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114-429: Topography along the river includes low, rolling mountains, plains and lowlands, moderately high rugged mountainous land, and some gently sloped plateaus and highlands . The river contains an exceptional population of sheefish ( Stenodus Nelma ), a large predatory whitefish within the salmon family , which spawns in the river's upper reaches during the autumn. A portion of the vast Western Arctic caribou herd utilize

228-400: A Digital Land Surface Model in the form of a TIN . The DLSM can then be used to visualize terrain, drape remote sensing images, quantify ecological properties of a surface or extract land surface objects. The contour data or any other sampled elevation datasets are not a DLSM. A DLSM implies that elevation is available continuously at each location in the study area, i.e. that the map represents

342-492: A complete surface. Digital Land Surface Models should not be confused with Digital Surface Models, which can be surfaces of the canopy, buildings and similar objects. For example, in the case of surface models produces using the lidar technology, one can have several surfaces – starting from the top of the canopy to the actual solid earth. The difference between the two surface models can then be used to derive volumetric measures (height of trees etc.). Topographic survey information

456-427: A flood of ice and water moves powerfully downstream. These annual spring break-up events have several important consequences. First, the river has deeply undercut and eroded banks, caused by large, fast-moving chunks of ice carving out the river's channel before it begins spilling out onto its floodplain, which averages between 1 and 6 miles (1.6 and 9.7 km) wide except at confluences with major tributaries. Second,

570-415: A high gradient to turn a newly forming Kobuk River into a fast-working sediment transport system. The river picked up glacial till from its upper reaches and transported it downstream until the gradient diminished. When the river encountered flatter ground, it deposited its sediment load resulting in the creation of broad, flat floodplains , alluvial fans , and meander bends through aggradation . After

684-694: A large daily-average solar flux reaching the top of the atmosphere in these regions. On the June solstice 36% more solar radiation reaches the top of the atmosphere over the course of the day at the North Pole than at the Equator. However, in the six months from the September equinox to March equinox the North Pole receives no sunlight. The climate of the Arctic also depends on the amount of sunlight reaching

798-581: A long time on its original floodplains to newer floodplains even further downstream. Further down in the Kobuk watershed, the river worked in concert with the wind to create one of the more famous landforms in Alaska: the Kobuk Dunes. These large sand dunes are the modern ancestor of alluvial deposits that became shaped and dominated by an exchange of aeolian and fluvial processes. In moister climates,

912-405: A part of geovisualization , whether maps or GIS systems. False-color and non-visible spectra imaging can also help determine the lie of the land by delineating vegetation and other land-use information more clearly. Images can be in visible colours and in other spectrum. Photogrammetry is a measurement technique for which the co-ordinates of the points in 3D of an object are determined by

1026-583: A place or places, what is now largely called ' local history '. In Britain and in Europe in general, the word topography is still sometimes used in its original sense. Detailed military surveys in Britain (beginning in the late eighteenth century) were called Ordnance Surveys , and this term was used into the 20th century as generic for topographic surveys and maps. The earliest scientific surveys in France were

1140-521: A result, expeditions from the second half of the nineteenth century began to provide a picture of the Arctic climate. The first major effort by Europeans to study the meteorology of the Arctic was the First International Polar Year (IPY) in 1882 to 1883. Eleven nations provided support to establish twelve observing stations around the Arctic. The observations were not as widespread or long-lasting as would be needed to describe

1254-522: A specially designed ship, the Fram , into the sea ice and allowing it to be carried across the ocean. Meteorological observations were collected from the ship during its crossing from September 1893 to August 1896. This expedition also provided valuable insight into the circulation of the ice surface of the Arctic Ocean. In the early 1930s the first significant meteorological studies were carried out on

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1368-415: A temperature of 0 °C (32 °F), and any extra energy from the sun goes to melting more ice, not to warming the surface. Air temperatures, at the standard measuring height of about 2 meters above the surface, can rise a few degrees above freezing between late May and September, though they tend to be within a degree of freezing, with very little variability during the height of the melt season. In

1482-598: A valuable set of information for large-scale analysis. The original American topographic surveys (or the British "Ordnance" surveys) involved not only recording of relief, but identification of landmark features and vegetative land cover. Remote sensing is a general term for geodata collection at a distance from the subject area. Besides their role in photogrammetry, aerial and satellite imagery can be used to identify and delineate terrain features and more general land-cover features. Certainly they have become more and more

1596-411: Is superficial human anatomy . In mathematics the concept of topography is used to indicate the patterns or general organization of features on a map or as a term referring to the pattern in which variables (or their values) are distributed in a space. Topographers are experts in topography. They study and describe the surface features of a place or region. Arctic climate The climate of

1710-562: Is at an altitude of 194 metres (636 ft) in the headwaters of the Kobuk River. Other surface water features within the basin include Lake Selby , Nutuvukti Lake, and Norutak Lake. Additionally, numerous small lakes and ponds occur in the lowlands along the river, some formed as detached oxbows of the meandering river and others formed where permafrost has melted and caused depressions. Flow records are available from USGS monitoring stations at Ambler and Kiana. Average annual flow for

