Given the question: Information:  - The Catholic Monarchs is the joint title used in history for Queen Isabella I of Castile and King Ferdinand II of Aragon. They were both from the House of Trastámara and were second cousins, being both descended from John I of Castile; on marriage they were given a papal dispensation to deal with consanguinity by Sixtus IV. They married on October 19, 1469, in the city of Valladolid; Isabella was eighteen years old and Ferdinand a year younger; this marriage united both kingdoms under one crown. It is generally accepted by most scholars (John Elliott being an English-speaking example) that the unification of Spain can essentially be traced back to the marriage of Ferdinand and Isabella. Some newer historical opinions propose that under their rule, what later became Spain was still a union of two crowns rather than a unitary state, as to a large degree Castile and Aragon remained separate kingdoms, with most of their own separate institutions, for decades to come. The court of Ferdinand and Isabella was constantly on the move, in order to bolster local support for the crown from local feudal lords.  - Rogaland is a county in Western Norway, bordering Hordaland, Telemark, Aust-Agder, and Vest-Agder counties. Rogaland is the center of the Norwegian petroleum industry. In 2016, Rogaland had an unemployment rate of 4.9%, one of the highest in Norway. In 2015, Rogaland had a fertility rate of 1.78 children per woman, which is the highest in the country.  - Leif Erikson or Leif Ericson (Icelandic: "Leifur Eiríksson"; Norwegian: "Leiv Eiriksson" c. 970  c. 1020) was an Icelandic explorer and the first known European to have discovered North America (excluding Greenland), before Christopher Columbus. According to the Sagas of Icelanders, he established a Norse settlement at Vinland, tentatively identified with the Norse L'Anse aux Meadows on the northern tip of Newfoundland in modern-day Canada. Later archaeological evidence suggests that Vinland may have been the areas around the Gulf of St. Lawrence and that the L'Anse aux Meadows site was a ship repair station.  - North America is a continent entirely within the Northern Hemisphere and almost all within the Western Hemisphere. It can also be considered a northern subcontinent of the Americas. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the west and south by the Pacific Ocean, and to the southeast by South America and the Caribbean Sea.  - The Arctic Ocean is the smallest and shallowest of the world's five major oceans. The International Hydrographic Organization (IHO) recognizes it as an ocean, although some oceanographers call it the Arctic Mediterranean Sea or simply the Arctic Sea, classifying it a mediterranean sea or an estuary of the Atlantic Ocean. Alternatively, the Arctic Ocean can be seen as the northernmost part of the all-encompassing World Ocean.  - A patronym, or patronymic, is a component of a personal name based on the given name of one's father, grandfather (i.e., an avonymic), or an even earlier male ancestor. A component of a name based on the name of one's mother or a female ancestor is a matronymic. Each is a means of conveying lineage. In such instances, a person is usually referred to by their given name, rather than their patronymic.  - Norway (; Norwegian: (Bokmål) or (Nynorsk); Sami: "Norgga"), officially the Kingdom of Norway, is a sovereign and unitary monarchy whose territory comprises the western portion of the Scandinavian Peninsula plus the island Jan Mayen and the archipelago of Svalbard. The Antarctic Peter I Island and the sub-Antarctic Bouvet Island are dependent territories and thus not considered part of the Kingdom. Norway also lays claim to a section of Antarctica known as Queen Maud Land. Until 1814, the Kingdom included the Faroe Islands (since 1035), Greenland (1261), and Iceland (1262). It also included Shetland and Orkney until 1468. It also included the following provinces, now in Sweden: Jämtland, Härjedalen and Bohuslän.  - Erik Thorvaldsson (950  c. 1003), known as Erik the Red was a Norwegian Viking, remembered in medieval and Icelandic saga sources as having founded the first Norse settlement in Greenland. The Icelandic tradition indicates that he was born in the Jæren district of Rogaland, Norway, as the son of Þorvald Ásvaldsson, he therefore also appears, patronymically, as Erik Thorvaldsson ("Eiríkr Þorvaldsson"). The appellation "the Red" most likely refers to his hair color and the color of his beard. Leif Erikson, the famous Icelandic explorer, was Erik's son.  - Spain, officially the Kingdom of Spain, is a sovereign state largely located on the Iberian Peninsula in southwestern Europe, with two large archipelagos, the Balearic Islands in the Mediterranean Sea and the Canary Islands off the North African Atlantic coast, two cities Ceuta and Melilla in the North African mainland and several small islands in the Alboran Sea near the Moroccan coast. Its mainland is bordered to the south and east by the Mediterranean Sea except for a small land boundary with Gibraltar; to the north and northeast by France, Andorra, and the Bay of Biscay; and to the west and northwest by Portugal and the Atlantic Ocean. It is the only European country to have a border with an African country (Morocco) and its African territory accounts for nearly 5% of its population, mostly in the Canary Islands but also in Ceuta and Melilla.  - Greenland  is an autonomous constituent country within the Danish Realm between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe (specifically Norway and Denmark, the colonial powers, as well as the nearby island of Iceland) for more than a millennium. The majority of its residents are Inuit, whose ancestors migrated began migrating from the Canadian mainland in the 13th century, gradually settling across the island.  - An island country is a country whose primary territory consists of one or more islands or parts of islands. As of 2011, 46 (approximately 24%) of the 193 UN member states are island countries.  - A lava field, also called a lava plain or lava bed, is a large expanse of nearly flat-lying lava flows. Such features are generally composed of highly fluid basalt lava, and can extend for tens or even hundreds of miles across the underlying terrain. The extent of large lava fields is most readily grasped from the air or in satellite photos, where their typically dark, nearly black color contrasts sharply with the rest of the landscape. According to the US Geological Survey, monogenetic volcanic fields are collections of cinder cones, and/or Maar vents and associated lava flows and pyroclastic deposits. Sometimes a stratovolcano is at the center of the field, as at the San Francisco Volcanic Field in Arizona. Monogenetic volcano fields have systematic growth patterns that suggest they represent single magmatic systems in the same way that stratovolcanoes do, but monogenetic volcanoes grow laterally rather than vertically (Wood and Shoan, 1984). Detailed mapping indicates that some cinder cones in monogenetic fields (e.g., Cima, California, and Timber Mountain Volcanic Field, Nevada) may have had multiple eruptions separated by tens to hundreds of thousands of years (Wells, et al., 1989). Thus, some monogenetic cones may actually be polygenetic. This possibility differs from observations of historic eruptions (Wood, 1979), and is physically difficult to understand because cinder cone conduits are narrow and must solidify within a few years of eruption. Nonetheless, such multiple eruptions appear to have happened at least twice: Other cinder cones need to be closely reexamined.  - Thorvald Asvaldsson ( Old Norse : Þórvaldr Ásvaldsson ) was the father of the colonizer of Greenland , Erik the Red , and grandfather of Leif Ericson , who visited North America centuries before Christopher Columbus . Thorvald 's father was Ásvald Ulfsson , whose father was Ulf Oxen - Thorisson , whose father was Oxen - Thorir , brother of Naddodd , discoverer of Iceland . Thorvald Ásvaldsson was born in Norway . He was exiled from Norway c. 960 , during the reign of King Harald Fairhair , for the crime manslaughter . He left with his son Erik to northwest Iceland , where he died before 980 .  - The Republic of Iceland, "Lýðveldið Ísland" in Icelandic, is a Nordic island country in the North Atlantic Ocean. It has a population of and an area of , making it the most sparsely populated country in Europe. The capital and largest city is Reykjavík. Reykjavík and the surrounding areas in the southwest of the country are home to over two-thirds of the population. Iceland is volcanically and geologically active. The interior consists of a plateau characterised by sand and lava fields, mountains and glaciers, while many glacial rivers flow to the sea through the lowlands. Iceland is warmed by the Gulf Stream and has a temperate climate, despite a high latitude just outside the Arctic Circle. Its high latitude and marine influence still keeps summers chilly, with most of the archipelago having a tundra climate.  - South America is a continent located in the western hemisphere, mostly in the southern hemisphere, with a relatively small portion in the northern hemisphere. It is also considered a subcontinent of the Americas, which is the model used in nations that speak Romance languages. The reference to South America instead of other regions (like Latin America or the Southern Cone) has increased in the last decades due to changing geopolitical dynamics (in particular, the rise of Brazil).  - The Arctic (or ) is a polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, adjacent seas, and parts of Alaska (United States), Canada, Finland, Greenland (Denmark), Iceland, Norway, Russia, and Sweden. Land within the Arctic region has seasonally varying snow and ice cover, with predominantly treeless permafrost-containing tundra. Arctic seas contain seasonal sea ice in many places.  - Christopher Columbus ( 20 May 1506) was an Italian explorer, navigator, colonizer, and citizen of the Republic of Genoa. Under the auspices of the Catholic Monarchs of Spain, he completed four voyages across the Atlantic Ocean. Those voyages and his efforts to establish permanent settlements on the island of Hispaniola initiated the European colonization of the New World.  - In physical geography, tundra is a type of biome where the tree growth is hindered by low temperatures and short growing seasons. The term "tundra" comes through Russian  ("tûndra") from the Kildin Sami word "tndâr" "uplands", "treeless mountain tract". There are three types of tundra: Arctic tundra, alpine tundra, and Antarctic tundra. In tundra, the vegetation is composed of dwarf shrubs, sedges and grasses, mosses, and lichens. Scattered trees grow in some tundra regions. The ecotone (or ecological boundary region) between the tundra and the forest is known as the tree line or timberline.  - Inuit (pronounced or ; Inuktitut: , "the people") are a group of culturally similar indigenous peoples inhabiting the Arctic regions of Greenland, Canada and Alaska. Inuit is a plural noun; the singular is Inuk. The oral Inuit languages are classified in the Eskimo-Aleut family. Inuit Sign Language is a critically endangered language isolate spoken in Nunavut.  - Reykjavík  is the capital and largest city of Iceland. It has a latitude of 64°08' N, making it the world's northernmost capital of a sovereign state, and is a popular tourist destination. It is located in southwestern Iceland, on the southern shore of Faxa Bay. With a population of around 130,000 (and over 200,000 in the Capital Region), it is the heart of Iceland's cultural, economic and governmental activity.    What entity does 'thorvald asvaldsson' has the relation 'occupation' with?
The answer is:
explorer