (2) Can some Friends tell me the meanings of the variables in'water.f' ?
> > (3) It is mentioned that 'water.f' is programed according to the new
> > algorithms for three
> > soil layers(dickinson & kennedy 8-88). Who can provide the formulas of new
> > algorithms or
> > correlative literatures of dickinson & kennedy 8-88 ?
> > I would be very grateful for anyone's help.
> >
> > sincerely yours: ljy_926
> > email: ljy_926@126.com
> > 2007. 3. 13
> >
> >
>
>
>------------------------------
>
>From: <gaoxj@cma.gov.cn>
>Subject: Re: [RegCNET] negative values in the fields of precipitation
>
>Hi Elena,
>
>This minor negative value is due to the error of the computer memory (truncation error, might be the right word). It happens sometimes. Simply reassign them to zero by either grads or fortran code.
>
>Gao
>
> ----- Original Message -----
> From: smirnova
> To: regcnet@lists.ictp.it
> Sent: Thursday, March 15, 2007 5:18 PM
> Subject: [RegCNET] negative values in the fields of precipitation
>
>
> Dear All,
>
> I have faced with problem. The fields of precipitation from CRUdata have negative values (-0,000686634) for some regions. What does it mean? And how to avoid them? As I know value -32767 is used for missing data.
>
> Thanks in advance for any help !
> Elena
>
>
>
>------------------------------------------------------------------------------
>
>
> _______________________________________________
> RegCNET mailing list
> RegCNET@lists.ictp.it
> https://lists.ictp.it/mailman/listinfo/regcnet
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