1824-460: Is concerned with underlying structures and processes to the surface, rather than with identifiable surface features. The digital elevation model (DEM) is a raster -based digital dataset of the topography ( hypsometry and/or bathymetry ) of all or part of the Earth (or a telluric planet ). The pixels of the dataset are each assigned an elevation value, and a header portion of the dataset defines

1938-420: Is considerable variability with both location and season. Winter temperatures average below freezing over all of the Arctic except for small regions in the southern Norwegian and Bering Seas, which remain ice free throughout the winter. Average temperatures in summer are above freezing over all regions except the central Arctic Basin, where sea ice survives through the summer, and interior Greenland. The maps show

2052-445: Is controlled by yearly cycles of freeze and thaw, much like its surrounding landscape. For six months of the year, the river is largely still, frozen on top by a thick layer of ice. In the spring, warmer temperatures cause this ice to begin to melt. But the resulting process is not gradual. Rather, the pressure of melting ice from upstream builds up upon ice "dams" in the river's channel, eventually causing an "ice break-up" event, in which

2166-428: Is essential for the planning and construction of any major civil engineering , public works , or reclamation projects. There are a variety of approaches to studying topography. Which method(s) to use depends on the scale and size of the area under study, its accessibility, and the quality of existing surveys. Surveying helps determine accurately the terrestrial or three-dimensional space position of points and

2280-438: Is historically based upon the notes of surveyors. They may derive naming and cultural information from other local sources (for example, boundary delineation may be derived from local cadastral mapping). While of historical interest, these field notes inherently include errors and contradictions that later stages in map production resolve. As with field notes, remote sensing data (aerial and satellite photography, for example),

2394-405: Is ice free, and some of the land areas adjacent to these seas, where the moderating influence of the open water helps melt the snow early. In most of the Arctic the significant snow melt begins in late May or sometime in June. This begins a feedback, as melting snow reflects less solar radiation (50% to 60%) than dry snow, allowing more energy to be absorbed and the melting to take place faster. As

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2508-406: Is ice-covered for an average of six months of the year and in general, late October to late May is a period of relatively low flow. Annually, the hydrograph reflects two flood peaks: the first is associated with spring break-up and the second, a lesser peak, is associated with late summer precipitation. As the snowpack begins to melt toward the end of May, flow in the Kobuk River increases with most of

2622-655: Is located just north of the Arctic Circle and has a continental climate . The summers are short and warm, while winters are long and cold. The mean annual temperature in the middle and upper portions of the Kobuk Valley is -6 °C, and the mean temperature in July is 15 °C. An average of 21 inches (53 cm) of precipitation falls in the basin. However, actual precipitation can range from 15 to 40 inches (40–100 cm), with greater amounts falling in

2736-552: Is no sunlight, the thermal radiation emitted by the atmosphere is one of this region's main sources of energy in winter. A cloudy sky can emit much more energy toward the surface than a clear sky, so when it is cloudy in winter, this region tends to be warm, and when it is clear, this region cools quickly. In winter, the Canadian Archipelago experiences temperatures similar to those in the Arctic Basin, but in

2850-527: Is not part of the Arctic because its continental climate also allows it to have warm summers, with an average July temperature of 15 °C (59 °F). In the figure below showing station climatologies, the plot for Yakutsk is representative of this part of the Far East; Yakutsk has a slightly less extreme climate than Verkhoyansk. The Arctic Basin is typically covered by sea ice year round, which strongly influences its summer temperatures. It also experiences

2964-547: Is often considered to include the graphic representation of the landform on a map by a variety of cartographic relief depiction techniques, including contour lines , hypsometric tints , and relief shading . The term topography originated in ancient Greece and continued in ancient Rome , as the detailed description of a place. The word comes from the Greek τόπος ( topos , "place") and -γραφία ( -graphia , "writing"). In classical literature this refers to writing about

3078-501: Is presently considered the most severe environmental stress in the Kobuk River Basin and throughout Alaska. As a specific example, climate change will cause widespread thawing of permafrost in the discontinuous zone and significant changes in the continuous zone. Thawing permafrost can lead to a landscape of irregular depressions ( thermokarst ) due to subsiding soils. This can alter drainage patterns and even change

3192-588: Is raw and uninterpreted. It may contain holes (due to cloud cover for example) or inconsistencies (due to the timing of specific image captures). Most modern topographic mapping includes a large component of remotely sensed data in its compilation process. In its contemporary definition, topographic mapping shows relief. In the United States, USGS topographic maps show relief using contour lines . The USGS calls maps based on topographic surveys, but without contours, "planimetric maps." These maps show not only

3306-425: Is the study of the forms and features of land surfaces . The topography of an area may refer to the land forms and features themselves, or a description or depiction in maps. Topography is a field of geoscience and planetary science and is concerned with local detail in general, including not only relief , but also natural , artificial, and cultural features such as roads, land boundaries, and buildings. In

3420-422: Is to something else). Topography has been applied to different science fields. In neuroscience , the neuroimaging discipline uses techniques such as EEG topography for brain mapping . In ophthalmology , corneal topography is used as a technique for mapping the surface curvature of the cornea . In tissue engineering , atomic force microscopy is used to map nanotopography . In human anatomy , topography

