Academic literature on the topic 'Winds Speed Antarctica'

Surface wind trends and variability over Antarctica and the Southern Ocean and their implications to wind energy in the region are analyzed using the gridded ERA-Interim reanalysis data between 1979 and 2017 and the Self-Organizing Map (SOM) technique. In general, surface winds are stronger over the coastal regions of East Antarctica and the Transantarctic Mountains and weaker over the Ross and Ronne ice shelves and the Antarctic Peninsula; and stronger in winter and weaker in summer. Winds in the southern Indian and Pacific Oceans and along coastal regions exhibit a strong interannual variability that appears to be correlated to the Antarctic Oscillation (AAO) index. A significantly positive trend in surface wind speeds is found across most regions and about 20% and 17% of the austral autumn and summer wind trends, respectively, and less than 1% of the winter and spring wind trends may be explained by the trends in the AAO index. Except for the Antarctic Peninsula, Ronne and Ross ice shelves, and small areas in the interior East Antarctica, most of the continent is found to be suitable for the development of wind power.

An acceleration of the katabatic winds during periods of blowing snow was observed in Adelie Land, Antarctica. Data collected by Automatic Weather Stations' (AWS) showed a change in the relationship between the katabatic term of the surface geostrophic wind (katabatic force) and the wind speed for periods of blowing snow. When measurements of the katabatic force were plotted against the cube of the wind speed, the slope was steeper for wind speeds at less than a threshold speed for blowing snow. The difference between these two slopes was partly explained by the effect of blowing snow entrained into the atmospheric boundary layer.

An acceleration of the katabatic winds during periods of blowing snow was observed in Adelie Land, Antarctica. Data collected by Automatic Weather Stations' (AWS) showed a change in the relationship between the katabatic term of the surface geostrophic wind (katabatic force) and the wind speed for periods of blowing snow. When measurements of the katabatic force were plotted against the cube of the wind speed, the slope was steeper for wind speeds at less than a threshold speed for blowing snow. The difference between these two slopes was partly explained by the effect of blowing snow entrained into the atmospheric boundary layer.

Abstract. Low-level easterly winds encircling Antarctica help drive coastal currents which modify transport of circumpolar deep water to ice shelves, and the formation and distribution of sea ice. Reanalysis datasets are especially important at high southern latitudes where observations are few. Here, we investigate the representation of the mean state and short-term variability of coastal easterlies in three recent reanalyses, ERA5, MERRA-2 and JRA-55. Reanalysed winds are compared with summertime marine near-surface wind observations from the Advanced Scatterometer (ASCAT) and surface and upper air measurements from coastal stations. Reanalysis coastal easterlies correlate highly with ASCAT (r= 0.91, 0.89 and 0.85 for ERA5, MERRA-2 and JRA-55, respectively) but notable wind speed biases are found close to the coastal margins, especially near complex orography and at high wind speeds. To characterise short-term variability, 12-hourly reanalysis and coastal station winds are composited using self-organising maps (SOMs), which cluster timesteps under similar synoptic and mesoscale influences. Reanalysis performance is sensitive to the flow configuration at stations near steep coastal slopes, where they fail to capture the magnitude of near-surface wind speed variability when synoptic forcing is weak and conditions favour katabatic forcing. ERA5 exhibits the best overall performance, has more realistic orography, and a more realistic jet structure and temperature profile. These results demonstrate the regime behaviour of Antarctica's coastal winds and indicate important features of the coastal winds which are not well characterised by reanalysis datasets.

Weather in Antarctica is subject to frequent and sudden changes. Strong winds and blizzards dominate Antarctic weather. A combination of blowing snow, gale force wind and very low visibility is normally defined as blizzard. Meteorological data recorded at Indian Antarctic Station Maitri, in respect of blizzards recorded during the period 1990-2005 has been studied to find out climatological features of blizzards affecting Schirmacher Oasis. At Maitri the blizzard is mostly associated with extra-tropical storms and is normally preceded by precipitation. On average during the year about 21 blizzards affects the station for 45 days during the year. During the month of April to August 3 to 4 blizzards affects the station. Maximum number of blizzards occurs in the month of August with about 7 blizzard days. Average wind speed recorded during the blizzard is about 52 kt but it exceeded 100 kt on several occasions. The duration may vary from hours to days with average of 25 hours. Longest duration of 168 hours was recorded in June 1997. There are about 12 such occasions when blizzard lasted more than 72 hours. No correlation has been found between maximum wind speed and temperature rise during blizzard and the speed is also not correlated with pressure departure during the period.

