# 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.

#### Ming Chen

##### Moderator
Staff member
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?

#### Debjit_Paul

##### New member
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.

#### Ming Chen

##### Moderator
Staff member
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.

#### Debjit_Paul

##### New member
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?

#### Ming Chen

##### Moderator
Staff member
No, MPAS doesn't provide such information.

#### Debjit_Paul

##### New member
Ok, thank you Sir.