3534-605: The Rodgers , who was carried to sea on the ice and lost in 1882. Lt. J. C. Cantwell , USRCS , also explored the river in 1884 and 1885 and spelled the name "Koowak" on his map and "Kowak" in his text. Ivan Petroff spelled the river name "Kooak" in 1880, and W. H. Dall spelled it "Kowk" in 1870. Lt. H. T. Allen, US Army, transcribed the Koyukon Indian name for the river in 1885, which he spelled "Holooatna" and "Holoatna." Native peoples have hunted, fished, and lived along

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3648-634: The Cassini maps after the family who produced them over four generations. The term "topographic surveys" appears to be American in origin. The earliest detailed surveys in the United States were made by the "Topographical Bureau of the Army", formed during the War of 1812 , which became the Corps of Topographical Engineers in 1838. After the work of national mapping was assumed by the U.S. Geological Survey in 1878,

3762-557: The Greenland Ice Sheet on 22 December 1991, as the lowest in the Northern Hemisphere. The record was measured at an automatic weather station and was uncovered after nearly 30 years. Among the coldest location in the Northern Hemisphere is also the interior of Russia's Far East, in the upper-right quadrant of the maps. This is due to the region's continental climate , far from the moderating influence of

3876-483: The Hotham Inlet of Kotzebue Sound approximately 30 miles (48 km) southeast of the city of Kotzebue . The Kobuk's Inuit name, Kuuvak , means "great river". It was first transcribed by John Simpson in 1850 as "Kowuk". The river was explored by Lt. G. M. Stoney , USN , in 1883–1886, who wrote the name "Ku-buck" but proposed that it be called "Putnam" in honor of Master Charles Putnam , USN, an officer of

3990-667: The Kallarichuk , Kaliguricheark , and Adillik rivers. All of their headwaters are in the Baird Mountains . The major tributaries flowing north from the Waring Mountains are the Pah River , Pick River , and Niaktuvik Creek . The Pah River drains a lowland area of the basin. Most major tributaries draining high-relief areas have higher unit runoff than tributaries draining the lower-relief areas. Walker Lake

4104-518: The Archipelago because of their closer proximity to areas of thin, first-year sea ice cover or to open ocean in the Baffin Bay and Greenland Sea. The coastal regions in the southern part of the island are influenced more by open ocean water and by frequent passage of cyclones , both of which help to keep the temperature there from being as low as in the north. As a result of these influences,

4218-462: The Arctic is characterized by long, cold winters and short, cool summers. There is a large amount of variability in climate across the Arctic , but all regions experience extremes of solar radiation in both summer and winter. Some parts of the Arctic are covered by ice ( sea ice , glacial ice , or snow ) year-round, and nearly all parts of the Arctic experience long periods with some form of ice on

4332-537: The Arctic Ocean with a network of 20 to 30 buoys. The end of the Soviet Union in 1991 led to a dramatic decrease in regular observations from the Arctic. The Russian government ended the system of drifting North Pole stations, and closed many of the surface stations in the Russian Arctic. Likewise the United States and Canadian governments cut back on spending for Arctic observing as the perceived need for

4446-419: The Arctic and Antarctic ( IPY ). Modern researchers in the Arctic also benefit from computer models . These pieces of software are sometimes relatively simple, but often become highly complex as scientists try to include more and more elements of the environment to make the results more realistic. The models, though imperfect, often provide valuable insight into climate-related questions that cannot be tested in

4560-417: The Arctic and occasionally some other climate-related information. By the early 19th century some expeditions were making a point of collecting more detailed meteorological, oceanographic, and geomagnetic observations, but they remained sporadic. Beginning in the 1850s regular meteorological observations became more common in many countries, and the British navy implemented a system of detailed observation. As

4674-466: The Arctic from the sun is slow to have a significant impact because it is mostly reflected away without warming the surface. By May, temperatures are rising, as 24-hour daylight reaches many areas, but most of the Arctic is still snow-covered, so the Arctic surface reflects more than 70% of the sun's energy that reaches it over all areas but the Norwegian Sea and southern Bering Sea, where the ocean

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4788-587: The Arctic, but also of other, perhaps less-expected, variables, including surface and atmospheric temperatures, atmospheric moisture content, winds, and ozone concentration. Civilian scientific research on the ground has certainly continued in the Arctic, and it is getting a boost from 2007 to 2009 as nations around the world increase spending on polar research as part of the third International Polar Year. During these two years thousands of scientists from over 60 nations will co-operate to carry out over 200 projects to learn about physical, biological, and social aspects of

4902-652: The Arctic, lying between the USSR and North America, became a front line of the Cold War , inadvertently and significantly furthering our understanding of its climate. Between 1947 and 1957, the United States and Canadian governments established a chain of stations along the Arctic coast known as the Distant Early Warning Line (DEWLINE) to provide warning of a Soviet nuclear attack. Many of these stations also collected meteorological data. The Soviet Union

5016-514: The Arctic, with average January temperatures of −45 to −30 °C (−49 to −22 °F), depending on location and on which data set is viewed. Minimum temperatures in winter over the higher parts of the ice sheet can drop below −60 °C (−76 °F)(CIA, 1978). In the station climatology figure above, the Centrale plot is representative of the high Greenland Ice Sheet. In summer, the coastal regions of Greenland experience temperatures similar to

