Dealing with multinational glaciers
Assigning a country code to each glacier (as we do with POLITICAL_UNIT
) may be a convenience to users, but presents a number of issues for data validation and maintenance over time:
- Countries, borders, and the country codes that represent them change over time.
- Glaciers are 2-dimensional objects which can occupy more than one country.
Current examples of the latter include large valley glaciers that originate in Canada and terminate in the United States, like Hubbard, Logan, Chitina and Walsh [6597, 6600, 6601, 6605] and small glaciers on the border between countries, like Colle Gnifetti in Switzerland/Italy [503] and Toro 1, Toro 2, Guanaco, and Del Potro in Chile/Argentina [232, 233, 235, 2027].
The result is that glacier country (T.POLITICAL_UNIT
) can be arbitrary, and that glacier coordinates (T.LAT
, T.LON
) and survey point coordinates (TTT.POINT_LAT
, TTT.POINT_LON
) can end up being in a different country.
One solution, at least for data validation, is to bring glacier coordinates and glacier country into agreement by choosing a side. The other is to simply drop POLITICAL_UNIT
. The data can be more accurately and precisely filtered using coordinates.