Arctic North Slope Research Articles

Tropopause Characteristics Based on Long-Term ARM Radiosonde Data: A Fine-Scale Comparison at the Extratropical SGP Site and Arctic NSA Site

The variations in the characteristics of the tropopause are sensitive indicators for the climate system and climate change. By using Atmospheric Radiation Measurement (ARM) radiosonde data that were recorded at the extratropical Southern Great Plains (SGP) and Arctic North Slope of Alaska (NSA) sites over an 18-year period (January 2003 to December 2020), this study performs a fine-scale comparison of the climatological tropopause features between these two sites that are characterized by different climates. The static stability increases rapidly above the tropopause at both sites, indicating the widespread existence of a tropopause inversion layer. The structures of both the tropopause inversion layer and the stability transition layer are more obvious at NSA than at SGP, and the seasonal variation trends of the tropopause inversion layer and stability transition layer are distinctly different between the two sites. A fitting method was used to derive the fitted tropopause height and tropopause sharpness (λ). Although this fitting method may determine a secondary tropopause rather than the primary tropopause when multiple tropopause heights are identified on one radiosonde profile, the fitted tropopause heights generally agree well with the observed tropopause heights. Broad tropopause sharpness values (λ > 2 km) occur more frequently at SGP than at NSA, resulting in a greater average tropopause sharpness at SGP (1.0 km) than at NSA (0.6 km). Significant positive trends are exhibited by the tropopause heights over the two sites, with rates of increase of 23.7 ± 6.5 m yr−1 at SGP and 28.0 ± 4.0 m yr−1 at NSA during the study period.

Investigating the structure of cold microbiomes: The Chesapeake Bay in winter and arctic North Slope in summer

Investigating the structure of cold microbiomes: The Chesapeake Bay in winter and arctic North Slope in summer

Rain-on-snow events in Alaska, their frequency and distribution from satellite observations

Wet snow and the icing events that frequently follow wintertime rain-on-snow (ROS) affect high latitude ecosystems at multiple spatial and temporal scales, including hydrology, carbon cycle, wildlife, and human development. However, the distribution of ROS events and their response to climatic changes are uncertain. In this study, we quantified ROS spatiotemporal variability across Alaska during the cold season (November to March) and clarified the influence of precipitation and temperature variations on these patterns. A satellite-based daily ROS geospatial classification was derived for the region by combining remote sensing information from overlapping MODIS and AMSR sensor records. The ROS record extended over the recent satellite record (water years 2003–2011 and 2013–2016) and was derived at a daily time step and 6 km grid, benefiting from finer (500 m) resolution MODIS snow cover observations and coarser (12.5 km) AMSR microwave brightness temperature-based freeze–thaw retrievals. The classification showed favorable ROS detection accuracy (75%–100%) against in situ climate observations across Alaska. Pixel-wise correlation analysis was used to clarify relationships between the ROS patterns and underlying physiography and climatic influences. Our findings indicate that cold season ROS events are most common during autumn and spring months along the maritime Bering Sea coast and boreal interior regions, but are infrequent on the colder arctic North Slope. The frequency and extent of ROS events coincided with warm temperature anomalies (p < 0.1), but showed a generally weaker relationship with precipitation. The weaker precipitation relationship was attributed to several factors, including large uncertainty in cold season precipitation measurements, and the important contribution of humidity and turbulent energy transfer in driving snowmelt and icing events independent of rainfall. Our results suggest that as high latitude temperatures increase, wet snow and ROS events will also increase in frequency and extent, particularly in the southwestern and interior regions of Alaska.

The Plecoptera and Trichoptera of the Arctic North Slope of Alaska

ABSTRACT. The Arctic is currently experiencing changes in climate more rapid than in any other biome. This warming trend has resulted in significant abiotic changes to the seasonal patterns of freshwater ecosystems. Thorough inventories of freshwater insect communities are required to provide benchmarks for the detection of range shifts in response to a warming climate. Though statewide studies have been conducted for Trichoptera and Plecoptera, species accounts for these orders in Arctic Alaska have received relatively little attention. We surveyed Plecoptera and Trichoptera of Alaska's Arctic North Slope at a variety of habitat types over an 11-year period. We document new and historical collection records for 24 species of Plecoptera and 33 species of Trichoptera on Alaska's North Slope. Among these are 19 new North Slope records for Trichoptera (4 new state records) and 2 new North Slope records for Plecoptera. Our assessment of these taxa reveals communities of stoneflies and caddisflies that are dis...

