Antarctica/Tagging

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Antarctica is quite a bit different from other continents due to the climate and the resulting abundance of ice. This page describes some of these differences and possible ways to represent them in OSM data.

Inland ice

Most of Antarctica is covered by ice up to the coast, therefore ice free areas are the exception rather than the rule. The ice free areas none the less need to be mapped. Because it is practically unfeasible to create a huge multipolygon for the antarctic ice sheet with tens of thousands of inner rings representing the ice free area it has been decided in 2013 that land areas south of 60 degree south - including islands (this line being the 'political border' of Antarctica and also a reasonable logical division) - are assumed to be covered by ice, i.e. are meant to be treated like natural=glacier.

In OpenStreetMap Carto this rule is implemented with the icesheet_proc process which is run on a daily basis by FOSSGIS and the results of this are available as open data for everyone to use.

Practically that means the land ice does not need to be mapped explicitly - though mappers can add natural=glacier for dedicated mapping of individual glaciers. Glaciers or ice streams within the ice sheet without verifiable boundaries can also be mapped with linear ways or nodes.

Ice free areas need to be explicitly mapped to be considered as such - practically that is mostly natural=bare_rock and natural=scree. This in particular also applies to ice free islands which - in addition to the coastline - need either a second way or a multipolygon relation with the coastline as member tagged natural=bare_rock. Otherwise they will be and should be interpreted to be ice covered.

Rather than having a huge multipolygon for the ice it might be a good idea to consider ice to be the default land cover for Antarctica and map the ice free areas individually as polygons (mostly natural=bare_rock, natural=scree). This would require support from the renderers. Individual glacial features could still be mapped (for example to name glaciers) by drawing them like elsewhere above the default ice.

Ice shelves

Coast forms in Antarctica

The ice shelves around Antarctica are thick plates of ice (thickness of 100m and more) which exist at 44 percent of the antarctic coast. More details can be found on Wikipedia. How exactly this looks like in principle and where the various lines talked about in the following are can be seen in the image on the right.

Consensus in OpenStreetMap is that the coastline is to be mapped at the outer edge of the ice shelves (the calving line) even though the ice shelves are floating on sea water. We do that because this is the logical coastline with regards to human activities. Typical ocean use (i.e. ships) can only take place outside this line and typical land use (like buildings, airfields etc.) is fairly unrestricted on the ice shelf. Ice shelves are not simply thin floating ice, they are thick and stable over decades and more. Also see Sea ice below.

Typical coastal profile of the Antarctic ice shelf coast - approximately to scale except for vertical exaggeration

The ice shelves are represented as mutipolygons and are - corresponding to Proposed_features/Glaciers_tags - tagged glacier:type=shelf. Map rendering should best show them in a distinct way, different from normal glaciers.

In addition the outer edge (the calving line) and the inner edge (the grounding line) get different tags for the corresponding ways:

Sea ice

Sea ice is relatively thin, much thinner as the ice shelf and it is seasonal, so it changes with the time of year. Around the North Pole you have only sea ice, but not ice shelf. Sea ice is not mapped at all in OSM because it changes all the time.

Islands

Antarctica islands are called islands no matter if they are in the free ocean or enclosed in ice shelf. Their perimeter (ie the way) should be tagged as place=island in both cases (in case of islands enclosed in the ice shelf the edge would be the grounding line). If and only if they are in open water they are also tagged with natural=coastline. Like with all islands a node with place=island and a name can be put in the middle of the island.

Long lines

Long straight lines are problematic in OSM everywhere. The earth is round and depending on the projection used for a map those straight lines should sometimes be rendered as curves. But the computer doesn't know that and will still just render a straight line between the two end points. This problem is not specific to Antarctica, but it is seen there more often than in other places, because map distortions are often greater and because features are often drawn with less detail than in other places in the world.

To mitigate this problem you should split up long straight lines every 100km or so with extra nodes.

Names

Many natural features in Antarctica have multilingual names. In addition to language-specific name tags, an emerging convention is to assign the main name=* tag according to the language of the nearest permanent station. This seems generally avoided for elements that are far from any station by land or sea. It may be sensible to do this only for features easily accessible from the station by land or water that are relevant to frequent station operations, and treat more distant features as shared, preferring the name in the most internationally recognized language. For example, as of 2023, on the Fildes Peninsula, most land features south of ASPA 125a (Fossil Hill) are closer to the Chinese Great Wall Station, so their main name=* should be in Chinese. Many features between Norma Cove and the Central Pass are closer to the Russian Bellingshausen Station, so their main name should be in Russian. Most other land features in the peninsula are closer to the Chilean outpost Villa Las Estrellas and its bases, so their main name should be in Spanish.

