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Zmienność kierunku i prędkości wiatru nad NW Spitsbergenem w okresie 1901–2010 z użyciem reanaliz ERA-20C

Strzyżewski T., Ulandowska-Monarcha P.

Przegląd Geofizyczny

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2016

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Z. 1-2

31--44

PL

Celem opracowania jest poznanie warunków anemologicznych w okresie 1901-2010 w rejonie północno-zachodniego Spitsbergenu. W tym celu posłużono się reanalizami ERA-20C. Uzyskane wyniki porównano z przebiegiem temperatury powietrza w tym rejonie. Nad obszarem NW Spitsbergenu przeważają kierunki wiatru NNE i NE (w sumie 21,9%). Najrzadziej występuje wiatr z kierunków zachodnich (W, WNW, NW, WSW, łącznie 9,7%). Można również zaobserwować, wyraźnie różniącą się strukturę częstości kierunków wiatru w porach roku. Średnia prędkość wiatru według reanaliz w latach 1901-2010 w przyjętym punkcie węzłowym wyniosła 5,6 ms-1. Prędkość wiatru w tym okresie wykazała znaczną zmienność z roku na rok. Stwierdzono przy tym istotny statystycznie (na poziomie 0,05) rosnący trend prędkości wiatru, wynoszący 0,5 ms-1 /100 lat.

EN

The aim of the study was to know the wind conditions in the period 1901-2010 over the north-western Spitsbergen. For this purpose they are used ERA-20C reanalises. The results were compared with the course of air temperature in this region. Over the area of NW Spitsbergen predominate wind direction NNE and NE (total of 21.9%). The least frequent wind direction is from the west (W, WNW, NW, WSW, a total of 9.7%). Observed also differing structure of the frequency of wind direction, depending on the season. The average wind speed in the years 1901-2010 in the was 5.6 ms-1. Wind speed during this period showed considerable variability from year to year. It has been found that a statistically significant (at the 0.05 level) growing trend of wind speed (0.5 ms-1 /100 years).

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Mechanical Aspects of Circular Runway Aspects

Jeż M.

Machine Dynamics Research

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2014

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Vol. 38, No. 1

29-37

EN

The project „Endless Runway” was conceived during meetings of EREA (European Research Establishments in Aeronautics) association. Five of them, under leadership of Dutch NLR, formulated the proposal concerning future airport configuration. Using extended versions of current airport software and a lot of consultations with airports stakeholders and airline pilots a circular runway parameters were agreed upon for future prototype realization.

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Osady eoliczne (wydmowe) w suchym i półsuchym regionie płaskowyżu Alashan (MongoliaWewnętrzna, Chiny)

Kenig K.

Przegląd Geologiczny

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2012

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Vol. 60, nr 5

267--272

EN

In northern China, sandy and rocky deserts are located in arid regions west of the Helan Mountains (Helan Shan), while the areas of fixed sand dunes stretch in semi-arid regions east of the Helan Mountains. Helan Mountains, trending nearly NS in the northern part of China's Inner Mongolia Autonomous Region, are a natural border between the dry climate to the west and the semi-dry climate to the east. In the Badain Jaran Desert (part of the Alashan Desert), there are the largest dunes in China, and possibly the largest in the world. They attain a height of up to 460 m in the southeastern part of the desert. Due to their size, they are called megadunes by the Chinese researchers. They are accompanied by numerous smaller dunes, developed in various forms, which cover their slopes. As a result, megadune complexes form, reaching 10 km in length. The general direction of the dunes is NE-SW. In their lower parts, they are covered with sparse xerophytic vegetation, mainly Artemisia and Ephedra. In interdunal depressions of the Badain Jaran Desert, there are numerous (140) permanent, relatively shallow and drying-up lakes, overgrowing with vegetation. Their average depths are 2 m, rarely reaching 16 m mainly in the northern part. The water in the lakes is highly alkaline, with pH values of up to 10.5. Sometimes, the accumulation of salt is so substantial that allows it to be extracted. The groundwater in the immediate surroundings of dunes shows a much lower alkalinity and the average pH is 7.8. To the east of the Helan Mountains, there are several deserts of generally smaller areas and specific environmental nature. This is a sandy land of Hunshandake. Dunes and dune fields are lower and less well developed morphologically, reaching an average of 5-10 m in height. They are mostly stabilized completely or partially by vegetation. The main trend of dunes here is WNW-ESE. Locally, shallow lakes occur in interdunal areas. Studies of mineral and chemical composition of silt material are important for the considerations of the source and direction of silt transport in Asia. One of the diagnostic components of detrital minerals is dolomite. The newest studies of silts recently deposited in Beijing provide information about the wind-transportation direction. It appears that there is a fundamental difference in the mineral composition of silts originating from the dust storm (in 2006) and silts from the entire spring period. Such conclusions are also confirmed by the content of rare earths elements in the 2006 dust storm sediments from Beijing and, comparatively, from other deserts as potential source areas of silts (Yang et al., 2007b). Isotopic investigations of Nd and Sr in aeolian sediments of northern China confirm such a possibility. An important problem for the areas located in northern China is the process of desertification. Noticeable differences have occurred already during the last three decades. They consist in changes in the distribution of movable dunes, which is relative to the humidity and temperature. It is believed that the climate may be the main factor causing desertification in Hunsheandake. In other regions of China, there is another significant factor: human activity, especially shepherding that causes the process of desertification and environmental degradation.

4

Initial foredune field as a factor of accumulative character of coastal dunes of the Swina Gate Barrier (west Polish coast)

Łabuz T. A.

Oceanological and Hydrobiological Studies

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2003

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Vol. 32, No. 1

39-56

EN

Many of the Polish sandy coasts covered by several dune ridges are in danger, threatened by high wave storms and sea level rise. Some of the sandy coasts are accumulative. Accumulated on beach sand may cause growth and development of ridge. When upper beach at the front of the first dune is densely covered by plants sand may be fixed on beach. In this way on the upper beach may be built small hillocks or shadow dunes. It is important to know how fast a new dune ridge rises. This paper shows the importance of dune field formation on the upper beach in front of the foredune for new dunes accumulation. This field has possibilities to change in an initial dune ridge. Continuous aeolian accumulation of the sand on the dune field leads to the building of a new dune ridge. This process was observed on spit of Swina Gate Barrier on west Polish coast. The accumulation was forced by pioneer vegetation, which was covering hillocks and trapping transported sand from the beach. Also speeds and wind directions (measured in Świnoujście) may cause bigger and faster accumulation.