Land of extremes: a natural history of the Arctic North Slope of Alaska

Land of extremes: a natural history of the Arctic North Slope of Alaska

Remote sensing analysis of physical complexity of North Pacific Rim rivers to assist wild salmon conservation

AbstractSalmon populations are highly variable in both space and time. Accurate forecasting of the productivity of salmon stocks makes effective management and conservation of the resource extremely challenging. Furthermore, widespread and consistent data on the productivity of species‐specific and total salmon stocks in a river are almost nonexistent. Ranking rivers based on physical complexity derived from remote sensing allows rivers to be objectively compared. Our approach considered rivers with great geomorphic complexity (e.g. having expansive, multichanneled floodplains and/or on‐channel lakes) as likely to have greater productivity of salmon than rivers flowing in constrained or canyon‐bound channels. Our objective was to develop a database of landscape metrics that could be used to rank the rivers in relation to potential salmon productivity. We then examined the rankings in relation to existing empirical (monitoring) data describing productivity of salmon stocks. To extract the metrics for each river basin we used a digital elevation model and multispectral satellite imagery. We developed procedures to extract channel networks, floodplains, on‐channel lakes and other catchment features; variables such as catchment area, channel elevation, main channel length, floodplain area, and density of hydrojunctions (nodes) were measured. We processed 1509 catchments in the North Pacific Rim including the Kamchatka Peninsula in Russia and western North America. Overall, catchments were most physically complex in western Kamchatka and western Alaska, and particularly on the Arctic North Slope of Alaska. We could not directly examine coherence between potential and measured productivity except for a few rivers, but the expected relationship generally held. The resulting database and systematic ranking are objective tools that can be used to address questions about landscape structure and biological productivity at regional to continental extents, and provide a way to begin to efficiently prioritize the allocation of funding and resources towards salmon management and conservation. Copyright © 2010 John Wiley &amp; Sons, Ltd.

The character and bioactivity of dissolved organic matter at thaw and in the spring runoff waters of the arctic tundra North Slope, Alaska

The brief spring thaw period in the arctic is an important time when carbon is transferred from terrestrial to aquatic systems as melting snow and soil waters run off into the streams, lakes, and ocean. Measurements were made of the quantity and quality of dissolved organic carbon (DOC) in thawing soil and runoff waters in the foothills region of the Kuparuk River basin of arctic Alaska, during the thaw of May 1996. Incubations were performed using DOC and soil cores at the time of thaw from the surface layers of two major tundra types of the region, nonacidic and acidic tundra. Results indicated that there are major changes in both the quantity and quality of DOC as soil waters thaw and move to the streams and lakes. DOC concentrations were found to be reduced up to 90% as soil waters thawed and became free‐flowing soil waters with leachates from thawed soil cores averaging 116 mg DOC/L at thaw and soil waters averaging 20 mg DOC/L. Stream and inlet to Toolik Lake DOC concentrations averaged 12 and 10 mg DOC/L respectively indicating further dilution of DOC. Quality differences elucidated by XAD‐8/4 resin fractionation of DOC were observed for waters at various points in the ecosystem. The hydrophilic neutral fraction (HIN) accounted for 71% of the DOC in waters of thawing soil cores, but was only 23% in flowing waters of soils, and 9–20% in stream waters. A 14 day 4°C incubation of DOC from thawing soil core waters reduced DOC an average of 39%, with 80% of that reduction occurring in the HIN fraction. Soil waters and stream waters were similar in DOC fraction composition, and fulvic acid fractions were dominant. Initial 14 day DOC respiration rates with high HIN waters were 10 mg CO2‐C/g DOC/d, and reduced to 1.2–1.7 mg CO2‐C/g DOC/d after 34 days incubation. Respiration rates of thawed cores ranged from 0.12 to 0.06 and 0.03 mg CO2‐C/g C/d for nonacidic and acidic cores, respectively.

Natural Gas Hydrates in the Alaskan Arctic

Summary The occurrence of in-situ natural gas hydrates in the arctic North Slope of Alaska is governed by several thermodynamic and geologic parameters, such as mean annual surface temperature, geothermal gradients above and below the base of the permafrost, pore-fluid salinity, permafrost base depth and temperature, subsurface pressure, and composition. Accurate knowledge of these parameters is necessary to determine the depths and thicknesses of zones of potential hydrate occurrences. The role of the parameters Is discussed in this paper. To determine the hydrate-stability zone, a nomogram has been developed and has been used for several Alaskan wells. For further delineation of gas hydrates, the neutron-transit-time crossplots have served as a valuable tool. To quantify gas hydrate deposits in terms of thickness, porosity, and saturation; use of neutron- and sonic-porosity-correction factors and Pickett crossplots is recommended.