5130-415: The Arctic. As the Arctic continues receiving energy from the sun during this time, the land, which is mostly free of snow by now, can warm up on clear days when the wind is not coming from the cold ocean. Over the Arctic Ocean the snow cover on the sea ice disappears and ponds of melt water start to form on the sea ice, further reducing the amount of sunlight the ice reflects and helping more ice melt. Around

5244-400: The Canadian Archipelago, the many melt ponds and lack of snow cause about half of the sun's energy to be absorbed, but this mostly goes toward melting ice since the ice surface cannot warm above freezing. Frequent cloud cover, exceeding 80% frequency over much of the Arctic Ocean in July, reduces the amount of solar radiation that reaches the surface by reflecting much of it before it gets to

5358-871: The Cold-War decades, sometimes benefiting logistically or financially from the military interest. In 1966 the first deep ice core in Greenland was drilled at Camp Century, providing a glimpse of climate through the last ice age . This record was lengthened in the early 1990s when two deeper cores were taken from near the center of the Greenland Ice Sheet. Beginning in 1979 the Arctic Ocean Buoy Program (the International Arctic Buoy Program since 1991) has been collecting meteorological and ice-drift data across

5472-526: The DEWLINE declined. As a result, the most complete collection of surface observations from the Arctic is for the period 1960 to 1990. The extensive array of satellite-based remote-sensing instruments now in orbit has helped to replace some of the observations that were lost after the Cold War, and has provided coverage that was impossible without them. Routine satellite observations of the Arctic began in

5586-444: The Kobuk River at Ambler ranged from 5,839 cubic feet per second (165.3 m/s) to 14,890 cubic feet per second (422 m/s) over the period of record from 1966 to 1978, with peak discharge ranging between 30,000 cubic feet per second (850 m/s) and 95,000 cubic feet per second (2,700 m/s). Near Kiana, average annual flow ranged from 10,020 cubic feet per second (284 m/s) to 24,960 cubic feet per second (707 m/s) for

5700-648: The Kobuk River valley as winter range . It is commonly assumed that the Kobuk River issues from Walker Lake , but the headwaters of the river are actually to the east of Walker Lake in the Endicott Mountains within Gates of the Arctic National Park and Preserve , just north of the Arctic Circle . The river flows briefly south, descending from the mountains through two spectacular canyons (Upper and Lower Kobuk Canyon), then generally west along

5814-523: The Kobuk for at least 12,500 years and it has long been an important transportation route for inland peoples. In 1898, the river was the scene of a brief gold rush called the Kobuk River Stampede , which involved about 2,000 prospectors in total. Hearing of gold along the Kobuk and its tributaries, miners set out from Seattle and San Francisco on ships to reach the mouth of the Kobuk. Upon arrival they were informed by native people that it

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5928-569: The United States, topography often means specifically relief , even though the USGS topographic maps record not just elevation contours, but also roads, populated places, structures, land boundaries, and so on. Topography in a narrow sense involves the recording of relief or terrain , the three-dimensional quality of the surface, and the identification of specific landforms ; this is also known as geomorphometry . In modern usage, this involves generation of elevation data in digital form ( DEM ). It

6042-653: The accompanying figure. The Kobuk River is a periglacial river, fed by a remnant glacial lake (Walker Lake) and mountain snowmelt in the Brooks Range . It cuts a channel through a landscape otherwise dominated by permafrost . The Kobuk's current form and structure is a direct result of several stages of erosion and channel formation following the last glacial retreat. As the glacier first retreated and melted, large amounts of highly erodible, fine-grained sediment dropped out in relatively high mountain valleys. The availability of this fine-grained, loose sediment combined with

6156-669: The area of coverage, the units each pixel covers, and the units of elevation (and the zero-point). DEMs may be derived from existing paper maps and survey data, or they may be generated from new satellite or other remotely sensed radar or sonar data. A geographic information system (GIS) can recognize and analyze the spatial relationships that exist within digitally stored spatial data. These topological relationships allow complex spatial modelling and analysis to be performed. Topological relationships between geometric entities traditionally include adjacency (what adjoins what), containment (what encloses what), and proximity (how close something

6270-466: The average low temperature in July is above freezing, though temperatures below freezing are observed every month of the year. The straits between these islands often remain covered by sea ice throughout the summer. This ice acts to keep the surface temperature at freezing, just as it does over the Arctic Basin, so a location on a strait would likely have a summer climate more like the Arctic Basin, but with higher maximum temperatures because of winds off of

6384-469: The average temperature in these areas in January is considerably higher, between about −20 to −4 °C (−4 to 25 °F). The interior ice sheet escapes much of the influence of heat transfer from the ocean or from cyclones, and its high elevation also acts to give it a colder climate since temperatures tend to decrease with elevation. The result is winter temperatures that are lower than anywhere else in

6498-513: The average temperature over the Arctic in January and July, generally the coldest and warmest months. These maps were made with data from the NCEP/NCAR Reanalysis , which incorporates available data into a computer model to create a consistent global data set. Neither the models nor the data are perfect, so these maps may differ from other estimates of surface temperatures; in particular, most Arctic climatologies show temperatures over