Abstract An analysis of the surface wind field across the Ross Ice Shelf, Antarctica, is conducted for austral autumn 2005. The airflow is divided into dominant wind regimes identifying similar wind patterns and the associated typical atmospheric forcing. The results of previous research and a seasonal analysis of the recently expanded network of automatic weather stations in the Ross Ice Shelf region are used to define the dominant wind regimes. Events composing each wind regime are identified by matching wind speed and wind direction observations at several automatic weather station sites for durations of at least 10 h. The four different dominant wind regimes are barrier wind, strong katabatic, weak katabatic, and light wind. Each wind regime is studied through the use of wind rose plots and sea level pressure fields from the Antarctic Mesoscale Prediction System. The sea level pressure fields are used to characterize the forcing of the surface wind field by synoptic pressure gradients. The four dominant wind regimes result in classifying less than 50% of the total hours for austral autumn 2005. The results indicate that previous studies of the Ross Ice Shelf surface wind field, focusing on katabatic winds and barrier winds, represent less than one-half of the observed winds. This study provides a better understanding of the composition of the surface wind field in Antarctica and more insight into the characteristics of the Ross Ice Shelf airstream.

AbstractIn November 2008 an automated meteorological station was established at Lake Untersee in East Antarctica, producing a 5-yr data record of meteorological conditions at the lake. This dataset includes five austral summer seasons composed of December, January, and February (DJF). The average solar flux at Lake Untersee for the four years with complete solar flux data is 99.2 ± 0.6 W m−2. The mean annual temperature at Lake Untersee was determined to be −10.6° ± 0.6°C. The annual degree-days above freezing for the five years were 9.7, 37.7, 22.4, 7.0, and 48.8, respectively, with summer (DJF) accounting for virtually all of this. For these five summers the average DJF temperatures were −3.5°, −1.9°, −2.2°, −2.6°, and −2.5°C. The maximum (minimum) temperatures were +5.3°, +7.6°, +5.7°, +4.4°, and +9.0°C (−13.8°, −12.8°, −12.9°, −13.5°, and −12.1°C). The average of the wind speed recorded was 5.4 m s−1, the maximum was 35.7 m s−1, and the average daily maximum was 15 m s−1. The wind speed was higher in the winter, averaging 6.4 m s−1. Summer winds averaged 4.7 m s−1. The dominant wind direction for strong winds is from the south for all seasons, with a secondary source of strong winds in the summer from the east-northeast. Relative humidity averages 37%; however, high values will occur with an average period of ~10 days, providing a strong indicator of the quasi-periodic passage of storms across the site. Low summer temperatures and high wind speeds create conditions at the surface of the lake ice resulting in sublimation rather than melting as the main mass-loss process.

Abstract The Ross Ice Shelf airstream (RAS) is a barrier parallel flow along the base of the Transantarctic Mountains. Previous research has hypothesized that a combination of katabatic flow, barrier winds, and mesoscale and synoptic-scale cyclones drive the RAS. Within the RAS, an area of maximum wind speed is located to the northwest of the protruding Prince Olav Mountains. In this region, the Sabrina automatic weather station (AWS) observed a September 2009 high wind event with wind speeds in excess of 20 m s−1 for nearly 35 h. The following case study uses in situ AWS observations and output from the Antarctic Mesoscale Prediction System to demonstrate that the strong wind speeds during this event were caused by a combination of various forcing mechanisms, including katabatic winds, barrier winds, a surface mesocyclone over the Ross Ice Shelf, an upper-level ridge over the southern tip of the Ross Ice Shelf, and topographic influences from the Prince Olav Mountains. These forcing mechanisms induced a barrier wind corner jet to the northwest of the Prince Olav Mountains, explaining the maximum wind speeds observed in this region. The RAS wind speeds were strong enough to induce two additional barrier wind corner jets to the northwest of the Prince Olav Mountains, resulting in a triple barrier wind corner jet along the base of the Transantarctic Mountains.