Transportation Requirements for Drilling Operations on the Arctic North Slope of Alaska

Summary Since the OPEC oil embargo of 1973, U.S. oil companies have been placing increasing emphasis on exploring for and producing oil located within the U.S. Alaska's North Slope has received a great amount of attention recently as there exists a known transportation system (the Trans Alaska pipeline) and because geological information indicates the potential for pipeline) and because geological information indicates the potential for large producing reservoirs. Drilling on Alaska's Arctic North Slope poses a number of interesting operational problems, including transporting and supporting drilling rigs to their respective locations. Sohio Alaska Petroleum Co. has extensive experience in transporting and supporting drilling figs in development operations (Prudhoe Bay) and exploration locations both on- and offshore Alaska's Noah Slope. This paper addresses how arctic drilling figs are transported to development locations within the Prudhoe Bay Unit and to remote on- and offshore locations. Principal topics deal with the current methods by which rigs are moved and how daily drilling operations are supported. In addition, this paper discusses transportation systems that may be required when drilling operations extend beyond the Barrier Islands of Alaska's North Slope. Introduction Drilling operations on Alaska's North Slope have come a long way since the discovery of oil at Prudhoe Bay in 1968. During the early days of drilling at Prudhoe, rigs were transported to the Slope by Hercules C-130 aircraft, barges up the west coast of Alaska, or cat trains up the 375-mile [603-km] winter-haul road out of Fairbanks. In 1975, the all-weather Trans Alaska pipeline haul road to Prudhoe Bay was completed, which provided an pipeline haul road to Prudhoe Bay was completed, which provided an alternative method to bring rigs to the slope. This paper explains how drilling figs are transported to drilling locations on Alaska's North Slope. The figs and support equipment now being used in the development of Prudhoe Bay have day rates that exceed $50,000. To minimize the time it takes in the Prudhoe Bay field to move a fig from one well to the next requires the use of specially designed fig-transportation systems. Two such systems are described, one with rollers on skids and another with rubber-tire wheels coupled to a jacking system. Exploration drilling up to 60 miles [97 km] from Prudhoe Bay is being conducted. This work involves moving Prudhoe Bay development rigs to both on- and offshore locations. This paper discusses moving rigs to exploration locations by Hercules aircraft, rolligons, trucks over ice roads, and barges-the methods being used by most operators drilling on the North Slope. Arctic North Slope Environment The North Slope of Alaska is bordered to the north by the Chukchi and Beaufort Seas and to the south by the Brooks Mountain Range (Fig. 1). The entire 90,000 sq miles [233 099 km 2] of land making up the North Slope lies wholly above the Arctic Circle. Prudhoe Bay, the largest oil field in North America, is located within this region and occupies about 0.5% of the overall area. Situated on the edge of the Beaufort Sea, Prudhoe Bay is approximately 250 miles [402 km] north of the Arctic Circle and 1,300 miles [2092 km] south of the North Pole. JPT p. 2308

Geology of Kuparuk River Oil Field, Alaska: ABSTRACT

The Kuparuk River oil field is located on the Alaskan Arctic North Slope in the Colville-Prudhoe trough some 25 mi (40 km) west of the Prudhoe Bay field. The 23° API crude is similar in type to that in the Prudhoe Bay field. The Kuparuk reservoir, however, is in Early Cretaceous clastics of the Kuparuk River Formation, stratigraphically higher than at Prudhoe. The origin of the oil is believed to be predominantly from the Jurassic Kingak Formation with migration occurring along the basal Cretaceous unconformity. The dominant trapping mechanism is stratigraphic pinch-out and truncation of the reservoir at an intraformational unconformity along the southern and western flanks of a southeast plunging antiform. Structural dip closure exists along the northern and eastern flanks with a tilted oil-water contact at approximately 6,675 ft (2,034.5 m) subsea. The reservoir sandstones occur within cleaning and coarsening-upward sequences which are interpreted as shallow-marine and sublittoral in origin and deposited as southwesterly trending sand bodies with a provenance to the northeast. Two of the four major lithostratigraphic units mapped exhibit good reservoir characteristics and extend over an area in excess of 200 sq mi (510 sq km). The cumulative net pay ranges up to 90 ft (27 m) and the estimate of developable oil in place is 4.3 billion stock tank barrels. There is no gas cap. About 10% of the oil is estimated to be recoverable by primary depletion and it is believed that a further 17% may be recoverable by secondary waterflood. Kuparuk therefore ranks as one of the largest oil fields in the United States. First production is planned for early 1982. End_of_Article - Last_Page 577------------

