Feature request: obs_seq splitter and joiner script

[johnsonbk]

Use case

Many bash and csh scripts exist within the DART repository that use the obs_sequence_tool to partition obs_seq files into smaller files that only contain observations valid during a given assimilation cycle or to merge different obs_seq files into composite files. DAReS staff would like to create a general purpose python script that can replicate the functionality of the existing scripts.

Is your feature request related to a problem?

A long-term goal of creating such a script would be to remove many of the bash and csh scripts that have redundant functionality.

Describe the your preferred solution

An outline of a preferred solution is contained in a design document in the shared DAReS Google Drive (please note: this document is only viewable by DAReS staff).

Describe any alternatives you have considered

None.

[hkershaw-brown]

Merging issue #556 into this issue.
nancycollins commented on Oct 5, 2023

Use case
People frequently need obs_seq files split into multiple files that each cover a shorter time period

Is your feature request related to a problem?
we currently point people at a variety of shell scripts. all of them are pretty incomprehensible because they have to do math with dates and convert between gregorian time (day/seconds since 1601) and Y/M/D/H/m/S time formats. also, they use 'sed' to edit an input.nml to set the output filenames and start/stop times for each run of the obs_sequence_tool.

Describe your preferred solution
A splitting program could hide all the date manipulations and be simpler to run. I wrote up this proposal document for how a program like this could work. The 'advance_time' program is a heavy inspiration for how to specify time intervals and output filenames.

Describe any alternatives you have considered
we can exist as we always have with shell scripts, but they're hard for users (they're often hard for me and i wrote a billion of them).