Recent warming on Spitsbergen - influence of atmospheric circulation and sea ice cover

Spitsbergen has experienced some of the most severe temperature changes in the Arctic during the last three decades. This study relates the recent warming to variations in large-scale atmospheric circulation (AC), air mass characteristics, and sea ice concentration (SIC), both regionally around Spitsbergen and locally in three fjords. We find substantial warming for all AC patterns for all seasons, with greatest temperature increase in winter. A major part of the warming can be attributed to changes in air mass characteristics associated with situations of both cyclonic and anticyclonic air advection from north and east and situations with a nonadvectional anticyclonic ridge. In total, six specific AC types (out of 21), which occur on average 41% of days in a year, contribute approximately 80% of the recent warming. The relationship between the land-based surface air temperature (SAT) and local and regional SIC was highly significant, particularly for the most contributing AC types. The high correlation between SAT and SIC for air masses from east and north of Spitsbergen suggests that a major part of the atmospheric warming observed in Spitsbergen is driven by heat exchange from the larger open water area in the Barents Sea and region north of Spitsbergen. Finally, our results show that changes in frequencies of AC play a minor role to the total recent surface warming. Thus, the strong warming in Spitsbergen in the latest decades is not driven by increased frequencies of “warm” AC types but rather from sea ice decline, higher sea surface temperatures, and a general background warming

Air temperature changes in Toruń (central Poland) from 1871 to 2010

The article presents a detailed analysis of changes in air temperature in Toruń in the period 1871–2010 on the basis of homogenised monthly, seasonal and annual air temperature series which have been newly constructed (i.e. extended by the 50 years of 1871–1920). Over the 140-year study period, a sizeable and statistically significant increase of 0.1 °C per decade was found in the air temperature in Toruń. The greatest increases occurred for spring and winter, at 0.12 and 0.11 °C, respectively. A lesser warming, meanwhile, was recorded for autumn (0.10 °C/10 years), and particularly for summer (0.07 °C/10 years). The air temperature trends are statistically significant for all seasons. Air temperature differences between the monthly averages of three analysed subperiods (1871–1900, 1901–1950 and 1951–2010) and averages for the entire period under review rarely exceeded ± 0.5 °C. In all of these periods, the highest average air temperatures occurred in July and the lowest in January. The period of 1981–2010 had the highest frequency of occurrence of very and extremely warm seasons and years. Meanwhile, the highest frequency of very and extremely cool seasons and years was recorded in the 1940s and in the nineteenth century. In the period of 1871–2010, winters shortened markedly (by 7%) and summers lengthened by 3.8%. All of the presented aspects of air temperature in Toruń, which is representative of the climate of central Poland, are in close agreement with the findings of analogous studies of the same for other areas of Poland and Central Europe

Variability of atmospheric circulation above Spitsbergen in the second half of 20th Century

