Wyniki wyszukiwania - BazTech

1

The features of snow loads on building roofs

Pichugin S. F., Dryzhyruk Y. V., Popovich N. M., Chernetska I. V.

Czasopismo Techniczne. Budownictwo

|

2015

|

Y. 112, iss. 2-B

441--449

EN

In this paper the probabilistic model of the snow accumulation on the roofs with height discontinuity was worked out, the decreasing coefficient for the snow load weight was received and the ways of their application in the designing were elaborated. The probabilistic model for impulse stochastic process of snowfall sequence was developed. Data from meteorological stations in Ukraine allow determination of statistical characteristics: average annual snowfall amount and exponential distribution of values of one snowfall. The law of intensity distribution of snow melting has been determined experimentally. The territorial zoning map of Ukraine by characteristic values of the snow load on the roofs that emanate heat was developed.

PL

W pracy opracowano probablilistyczny model akumulacji śniegu przy zmianie wysokości dachu, otrzymano współczynnik zmniejszający dla obciążenia śniegiem oraz wypracowano sposoby jego wykorzystania w projektowaniu. Rozwinięto model probablistyczny dla impulsowego procesu stochastycznego dotyczącego opadu śniegu. Dane ze stacji meteorologicznych na Ukrainie pozwoliły określić charakterystyki statystyczne: średni roczny opad śniegu i wykładniczy rozkład wielkości w pojedynczym opadzie śniegu. Prawo rozkładu intensywności topnienia śniegu zostało określone eksperymentalnie. Rozwinięto mapę stref terytorialnych Ukrainy za pomocą charakterystycznych wielkości obciążenia śniegiem dachów wydzielających ciepło.

2

Badania glacjologiczne współczesnych zmian Lodowca Ireny, Svalbard

Sobota I.

Problemy Klimatologii Polarnej

|

2010

|

nr 20

143-159

PL

Badania glacjologiczne przeprowadzono na Lodowcu Ireny, o powierzchni 4,1 km2 (2009), zlokalizowanym na Kaffioyrze na północno-zachodnim Spitsbergenie. Obejmowały one zagadnienia topnienia lodowca, zmienności akumulacji śniegu w sezonie wiosennym i letnim oraz zmian bilansu masy, powierzchni i położenia czoła lodowca. Szczegółowo przeanalizowano lata 2008 i 2009. Różniły się one wyraźnie warunkami pogodowymi, zwłaszcza w okresie letnim, co miało istotny wpływ na poszczególne elementy określające wielkość zmian i dynamiki lodowca. W dłuższym przedziale czasowym (2002-2009), lodowiec Ireny charakteryzuje się wyraźnie negatywnymi zmianami, zwłaszcza ujemnym bilansem masy, jak również cofaniem się czoła i zmniej-szaniem powierzchni. Jednakże występują lata, które wyraźnie różnią się od ogólnego negatywnego kierunku zmian. Przykładowo sytuacja taka miała miejsce w roku 2008.

EN

The glaciological investigations of the Irene Glacier changes, a 4.1 km2 glacier located in NW Spitsbergen, Svalbard, were undertaken. Traditional glaciological mass balance measurements by stake readings and snow surveying have been conducted annually since 2002. In this paper 2008 and 2009 mass balance years were analyzed in details.. Glaciological research of the Irene Glacier refers to the following issues: glacier's melting, changes in the snow accumulation during the spring and summer seasons, and the changes of the area and the position of the glacier’s tongue. The years 2008 and 2009 were distinct in terms of the weather conditions, especially during the summer season. This significantly influenced the individual elements which describe the changes and dynamics of the glacier. Glaciological methods of mass balance estimation involve repeated stake measurements at the glacier surface to determine the rates of ablation and accumulation. These methods involve estimation of local mass balance using ablation poles, supplemented with studies of the snow cover in pits. At the end of the 2008 ablation season snow cover occured on about half of the glacier surface. In 2009 in the same time snow was visible only in the upper part of the accumulation zones of this glacier and at the foot of the mountain slopes. The 2008 winter balance of the Irene Glacier was 55 cm w.e, and 65 cm e.w.in 2009. In the balance year 2009, in spite of the winter snow accumulation higher than the average, the annual net mass balance of the Irene Glacier was definitely negative. In 2008 mean annual mass balance of the Irene Glacier was -38 cm w.e. In 2009 mean annual mass balance of the Irene Glacier was -63 cm w.e. and was very similar to the mean multi-annual value of the annual net mass balance of this glacier. Spatial diversity of mass balance of the Irene Glacier is mainly influenced by weather conditions over a specific part of the glacier and by local morphology. In 2009, the spatial diversity of the net mass balance of the Irene Glacier was mostly influenced by its negative value in the ablation area. The net mass balance in the ablation area of the glacier was up to -250 cm w.e. The zone of the negative net balance covered a larger area if compared to the previous years and especially to the year 2008. Such a situation predominantly resulted from a higher ablation. In 2009 mean annual mass balance of the Irene Glacier was similar to the mean multi-annual value of the net mass balance of this glacier. In the balance year 2009, in spite of the winter snow accumulation, higher than the average, the annual mass balance of the Irene Glacier was definitely negative. This was the result of intensive ablation during the summer season. The negative net mass balance of the Kaffiřyra region glaciers recorded in recent years influences their geometry, especially shrinking the area and lowering the surface, as well as changing their front positions. Between 2000 and 2009, the area of the Irene Glacier decreased by about 3%. In the years 2002-2009 the Irene Glacier showed negative tendencies, especially in its mass balance. Moreover, the retreat of the tongue and the decrease of the glacier’s area were recorded. However, there were also years which differed a lot from the general negative trend of changes. For instance, such a situation was recorded in 2008. It must be stressed that large winter snow accumulation does not necessarily influence the lower negative mass balance. Similarly, intensive melting during the summer season does not necessarily mean significant negative mass balance value. It is connected with the weather conditions in a given year and seasonal balance, as well as with other local conditions of the glacier. As a result, the inter-dependency between climate and mass balance may be slightly distorted. Nevertheless, mass balance of a glacier remains one of the most important indexes of modern climate changes. Glaciological studies of the Irene Glacier pose an important element in the estimation of modern changes in the cryosphere of the Kaffiřyra Region, which is an example of changes in the environment of the NW Spitsbergen.

