Is your feature request related to a problem? Please describe.
UngriddedData is very difficult to read and it is unclear what is the programming interface and what is internal necessity. A interface with only the needed functionality should be extracted, with the current UngriddedData as an implementation. Another implementation should be added, with the hope to improve readability and memory consumption. In the long range, several implementations could co-exist, e.g. depending on different reader e.g. pyaro-base (timeseries/stations) or satellite data.

Describe the solution you would like to see
A clear and concise description of what you want to happen.

• Extract an interface
• Implement current UngriddedData as implementation of that interface
• Add another implementation
• Compare implementations
• Decide, which implementation to use for the next release