| 1. |
- Linderson, Maj-Lena
(författare)
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Spatial distribution of meso-scale precipitation in Scania, southern Sweden
- 2003
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Ingår i: Geografiska Annaler. Series A. Physical Geography. - : Informa UK Limited. - 0435-3676 .- 1468-0459. ; 85:2, s. 183-196
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study is to analyse the spatial variability of meso-scale precipitation in Scania and to assess the influence of synoptic scale atmospheric circulation. The modes of spatial variation are revealed by EOF analysis of monthly precipitation totals between 1963 and 1990, which were obtained from a dense rain-gauge network in Scania. southern Sweden. The influence of local physiography on the spatial distribution of precipitation is assessed by GIS techniques using a digital elevation model of Scania. The relation to synoptic scale atmospheric circulation is analysed using regional circulation indices and weather types. It is shown that the daily precipitation distribution in the area is significantly influenced by synoptic scale pressure patterns. Nevertheless. the covariability of the monthly precipitation within Scania is high. About 80% of the precipitation variability is connected to the passage of low-pressure centres over or close to the region. which are likely to produce precipitation over the whole area. A wind-direction dependency found in the distribution indicates that there might be a limit between precipitation regimes within the landscape. Topography greatly influences the spatial distribution in Scania. The distribution of land and surrounding sea is also an important factor and makes the relationship between physiography and precipitation rather complex. The physiographical effects vary over a single year. The dampening effect of the sea on the atmospheric temperature influences the local stability in coastal areas and results in seasonally dependent precipitation patterns.
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| 2. |
- Klingbjer, Per
(författare)
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Recurring jökulhlaups in Sälka, northern Sweden
- 2004
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Ingår i: Geografiska Annaler. Series A, Physical Geography. - : John Wiley & Sons, Inc.. - 0435-3676 .- 1468-0459. ; 86:2, s. 169-179
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Tidskriftsartikel (refereegranskat)abstract
- An ice-dammed lake at the margin of the glacier Slkaglaciren, in the Kebnekaise Mountains in northern Sweden, drained suddenly in July 2003 producing a flood with a measured peak discharge of 9.5±0.25 m3s-1. The total lake volume of 4.55×105 million3 drained within two days. The hydrograph of this event is characteristic of a jökulhlaup controlled by a single basal ice tunnel that enlarges due to melting. The jökulhlaup had an exponential rise to a peak discharge, and following the peak, a very steep fall in discharge as the water supply to the drainage system ceased. A similar jökulhlaup was observed in August 1990 with an estimated release of 8.05×105 m3 water. Jökulhlaups at Slkaglaciren are recurring events and have been indirectly observed since the 1950s.
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| 3. |
- Nihlen, Tomas
(författare)
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Palsas in Harjedalen, Sweden : 1910 and 1998 compared
- 2000
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Ingår i: Geografiska Annaler. Series A, Physical Geography. - 0435-3676 .- 1468-0459. ; 82A:1, s. 39-44
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Tidskriftsartikel (refereegranskat)abstract
- In 1998 on area near Helagsfjallet in Harjedalen was investigated in an attempt to relocate palsas discovered by the botanist Harry Smith in 1910. Several small palsa-like features with ice cores were detected. The palsas were found on an almost flat peat bog at 950 m, 3 km NW of NL Helagsfjallet. Five clearly elevated mounds and some indistinct ones with palsa-like features were traced. The Five mounds were about 0.6 m high and had an area of about 2 x 3 m. One of the mounds was examined in more detail. At a depth of 0.3 m in the peat an ice body with 3 hard ice core was found. This location is the most southerly area known with occurrence of palsa-like forms in Sweden at the present time. In spite of a warmer climate towards the latter part of this century, palsa-like features have survived in this area. The mean annual temperature barely fits the criterion for palsa formation while the mean annual precipitation is too high as compared with the general assumptions. The palsa formation is probably dependent on strong winds thinning out the snowcover.
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| 4. |
- Sundborg, A, et al.
