The polar bear ("Ursus maritimus") is a carnivorous bear whose native range lies largely within the Arctic Circle, encompassing the Arctic Ocean, its surrounding seas and surrounding land masses.
 It is a large bear, approximately the same size as the omnivorous Kodiak bear ("Ursus arctos middendorffi").
 A boar (adult male) weighs around 350 – , while a sow (adult female) is about half that size.
 Although it is the sister species of the brown bear, it has evolved to occupy a narrower ecological niche, with many body characteristics adapted for cold temperatures, for moving across snow, ice and open water, and for hunting seals, which make up most of its diet.
 Although most polar bears are born on land, they spend most of their time on the sea ice.
 Their scientific name means "maritime bear" and derives from this fact.
 Polar bears hunt their preferred food of seals from the edge of sea ice, often living off fat reserves when no sea ice is present.
 Because of their dependence on the sea ice, polar bears are classified as marine mammals.
The polar night occurs in the northernmost and southernmost regions of the Earth when the night lasts for more than 24 hours.
 This occurs only inside the polar circles.
 The opposite phenomenon, the polar day, or midnight sun, occurs when the Sun stays above the horizon for more than 24 hours.
 "Night" is understood as the center of the Sun being below a free horizon.
 Since the atmosphere bends the rays of the Sun, the polar day is longer than the polar night, and the area that is affected by polar night is somewhat smaller than the area of midnight sun.
 The polar circle is located at a latitude between these two areas, at the latitude of approximately 66.5 degrees.
 In the most northern city of Sweden, Kiruna, at 67°51'N, the polar night lasts for around 28 twenty-four-hour periods, while the midnight sun lasts around 50 twenty-four-hour periods.
 While it is day in the Arctic Circle it is night in the Antarctic Circle.
Naval War: Arctic Circle (NWAC) is a real time naval strategy game developed by Norwegian development company Turbo Tape Games and published by Swedish video game publisher Paradox Interactive.
 It was released on April 10, 2012.
 "Naval War: Arctic Circle" was announced at the 2011 Paradox Interactive Convention held in New York.
 The game is supported by the Norwegian Film Institute, Innovation Norway and the Norwegian Research Council, and is developed in close consultation with the Royal Norwegian Navy.
A polar circle is either the Arctic Circle or the Antarctic Circle.
 On Earth, the Arctic Circle is located at a latitude of 9°′″  N, and the Antarctic Circle is located at a latitude of 9°′″  S.
The Arctic Circle is the most northerly of the abstract five major circles of latitude as shown on maps of the Earth.
 It marks the northernmost point at which the noon sun is just visible on the northern winter solstice and the southernmost point at which the midnight sun is just visible on the northern summer solstice.
 The region north of this circle is known as the Arctic, and the zone just to the south is called the Northern Temperate Zone.
 North of the Arctic Circle, the sun is above the horizon for twenty-four continuous hours at least once per year (and therefore visible at midnight) and below the horizon for twenty-four continuous hours at least once per year (and therefore not visible at noon); this is also true within the equivalent polar circle in the Southern Hemisphere, the Antarctic Circle.
The Russian polar expedition of 1900–1902 was commissioned by the Saint Petersburg Academy of Sciences to study the Arctic Ocean north of New Siberian Islands and search for the legendary Sannikov Land.
 It was led by the Russian geologist and Arctic explorer Baron Eduard Toll on the ship "Zarya".
 Toll and his three assistants vanished in late 1902 while exploring Bennett Island.
 One of the key members of the expedition was Alexander Kolchak, then a young researcher and lieutenant of the Russian Navy, and later a ruler of Russia.
The Arctic policy of Russia is the domestic and foreign policy of the Russian Federation with respect to the Russian region of the Arctic.
 The Russian region of the Arctic is defined in the "Russian Arctic Policy" as all Russian possessions located north of the Arctic Circle.
 (About one-fifth of Russia's landmass is north of the Arctic Circle.)
 Russia is one of five countries bordering the Arctic Ocean.
 In 2011, out of 4 million inhabitants of the Arctic, roughly 2 million lived in arctic Russia, making it the largest arctic country by population.
 However, in recent years Russia's Arctic population has been declining.
Alexander Vasilyevich Kolchak CB (Russian: Алекса́ндр Васи́льевич Колча́к , 16 November [O.S. 4 November] 1874 – 7 February 1920) was a polar explorer and commander in the Imperial Russian Navy, who fought in the Russo-Japanese War and the First World War.
 During the Russian Civil War, he established an anti-communist government in Siberia—later the Provisional All-Russian Government—and was recognised as the "Supreme Ruler and Commander-in-Chief of All Russian Land and Sea Forces" by the other leaders of the White movement from 1918 to 1920.
 His government was based in Omsk, in southwestern Siberia.
Arctic ecology is the scientific study of the relationships between biotic and abiotic factors in the arctic, the region north of the Arctic Circle (66 33’).
 This is a region characterized by stressful conditions as a result of extreme cold, low precipitation, a limited growing season (50–90 days) and virtually no sunlight throughout the winter.
 The Arctic consists of taiga (or boreal forest) and tundra biomes, which also dominate very high elevations, even in the tropics.
 Sensitive ecosystems exist throughout the Arctic region, which are being impacted dramatically by global warming.
 The earliest inhabitants of the Arctic were the Neanderthals.
 Since then, many indigenous populations have inhabited the region, which continues to this day.
 Since the early 1900s, when Vilhjalmur Stefansson led the first major Canadian Arctic Expedition, the Arctic has been a valued area for ecological research.
 In 1946, The Arctic Research Laboratory was established in Point Barrow, Alaska under the contract of the Office of Naval Research.
 This launched an interest in exploring the Arctic examining animal cycles, permafrost and the interactions between indigenous peoples and the Arctic ecology.
 During the Cold War, the Arctic became a place where the United States, Canada, and the Soviet Union performed significant research that has been essential to the study of climate change in recent years.
 A major reason why research in the Arctic is essential for the study of climate change is because the effects of climate change will be felt more quickly and more drastically in higher latitudes of the world as above average temperatures are predicted for Northwest Canada and Alaska.
 From an anthropological point of view, researchers study the native Inuit peoples of Alaska as they have become extremely accustomed to adapting to ecological and climate variability.
The Coast Guard Arctic Service Medal was established on 20 May 1976 by Commandant of the Coast Guard Admiral Owen W. Siler.
 The medal is awarded to any member of the United States Coast Guard who performs twenty one days of consecutive duty afloat or ashore north of the Arctic Circle.
 Air crews flying in and out of areas north of the Arctic Circle may also be awarded the medal for 21 days of non-consecutive service.
 The medal depicts a polar bear under the North Star, while the reverse side carries the Coast Guard Shield.

Question: Which Russian ruler and naval commander also took part in polar expeditions to study the Arctic Circle?
Answer: Alexander Kolchak