# Post-processing of precipitation from MPAS model

#### Debjit

##### New member
I have simulated the MPAS model at 120km horizontal resolution for 5 months with the bucket option activated. I want to visualize the precipitation. I have calculated the total accumulated precipitation by taking into account the i_rainc, i_rainnc, and the bucket size using the formula :

rain = (rainc+i_rainc*100) + (rainnc+i_rainnc*100) ; where 100 is the bucket size.

But I am not able to de-accumulate the rainfall amount. The size of rainc, rainnc, i_rainc, i_rainnc is 360*180*153, where 153 is the number of time steps. I tried to de-accumulate the amount using the following:

for i=2:153
rain_de[:,: ,i-1] = rain [:,:,i] - rain [:,:,i-1]

The overall pattern seems good, but I am not sure if I am doing this correctly because the values differ from the observations by a significant margin.

Would you please clarify the meaning of "The size of rainc, rainnc, i_rainc, i_rainnc is 360*180*153, where 153 is the number of time steps" ? I am not quite sure what this sentence means.
Also, by 'de-accumulate', you want to obtain rainfall over a specific time period?

I have converted the MPAS output file into latitude-longitude grids using the convert_mpas utility. After converting the file, the dimension of the variables are 360*180*153; where 360 is the number of longitude points, 180 is the latitude points and 153 is the time step.

MPAS gives accumulated rainfall, so I want to get the rainfall for each day.

Your simulation period covers 5 months and you have '153' time steps, --- I would suppose you output history files at 24-hr intervals (i.e., each day). Please let me know if I am wrong.

In this case, your method to calculate daily precipitation, i.e.,

for i=2:153
rain_de[:,: ,i-1] = rain [:,:,i] - rain [:,:,i-1]

is correct.

As for the bias from observation, I would say that with such a coarse resolution (~120km), I cannot expect highly accurate precipitation simulation.

Thank you Sir. Yes, I did the simulation for 5 months and stored the output files at 24 hr interval.
Actually I have just started simulating the model, so I started with this coarse resolution. I can understand that the results would not be of very high accuracy.

I had another question, is there any way to derive cloud top height or cloud top temperature from the outputs that are being generated by MPAS?

No, MPAS doesn't provide such information.

Ok, thank you Sir.