SHOM Raster GeoTIFF Marine Charts – Antarctic Ocean

Introduction

SHOM raster GeoTIFF marine charts of the Antarctic Ocean, also known as the Southern Ocean, are georeferenced digital charts designed for planning, analysing and studying navigation in southern maritime regions. They allow a digital representation of marine cartography to be used in a computer environment or with navigation software compatible with GeoTIFF raster data.

The Antarctic Ocean, also known as the Southern Ocean, surrounds the Antarctic continent and is one of the most isolated and demanding maritime areas in the world. Navigation in these regions involves scientific vessels, logistical and support vessels, expedition ships and some sailing yachts undertaking southern voyages.

Conditions can be very different from those encountered in temperate regions: sea ice, icebergs, very low temperatures, rapidly changing weather, long distances without shelter and limited port infrastructure.

In this context, georeferenced digital cartography is an important tool for planning a route and studying the geographical and hydrographic characteristics of the areas to be crossed.

What is a SHOM raster GeoTIFF marine chart?

A raster marine chart is a digital image-based representation of a nautical chart. It therefore preserves the graphical appearance of the original cartography and the information represented on the relevant chart reference.

Depending on the chart used, it may include:

• soundings and depths;

• bathymetric contours;

• coastlines;

• shoals;

• rocks;

• hazards;

• wrecks;

• navigation aids;

• lights;

• special areas;

• hydrographic information represented on the chart.

The GeoTIFF format adds georeferencing information to the image, allowing compatible software to position the chart accurately on the Earth's surface.

It is important to distinguish a GeoTIFF file from a simple TIFF image. A GeoTIFF contains the geographical information required for positioning, whereas a standard image does not necessarily provide the information needed for use as a chart in navigation software.

Why use a SHOM digital marine chart in the Antarctic Ocean?

Navigation in the Antarctic Ocean requires particularly thorough chart preparation.

Distances are considerable, shelter is limited and weather conditions can change rapidly. The presence of sea ice adds another important dimension to route planning.

A SHOM raster GeoTIFF marine chart can be used to:

• prepare a Southern Ocean voyage;

• study a route around the Antarctic Peninsula;

• prepare approaches to a research base or scientific station;

• analyse a maritime area before an expedition;

• prepare a route towards the Southern Ocean islands;

• study navigation between South America and Antarctica;

• work with navigation software compatible with georeferenced raster data.

Digital cartography can therefore be used to prepare the general route and analyse the different areas before departure.

Geographical coverage of the Antarctic Ocean

The Southern Ocean extends around the Antarctic continent and includes vast maritime areas between Antarctica and the continents located further north.

The exact coverage of a SHOM GeoTIFF chart nevertheless depends on the relevant chart reference. It is therefore essential to check the geographical area covered by each reference before using it to plan a voyage.

Areas that may be studied as part of a Southern Ocean voyage can include:

• approaches to the Antarctic Peninsula;

• maritime areas south of the Atlantic Ocean;

• approaches to sub-Antarctic islands;

• maritime areas around the Antarctic continent;

• routes linking South America with Antarctic regions;

• certain Southern Ocean routes.

A chart covering a very large region does not necessarily provide the level of detail required for a coastal approach or navigation close to a research station.

Navigation around the Antarctic Peninsula

The Antarctic Peninsula is one of the main navigation areas providing access to the Antarctic continent.

Its geography is complex, with numerous bays, islands, channels, passages and areas affected by sea ice.

When planning navigation in this region, the chart must make it possible to study the overall configuration of the coastline and the different passages.

A georeferenced raster chart preserves a clear graphical representation of the hydrographic information contained in the relevant reference.

Scale is particularly important. A general chart may be suitable for overall route planning, while more detailed cartography is required for coastal approaches and confined navigation areas.

Ice, icebergs and Southern Ocean navigation

The presence of ice is a fundamental difference between Antarctic navigation and navigation in most other parts of the world.

Marine cartography provides geographical and hydrographic information about an area, but it should not be considered a real-time representation of the position of sea ice or icebergs.

Antarctic navigation planning must therefore incorporate additional information relating to:

• ice concentration;

• iceberg drift;

• weather conditions;

• winds;

• swell;

• temperatures;

• local navigation conditions.

Chart data and operational information should be used together.

Example: navigation between South America and Antarctica

Consider a vessel or sailing yacht preparing a route between Tierra del Fuego and the Antarctic Peninsula.

Planning can begin with a chart covering a sufficiently large area to study the overall route.

The navigator can then analyse successively:

1. the departure area in South America;

2. the route towards the Southern Ocean;

3. approaches to the Antarctic Peninsula;

4. passages between the islands;

5. the destination area and its approaches.

At each stage, the level of cartographic detail should be appropriate to the navigation being undertaken.

Planning should also incorporate available weather and ice information, together with up-to-date nautical information.

Raster GeoTIFF or vector chart?

A raster chart is a georeferenced image reproducing the graphical representation of a marine chart. It therefore preserves the symbols, colours and cartographic conventions of the reference.

A vector chart consists of separate digital geographical objects. The data can be interpreted and dynamically displayed by the software.

Raster has the particular advantage of retaining a representation close to that of a traditional marine chart.