3

Charakterystyka zmienności pokrywy śnieżnej w sezonie letnim (ablacyjnym) na lodowcach rejonu Kaffioyry (NW Spitsbergen)

Sobota I.

Problemy Klimatologii Polarnej

|

2007

|

nr 17

135-145

PL

Przeanalizowano wielkość oraz przestrzenną zmienność akumulacji śniegu na lodowcach rejonu Kaffioyry w sezonie letnim 2006 roku. Pokrywa śnieżna na lodowcach Waldemara i Ireny występowała do połowy sierpnia, a w najwyższych partiach pól akumulacyjnych i u podnóża stoków górskich przez cały sezon ablacyjny. W przypadku Lodowca Elizy pod koniec sezonu śnieg zajmował wyraźnie większą powierzchnię. Na podstawie szczegółowych pomiarów dokonano oceny zmienności akumulacji z wysokością nad poziomem morza oraz zróżnicowanie gęstości śniegu. Pozwoliło to określić ekwiwalent wodny pokrywy śnieżnej. Stwierdzono, że znajomość miąższości i przestrzennego zróżnicowania pokrywy śnieżnej w okresie letnim oraz stref glacjalnych na lodowcu stanowi ważny element w badaniach i ocenie tempa ablacji lodowcowej.

EN

Size and spatial variability of snow accumulation on the Kaffiřyra glaciers were analysed in the summer of 2006. The values of accumulation changeability at the growing altitude and the diversity of accumulation density were based on detailed measurements. This enabled to estimate the thickness of the snow cover in water equivalent (w.e.). In the summer season of 2006 average snow accumulation on the Waldemar Glacier was 9.3 cm of water equivalent. On average, it changed from 24.1 cm w.e. at the beginning of the summer season to 1.1 cm w.e. in August. Mean snow accumulation on the Irene Glacier amounted to 7.3 cm e.w.; on average it changed from 15.6 to 1.0 cm w.e. Mean snow accumulation on the Elise Glacier was 25.8 cm w.e. and it changed from 36.1 July to 12.0 cm w.e. at the end of August. The largest diversity of snow accumulation at the growing altitude was recorded on the Elise Glacier. From both the Waldemar Glacier and Irene Glacier the snow cover disappeared quickly. As a result, at the end of the ablation season snow was only visible in the upper parts of the accumulation zones of those glaciers and at the foot of the mountain slopes. The Elise Glacier had a longer-lasting snow cover on large areas which survived until the end of the season. This was not only the outcome of the weather conditions but, predominantly, larger altitude diversity between the snout of this glacier and its accumulative pars as well. In higher parts of the glacier a larger snow loss in time is recorded. Mean snow thickness in the summer season is nearly twice higher than during the spring season with the snow cover. There is a correlation between the snow cover thickness and the altitude. However, with time and the diminishing snow cover this interrelation is less distinct. Another distinct interrelation exists between spatial diversity of snow accumulation and the size and spatial diversity of snow ablation. Melting of the snow cover during the summer season favours the creation of different glacial zones which influence the intensity of summer ablation. The knowledge of the thickness and spatial variability of the snow cover during the summer season, as well as the glacial zones poses an important element of the study and assessment of the rate of glacial ablation.

4

Kryteria podobieństwa w badaniach modelowych zjawisk transportu i akumulacji śniegu w tunelu aerodynamicznym

Kimbar G.