6612-455: The basis for much derived topographic work. Digital Elevation Models, for example, have often been created not from new remote sensing data but from existing paper topographic maps. Many government and private publishers use the artwork (especially the contour lines) from existing topographic map sheets as the basis for their own specialized or updated topographic maps. Topographic mapping should not be confused with geologic mapping . The latter

6726-497: The central Arctic Ocean in July averaging just below freezing, a few degrees lower than these maps show (USSR, 1985) . An earlier climatology of temperatures in the Arctic, based entirely on available data, is shown in this map from the CIA Polar Regions Atlas. The World Meteorological Organization has recognized in 2020 a temperature of −69.6 °C (−93.3 °F) measured near the topographic summit of

6840-569: The climate in detail, but they provided the first cohesive look at the Arctic weather. In 1884 the wreckage of the Briya , a ship abandoned three years earlier off Russia's eastern Arctic coast, was found on the coast of Greenland. This caused Fridtjof Nansen to realize that the sea ice was moving from the Siberian side of the Arctic to the Atlantic side. He decided to use this motion by freezing

6954-436: The coast over mainland North America and Eurasia, the moderating influence of the Arctic Ocean quickly diminishes, and the climate transitions from the Arctic to subarctic , generally, in less than 500 kilometres (310 miles), and often over a much shorter distance. Due to the lack of major population centres in the Arctic, weather and climate observations from the region tend to be widely spaced and of short duration compared to

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7068-537: The coldest climate of any part of the Arctic. Coastal areas can be affected by nearby open water, or by heat transfer through sea ice from the ocean, and many parts lose their snow cover in summer, allowing them to absorb more solar radiation and warm more than the interior. Coastal regions on the northern half of Greenland experience winter temperatures similar to or slightly warmer than the Canadian Archipelago, with average January temperatures of −30 to −25 °C (−22 to −13 °F). These regions are slightly warmer than

7182-454: The contours, but also any significant streams or other bodies of water, forest cover , built-up areas or individual buildings (depending on scale), and other features and points of interest. While not officially "topographic" maps, the national surveys of other nations share many of the same features, and so they are often called "topographic maps." Existing topographic survey maps, because of their comprehensive and encyclopedic coverage, form

7296-403: The course of streams, whereas other areas could become swamp-like. In addition, slope stability will decrease and permafrost degradation could lead to erosion of river banks resulting in an increase in sediment transport by the rivers. These physical changes will impact nutrient cycling and biological processes within the basin as well. Permafrost regions along the Kobuk River are shown in

7410-399: The detail on maps of the Arctic through the eighteenth century, but largely neglected other scientific observations. Expeditions from the 1760s to the middle of the 19th century were also led astray by attempts to sail north because of the belief by many at the time that the ocean surrounding the North Pole was ice-free . These early explorations did provide a sense of the sea ice conditions in

7524-515: The direct survey still provides the basic control points and framework for all topographic work, whether manual or GIS -based. In areas where there has been an extensive direct survey and mapping program (most of Europe and the Continental U.S., for example), the compiled data forms the basis of basic digital elevation datasets such as USGS DEM data. This data must often be "cleaned" to eliminate discrepancies between surveys, but it still forms

7638-476: The distances and angles between them using leveling instruments such as theodolites , dumpy levels and clinometers . GPS and other global navigation satellite systems (GNSS) are also used. Work on one of the first topographic maps was begun in France by Giovanni Domenico Cassini , the great Italian astronomer. Even though remote sensing has greatly sped up the process of gathering information, and has allowed greater accuracy control over long distances,

7752-548: The early 1970s, expanding and improving ever since. A result of these observations is a thorough record of sea-ice extent in the Arctic since 1979; the decreasing extent seen in this record ( NASA Archived February 21, 2011, at the Wayback Machine , NSIDC ), and its possible link to anthropogenic global warming, has helped increase interest in the Arctic in recent years. Today's satellite instruments provide routine views of not only cloud, snow, and sea-ice conditions in

7866-399: The edges of the Arctic Ocean the ice will melt and break up, exposing the ocean water, which absorbs almost all of the solar radiation that reaches it, storing the energy in the water column. By July and August, most of the land is bare and absorbs more than 80% of the sun's energy that reaches the surface. Where sea ice remains, in the central Arctic Basin and the straits between the islands in

7980-507: The figure above showing station climatologies, the lower-left plot, for NP 7–8, is representative of conditions over the Arctic Basin. This plot shows data from the Soviet North Pole drifting stations, numbers 7 and 8. It shows the average temperature in the coldest months is in the −30s, and the temperature rises rapidly from April to May; July is the warmest month, and the narrowing of the maximum and minimum temperature lines shows

8094-405: The first stage of aggradation and sediment transport, the Kobuk began a new phase of erosion and landform development. The river exhausted its supply of easily erodible sediment upstream, thus decreasing its sediment load and increasing its load carrying capacity downstream. With more capacity downstream, the river began to incise into the alluvial fan it previously created, moving sediment stored for