Off the coast of Victoria Land, Antarctica an area of open water—the Terra Nova Bay Polynya (TNBP)—persists throughout the austral winter. The development of this coastal polynya is driven by extreme katabatic winds blowing down the slopes of Transantarctic Mountains. The surface-atmosphere coupling and ABL transformation during the katabatic wind events between 18 and 25 September 2012 in Terra Nova Bay are studied, using observations from Aerosonde unmanned aircraft system (UAS), numerical modeling results and Antarctic Weather Station (AWS) measurements. First, we analyze how the persistence and strength of the katabatic winds relate to sea level pressure (SLP) changes in the region throughout the studied period. Secondly, the polynya extent variations are analysed in relation to wind speed changes. We conclude that the intensity of the flow, surface conditions in the bay and regional SLP fluctuations are all interconnected and contribute to polynya development. We also analyse the Antarctic Mesoscale Prediction System (AMPS) forecast for the studied period and find out that incorrect representation of vertical ABL properties over the TNBP might be caused by overestimated sea ice concentrations (SIC) used as model input. Altogether, this research provides a unique description of TNBP development and its interactions with the atmosphere and katabatic winds.

Data from six automatic weather stations deployed around the interior of the Lambert Glacier basin, Antarctica, at surface elevations of 1830-2741 m are used to compile a surface climatology of this part of interior Antarctica for the period 1994-96. The stations measure air pressure, near-surface wind speed and air temperature at several levels, wind direction and firn temperatures. The topography of the basin, which extends more than 800 km inland, controls the katabatic wind regime and strongly influences the surface climate of the region. Windiest sites are on the steep coastal slopes, and within the depression of the Lambert and Mellor Ice Streams where the flow is topographically channelled. Surface winds here show greater seasonal variation in speed but less variation in direction than elsewhere. The annual mean temperatures on the relatively steep slopes on the eastern side of the basin are 4-5°C warmer than at equivalent altitude on the western side. During winter, near-synchronous synoptic temperature and pressure increases occur throughout the basin to at least 1000 km from the coast. There is a consistent pattern of diurnal wind variation in the summer at all stations, with maximum wind speed at about 0900 LST (local solar time), and the most easterly direction at 1300 LST.

Bibliography: leaves 140-151
151, [2] leaves : ill ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
Thesis (Ph.D.)--University of Adelaide, Mawson Institute, 1989

Thesis (M.S.)--University of Wisconsin--Madison, 1994.
Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 111-113).

Probability distributions plotted to date from large volumes of high quality atmospheric observations invariably have ‘long tails’: relatively rare but intense events make significant contributions to the mean. Atmospheric fields are intermittent. Gaussian distributions, which are assumed to accompany second moment statistics and power spectra, are not seen. An inherently stochastic approach, that of statistical multifractals, was developed as generalized scale invariance by Schertzer and Lovejoy (1985, 1987, 1991); it incorporates intermittency and anisotropy in a way Kolmogorov theory does not. Generalized scale invariance demands in application to the atmosphere large volumes of high quality data, obtained in simple and representative coordinate systems in a way that is as extensive as possible in both space and time. In theory, these could be obtained for the whole globe by satellites from orbit, but in practice their high velocities and low spatial resolution have to date restricted them to an insufficient range of scales, particularly if averaging over scale height-like depths in the vertical is to be avoided; analysis has been successfully performed on cloud images, however (Lovejoy et al. 2001). Some suitable data were obtained as an accidental by-product of the systematic exploration of the rapid (1–4% per day) ozone loss in the Antarctic and Arctic lower stratospheric vortices during winter and spring by the high-flying ER-2 research aircraft in the late 1980s through to 2000. Data initially at 1Hz and later at 5Hz allowed horizontal resolution of wind speed, temperature, and pressure at approximately 200 m and later at 40 m, with ozone available at 1 Hz, over the long, direct flight tracks necessitated by the distances involved between the airfield and the vortex. Some later flights also had data from other chemical instruments, such as nitrous oxide, N2O, reactive nitrogen, NOy, and chlorine monoxide, ClO, which could sustain at least an analysis for H1, the most robust of the three scaling exponents. Better than four decades of horizontal scale were available for 1Hz and 5Hz data. Since then, a lesser volume of adequate data has been obtained away from the polar regions by the WB57F.