Sometimes the same element has more than one name in different countries that use the same language, like Argentina and Chile, or Australia and the US. To avoid adding multiple disputed names, it is sensible to assign the main name for a language according to the country of the nearest permanent research station that uses that language, adding the other name to the language-specific alt_name=* tag. If both are considered to be the main name in the two countries, and the feature is not next to a station in either country, it is sensible to assign both names as the main name in their language separated by a slash sorted alphabetically, as is often done for multilingual names on country borders. For example, as of 2023, Keuken Island's main name comes from the Australian Antarctic Gazetteer, as the feature is closest to the Australian Davis Station, while the name Keuken Rock in the United States Gazetteer should be an alternative name, as as there are no closer US stations. Likewise, the main Spanish name (name:es=*) for the Exotic Point on the Fildes Peninsula should be the Chilean name Cabo Eusebio from the Chile Gazetteer as it is closer to the Chilean outpost Villa Las Estrellas and its bases, while the name Cabo Sarratea from the Argentine Antarctic Nomenclator should be an alternative name in Spanish (alt_name:es=*).

Naming by proximity to summer-only stations generally doesn't seem to make much sense, as these stations are comparatively very small and historically have a high chance of being closed in the near feature, although it may make sense to include larger ones, like Mario Zucchelli Station.

Official localized names are always unquestionably preferred, but when they do not exist, translations should be permitted in Antarctica to produce readable maps, provided they follow the usual standards in official maps and gazetteers. Translated labels can be viewed on OpenMapTiles, openstreetmap.de and openstreetmap.fr. The usual pattern in most languages is to always translate the designation (eg. cove, hill, creek, island, etc.), translate descriptive (ie. not  proper) toponyms (eg. Rocky, Butterfly, Hydrographers, Two Summit) when the language of origin is in the same  language family (eg. Каменистая to Rocky, but 나비, meaning butterfly, is not translated to English or Spanish since Korean is not part of the Indo-European language family), transcribe toponyms from different writing systems (eg. Китеж to Kitezh, 나비 to Nabi, Ardley to Chinese as 阿德利), and copy toponyms from the same writing system (eg. Narębski). Some toponyms may seem descriptive but are actually proper (eg. Harmony Point and Harmony Cove, both named after a ship), so it is important to check their origin before deciding to translate, for example by reading the descriptions in gazeteers. As of 2023, about 40% of those working in Antarctica speak English natively, about 20% speak Spanish, about 6% speak French and about 5% speak Russian, according to  Research stations in Antarctica. Their distribution is not uniform and doesn't always correspond exactly to territorial claims in Antarctica. English is a lingua franca, so name:en=* is generally expected. Russian is spoken at various places, so name:ru=* is also generally expected. Spanish is spoken in the Antarctic Peninsula and at the Belgrano II Base, so name:es=* is generally expected in this region. Chinese is spoken along the Zhongshan-Kunlun traverse and near Great Wall Station. French is spoken along the Route du Raid. German is spoken along the Kohnen Traverse, at Dallmann and at GARS. The influence of other languages is much more local.

Settlements and outposts

population=* refers to the permanent population of a settlement or, by analogy, to the occupancy of a year-round  station, implying that summer-only facilities could be, at most, place=locality. A likely more useful distinction that closely respects OSM definitions is as follows:

Research stations may additionally receive office=research. Summer-only stations, bases and camps may additionally receive seasonal=summer.

Life cycle

An outpost used intermittently is considered active and mapped like other active outposts. For inactive outposts, if its structures are not deteriorated or covered in snow, simply add disused=yes if the outpost was officially closed or mothballed (preserved in place) or abandoned=yes if it was abandoned.

Map eliminated, decomissioned, deteriorated or partially snowed-in outposts as place=locality and use a lifecycle prefix for tags related to the previous function, such as as office=*, operator=* and end_date=*. Use demolished:*=* if its structures were actively removed, destroyed:*=* + damage:*=* if they were eliminated by a natural event, disused:*=* or abandoned:*=* if known to be in good condition, or ruins:*=* otherwise. If its structures are probably mostly covered in snow (eg. abandoned for more than 50 years), add location=underground. If it is listed as a  historic site in Antarctica, add historic=ruins + ruins=building.

Roads and routes

information sign

This proposal is being discussed and disputed on the tagging mailing list.

Although many roads in Antarctica are covered in ice or snow, few meet the criteria for ice_road=yes. Use this tag only for roads that disappear during the summer due to melting, and for roads on ice shelves, such as the South Pole Traverse, which is on the Ross Ice Shelf.

Based on highway tagging assumptions, a possible assignment could be as follows:

Addresses

McMurdo Station has few named ways, and its building numbers are unique within the station and refer to it, not the ways. For correct rendering and geocoding, use addr:housenumber=* + addr:place=McMurdo Station.

Other features

There are certainly further features which are rare or non-existent on other continents. The above are only the large scale phenomena that will be important for the import. Feel free to add other things here to help develop uniform standards for mapping.

Penguin colonies are often featured on official maps. They can be mapped using natural=birds_nest + birds_nest=penguin + nest_platform=no. The same scheme may be used for other bird species, for example, birds_nest=southern_giant_petrel. Seal wallows and haul-out sites are also frequently featured. They can be mapped using natural=wallow.

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