The study presents variability of different circulation indices above the Spitsbergen for the period 1951-2000. Investigated area covers the part of the Atlantic sector of the Arctic located between 75-80°N and 0-30°E. The study based on the original calendar of circulation types (Niedźwiedź 1981, 2001), prepared with the help of the synoptic maps of Europe (Europäischer Wetterbericht, 1976-2000, Tägliche Wetterbericht 1950-1975). Twenty circulation types have been distinguished. The advection directions are marked by the capital letters while the anticyclonic situations by the subscript a and the cyclonic ones by subscript c; for example, Wa and Wc denote the anticyclonic and cyclonic situations respectively, with the air advection from the West. Thus, there are 16 circulation types with definite directions of the air masses. The other 5 situations are nonadvective: Ca - centre of anticyclone, Ka - anticyclonic wedge, Cc - centre of cyclone, Bc - cyclonic trough, and x - col and the situations which cannot be classified. This classification is similar to Lamb (1972) types and based on methods described in the most important works in synoptic climatology (Barry an Perry 1974, Yarnal 1993). The frequencies of the occurrence of all the distinguished circulation types for the 50-years period of 1951-2000 are presented on the table 4. On the average, the anticyclonic wedge (Ka ? 10.4 %) is the most frequent in the Spitsbergen. The second one is situation Ec and NE occurs during 9.9 and 8.8% of the days. The centre of high pressure over Spitsbergen (1.3 % of the days) and the NW situation (1.5 % of the days) are the least frequent. Weather and climate of Spitsbergen are modelled by the intensive cyclonic activity during 56 % of the days in a year. The largest frequency of the occurrence of low pressure systems is characteristic for the period from September to March with maximum in November (66 %), December and January (65%). The number of days with high pressure systems exceeds 50 % only in May (59 %). The variability of circulation have been obtained using the simple circulation indices: zonal westerly circulation W index, similar to P progression index, index of southerly circulation - S, and index of cyclonicity - C, as proposed by R. Murray and R. Lewis (1966) with some modifications. The author of this paper calculated these indices for each year, season and month (tables 1-3). The most characteristic for Spitsbergen is the zonal form of circulation with the eastern component (W = -147 for a year) with the great intensity in the period from October to April (March ?20.9). The minimum in the eastern air-flow can be observed in summer (July +0.7). Another characteristic feature for Spitsbergen is predomination of the cyclonic patterns (index C = 56 for a year), especially in the period from September to March (November 12.8). In May the index C is negative (-9.4), which confirms the great activity of anticyclonic pattern. Among the southerly circulation forms the northern component dominates (index S = -36 for a year). Only in July and August the opposite situation can be observed. Circulation forms over Spitsbergen have been fluctuated in the long-term period. In 1951-2000 the greatest changes have been observed in the indices C and W (fig. 3-7). Significant increasing trend was observed in annual values of C and S indices. Southerly circulation index S is well connected with North Atlantic Oscillation (NAO) index (table 6). The best correlation between the mean temperature at Hornsund and circulation indices exists for the S index (table 7)

The main forms of atmospheric circulation above Spitsbergen (December 1950 - September 2006)

Praca omawia najważniejsze zmiany jakie zachodziły w cyrkulacji atmosfery nad Spitsbergenem w latach 1950–2006. Po analizie zmienności typów i wskaźników cyrkulacji Niedźwiedzia stwierdzono wyraźny wzrost wartości wskaźnika cyrkulacji zachodniej (zwłaszcza latem i zimą) i południowej (głównie zimą i latem) oraz wzrost aktywności niżów we wszystkich porach roku, a zwłaszcza w zimie. Gwałtowny wzrost intensywności cyrkulacji południowej, który wystąpił w styczniu i kwietniu 2006 r. zaznaczył się dużymi anomaliami termicznymi (12.4–12.6K powyżej średniej wieloletniej). Być może rok 2006 stanie się najcieplejszym w całym okresie obserwacji instrumentalnych temperatury na Spitsbergenie.The study presents variability of 21 circulation types and simple circulation indices above Spitsbergen for the period December 1950 – September 2006, based on original calendar of synoptic divided from the synoptic maps (Niedźwiedź 1992, 1997a). Classification of circulation types, based on method of H.H. Lamb (1972), used the direction of airflow (gradient wind) and pressure pattern (a – anticyclonic, c – cyclonic) as the main elements. After calculation of synoptic types frequencies the further results have been obtained using the simple circulation indices: W – westerly, zonal index, S – southerly – meridional index, C – cyclonicity index, as proposed by R. Murray and R. Lewis (1966) with some modifications (Niedźwiedź 1997b, 2001). The anticyclonic wedge (Ka – 10.5%) was the most frequent synoptic situation in the Spitsbergen (Table 1). The second one is circulation type Ec (9.9%) and NEc (8.7%). Weather and climate of Spitsbergen was modelled by the intense cyclonic activity during 56% of the days in a year (Fig. 1). The largest frequency of cyclonic types was noticed in November (67%). For May was typical the maximum frequency of the high pressure systems (59.7%). The annual variability of different airflows above Spitsbergen is presented on the Figures 2–5. The negative value of W index is typical for Spitsbergen, according to great frequency of eastern airflow (Table 2, Fig. 6). The great intensity of eastern airflow was observed from October to April, the weakest – during summer months. For the last 56 years was observed the increased tendency of index W. The most intense of southerly circulation index S was noticed on 1984–1994 (Table 3, Fig. 7). Positive trend was observed for winter, spring and summer. Only in autumn the tendency of S index was negative. For the Spitsbergen is typical predomination of cyclonic patterns (annual value of index C is +60), with highest values of index C from September to March (Table 4, Fig. 8). Only in May index C is negative (–10) thanks to great activity of anticyclones. For the last 56 years was observed the increasing activity of cyclonic weather above the Spitsbergen. For the last three years (2004–2006) was typical the concentration of extreme intensity of the particular forms of circulation, mainly in southerly one

