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Precipitation map with RAINC and RAINNC (WRF model output)


New member
I am new in WRF model.

I have a WRF model output, I need to make a map with these data.

Can you explaime how to do it ?
Can I use Python?

If it's WRF-ARW, I use ARWpost to post process the data to GRIB format, then plot them in GrADS.
You can search for ARW post and GrADS for more details.

I believe you can use Python too, but I didn't use.
While on the subject of RAINC and RAINNC, I have hourly output of WRF runs. I want to plot 24 -hour total rainfall. I have "history_interval = 60" in my namelist.input. I am assuming RAINC and RAINNC are hourly accumulations. So my total rainfall in calculated as 24hrtotal=sum(t=01, t=24(i.e. 00 of next day)). I need advice if this is correct. WRFUserguide is not helpful on this. We are currently in the dry season, so I do not have any rainfall values to check if they look reasonable.
Sorry I do not see where I can make a new, which is why I used this post.
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RAINC and RAINNC are accumulated in wrfout files. If you have hourly wrfout, then the 24th wrfout files will contain the 24-h accumulated rainc and rainnc. You don't need to use the' sum' function.
NCL, ARWpost and Python etc all can process wrfout data and produce plots.
Thanks for that info. I then assume that 24h total rainfall at T+48H will be R(at T+48H)-R(at T+24H). Please advise.
No. The 24-hr precipitation for the period 24-28hr simulation should be:
[rainc +rainnc (at 48hr)] - [rainc+rainnc (at 24hr)]
I am also new in WRF model and using 6 hour based simulation. Can someone tell me? I use frames_per_outfile=1 and I get separate files for every timestep. In this case, is the rain on the second time step (6hr to 12hr) accumulated in the pervious step? Like, will the output be from 0hr to 12hr OR 6hr to 12hr?
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You are right. RAINC and RAINNC at wrfout files are accumulative rainfall from the initial time (00hr). Suppose you have wrfout files after 6hr and 12hr of integration, rainc+rainnc in wrfout.6hr is the total precipitation during 00-06hr, and in wrfout.12hr it is the total during 0-12hr.
Thankyou Ming for your reply
I want to ask how can I convert wrfout nc file's Lambert projection to WGS-84 projection. Which is the easiest way to do? Thanks
Hello Ming,
Thanks for your reply
I am getting almost same result of rainfall for nesting domain and 1st domain. Can you look into my namelist.wps and namelist.input files and check whether they are correct or not? or any hint to get better result of rainfall for nesting domain.


  • namelist.input
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  • namelist.wps
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Your namelist.input looks fine except that time step is too small.
I would suggest that you set time_step = 150. In addition, your domain size is way small. A larger domain (both D01 and D02) might give you better results.
As for the similar results between D01 and D02, this is not surprising because you turned feedback on, which means that D02 results will feedback to D01. Usually when we run a nesting case, we are only concerned of results over the fine-resolution domain.
Thanks for your valuable suggestions. But for greater time_step > 30 my core dumps after some time. What will you say about that? Is this a system problem? or what
Please take a look at your rsl files. can you find error message like CFL violation or something else? Core dump could be caused by segmentation fault or integration instability. Something wrong in physics can also lead to model crash. those error messages in rsl files are important for us to figure out what is wrong.
RAINC and RAINNC are accumulated in wrfout files. If you have hourly wrfout, then the 24th wrfout files will contain the 24-h accumulated rainc and rainnc. You don't need to use the' sum' function.
NCL, ARWpost and Python etc all can process wrfout data and produce plots.
Hi @Ming Chen , how can we calculate the rain rate (mm/hr) from accumulated RAINNC? I have a simulation for one month.
How frequent do you output wrfout files? Suppose you output wrfout at hourly interval, then the different between the wrfout file and the one in the previous hour will be the precipitation rate (mm/hr). if you output wrfout at 6-hr interval, then the difference between two consecutive wrfout files divided by 6 will yield the precipitation rate (mm/hr) during the 6-hr interval.
@Ming Chen i have wrfout for every 10min. By doing precip_rate=(rainnc[i+1]-rainnc)*6, which will be in mm/hr ( dx,dy:2km), the WRF precipitation rate overestimates the radar precipitation rate almost by factor 2.5. Hence, I am confused about whether my way of calculation is wrong. (Since i turn off the cumulus scheme, rainc will be zero). Am i doing right or is there any other way to calculate the precipitation rate from accumulated precipitation?

Thank you in advance.
Note that rainc and rainnc are accumulated precipitation in wrfout file. if you output wrfout at 10-min, then your way to calculate rainfall rate actually gives you the hourly rate at the 10-min period. If you compare with the value rate = rainc(i+6) -rainc(i), can you get similar results?

How is your radar precipitation rate obtained? It is derived from continuous observation?
The way i described above and rate = rainc(i+6) -rainc(i) gives almost similar results. The radar data is continuous.
This indicates that WRF overestimates precipitation. Does such kind of overestimation appear everywhere?