Offshore wind power is an emerging technology capable of providing coastal cities, states, and countries with a substantial portion of their energy needs. The vast potential of offshore wind power has not been fully explored. This work endeavors to perform a review of the literature on offshore wind power. Structural, economic, and environmental aspects are discussed keeping in mind the current status of offshore wind power development around the world. Offshore wind power is a relatively new technology being used by countries such as Denmark, the United Kingdom, the United States, Germany, and China to provide larger and larger portions of their total energy needs. In 1991 Denmark opened its first commercial offshore wind farm in Vindeby producing a mere 4.95 MW of power. More ambitious projects followed and in 2001 the Middelgrunden, Copenhagen wind farm opened producing 40 MW of power. Then in 2000 the Horns Rev wind farm was put online producing 160 MW of power. The United Kingdom has many offshore wind power projects as well. The Blyth Offshore was opened in 2000 and produces 3.8 MW of power and several others in the United Kingdom produce anywhere from 10 to 90 MW of power. By 2007 end, Denmark had 402 MW and the UK had 395 MW, Ireland, Sweden and the Netherlands had varying amounts. Countries such as China and Germany are also leaders in the development of offshore wind power. In the United States, commercial offshore wind projects had a late start. The first operational offshore wind farms opened in 2007. However, the United States does not lag behind in wind power. In 2008 the United States produced more megawatt of wind power than any other country, making them the leader of wind power production. Offshore wind, however, only constitutes a tiny portion of the total wind power production of the United States. Recent advancements in the technology associated with wind power as a renewable energy source have made it a feasible form of climate change mitigation. Recent development has led countries such as Denmark, Portugal, and Spain to devote as much as 19% of their total energy production to wind power as of 2008, and is encouraging many other developed countries to do the same. This paper performs a review of the status of offshore wind projects internationally. It considers specifically the potential of the West Wind Drift near the southernmost tip of South America and the Antarctic Peninsula as a geographically and meteorologically advantageous location for the implementation of these wind technologies. Many of the more general problems associated with the use of wind turbines are eliminated by location alone. The winds that cause the Antarctic Circumpolar Currents (ACC) have a consistent west to east pattern and are some of the strongest winds on Earth, both ideal qualities when considering the possibility of wind power, and the wind in this area has very low intermittency. The average wind speed between 40°S and 60°S is 15 to 24 knots with strongest winds typically between 45°S and 55°S. Cape Horn is about 56°S [1]. Historically, the ACC has been called the ‘West Wind Drift’ because the prevailing westerly wind and current are both eastward. Owing to the remoteness of the Cape Horn area and Antarctica, many of the social matters associated with the development of wind farms are eliminated. Obvious factors must be considered when developing in such an area. The paper will cover the engineering requirements of turbines functioning in subzero temperatures consistently as well as the long distance transmission associated with development in this area and its economic feasibility. It will also cover the environmental and regulatory issues associated with the development in such an area.

In November, 2001, the national weather services of the United States and Canada, recognizing inaccuracies in the original, adopted a revised Wind Chill Temperature (WCT) chart. This revision was developed by the authors under a mandate from a joint action group for temperature indicies (JAG/TI) formed by the U.S. Office of the Federal Coordinator for Meteorology. This new chart provides, for a given air temperature and recorded wind speed, that air temperature, the WCT, which would result in the same rate of heat loss from exposed human skin in still air. Values of the WCT are given for a range of air temperatures from −45°F to 40°F and a range of wind speeds from 5 mph to 60 mph. For Canada, the ranges are from −50°C to 10°C and 10 km/hr to 80 km/hr. The new chart was developed using principles of heat transfer, including conduction, forced convection and radiation. Skin tissue resistance was obtained from human studies. This paper describes the application of these principles and will show how these same principles have been used to demonstrate the errors in the original chart developed over 60 years ago by our military in Antarctica and adopted by the U.S. Weather Service in 1973. As was the case for the original chart, a clear night sky has been assumed, thus ignoring any direct solar radiation that would otherwise tend to elevate the WCT. The new chart is unlikely to be the final version long term and this paper will also discuss possible future modifications.