Zero mean for precipitation

Hi there!
Thank you for sharing the repository!

During the processing of raw precipitation data there are 2 lines where mean values are set to zero (link is below).
Could you please explain the reason behind this?

https://github.com/aditya-grover/climate-learn/blob/b48fb0242acc47e365af86bfbd9dd86e9dcbd6d2/src/climate_learn/data/processing/nc2npz.py#L152C1-L153C77

Best, Daria