Zeszyty Naukowe. Budownictwo / Politechnika Śląska

|

2005

|

z. 104

163-170

PL

Artykuł przedstawia kryteria podobieństwa wyprowadzone z analizy wymiarowej przydatne przy przeprowadzaniu eksperymentów tunelowych z udziałem fazy rozproszonej, ze szczególnym uwzględnieniem symulacji transportu i akumulacji śniegu.

EN

The paper shows similarity criteria derived from dimensional analysis applicable during setting up tunnel experiments involving dispersed phase, with special attention to simulation of snow transport and accumulation.

5

Związek akumulacji śniegu na lodowcach północno-zachodniego Spitsbergenu z cyrkulacją atmosferyczną, opadami i temperaturą powietrza w okresach zimowych

Grabiec M.

Problemy Klimatologii Polarnej

|

2003

|

nr 13

161-171

EN

This work attempts to determine connections between glaciers' winter mass balance and meteorological factors of winter seasons. Detailed analysis was carried out between the snow accumulation of Austre Broggerbreen and the meteorological data from Ny-Alesund station (Kongsfjord region) from 1975 to 1998. Relation has been found between the snow accumulation and warm and humid air masses frequency in winter seasons (X - V). Those masses are mainly from southerly and southwesterly directions for Svalbard. The winter mass balance shows very clear connection with air temperature and precipitation factors of winter seasons (sum of winter precipitation, number of days with precipitation intensity >= 5 mm per day, winter mean air temperature, and number of days with maximum daily air temperature >= 0°C). A particularly close connection is observed between winter mass balance and number of days with precipitation intensity >= 5 mm per day at the positive daily maximum air temperature (LPTmax) (r = 0.81) - Fig. 8. The winter mass balance multiply regression (Wb) was worked with the use of the elementary meteorological factors: the average winter temperature (T) and the sum of precipitation in the same period (P). On the basis of the multiply regression of winter balance it is possible to predict snow accumulation changes. Over the next 50 years the winter snow accumulation of Austre Broggerbreen could increase about 15% if the scenario of climatic changes by Hanssen-Bauer (2002b) is used. If, in addition, one assumes the stability of ablation, the mass balance of glaciers will rise by 24%, but the mass balance will still be negative.

6

Warunki meteorologiczne i wybrane problemy akumulacji śniegu na Równinie Kaffioyra (NW Spitsbergen) w okresie od lipca 2001do kwietnia 2002 roku

Sobota I.

Problemy Klimatologii Polarnej

|

2003

|

nr 13

139-149

EN

The paper presents the results of meteorological measurements carried out in the Kaffioyra Plain in the summer season of 2001 and in the period form July 2001 to April 2002. The main meteorological observations were conducted in N.Copernicus Polar Station. situated in northern part of the Kaffioyra (NW Spitsbergen). The paper also presents the results of snow accumulation measurements on the Waldemar Glacier and Irene Glacier. which are located at Kaffioyra Region. The mean air temperature in the summer period (21.07. to 31.08.2001) was 5.9°C and was visibly higher then the long-term average. The sum of precipitation in this time was 37 mm and was lowest then the long-term average. The comparison between summer season 2001 and mean values from the years 1975-2001 in the common period shows that this season was characterised by air temperature higher then many year?s values. The mean air temperature in the period from July 2001 to April 2002 was -5.3°C. The highest monthly air temperature was in August (5.2°C) and the lowest was in March (-14.7°C). The sum of precipitation in the time with snow cover at Kaffioyra was 86.6 mm. Investigations of a snow cover on the Kaffioyra have been carried out in two points. Snow cover on the Kaffioyra was started to form in the end of September. Winter snow accumulation equal to 91 cm in point B and 18 cm in point B. The changes of snow thickness was depended from a velocity of wind. Investigations of a snow cover on the Waldemar Glacier and the Irene Glacier have been carried out form September 2001 to April 2002. The Waldemar Glacier and Irene Glacier are located in the northern part of the Oscar II Land (Northwestern Spitsbergen). In spite of small areas of these glaciers. there is great spatial variation in snow deposition. During the winter 2002 the highest snow accumulation of the Waldemar Glacier was noted in the northern part of the glacier. both on its accumulation part and at foot of Grafjellet which surrounds the glacier from the south. The lowest thickness of a snow cover was observed at terminus of the glacier and at foot of the medial moraine (up to 40 cm w.e.). On the Irene Glacier the highest snow accumulation was observed in two accumulation parts (up to 120 cm w.e.). The lowest thickness of a snow cover was observed at terminus of the glacier and at central part of glacier (up to 20 cm w.e.). Winter snow accumulation of the Waldemar Glacier was equal to 63.2 cm w.e. On the Irene glacier it was similar and equal to 64.7 cm w.e.