8208-563: The frozen ground. These characteristics also translate into a relatively variable habitat for the Kobuk's native species. Farthest west, the Kobuk empties into Hotham Inlet, the easterly arm of Kotzebue Sound . During recent geologic times, however, when sea level was lower, the Noatak , Kobuk, and Selawik Rivers were joined. Now, they have separate deltas with many lakes and swamps and intricately webbed channel systems. The deltas are composed primarily of silt, sand, and gravel. The Kobuk River

8322-661: The historical exploration in the Arctic was motivated by the search for the Northwest and Northeast Passages . Sixteenth- and seventeenth-century expeditions were largely driven by traders in search of these shortcuts between the Atlantic and the Pacific. These forays into the Arctic did not venture far from the North American and Eurasian coasts, and were unsuccessful at finding a navigable route through either passage. National and commercial expeditions continued to expand

8436-411: The ice and areas of open water helps to moderate the climate some, keeping average winter temperatures around −30 to −35 °C (−22 to −31 °F). Minimum temperatures in this region in winter are around −50 °C (−58 °F). In summer, the sea ice keeps the surface from warming above freezing. Sea ice is mostly fresh water since the salt is rejected by the ice as it forms, so the melting ice has

8550-409: The ice thickness and extent as they went. These data became available after the Cold War, and have provided evidence of thinning of the Arctic sea ice. The Soviet navy also operated in the Arctic, including a sailing of the nuclear-powered ice breaker Arktika to the North Pole in 1977, the first time a surface ship reached the pole. Scientific expeditions to the Arctic also became more common during

8664-510: The interior of the Greenland ice sheet . These provided knowledge of perhaps the most extreme climate of the Arctic, and also the first suggestion that the ice sheet lies in a depression of the bedrock below (now known to be caused by the weight of the ice itself). Fifty years after the first IPY, in 1932 to 1933, a second IPY was organized. This one was larger than the first, with 94 meteorological stations, but World War II delayed or prevented

8778-471: The islands in the Canadian Archipelago, averaging just a few degrees above freezing in July, with slightly higher temperatures in the south and west than in the north and east. The interior ice sheet remains snow-covered throughout the summer, though significant portions do experience some snow melt. This snow cover, combined with the ice sheet's elevation, help to keep temperatures here lower, with July averages between −12 and 0 °C (10 and 32 °F). Along

8892-431: The lack of observations over the Arctic. Almost all of the energy available to the Earth's surface and atmosphere comes from the sun in the form of solar radiation (light from the sun, including invisible ultraviolet and infrared light). Variations in the amount of solar radiation reaching different parts of the Earth are a principal driver of global and regional climate. Latitude is the most important factor determining

9006-427: The longest period without sunlight of any part of the Arctic, and the longest period of continuous sunlight, though the frequent cloudiness in summer reduces the importance of this solar radiation. Despite its location centered on the North Pole, and the long period of darkness this brings, this is not the coldest part of the Arctic. In winter, the heat transferred from the −2 °C (28 °F) water through cracks in

9120-439: The measurements made in two photographic images (or more) taken starting from different positions, usually from different passes of an aerial photography flight. In this technique, the common points are identified on each image . A line of sight (or ray ) can be built from the camera location to the point on the object. It is the intersection of its rays ( triangulation ) which determines the relative three-dimensional position of

9234-601: The midlatitudes and tropics. Though the Vikings explored parts of the Arctic over a millennium ago, and small numbers of people have been living along the Arctic coast for much longer, scientific knowledge about the region was slow to develop; the large islands of Severnaya Zemlya , just north of the Taymyr Peninsula on the Russian mainland, were not discovered until 1913, and not mapped until the early 1930s Much of

9348-480: The most applications in environmental sciences , land surface is represented and modelled using gridded models. In civil engineering and entertainment businesses, the most representations of land surface employ some variant of TIN models. In geostatistics , land surface is commonly modelled as a combination of the two signals – the smooth (spatially correlated) and the rough (noise) signal. In practice, surveyors first sample heights in an area, then use these to produce

9462-438: The most incoming solar radiation at the surface out of anywhere in the Arctic. However, the high elevation, and corresponding lower temperatures, help keep the bright snow from melting, limiting the warming effect of all this solar radiation. In the summer, when the snow melts, Inuit live in tent-like huts made out of animal skins stretched over a frame. In September and October the days get rapidly shorter, and in northern areas

9576-444: The nearby warm islands. Climatically, Greenland is divided into two very separate regions: the coastal region, much of which is ice free, and the inland ice sheet . The Greenland Ice Sheet covers about 80% of Greenland, extending to the coast in places, and has an average elevation of 2,100 m (6,900 ft) and a maximum elevation of 3,200 m (10,500 ft). Much of the ice sheet remains below freezing all year, and it has

9690-574: The ocean, and to the valleys in the region that can trap cold, dense air and create strong temperature inversions , where the temperature increases, rather than decreases, with height. The lowest officially recorded temperatures in the Northern Hemisphere is −67.7 °C (−89.9 °F) which occurred in Oymyakon on 6 February 1933, as well as −67.8 °C (−90.0 °F) in Verkhoyansk on 5 and 7 February 1892, respectively. However, this region

