precipitation -rainfall

[Anh Nguyen]

Dear all,

when working with APEX, I used my observation rainfall data from local weather stations from 2021-2024. However, after running APEX (2006 - 2024), in the SAD file, there are PRCP value from .SAD file but these data were not match with my input data. 

What could be the reason? How can I ask APEX to use my observations rainfall data to use for simulation?

Thanks

Anh

[Arjun Thapa]

Hello Anh,

Mine works file as shown in attached file. You need to change Line 1, row 6 NGN0 value 2345 (Input code for weather variable) in COntrol file (APEXCONT.DAT) . If you already changed and still not working, then disregard my suggestion.

Thanks,

Arjun Thapa

[Anh Nguyen]

Thanks Arjun.

I selected 2345, and now I switch to 1235 , which includes 1 precipitation, and it works. 

Anh

[Luca Doro]

Dear Ann,

As suggested by Arjun, you can use the variable NGN to tell the model which weather variables in the daily weather file must be used for the simulation. Detailed information is available in the APEX user manual available at the Blackland website.

According to the manual, "If any daily weather variables are input, precipitation must also be input. Thus, it is not necessary to specify ID=1 unless rain is the only input variable".

So, if you are providing any other weather data, no need to specify 1.

Also, make sure the format of the daily weather file is correct.

Let us know if you need more help.

Luca

[Daniel Perkins]

I'm fairly new to APEX, but am using observed rainfall data in my simulations. Is NGNO =1 (mine is set to 2345, as I'm giving APEX all weather vars) in the APEXCONT.DAT file? 

[Anh Nguyen]

Thanks Luca. 

I figured out that my weather data is from 2007, and my simulation started in 2006; the model did not perform precipitation as observation data. I started my simulation from later year, then it used observation precipitation now.

Anh

[Luca Doro]

Dear Anh,

Yes, if the simulation begins before the first day of weather data available, the model will generate weather data for the entire simulation regardless of the setting of NGN.

Glad you solved the problem.

Best,

Luca

[Luca Doro]

" I'm fairly new to APEX, but am using observed rainfall data in my simulations. Is NGNO =1 (mine is set to 2345, as I'm giving APEX all weather vars) in the APEXCONT.DAT file?  "

Hi,

I am not sure if I am understanding your question, but yes, you can set NGN in the APEX control file which is called APEXCONT.DAT

Please, let us know if you need more help.

Luca