The difference between two surface data

[lby]

Hello, now that I am learning how to use this model, I would like to ask what is the difference between the two surface data and whether they will affect the test results?
Their names are: surfdata_0.9x1.25_hist_78pfts_CMIP6_simyr1850_c190214.nc and surfdata_0.9x1.25_hist_16pfts_Irrig_CMIP6_simyr2000_c190214.nc, thank you for your help

 

[oleson]

They will affect the simulation results. The simyr1850 file represents year 1850 land surface conditions, while the simyr2000 file represents year 2000 land surface conditions. Furthermore, the file with 78pfts in the name is suited for simulations with the crop model on while the file with 16pfts is used for simulations with the crop model off.

 

[lby]

They will affect the simulation results. The simyr1850 file represents year 1850 land surface conditions, while the simyr2000 file represents year 2000 land surface conditions. Furthermore, the file with 78pfts in the name is suited for simulations with the crop model on while the file with 16pfts is used for simulations with the crop model off.

Thank you for your answer olesn. I would like to ask you some questions. Question 1. What are the sources of surface data for simyr2000 and simyr1850? 2. I used ncl to draw the difference of some variables (such as ALB_ROOF) between the two data, and found that the result was zero. Then how to reflect the difference

 

[oleson]

The sources of the surface data can be found in this chapter of the CLM5 technical note:

2.2. Surface Characterization, Vertical Discretization, and Model Input Requirements — ctsm release-clm5.0 documentation

The urban data, e.g., ALB_ROOF, does not change with time, it is static.

A description of how the surface data can change in transient mode can be found here. Not all data changes with time.

2.27. Transient Land Use and Land Cover Change — ctsm release-clm5.0 documentation

 

[lby]

The sources of the surface data can be found in this chapter of the CLM5 technical note:

2.2. Surface Characterization, Vertical Discretization, and Model Input Requirements — ctsm release-clm5.0 documentation

The urban data, e.g., ALB_ROOF, does not change with time, it is static.

A description of how the surface data can change in transient mode can be found here. Not all data changes with time.

2.27. Transient Land Use and Land Cover Change — ctsm release-clm5.0 documentation

Thank you for your answer, oleson. It helped me a lot.

 

[lby]

表面数据的来源可以在CLM5技术说明的这一章中找到：

https://escomp.github.io/ctsm-docs/...note/Ecosystem/CLM50_Tech_Note_Ecosystem.html

城市数据，例如ALB_ROOF，不会随时间变化，它是静态的。

可在此处找到有关表面数据在瞬态模式下如何变化的说明。并非所有数据都会随时间而变化。

https://escomp.github.io/ctsm-docs/...over/CLM50_Tech_Note_Transient_Landcover.html

你好，奥莱森。我了解了您分享的相关知识，但我仍然有疑问。1. 首先，为什么simyr2000和simyr1850的反照率和城市比是恒定的？如果他们分别模拟1850年和2000年的地表条件，那是不合理的，因为地表条件会随着时间的变化而变化。2. 其次，如果它们是静态的，是什么让测试结果不同？期待您的回答

 

[lby]

The sources of the surface data can be found in this chapter of the CLM5 technical note:

2.2. Surface Characterization, Vertical Discretization, and Model Input Requirements — ctsm release-clm5.0 documentation

The urban data, e.g., ALB_ROOF, does not change with time, it is static.

A description of how the surface data can change in transient mode can be found here. Not all data changes with time.

2.27. Transient Land Use and Land Cover Change — ctsm release-clm5.0 documentation

Hello, Olesen. I understand the relevant knowledge you shared, but I still have questions. 1. First of all, why is the albedo and city ratio of simyr2000 and simyr1850 constant? If they simulated the surface conditions in 1850 and 2000 respectively, it would not be reasonable, because the surface conditions change over time. 2. Second, if they are static, what makes the test results different? Looking forward to your reply

 

[slevis]

Hello, Olesen. I understand the relevant knowledge you shared, but I still have questions. 1. First of all, why is the albedo and city ratio of simyr2000 and simyr1850 constant? If they simulated the surface conditions in 1850 and 2000 respectively, it would not be reasonable, because the surface conditions change over time. 2. Second, if they are static, what makes the test results different? Looking forward to your reply

1. The data in simyr2000 and simyr1850 are constant by design because they represent time slices rather than time series. I will not discuss here whether this is reasonable.
2. I don't think that you have described the test. If you ran the model once with simyr2000 and once with simyr1850, then the results would be different because the contents of the two files (simyr2000 and simyr1850) are different.

 

[slevis]

I think I misunderstood your questions in my first response. Here is another response, and I hope I understood correctly this time.

1. You are right. In upcoming versions of the CTSM we will be representing changes in urban area over time.
2. I don't think that you have described the test. Did you run the model once with simyr2000 and once with simyr1850? The results may be different because other parts of the grid cells are different, even if the urban parts are not different.

 

[lby]

I think I misunderstood your questions in my first response. Here is another response, and I hope I understood correctly this time.

1. You are right. In upcoming versions of the CTSM we will be representing changes in urban area over time.
2. I don't think that you have described the test. Did you run the model once with simyr2000 and once with simyr1850? The results may be different because other parts of the grid cells are different, even if the urban parts are not different.

Thank you so much for your patience, slevis. It helped me a lot