9804-492: The period from 1977 to 1999, with peaks of 45,000 cubic feet per second (1,300 m/s) to 161,000 cubic feet per second (4,600 m/s). Peak flows can result from large volumes of water released when ice jams fail. Flow records are also available for Dahl Creek, a tributary of the Kobuk River with a confluence near the town of Kobuk. 66°55′16″N 160°48′48″W  /  66.92111°N 160.81333°W  / 66.92111; -160.81333 Topography Topography

9918-525: The point. Known control points can be used to give these relative positions absolute values. More sophisticated algorithms can exploit other information on the scene known a priori (for example, symmetries in certain cases allowing the rebuilding of three-dimensional co-ordinates starting from one only position of the camera). Satellite RADAR mapping is one of the major techniques of generating Digital Elevation Models (see below). Similar techniques are applied in bathymetric surveys using sonar to determine

10032-475: The position of any feature or more generally any point in terms of both a horizontal coordinate system such as latitude, longitude, and altitude . Identifying (naming) features, and recognizing typical landform patterns are also part of the field. A topographic study may be made for a variety of reasons: military planning and geological exploration have been primary motivators to start survey programs, but detailed information about terrain and surface features

10146-409: The publication of much of the data collected during it. Another significant moment in Arctic observing before World War II occurred in 1937 when the USSR established the first of over 30 North-Pole drifting stations . This station, like the later ones, was established on a thick ice floe and drifted for almost a year, its crew observing the atmosphere and ocean along the way. Following World War II,

10260-458: The real world. They are also used to try to predict future climate and the effect that changes to the atmosphere caused by humans may have on the Arctic and beyond. Another interesting use of models has been to use them, along with historical data, to produce a best estimate of the weather conditions over the entire globe during the last 50 years, filling in regions where no observations were made ( ECMWF ). These reanalysis datasets help compensate for

10374-471: The reason that Antarctica is so much colder than the Arctic. In summer, the presence of the nearby water keeps coastal areas from warming as much as they might otherwise. There are different definitions of the Arctic. The most widely used definition, the area north of the Arctic Circle , where the sun does not set on the June Solstice , is used in astronomical and some geographical contexts. However

10488-436: The reduced solar radiation at the surface, ensures an end to the warm days those areas may experience in summer. By November, winter is in full swing in most of the Arctic, and the small amount of solar radiation still reaching the region does not play a significant role in its climate. The Arctic is often perceived as a region stuck in a permanent deep freeze. While much of the region does experience very low temperatures, there

10602-420: The river has more water and thus more power, and cuts down through a sandy bed. In times of drier climate, wind dominates and blows a lot of sediment into a weaker fluvial system, leading to aggradation and floodplain re-distribution. Currently, the Kobuk River in its middle and lower reaches is an anastomosing stream, with several braided channels in places, wide migrating meander bends, and oxbow lakes . It

10716-502: The river moves laterally very quickly and dramatically, re-inventing side channels every year as its secondary streams become drowned in each yearly flood by an overwhelming amount of sediment. Lastly, since the river is surrounded mostly by permafrost and because during the spring break-up event there are still large parts of frozen ground close to its banks, floods often transport large amounts of fine sediment across broad expanses of floodplain in thin sheets of water that slide easily across

10830-642: The runoff occurring during June. Flow during the summer (July through September) is dominated by variable precipitation events. Most of the major tributaries of the Kobuk River flow from the north, draining the mountains in the southern Brooks Range . From east to west, these include the Reed River , Beaver Creek, Mauneluk River , Kogoluktuk River , Shungnak River , Ambler River , Akillik River , Tutuksuk River , Salmon River , and Squirrel River . Within Kobuk Valley National Park are

10944-579: The snow disappears on land, the underlying surfaces absorb even more energy, and begin to warm rapidly. At the North Pole on the June solstice, around 21 June, the sun circles at 23.5° above the horizon. This marks noon in the Pole's year-long day ; from then until the September equinox, the sun will slowly approach nearer and nearer the horizon, offering less and less solar radiation to the Pole. This period of setting sun also roughly corresponds to summer in

11058-464: The solar radiation that reaches it, and snow covers most of the Arctic land and ice surface in winter. These factors result in a negligible input of solar energy to the Arctic in winter; the only things keeping the Arctic from continuously cooling all winter are the transport of warmer air and ocean water into the Arctic from the south and the transfer of heat from the subsurface land and ocean (both of which gain heat in summer and release it in winter) to

11172-625: The southern flank of the western Brooks Range in a broad wetlands valley. In the valley it passes a connected community of inland native villages, including Kobuk, Shungnak, and Ambler, where it receives the Ambler River . In the river's lower reaches, where it passes between the Baird Mountains and Waring Mountains, it traverses Kobuk Valley National Park , the location of the 25 square miles (65 km) Kobuk Sand Dunes. It then passes Kiana , entering its broad delta approximately 10 miles (16 km) southwest of town. The Kobuk empties into

11286-443: The summer months of June to August, the presence of so much land in this region allows it to warm more than the ice-covered Arctic Basin. In the station-climatology figure above, the plot for Resolute is typical of this region. The presence of the islands, most of which lose their snow cover in summer, allows the summer temperatures to rise well above freezing. The average high temperature in summer approaches 10 °C (50 °F), and