(författare)
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Water discharges determined from sediment distributions : A palaeohydrological method
- 2001
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Ingår i: Geografiska Annaler. Series A, Physical Geography. - 0435-3676 .- 1468-0459. ; 83A:1-2, s. 39-54
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Tidskriftsartikel (refereegranskat)abstract
- The article presents a simple sediment deposition model, based on current knowledge of the processes of transport and deposition of suspended material. It indicates possibilities of interpreting flow conditions from grain-size distributions at two localities, situated along the water flowline. The model reveals new information an ancient hydrological and sedimentological processes and events. Previously the model has been applied to forecast trap efficiency of reservoirs and predict reservoir sedimentation. In this study the model is used as a palaeohydrological method in studies of annual varves. In varve geochronology a major attention has been paid to varve correlations and valve thickness variations, whereas other sedimentological data have been more or less disregarded. In this article new information on the spatial distribution of particle sizes demonstrate that further knowledge can be gained by careful studies of the patterns of grain-size distributions. Annual variations in water discharges during late glacial time were studied in the Indalsalven and Dalalven valleys in Sweden. Water discharges during the deglaciation seem to have been of the same order of magnitude as in present-day rivers during normal years. During some years catastrophic events occurred, resulting in exceptional water discharges. The magnitudes of these discharges were estimated, and drainage directions were established. It appears from the studies that there are promising prospects of finding out both the magnitude and frequency of processes that until now have been described only in qualitative terms.
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| 5. |
- Ekström, Marie
(författare)
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Estimating monthly surface winds for Scania, southern Sweden, using geostrophic wind (1899-1997)
- 2002
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Ingår i: Geografiska Annaler. Series A. Physical Geography. - 0435-3676. ; 84A:2, s. 113-126
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Tidskriftsartikel (refereegranskat)abstract
- Wind direction conditions during the 20th century in Scania, southern Sweden, are investigated using an estimated series of monthly wind vector components (east-west u component and north-south v component). The series is developed from a regression relationship between pairwise (1973 to 1997) monthly averages of 10-m surface wind from Scania and a monthly geostrophic wind, based on mean sea level (MSL) pressure data from the National Center of Atmospheric Research (NCAR). The wind conditions during the 20th century are dominated by winds from southwesterly and westerly directions, particularly during summer and autumn. From the 1980s onwards, increased frequencies of westerly winds are evident in spring and summer; however, similarly large frequencies of westerly winds are also found during the early part of the 20th century. Analysis of the estimated wind series indicates large variation in wind direction during the investigated time period, particularly during 1930 to 1960 when large increases of easterly winds are evident in spring. Increased frequencies of easterly winds were also found in other months during this period but not to the same extent as during the spring season. Thus, the presence of periods with quite different wind characteristics suggests that the overall atmospheric circulation has experienced some shifts in this region during the 20th century.
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| 6. |
- Linderholm, Hans W., 1968, et al.
(författare)
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Summer moisture variability in east central Sweden since the mid-eighteenth century recorded in tree rings
- 2004
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Ingår i: Geografiska Annaler Series a-Physical Geography. - 0435-3676. ; 86A:3, s. 277-287
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Tidskriftsartikel (refereegranskat)abstract
- To make predictions of future climate it is necessary to understand the past climate-temperature as well as precipitation. While a wealth of temperature proxies exist from northern latitudes, there is still a lack of information about past precipitation variability. Here we present a 300-year-long tree-ring width chronology from xeric-site Scots pines (Pinus sylvestris L.) in Tyresta National Park, east central Sweden. Tree-ring widths were compared to the long observed temperature and precipitation records from Stockholm during 1786-2000. Analyses of the climate/growth relationship showed that, in general, May-June precipitation had a dominating influence on pine growth. However, during dry periods, negative responses to June-July temperature were stronger, especially evident in the late nineteenth century. Periods of below-average growth were associated with dry conditions in May-June, but occasionally periods of wet and cool summers also produced narrow rings. Periods of above-average growth were linked to wet, but sporadically also cool and dry, early summers. The years between 1815 and 1833 appear to be particularly dry in the 300-year context. Since growth anomalies are found in other Swedish drought-sensitive tree-ring chronologies during this period, it is likely that this dry period had a regional extent. This is the first tree-ring chronology from southern Sweden that provides multi-century information of past summer drought and moisture variability with high resolution and the study will add important information regarding past climate variability in southern Sweden.
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| 7. |
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| 8. |
- Sundborg, A, et al.
(författare)
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Water discharges determined from sediment distributions: A palaeohydrological method
- 2001
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Ingår i: GEOGRAFISKA ANNALER SERIES A-PHYSICAL GEOGRAPHY. - : BLACKWELL PUBL LTD. - 0435-3676. ; 83A:1-2, s. 39-54
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Tidskriftsartikel (refereegranskat)abstract
- The article presents a simple sediment deposition model, based on current knowledge of the processes of transport and deposition of suspended material. It indicates possibilities of interpreting flow conditions from grain-size distributions at two localit
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