WX BRIEF

Arctic operations

With more use of polar routes, understanding high latitude conditions has never been more important.



By Karsten Shein
Comm-Inst, Climate Scientist


Gulfstream IV flies over the rugged, ice covered Arctic terrain of Greenland in late February. While surface conditions may be harsh, winter tends to be the least cloudy or windy of the Arctic's seasons.

This September, the National Snow and Ice Data Center in Boulder CO issued a report that Arctic sea ice had reached its smallest extent ever measured. While this has some significant repercussions for environmental changes—without the sea ice reflecting vast amounts of solar radiation, much of that radiation is instead absorbed by open water—it also has broad implications for global business.

At this pace, a sea-ice-free Arctic summer may not be a long way off, meaning more shipping taking advantage of the shorter sea routes between Europe, Asia and North America.

As shipping increases, so will the pressure to expand Arctic ports and their communities. In addition, that absorption of solar heat by the open water means a steady warming of the water and a corresponding warming of the region as a whole.

While this may mean problems for the region's ecosystems—and for the buildings and transportation infrastructure that are built almost entirely on permafrost—it will also help uncover natural resources long locked beneath the frozen landscape, and provide a longer summer season during which those resources can be extracted and transported to industry around the world.

This in turn means a greater need for aviation to ferry in the labor, food and supplies required to support construction and operation efforts across the Arctic.
Many Pro Pilot readers are already familiar with flying into and out of Arctic (and even Antarctic) airstrips, as well as transiting the poles as they wing their globehopping business jets along great circle and transpolar routes to reach a destination on another continent.

But, due to increased business activity in the Arctic, more pilots are being asked to make these sorts of trip. Unfortunately for those of us used to flying between major airports—and over countries that provide real-time weather conditions from satellites, radars, balloons, weather forecast models and surface stations—flying over the Arctic or Antarctic can present some challenges due to the much lower density of available weather information.

Observing the Arctic

ICAO Areas H and I cover significant weather prognostics for the Arctic. (Area J covers Antarctica.) Because the cold Arctic air compresses the troposphere, the stratosphere can reside at these high levels, meaning less chance of encountering significant high-altitude weather conditions.

This is not to say there are no weather observations or forecast model coverage over the poles. Rather the opposite—worldwide there are several hundred surface weather stations located above the Arctic and Antarctic Circles. Most are automated and transmit real-time or near-real-time (hourly) weather data.

In addition, there are roughly 100 upper air stations in the high latitudes, sending weather balloons aloft at least once a day to give us insight on temperatures and winds aloft. (See weather.uwyo. edu/ upperair/sounding.html.) Furthermore, thanks to a need for satellite imagery over the same locations at roughly the same time each day and the ability to obtain global coverage from a single satellite, the world's space agencies have placed a number of weather satellites in polar orbits.

While at lower latitudes a polar orbiting satellite may only scan a given location once or twice a day, because they orbit directly over the poles these same satellites visit each pole about 14 times per day. Basically, this means that the Arctic and Antarctic have more current satellite imagery than most of the rest of the planet.

What's more, because they are continually orbiting Earth to get a global snapshot, they are positioned in a lower orbit (about 750 km), meaning the instruments on polar orbiters cover a smaller swath of Earth with higher resolution than the geosynchronous weather satellites that are positioned over the Equator in higher orbit (about 35,800 km) to capture a greater field of view and synchronized with Earth's rotation to capture continuous images of the same region of the planet.

The result is frequent, higher-resolution images of the Arctic and Antarctic that pilots can access through aviationweather.gov, Environment Canada and other aviation weather outlets.

Beyond observations, forecasters in the meteorological offices of Arctic nations routinely produce significant weather maps and forecasts for their Arctic airspace, as well as much of the Arctic as a whole.

For example, Nav Canada has an entire website for delivering aviation weather information to pilots (flightplanning.navcanada.ca). Although these forecasts serve the relatively small Arctic population, their primary beneficiaries are the ever increasing number of transcontinental flights using Arctic airspace.

Infrared satellite image of clouds and ice cover (milky white) over much of the interior Arctic region. Current satellite imagery of the Arctic is widely available and can be very useful for planning flights within or over the region.

Forecasts of these regions are derived from several computer forecast models, including some, such as the Polar Weather Research & Forecasting model (Polar WRF), that are designed specifically to forecast conditions in the polar regions. Plots from these models can be viewed from the Polar Meteorology Group at Ohio State University (polarmet. osu.­edu).

Although many of the community airstrips in the Arctic have automated weather stations issuing regular Metars, and the forecast models do produce forecasts that cover those areas, terminal area forecasts (TAFs) are not always produced for all of them. Furthermore, due to expense, maintenance and need, there are only a handful of weather radar installations circling the poles.

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