11400-436: The sun disappears from the sky entirely. As the amount of solar radiation available to the surface rapidly decreases, the temperatures follow suit. The sea ice begins to refreeze, and eventually gets a fresh snow cover, causing it to reflect even more of the dwindling amount of sunlight reaching it. Likewise, in the beginning of September both the northern and southern land areas receive their winter snow cover, which combined with

11514-495: The surface and atmosphere. Arctic days lengthen rapidly in March and April, and the sun rises higher in the sky, both bringing more solar radiation to the Arctic than in winter. During these early months of Northern Hemisphere spring most of the Arctic is still experiencing winter conditions, but with the addition of sunlight. The continued low temperatures, and the persisting white snow cover, mean that this additional energy reaching

11628-406: The surface, and being absorbed by the surface. Variations in cloud cover can cause significant variations in the amount of solar radiation reaching the surface at locations with the same latitude. Differences in surface albedo due for example to presence or absence of snow and ice strongly affect the fraction of the solar radiation reaching the surface that is reflected rather than absorbed. During

11742-538: The surface. The Arctic consists of ocean that is largely surrounded by land. As such, the climate of much of the Arctic is moderated by the ocean water, which can never have a temperature below −2 °C (28 °F). In winter, this relatively warm water, even though covered by the polar ice pack , keeps the North Pole from being the coldest place in the Northern Hemisphere , and it is also part of

11856-411: The surface. Unusual clear periods can lead to increased sea-ice melt or higher temperatures ( NSIDC Archived December 23, 2007, at the Wayback Machine ). Greenland: The interior of Greenland differs from the rest of the Arctic. Low spring and summer cloud frequency and the high elevation, which reduces the amount of solar radiation absorbed or scattered by the atmosphere, combine to give this region

11970-406: The temperature does not vary far from freezing in the middle of summer; from August through December the temperature drops steadily. The small daily temperature range (the length of the vertical bars) results from the fact that the sun's elevation above the horizon does not change much or at all in this region during one day. Much of the winter variability in this region is due to clouds. Since there

12084-399: The term topographical remained as a general term for detailed surveys and mapping programs, and has been adopted by most other nations as standard. In the 20th century, the term topography started to be used to describe surface description in other fields where mapping in a broader sense is used, particularly in medical fields such as neurology . An objective of topography is to determine

12198-417: The terrain of the ocean floor. In recent years, LIDAR ( LI ght D etection A nd R anging), a remote sensing technique that uses a laser instead of radio waves, has increasingly been employed for complex mapping needs such as charting canopies and monitoring glaciers. Terrain is commonly modelled either using vector ( triangulated irregular network or TIN) or gridded ( raster image ) mathematical models. In

12312-458: The tracks of drifting stations between 1958 and 1975. Another benefit from the Cold War was the acquisition of observations from United States and Soviet naval voyages into the Arctic. In 1958 an American nuclear submarine, the Nautilus was the first ship to reach the North Pole. In the decades that followed submarines regularly roamed under the Arctic sea ice, collecting sonar observations of

12426-420: The two most widely used definitions in the context of climate are the area north of the northern tree line , and the area in which the average summer temperature is less than 10 °C (50 °F), which are nearly coincident over most land areas ( NSIDC Archived January 30, 2013, at the Wayback Machine ). This definition of the Arctic can be further divided into four different regions: Moving inland from

12540-442: The upper reaches of the river basin. The Kobuk River Basin is very sensitive to changes in climate. Arctic climates have warmed at approximately twice the global rate in the last several decades. Records of air temperature from 1961 to 1990 logged at the latitudes of the Kobuk River show a warming trend of about 1.4 °F (0.78 °C) per decade. The warming has been strongest in the winter and spring months. Climate change

12654-435: The winter months of November through February, the sun remains very low in the sky in the Arctic or does not rise at all. Where it does rise, the days are short, and the sun's low position in the sky means that, even at noon, not much energy is reaching the surface. Furthermore, most of the small amount of solar radiation that reaches the surface is reflected away by the bright snow cover. Cold snow reflects between 70% and 90% of

12768-400: The yearly average amount of solar radiation reaching the top of the atmosphere; the incident solar radiation decreases smoothly from the Equator to the poles. Therefore, temperature tends to decrease with increasing latitude. In addition the length of each day, which is determined by the season , has a significant impact on the climate. The 24-hour days found near the poles in summer result in

12882-641: Was a scam, and only about 800 traveled upriver. The result was that little or no gold was found, and only on a few tributaries of the river. In 1980 the United States Congress designated 110 miles (177 km) of the river downstream from Walker Lake as the Kobuk Wild and Scenic River, part of the National Wild and Scenic Rivers System . The river is considered an outstanding destination for recreational floating. The Kobuk River Basin

12996-468: Was also interested in the Arctic and established a significant presence there by continuing the North-Pole drifting stations. This program operated continuously, with 30 stations in the Arctic from 1950 to 1991. These stations collected data that are valuable to this day for understanding the climate of the Arctic Basin. This map shows the location of Arctic research facilities during the mid-1970s and

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