Vector technology can offer other data-handling functions depending on the navigation system and software being used.

The choice therefore depends on the navigation requirements, software and available data.

Using the chart with navigation software

A SHOM GeoTIFF chart is not automatically compatible with all navigation software.

Some software, such as Adrena or ScanNav, can use certain georeferenced raster data. Exact compatibility nevertheless depends on the characteristics of the file and the software version.

Before use, it is advisable to check:

• supported file format;

• SHOM chart reference;

• geographical coverage;

• scale;

• resolution;

• coordinate reference system;

• map projection;

• software compatibility;

• licensing and terms of use;

• available information concerning updates.

The GeoTIFF format alone therefore does not guarantee compatibility with a particular software application.

How to prepare a voyage in the Antarctic Ocean?

Preparing an Antarctic voyage requires a particularly rigorous approach.

Digital cartography is one element of this preparation, but it must be combined with all available information.

It is particularly important to study:

• the overall route;

• charted depths and hazards;

• coastal approaches;

• known ice areas;

• weather conditions;

• winds and swell;

• currents;

• up-to-date nautical information;

• applicable restrictions or regulations;

• available shelter and infrastructure.

For a long-distance expedition, planning should also consider navigation redundancy and the ability to work with chart data offline.

What criteria should be checked before choosing a SHOM GeoTIFF chart?

Before selecting a SHOM raster GeoTIFF digital marine chart for the Antarctic Ocean, it is recommended to check:

• exact chart reference;

• geographical coverage;

• scale;

• level of detail;

• resolution;

• coordinate reference system;

• map projection;

• compatibility with the navigation software;

• licensing and terms of use;

• information concerning updates where applicable.

These checks are particularly important in Southern Ocean regions, where the availability of detailed charting can vary significantly between areas.

Conclusion

SHOM raster GeoTIFF marine charts of the Antarctic Ocean provide a georeferenced digital cartography solution for planning and analysing navigation in Southern Ocean regions.

The raster format preserves a graphical representation similar to that of a traditional marine chart, while GeoTIFF georeferencing allows the chart to be accurately positioned within compatible software.

In such a unique region as Antarctica, however, charting must be considered one component of an overall navigation plan. Information relating to sea ice and icebergs, weather, currents, nautical information and operational conditions must also be taken into account.

Choosing the correct chart reference, geographical coverage and scale is essential. A general chart intended for planning a Southern Ocean route does not necessarily replace detailed charting required for a coastal approach or confined navigation area.

FAQ – SHOM Raster GeoTIFF Marine Charts of the Antarctic Ocean

What is a SHOM raster GeoTIFF marine chart of the Antarctic Ocean?

It is a georeferenced digital marine chart representing SHOM cartography in raster format for a specific area of the Antarctic Ocean. The GeoTIFF format combines the cartographic image with the information required for geographical positioning.

What is a SHOM GeoTIFF marine chart used for in Antarctica?

It can be used to prepare a Southern Ocean voyage, study a route towards the Antarctic Peninsula, analyse a maritime area or prepare an approach to a research base or scientific station, subject to appropriate coverage and file compatibility.

Does a SHOM GeoTIFF chart cover the entire Antarctic Ocean?

This depends on the chart reference. Each file has its own geographical coverage and scale. The covered area must therefore be checked before use.

Can a GeoTIFF chart be used for navigation around the Antarctic Peninsula?

Yes, provided that the chart reference covers the relevant area and the software being used is compatible. For coastal approaches and confined passages, sufficiently detailed cartography is required.

Does a SHOM GeoTIFF chart show the position of icebergs?

No. A marine chart represents the hydrographic and geographical information associated with its chart reference. The position and movement of icebergs require additional, up-to-date operational and ice information.

Is a SHOM GeoTIFF chart sufficient for navigation in Antarctica?

No. It is one element of chart preparation. It should be supplemented by available weather, ice, nautical and regulatory information.

Can a SHOM GeoTIFF chart be used with Adrena?

Adrena can use certain georeferenced raster data. Exact compatibility should nevertheless be checked for the SHOM reference, GeoTIFF file and software version concerned.

Is a SHOM GeoTIFF chart compatible with ScanNav?

ScanNav can use certain georeferenced raster data. Compatibility should be checked for the specific file and software version being used.

What scale should be used for navigation in Antarctica?

The scale depends on the intended navigation. A general chart may be suitable for planning a long-distance Southern Ocean route, while a larger-scale chart is required to study a coastal area, channel or approach.

What is the difference between a raster GeoTIFF chart and a vector chart?

A raster chart is a georeferenced image reproducing the graphical representation of a marine chart. A vector chart consists of digital geographical objects that can be interpreted by the software.

Why should the SHOM chart reference be checked before using a GeoTIFF chart?

Because each reference has its own geographical coverage, scale and level of detail. A chart suitable for general route planning does not necessarily provide the precision required for coastal navigation.

Can a SHOM GeoTIFF chart be used to plan a voyage between Tierra del Fuego and Antarctica?

An appropriate GeoTIFF chart can contribute to planning such a route. Appropriate coverage is nevertheless required for the different stages of the voyage, and the charting must be supplemented by the necessary weather, ice and nautical information.