Influence of atmospheric circulation on the high precipitation in Hornsund (Spitsberegen)

Maximum daily precipitation and the number of days with precipitation 10.0 mm was analysed in Polish Polar Station in Hornsund (Spitsbergen), based on the measurements during 8008 days in the period 1978 June - 2000 July. The geographical coordinates of the station are following: j = 77°00? N, l = 15°33? E, Hs = 11 m a.s.l. This region is characterised by relatively large annual precipitation, varied from 230 mm in 1987 up to 640 mm in 1996. The largest diurnal total of precipitation - 58.3 mm was observed on August 1, 1994. The second high value 52.6 mm was noticed on September 6, 1996. During the observed period only 5 times daily precipitation exceeded 40 mm and 14 time was higher than 30 mm. Return period for possible daily precipitation greater than 70 mm is less than once in a hundred years. In the annual course the maximum of precipitation was observed mainly in August and September. Also the largest precipitation appears most often during the advection of air from the South and South-West with cyclones coming from the Atlantic Ocean. Special attention was made to the daily precipitation >=10 mm. they occurred during the 201 days (2.5%) and bringing about 35% of annual total. The probability of such events is highest in autumn (25%) during the south westerly cyclonic circulation type (SWc). Two other circulation types are caused also such precipitation: southern cyclonic type (Sc) with probability 24% and south westerly anticyclonic ones (SWa), with probability 11.5%. During the last decade of 20th century there was observed the increasing tendency in frequency of large precipitation in Hornsund. The sudden increase take place since 1994. These changes were connected with greater frequency in the intensity of westerly and southerly atmospheric circulation expressed by the zonal and meridional circulation indices

Role of atmospheric circulation on the January temperature variability in Spitsbergen

The study presents variability of simple circulation indices above Spitsbergen for the period 1899-2004 in January, based on original calendar of synoptic divided from the synoptic maps. After calculation of synoptic types frequencies the further results have been obtained using the simple circulation indices: W - westerly, zonal index, S - southerly - meridional index, C - cyclonicity index, as proposed by R. Murray and R. Lewis (1966) with some modifications, as well as Spitsbergen Oscillation (OS) defined as the standarized pressure difference between Bjornoya and Longyearbyen. The negative value of W index is typical for Spitsbergen, according to great frequency of eastern airflow. Variability of January temperature in Svalbard (t01SV) were investigated on the basis of averages from four stations: Isfjord Radio and Svalbard Lufthavn, as well as from Polish Polar Station in Hornsund Fiord on SW part of Spitsbergen, and from Bjornoya (Bear Island) - about 300 km SSE from Hornsund. After reconstructions of some lack data on the basis of linear regression, temperature data were obtained for the period of 1912-2004. For the temperature the main feature is period of cooling in the years 1912-1918 and then the great warming during the decade of 1930th (1933-1937). During the years 1937-1971 was observed the significant decreasing trend in January temperature to the cool period of years 1962-1971. The last period 1971-2004 has no any trend in temperature. But three large fluctuations took place with warm Januarys of 1972-1974, 1990-1992 and 1999-2001 and cool ones of 1975-1982, 1993-1998 and 2002-2004. Temperature of January changes in Spitsbergen depend on a great extend of circulation factors, mainly from the southern (S) and zonal circulation indices (W) or Spitsbergen Oscillation index (SO). Using the models of multiple regression was possible the recontruction of January temperature since 1899 on the basis of circulation indices. They explained about 63% of variance in temperature

Contemporary variability of atmospheric circulation, temperature and precipitation in Spitsbergen