Developments in Alaska in 1976

Thirteen exploratory wells were drilled in Alaska in 1976. There were no discoveries announced, but 4 suspended wells on the Arctic North Slope may have found oil. All 4 wells are in close proximity to the Prudhoe Bay field. There were 53 development wells drilled of which 3 were dry; 17 service wells were completed. Industry geologic-geophysical field activity consisted of 151.8 crew-months, a decrease of 32% compared with 1975. Most of the reduction occurred on the North Slope and in the Gulf of Alaska, but 5 areas showed increased activity from the previous year. Other exploratory developments included the drilling of a deep Continental Offshore Stratigraphic Test (COST) well in St. George basin and 3 shallow stratigraphic holes on the Kodiak shelf. During 1976, federal acreage under lease marginally increased owing to the successful Gulf of Alaska OCS sale. State acreage under lease decreased 13%. Oil production showed a decrease of 6.9%, but gas production was up 6.3% for the year. Development drilling registered a large increase in 1976 primarily because of new wells in the Prudhoe Bay field which is scheduled to start production in 1977. The future land situation in Alaska is confused by pending legislation and the lack of a reliable timetable for announced federal and state lease sales.

Developments in Alaska in 1974

Eleven exploratory wells were drilled in Alaska during 1974. There were no new discoveries. The 4 successful exploratory completions are classified as extensions of existing fields or pools, and all are in the Arctic North Slope region. All 20 development wells drilled were completed successfully with one finding a new gas zone in Kenai gas field. Geologic-geophysical field activity by industry was up 102% to 168.3 crew-months with all basins, except the Yukon-Kandik, sharing in the increase. Additionally, 41 crew-months of geologic-geophysical field work were undertaken by the U.S. Geological Survey, in part in cooperation with the Alaska Division of Geological and Geophysical Surveys. Other exploration developments were increased activity on Naval Petroleum Reserve No. 4, and consideration by industry of 4 tests as part of the Continental Offshore Stratigraphic Test program. Federal acreage under lease decreased 11.4% to 3,925, 150 acres, whereas state acreage under lease increased 18.2% to 4,938,181 acres. Oil production showed a slight decrease and gas production a slight increase for the year. Continuous state and federal lease sales are needed to increase and sustain the level of exploration activity in Alaska, and announcements of both state and federal sales schedules for the period of 1975-1978 are steps in the right direction. Indications point to a higher level of activity in 1975 in response to these announcements.

Developments in Alaska in 1973

Alaska petroleum exploration activity during 1973 continued at about the same low level as in the previous 2 years. Of the 11 exploratory wells, 8 were drilled in the Cook Inlet region and 3 in the Arctic North Slope region. One of the Cook Inlet tests resulted in a new deep-pool oil discovery. Federal oil and gas lease acreage continued to decline. State oil and gas lease acreage increased 5.3% as a result of 2 competitive lease sales held in the Cook Inlet region. Combined geologic and geophysical field activity increased 5% over the previous year. Geophysical activity increased in the Arctic North Slope and Gulf of Alaska offshore regions in anticipation of federal, native, and/or state lands becoming available for leasing in the near future. Development drilling durin 1973 continued at about the same low level as in 1972. A total of 21 development wells was drilled, 12 in the Cook Inlet region and 9 in the Arctic North Slope region. Oil and gas production at 73,139,415 bbl and 224,507 MMcf respectively was virtually unchanged from the previous year.

Developments in Alaska in 1969

In 1969, accelerated exploratory activity on the Arctic North Slope accounted for the substantial gain made in overall Alaskan exploration over the previous year. Total exploratory drilling increased 132% to 44 exploratory wells, of which 32 were in the Arctic North Slope area, 10 in the Cook Inlet basin, and 2 in other basins. The 17 successful wells, all on the Arctic North Slope, resulted in extension and definition of the Prudhoe Bay field boundaries, discovery of 1 new shallower pool within the field, and 2 new-field discoveries. In addition, exploratory drilling in 1969 confirmed and increased the original estimates of Prudhoe Bay field reserves of 5-10 billion bbl of oil to in excess of 10 billion bbl of oil. The high level of exploration on the North Slope will co tinue into 1970. The concentrated exploratory efforts in northern Alaska culminated in the record-setting September State Lease Sale that brought total accepted bonus bids of $900,041,605 for 412,548 acres within or in close proximity to the Prudhoe Bay field. As interest shifted to the extremely active Arctic North Slope, exploration in other parts of the state, confined to four major basins, declined from 1968. A significant development in the Gulf of Alaska was the drilling of the first offshore well. Industry's interest remains high in the Gulf of Alaska province and Bristol Bay basin, as offshore lease sales tentatively are scheduled or anticipated for 1970. Fifty-five development wells were drilled in the Cook Inlet basin, a decrease of 38% from 1968. Oil production increased 12% to 74,353,273 bbl and gas production rose 47% to 147,328,379 Mcf.

