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1.
Recent climate change: Rethinking drought in the context of Forest Fire Research in Ticino, South of Switzerland 总被引：3，自引：1，他引：3
Summary We analyse trends over the past 32 years in drought variables in the context of forest fire research and climate change in Ticino, Southern Switzerland. January to April and in particular the month of March have become drier. This is the time of the year when forest fires are most frequent. Our results show an increasing trend in all climatic variables favourable to drought and forest fires, including the length of episodes without precipitation, sunshine duration and temperature, and a decrease in relative humidity. The only exception is the number of “foehn” days, which have not significantly increased. 相似文献
2.
Tilo Usbeck Peter Waldner Matthias Dobbertin Christian Ginzler Christian Hoffmann Flurin Sutter Charlotte Steinmeier Richard Volz Gustav Schneiter Martine Rebetez 《Theoretical and Applied Climatology》2012,108(3-4):451-462
This study compares the surface wind speed and forest damage data of two exceptionally severe winter storms, Vivian 1990 and Lothar 1999. The study area comprises the region that suffered damage in Switzerland. The wind speed data were derived from simulations of MeteoSwiss (Federal Office of Meteorology and Climatology), measurements during the storm periods and expert analyses of the data. The remotely sensed forest damage data were provided by the Federal Office for the Environment and the forest cover data by Swiss Federal Statistical Office. We compared data on the peak gust and maximum average wind speed, with data on the spatially related forest area and forest damage area, and found some clear differences in the correlations between the different wind data and forest damage. Our results point generally to the damage-causing role of near-surface gusts at maximum wind speeds during the storm. These tended to be spatially distributed on a fine scale. In only a few cases were the results statistically significant. However, these results could probably be improved with better wind data. For example, gust measurements spatially closer to forests or simulations of gusts at maximum wind speed could be produced with a spatially higher resolution. 相似文献
3.
M. Rebetez 《Theoretical and Applied Climatology》2001,69(1-2):13-21
Summary An analysis of day-to-day variability was performed on two century-long daily minimum and maximum temperature series from
Switzerland. Warmer temperatures during the 20th century have been accompanied by a reduction in day-to-day variability, particularly for minimum temperatures and for winter.
There is a significant negative correlation between day-to-day variability and the skewness of the temperature distribution,
particularly in winter and for minimum temperatures. Lower variability is linked to a reduced number of cold days and nights.
Higher NAO index values tend to be associated not only with warmer temperatures but also with lower day-to-day variability.
This paper confirms that the temperature warming during the 20th century has happened mainly through the loss of the coldest part of the series, not only in the 24-hour or yearly cycle,
but also through the loss of the coldest episodes in each month.
Received September 20, 2000 Revised January 8, 2001 相似文献
4.
R. Heino R. Brázdil E. Førland H. Tuomenvirta H. Alexandersson M. Beniston C. Pfister M. Rebetez G. Rosenhagen S. Rösner J. Wibig 《Climatic change》1999,42(1):151-181
A study of the long-term changes of various climatic extremes was made jointly by a number of European countries. It was found that the changes in maximum and minimum temperatures follow, in broad terms, the corresponding well-documented mean temperature changes. Minimum temperatures, however, have increased slightly more than maximum temperatures, although both have increased. As a result, the study confirms that the diurnal temperature range has mostly decreased during the present century in Northern and Central Europe. Frost has become less frequent. Two extreme-related precipitation characteristics, the annual maximum daily precipitation and the number of days with precipitation 10 mm, show no major trends or changes in their interannual variability. An analysis of return periods indicated that in the Nordic countries there were high frequencies of extraordinary 1-day rainfalls both in the 1930s and since the 1980s. There have been no long-term changes in the number of high wind speeds in the German Bight. Occurrences of thunderstorms and hails show a decreasing tendency in the Czech Republic during the last 50 years. Finally, using proxy data sources, a 500-year temperature and precipitation event graph for the Swiss Mittelland is presented. It shows large interdecadal variations as well as the exceptionality of the latest decade 1986-1995. 相似文献
5.
Summary Large numbers of Scots pine are dying in the dry inner-alpine valleys of the European Alps; in Switzerland, locally almost half the Scots pine (Pinus sylvestris L.) population has died since 1995. As Switzerlands temperature has increased at more than twice the global average in the 20th century and as most of this increase has occurred during the last 20 years, we investigated possible relationships between the dying Scots pine and climatic parameters. We centred our studies in the upper Rhone valley.Our results show that the strong climatic warming that has occurred in recent years may well be the indirect cause of the mortality observed in these forests. Tree mortality was highest following the dry and hot year 1998, and tree defoliation, an indicator of tree vitality, showed a strong correlation with the previous years precipitation. While precipitation showed no clear significant trend over time, the number of warm days (mean>20°C, maximum>25°C) and potential evapotranspiration have significantly increased over the last 20 years.Higher temperatures favour pine wood nematodes and bark beetles, both of which are found at the study site, and increasing drought stress reduces tree resistance against pathogens. As these forests have in part protective functions, there is a need to better understand the mortality through interdisciplinary research and also to find means to change the species composition in order to establish tree species that are better able to withstand warmer temperatures. 相似文献
6.
