RCE class modifies input atmosphere

[olemke]

The RCE class changes the values of the input atmosphere:

konrad/konrad/core.py

Line 409 in 21e6c81

self.atmosphere["T"] += self.radiation["net_htngrt"] * self.timestep_days

This can have unexpected side effects if a user wants to do several RCE runs (even with newly created RCE instances) consecutively with the same input atmosphere.

To prevent side effects, it would be preferable to make a deepcopy of the input atmosphere when initializing the RCE class:

konrad/konrad/core.py

Line 157 in 21e6c81

self.atmosphere = atmosphere

If this is not desirable for other reasons, the documentation of the atmosphere parameter should at least contain a clear warning that this class will modify the input variable.

[lkluft]

So far, the reasoning has simply been that it seems obvious that the model run will change the atmospheric state. However, I see that one might expect the initial state and the internal model state to be independent.

I think it is fine to just do a deep copy at initialization (this needs to be done for the surface as well). It might actually break scripts of users who have adapted to the current behavior, i.e. expecting the atmosphere to change. But the output files aren't affected, and the change from atmosphere to rce.atmosphere seems doable.