Developments in Alaska in 1968

Exploration drilling declined 44% from 1967, with only 19 exploration wells drilled in 1968. Four of the wells were discoveries, resulting in discovery of a gas field and an oil field in Cook Inlet, and a major oil field on the Arctic North Slope; this newly discovered field has been estimated to contain reserves of 5-10 billion bbl of oil. The number of successful development wells in Cook Inlet doubled, and the production rate more than doubled from 1967. Three new platforms were added to the 11 already located in Cook Inlet. State lease sales in the Cook Inlet basin and the Alaska Peninsula netted the state $4,059,109 in bonus bids for the 234,906 acres leased. Exploration, restricted to 4 of the state's 10 basins, declined from 1967, except in the Arctic North Slope where activity increased significantly.

Alaskan Exploration: ABSTRACT

Alaskan Exploration: ABSTRACT

Significant Oil and Gas Developments in Alaska, 1965-1966: ABSTRACT

Recent oil exploration in Alaska is centered in five sedimentary basins: Cook Inlet basin; Arctic (North) Slope province; Bristol Bay basin; Gulf of Alaska province; and Copper River basin. Surface and seismic exploration parties have been active in each, greatest emphasis being in the Cook Inlet basin and the Arctic (North) Slope province. The oil industry in Alaska during 1965 drilled 19 exploratory wells, resulting in the discovery of 3 oil fields, 3 gas fields, and extensions of 2 oil fields and 1 gas field. The 3 oil discoveries, all under Cook Inlet waters, are Granite Point, Trading Bay, and McArthur River. The gas discoveries are on the upland area of the Cook Inlet basin at Birch Hill, North Fork, and Moquawkie. The Granite Point discovery was extended north more than 3 mi. by subsequent drilling. A discovery was made 6 mi. south of production at Middle Ground Shoal. Gas production at the Cook Inlet field was extended about 2 mi. southwest. Two exploratory wells drilled in 1965-66 on the Arctic (North) Slope were reported non-productive. Two shallow dry exploratory wells were drilled on the north flank of the Co per River basin. Both were unsuccessful. The first two permanent platforms in Cook Inlet were installed at Middle Ground Shoal oil field during 1965, and development drilling began. A twin 8-mi. crude-oil pipeline was completed connecting the two platforms with an onshore treating facility. This furnished the first outlet for crude oil other than that at the Swanson River field. Contracts were let for 6 additional offshore-drilling and production platforms to be erected during 1966. End_Page 2029------------------------------ The most significant event since the discovery of oil in the Lower Kenai Conglomerate (Hemlock) at Swanson River was the discovery of multiple-pay sandstone beds in the Middle Kenai Formation. These sandstone beds furnish an additional objective and have higher porosity and permeability than the Lower Kenai Conglomerate. Gas pay zones have been found in both the Middle Kenai and Upper Kenai sandstone zones. End_of_Article - Last_Page 2030------------

Developments in Alaska in 1962

During 1962, 23 exploratory wells were drilled compared with 20 in 1961. Development wells decreased from 29 to 13. First offshore drilling commenced in 1962 from 2 barges and 1 platform in Cook Inlet basin and from 1 platform along the Alaska Peninsula. Offshore drilling in Cook Inlet was discontinued in November due to winter ice but will be resumed in early, spring. First wells were drilled on the west side of Cook Inlet. Three new gas fields were discovered during 1962 and 1 offshore gas blow-out was burning. No oil fields were found. A seismic crew was air-lifted to the Arctic (North) Slope and shooting commenced in the area east of Naval Petroleum Reserve No. 4. This is the first seismic work in the area since the U. S. Navy Department discontinued exploration in 1953. Seismic mapping increased from 73¼ crew-months in 1961 to 81¼ crew-months in 1962 with all of the increase due to offshore sparker-gas exploder work. Surface geologic exploration decreased 25.9%. An increase in surface geologic work and also seismic activity is expected in 1963. The Arctic (North) Slope is to receive the greatest increase. Exploratory drilling may show a slight decline and development drilling a continued decline.