How to modify the albedo data in a latitude and longitude range?

[lby]

I want to modify the surface albedo in a latitude and longitude range, but I do not find any data directly representing the albedo in the input data. So I modified the restart file in the run file ***.clm2.r.0061-01-01-00000.nc but the mode did not run successfully, the log file shows：
ERROR: ERROR in BalanceCheckMod.F90 at line 612
WARNING:: BalanceCheck, solar radiation balance error (W/m2)
nstep = 1051201
errsol = -7.36850728126007
clm model is stopping - error is greater than 1e-5 (W/m2)
fsa = 81.7539913351873
fsr = 12.1659602845810
forc_solad(1) = 15.6580351343841
forc_solad(2) = 32.6339987339807
forc_solai(1) = 32.7580129994656
forc_solai(2) = 20.2384120331981
forc_tot = 101.288458901028
clm model is stopping
calling getglobalwrite with decomp_index= 54319 and clmlevel= pft
local patch index = 54319
global patch index = 29936
global column index = 22575
global landunit index = 8222
global gridcell index = 3228
gridcell longitude = 107.500000000000
gridcell latitude = 29.3684210526315
pft type = 77
column type = 277
landunit type = 2
ENDRUN:
ERROR: ERROR in BalanceCheckMod.F90 at line 612
WARNING:: BalanceCheck, solar radiation balance error (W/m2)
nstep = 1051201
errsol = 8.631797059663882E-003
clm model is stopping - error is greater than 1e-5 (W/m2)
fsa = 12.0327683809354
fsr = 12.0403453922800
forc_solad(1) = 4.110708501604315E-003
forc_solad(2) = 2.192147615883650E-002
forc_solai(1) = 12.0686523005869
forc_solai(2) = 11.9697974909084
forc_tot = 24.0644819761557
clm model is stopping
May I ask if I should modify it to run successfully? The complete log file is in the appendix. I am looking forward to your help!

 

[slevis]

A few comments:
1) Modifying the albedo in your restart file may work for "startup" or "hybrid" simulations, not for restart or branch. The last two continue simulations without change (as if the run never stopped), so you get the balance error.
2) Modifying the albedo in the restart file will have little effect on the simulation, because the model will calculate a new albedo soon thereafter. The new albedo will have no direct memory of the initial albedo from the restart file. It may have some indirect memory, probably negligible.
3) To really change the albedo, I can think of a few options:
- change soil color (in the fsurdat file)
- change lai and/or sai (in the fsurdat file if running SP cases)
- find albedo calculations in the code and modify directly

 

[CGL]

I want to know how to modify the albedo, if you have better and easy way to do:)

 

[lby]

A few comments:
1) Modifying the albedo in your restart file may work for "startup" or "hybrid" simulations, not for restart or branch. The last two continue simulations without change (as if the run never stopped), so you get the balance error.
2) Modifying the albedo in the restart file will have little effect on the simulation, because the model will calculate a new albedo soon thereafter. The new albedo will have no direct memory of the initial albedo from the restart file. It may have some indirect memory, probably negligible.
3) To really change the albedo, I can think of a few options:
- change soil color (in the fsurdat file)
- change lai and/or sai (in the fsurdat file if running SP cases)
- find albedo calculations in the code and modify directly

Thank you very much, slevis. You answered my doubts and prevented me from pursuing them on the wrong path. For example, the surface data of the test I used is surfdata_1.9x2.5_78pfts_CMIP6_simyr2000_c170824.nc, and modify it
int SOIL_COLOR(lsmlat=96, lsmlon=144);
:long_name = "soil color";
:units = "unitless"; This attribute? I only saw the long name of this one in relation to soil color. In addition, how should I check the albedo of each color of soil? Looking forward to your reply very much.

 

[lby]

I want to know how to modify the albedo, if you have better and easy way to do:)

I'm sorry that I haven't found a feasible way yet. If you have a feasible way, I hope you can share it with me

 

[slevis]

I don't think you need to worry about the units attribute.

