Reference map for Antarctica

[seongsujeong]

Checked for duplicates

Yes - I've already checked

Alternatives considered

Yes - and alternatives don't suffice

Related problems

The PR #8 includes land optimization for frame definition. It uses several reference shape files to identify the land area.
One of the reference data for the land area is Global Self-consistent, Hierarchical, High-resolution Geography (GSHHG) Database. This database includes Antarctica. based on grounding line boundary. However, in general glaciologists in Antarctica are interested not only grounded ice but also the ice ice shelf (downstream of the grounded ice that floating on, and flows into the ocean)

For OPERA project, using this reference data for Antarctica would suffice because the project does not cover Antartica. However, in case CSLC and COMPASS gets extended to Antarctica, the frame definition for this area might not be in a desired set up.
Therefore, the reference shape file for Antarctica needs to include ice shelf. It would be in lower priority than other tasks, but it needs to be in our TODO list.

Describe the feature request

• Search for reference data for Antarctica's coastline that includes ice shelves.
• Update the frame definition code to make use of the new reference data for Antarctica.