julianrvogel
New member
Dear WRF community,
I posted this already as a Github issue in the WRF repository, but I was asked to also post it here.
After switching from WRF 4.3.3 to 4.4, the simulation output changed significantly: Large positive biases to T2 temperature from weather stations are found. The case is a real case in Germany and a comparison to 20 DWD weather stations was performed. I used NoahMP as LSM, so I assume it could be related to the latest changes, although I am not aware that any of these changes are specifically important to my setup. I have previously ran this case with many different WRF versions, different grids and different parameterizations and the results were always more or less consistent, until I switched to 4.4.
The code compiled fine in all cases using the same libraries and the same gfortran compiler.
The expected metrics of the average of 12 rural weather stations compared to measurements look like this in WRF 4.3.1 and 4.3.3:
In WRF 4.4, the metrics show a large positive bias in T2:
A difference is also seen comparing the WRF output to sounding data from 3 stations. The visually inspected simulation output looks fine in both 4.3.1 and 4.4, but clearly different.
I first suspected the urban physics, because my first test with WRF 4.4 was using the BEP model and because there have been changes in the urban physics in the 4.3 bugfix releases and also in 4.4. But then I tested another case without urban model and had a similar T2 bias. Both cases used different PBL and surface layer models. Microphysics, cumulus, radiation and LSM were the same. I suspected NoahMP only because of the recent changes there and because I could not identify changes in the other physics options I was using.
Attached are my namelist.input files for the two cases I have run so far. I will do some more testing soon and I will also try to visually highlight the differences of the results between 4.3.3 and 4.4.
I posted this already as a Github issue in the WRF repository, but I was asked to also post it here.
After switching from WRF 4.3.3 to 4.4, the simulation output changed significantly: Large positive biases to T2 temperature from weather stations are found. The case is a real case in Germany and a comparison to 20 DWD weather stations was performed. I used NoahMP as LSM, so I assume it could be related to the latest changes, although I am not aware that any of these changes are specifically important to my setup. I have previously ran this case with many different WRF versions, different grids and different parameterizations and the results were always more or less consistent, until I switched to 4.4.
The code compiled fine in all cases using the same libraries and the same gfortran compiler.
The expected metrics of the average of 12 rural weather stations compared to measurements look like this in WRF 4.3.1 and 4.3.3:
| MBE | RMSE | |
| T2 / K | -0.069 | 1.476 |
| Q2 / g/kg | -0.530 | 1.132 |
| WS10 / m/s | 0.441 | 1.118 |
In WRF 4.4, the metrics show a large positive bias in T2:
| MBE | RMSE | |
| T2 / K | 0.940 | 2.004 |
| Q2 / g/kg | -0.692 | 1.270 |
| WS10 / m/s | 0.574 | 1.189 |
A difference is also seen comparing the WRF output to sounding data from 3 stations. The visually inspected simulation output looks fine in both 4.3.1 and 4.4, but clearly different.
I first suspected the urban physics, because my first test with WRF 4.4 was using the BEP model and because there have been changes in the urban physics in the 4.3 bugfix releases and also in 4.4. But then I tested another case without urban model and had a similar T2 bias. Both cases used different PBL and surface layer models. Microphysics, cumulus, radiation and LSM were the same. I suspected NoahMP only because of the recent changes there and because I could not identify changes in the other physics options I was using.
Attached are my namelist.input files for the two cases I have run so far. I will do some more testing soon and I will also try to visually highlight the differences of the results between 4.3.3 and 4.4.
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