For the albedo of each soil color, please look at the corresponding table in CLM5's technical note:

2.3. Surface Albedos — ctsm release-clm5.0 documentation

 

[lby]

I don't think you need to worry about the units attribute.

For the albedo of each soil color, please look at the corresponding table in CLM5's technical note:

2.3. Surface Albedos — ctsm release-clm5.0 documentation

Thank you for your patience, slevis. I see in CLM5's technical note that each soil color corresponds to four albedos: Dry vis, Saturated vis, Dry nir, Saturated nir.


How to calculate the comprehensive albedo? How are their weights chosen? Is adry=0.5 x Dry vis+0.5 x Dry nir?

 

[oleson]

Once the four soil albedos (vis direct and diffuse and nir direct and diffuse) are calculated with 2.3.61, reflected and absorbed solar radiation are calculated for each of the four components (vis direct and diffuse and nir direct and diffuse) and then the radiation components are added together to get total reflected and total absorbed. You could get a "total" albedo by taking total reflected over total incident. Keep in mind that for areas with vegetation, the soil albedo is treated as a bottom boundary condition in the two-stream radiation calculation.

 

[lby]

Once the four soil albedos (vis direct and diffuse and nir direct and diffuse) are calculated with 2.3.61, reflected and absorbed solar radiation are calculated for each of the four components (vis direct and diffuse and nir direct and diffuse) and then the radiation components are added together to get total reflected and total absorbed. You could get a "total" albedo by taking total reflected over total incident. Keep in mind that for areas with vegetation, the soil albedo is treated as a bottom boundary condition in the two-stream radiation calculation.

Thank you for your answer, oleson. I've come up with another idea. I don't know if it'll work. I calculated that the FSR/FSDS of the output data is equal to the albedo, and then found the corresponding albedo according to the latitude and longitude of each type of soil. Is this feasible?

 

[slevis]

Possibly. Just keep in mind that "albedo = FSR / FSDS" includes the effect of snow and plants, not just the soil.

 

[jialiu]

用 2.3.61 计算，refle

A few comments:
1) Modifying the albedo in your restart file may work for "startup" or "hybrid" simulations, not for restart or branch. The last two continue simulations without change (as if the run never stopped), so you get the balance error.
2) Modifying the albedo in the restart file will have little effect on the simulation, because the model will calculate a new albedo soon thereafter. The new albedo will have no direct memory of the initial albedo from the restart file. It may have some indirect memory, probably negligible.
3) To really change the albedo, I can think of a few options:
- change soil color (in the fsurdat file)
- change lai and/or sai (in the fsurdat file if running SP cases)
- find albedo calculations in the code and modify directly

Hi, selvis. I checked the soil_color and found that there are 20 different surface soil types that can be adjusted. Can I modify it to a specific value, such as 0.235?

 

[slevis]

The discussion above addresses your question. This post in particular has some relevant details:

How to modify the albedo data in a latitude and longitude range?

I want to modify the surface albedo in a latitude and longitude range, but I do not find any data directly representing the albedo in the input data. So I modified the restart file in the run file ***.clm2.r.0061-01-01-00000.nc but the mode did not run successfully, the log file shows： ERROR...

bb.cgd.ucar.edu

 

[jialiu]

The discussion above addresses your question. This post in particular has some relevant details:

How to modify the albedo data in a latitude and longitude range?

I want to modify the surface albedo in a latitude and longitude range, but I do not find any data directly representing the albedo in the input data. So I modified the restart file in the run file ***.clm2.r.0061-01-01-00000.nc but the mode did not run successfully, the log file shows： ERROR...

bb.cgd.ucar.edu

I have an additional question, what is the relationship between these variables.

Is there a formula to calculate the relationship between these variables.

 

[oleson]

Sorry, I'm not sure I understand your question. Those are the visible (vis) and near-infrared (nir) direct beam soil albedos. See the technical note reference above.