# Total cloud fraction with WRF-Python

#### cgiordano

##### New member
Dear wry users,

I am currently developing a code in python to extract wry outputs with wrf-python librairies.
I would like to compute the total cloud fraction with this librairie, but I don't really know how to proceed.
I have either the CLDRA values giving one value for each level and each grid point, and the python cloud frac given three values at low, mid and high altitudes.
I don't know exactly how to use these variables to have the total cloud fraction.
I read somewhere that using the maximum value of each CLDFRA profile is a good approach but I am not really sure about that.
So, could you please help me with these aspects knowing that I don't use NCL or UPP tools, only python.
If you have also references to add in my potential papers.

Best regards,

Dear wry users,

I am currently developing a code in python to extract wry outputs with wrf-python librairies.
I would like to compute the total cloud fraction with this librairie, but I don't really know how to proceed.
I have either the CLDRA values giving one value for each level and each grid point, and the python cloud frac given three values at low, mid and high altitudes.
I don't know exactly how to use these variables to have the total cloud fraction.
I read somewhere that using the maximum value of each CLDFRA profile is a good approach but I am not really sure about that.
So, could you please help me with these aspects knowing that I don't use NCL or UPP tools, only python.
If you have also references to add in my potential papers.

Best regards,
Hi, I'm currently experiencing this problem as well. I wonder if you have solved it?
I used wrf-python to output low, medium and high clouds, and also checked the CLDFRA cloud fraction, and found that the cloud fraction of wrf-python and CLDFRA are not the same, e.g., the cloud fraction of CLDFRA in the lower layer is 1, while the low cloud in wrf-python is 0.4. I don't understand why there is such a difference.
Also, if you need to calculate the total cloud, the easiest way to do it is to take the maximum value between the low, middle and high clouds, but this will make the total cloud fraction low. However, it is also possible to take the maximum-random overlap method, but this requires the amount of clouds in each layer, e.g. calculated using the data from "CLDFRA."

#### Attachments

• response-ecmwf-model-changes-cloud-overlap-assumption.pdf
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