Summary A series of anomalously cold and warm winters which occurred in Switzerland during the 15-year period from 1979 to 1993 has been analyzed in detail in terms of temperature minima. The warm winters between 1988–1992 were particularly marked in the Alps, where lack of snow had severe consequences for the tourist-based economies of mountain communities. The investigations presented here focus primarily on minimum temperature records for up to 88 climatological observing sites distributed over Switzerland.Analyses of the departures of temperature minima from the 15-year means in warm and cold winters has shown that there is a very significant altitudinal dependency of the anomalies except at low elevations which are subject to fog or stratus conditions; the stratus tends to decouple the underlying stations from processes occurring at higher altitudes. It is also shown that there is a switch in the gradient of the temperature anomaly with height from cold to warm winters. For warm winters, the higher the elevation, the stronger the positive anomaly; the reverse is true for cold winters. The statistics for the 88 observational stations provide a measure of the damping of the climate signal as an inverse function of height. The altitudinal dependency of temperature departures from the mean are the most important feature, followed by latitudinal effects (north and south of the Alps); continentality is not seen to be a major factor in determining the geographical distribution of temperature anomalies at this scale.The present investigation also emphasizes the fact that high elevation records can more readily identify significant interannual climatic fluctuations than at lower-elevation sites. This is also likely to be the case for longer-term climate change, where possibe greenhouse-gas warming would presumably be detected with more clarity at higher elevations. This type of study can help orientate future high-resolution climate model studies of climate change and in particular the assessment of model capability in reproducing a range of possible temperature anomalies and their altitudinal dependency.With 12 Figures 相似文献
7.
M. Beniston M. Rebetez F. Giorgi M. R. Marinucci 《Theoretical and Applied Climatology》1994,49(3):135-159
Summary An analysis of daily climatological data covering the period from 1901 to 1992 for four locations in Switzerland (Zurich, Lugano, Davos, and Säntis) has been made. The study has highlighted the fact that climate change this century is characterized by increases in minimum temperatures of about 2 K, a more modest increase in maximum temperatures (in some instances a decrease of maxima in the latter part of the record), little trend in the precipitation data, and a general decrease of sunshine duration through to the mid 1980s. The interannual variability is generally large, and filtering of the data to remove high-frequency noise shows that the regional climate undergoes a series of fluctuations of between 8 and 20 years' duration. The temperature change over this century is of greater magnitude than the global temperature changes published in the literature, reflecting an amplification of the global signal in the Alpine region; warming has been most intense in the 1940s, followed by the 1980s; the cooling which intervened from the 1950s to the late 1970s was not sufficient to offset the warming in the middle of the century.Pressure statistics have been compiled as a means of providing a link between the regional-scale climatological variables and the synoptic, supra-regional scale. These statistics show that pressure also exhibits a number of decadal-scale fluctuations, with the appearance of a new and anomalous behavior in the 1980s; in this decade, pressure reaches annual average values far higher than at other times this century. The pressure field is well correlated with the North Atlantic Oscillation (NAO) Index for distinct periods of the record (1931–1950 and 1971–1990) and is almost decorrelated from the NAO Index for the other decades of the century; this is indicative of transition from one climatic régime to another, dominated by zonal flow when the correlation with the NAO Index is high. In the 1980s, when zonal flow over the North Atlantic is strong, episodes of persistent, anomalously high pressures (blocking highs) are seen to occur over Switzerland, particularly during the winter season. The difference between the zonal and non-zonal régimes is particularly marked between the decade of the 1950s and that of the 1980s.The impact of this change between the 1950s and the 1980s on a number of climatological variables has been investigated statistically in order to provide an illustration of the manner in which changes in synoptic régimes (i.e., climate change) impacts upon climate characteristics on a regional scale. The analysis shows that temperature, precipitation, snow depth, and sunshine duration are indeed sensitive to large-scale influences; not only can yearly mean changes be quantified, but also seasonal and monthly fluctuations.With 26 Figures 相似文献
8.
Gaëlle Serquet Christoph Marty Martine Rebetez 《Theoretical and Applied Climatology》2013,114(3-4):437-444
A better understanding of the impact of changing temperatures on snow amounts is very important for the ski industry, but it is difficult to measure, particularly at different times of the snow season and not only on an annual or seasonal basis. Here, we analyze the snow day vs precipitation day ratios on a monthly basis from November to April in Switzerland and at 52 meteorological stations located between 200 and 2,700 m above sea level over a 48-year time span. Our results show that the conditions measured in the 1960s in November and March correspond to the present ones in December, January, and February. 相似文献
9.
Comte Valentin Schneider Léonard Calanca Pierluigi Rebetez Martine 《Theoretical and Applied Climatology》2022,147(1-2):423-436
Theoretical and Applied Climatology - In this study, we investigated the consequences of climate change on bioclimatic indices in vineyards along the edge of Lake Neuchatel in Switzerland. Like in... 相似文献
10.
Martine Rebetez 《Climatic change》1996,32(4):495-509
Human expectations regarding weather and climate sometimes lead to perceptions of climate change which are not supported by observational evidence. This paper analyses two very characteristic complaints about current climate in Switzerland, i.e., the lack of snow in winter and the lack of sunshine in summer, through a statistical investigation of climatological data. As one major problem of public perception of climate in mid-latitude regions is linked to the strong variability of the climatic parameters, the paper suggests means of presenting climatic data which include a measure of this variability. Such presentations would help overcome the common confusion between the terms weather and climate, and stress the fact that short-term extreme events are not necessarily indicative of a long-term shift in climate. 相似文献