The study presents variability of simple circulation indices above Spitsbergen for the period 1951-2002, based on original calendar of synoptic divided from the synoptic maps. After calculation of synoptic types frequencies the further results have been obtained using the simple circulation indices: W - westerly, zonal index, S - southerly - meridional index, C - cyclonicity index, as proposed by R. Murray and R. Lewis (1966) with some modifications. The negative value of W index is typical for Spitsbergen, according to great frequency of eastern airflow. Some complicated relations between above indices, NAO, temperature and precipitation were noticed in Spitsbergen. Variability of temperature and precipitation based on the data from Isfjord Radio and Svalbard Lufthavn stations, as well as from Polish Polar Station in Hornsund Fiord on SW part of Spitsbergen. They were compared with Bjornoya (Bear Island) - about 300 km SSE from Hornsund. For the temperature the main feature is period of cooling in the years 1961-1971 and around 1988, after the great warming during the decade of 1930th. During that coolest years also large annual temperature range was typical. The coldest was year 1968, and the warmest one -1984 (from -2 to -3°C). Next warm years were observed in 1990 and 1999, but in Jan Mayen the warmest was year 2002. The coolest winter (December-February) with average temperature below -20°C in Longyearbyen was in 1962/1963 (-21.5°C) and 1988/1989 (-20.1°C), and the warmest one on 1984/1985 (-8.3°C). Significant warming was noticed only in the warm half-year (V-X) about 1.2K since 1972 up to 2002. The warmest period V-X was in 1990, and coolest - in 1968. In summer (June-August) the temperature varied between 2°C in 1982 and 4.5°C (Hornsund) or 6.1°C (Longyearbyen) in 2002 (the warmest summer). Temperature changes in Spitsbergen depend on a great extend of circulation factors, mainly from the southern (S) and zonal circulation indices (W). The lowest temperatures were observed round the 1965. During the last decade of 1980 the period of little warming is observed again. For precipitation relative large increase of summer and September precipitation were noticed in the last years of the 20th century, mainly in 1994-1997. May be the part of its fallen in the form of snow in the upper parts of archipelago and supplied glaciers. The highest precipitation is typical for August and September. The largest diurnal precipitation totals - 58.3 mm was observed on August 1, 1994. The second high value 52.6 mm was noticed on September 6, 1996. During the observed period since 1978, only 5 time the daily precipitation in Hornsund exceeded 40 mm and 14 time were higher than 30 mm. In Hornsund annual total of precipitation twice exceeded 600 mm, in 1994 and 1996. This increase of precipitation was connected with greater frequency in the intensity of westerly and southerly atmospheric circulation expressed by the zonal and meridional circulation indices and the more intense cyclonic activity in autumn and winter season

Polar investigations of the University of Silesia in Katowice in meteorology and climatology

Opracowanie zawiera najważniejsze informacje o badaniach meteorologicznych i klimatologicznych obszarów polarnych wykonanych przez pracowników Wydziału Nauk o Ziemi Uniwersytetu Śląskiego. Badania te koncentrowały się głównie na Spitsbergenie w Arktyce. Po przedstawieniu krótkiej historii badań polarnych przedstawiono przegląd najważniejszych problemów jakie podejmowano w latach 1977-2015 w ramach omawianych nauk. Do najważniejszych należą publikacje z zakresu klimatologii synoptycznej dotyczące roli cyrkulacji atmosfery w kształtowaniu klimatu Arktyki bazujących na oryginalnym kalendarzu typów i wskaźników cyrkulacji dla Spitsbergenu. Dwie osoby uczestniczyły w opracowaniu obszernej monografii klimatycznej Polskiej Stacji Polarnej w Hornsundzie na Spitsbergenie, opublikowanej pod redakcją Andrzeja A. Marsza i Anny Styszyńskiej zarówno w języku polskim w roku 2007 oraz w języku angielskim w roku 2013. Artykuł zawiera też obszerną bibliografię prac z zakresu meteorologii i klimatologii polarnej opublikowanych przez pracowników naukowych Uniwersytetu Śląskiego.The paper contains information on the most significant meteorological and climatological research conducted in the Polar Regions by the staff of the University of Silesia in Katowice. The research was mainly carried out on Spitsbergen in the Arctic. A brief survey of polar research history is followed by the review of the most significant research topics studied in 1977-2015 period within the fields under consideration. The most significant papers cover the field of synoptic climatology. They discuss the role of atmospheric circulation in shaping the climate of the Arctic on the base of original calendar of circulation types and circulation indices for Spitsbergen. Two scientists contributed to the comprehensive climatic monography of Polish Polar Station in Hornsund on Spitsbergen. The monography was edited by Andrzej A. Marsz and Anna Styszyńska both in Polish and English and published in 2007 and 2013 respectively. The article includes also bibliography of works connected with polar meteorology and climatology published by the scientist of the University of Silesia in Katowice