We used the spatially distributed and physically based snow cover model SNOWGRID-CL to derive daily grids of natural snow conditions and snowmaking potential at a spatial resolution of 1 × 1 km for ...Austria for the period 1961–2020 validated against homogenized long-term snow observations. Meteorological driving data consists of recently created gridded observation-based datasets of air temperature, precipitation, and evapotranspiration at the same resolution that takes into account the high variability of these variables in complex terrain. Calculated changes reveal a decrease in the mean seasonal (November–April) snow depth (HS), snow cover duration (SCD), and potential snowmaking hours (SP) of 0.15 m, 42 days, and 85 h (26%), respectively, on average over Austria over the period 1961/62–2019/20. Results indicate a clear altitude dependence of the relative reductions (−75% to −5% (HS) and −55% to 0% (SCD)). Detected changes are induced by major shifts of HS in the 1970s and late 1980s. Due to heterogeneous snowmaking infrastructures, the results are not suitable for direct interpretation towards snow reliability of individual Austrian skiing resorts but highly relevant for all activities strongly dependent on natural snow as well as for projections of future snow conditions and climate impact research.
The density of new snow is operationally monitored by
meteorological or hydrological services at daily time intervals, or
occasionally measured in local field studies. However, meteorological
...conditions and thus settling of the freshly deposited snow rapidly alter the
new snow density until measurement. Physically based snow models and
nowcasting applications make use of hourly weather data to determine the
water equivalent of the snowfall and snow depth. In previous studies, a
number of empirical parameterizations were developed to approximate the new
snow density by meteorological parameters. These parameterizations are
largely based on new snow measurements derived from local in situ
measurements. In this study a data set of automated snow measurements at
four stations located in the European Alps is analysed for several winter
seasons. Hourly new snow densities are calculated from the height of new
snow and the water equivalent of snowfall. Considering the settling of the
new snow and the old snowpack, the average hourly new snow density is
68 kg m−3, with a standard deviation of 9 kg m−3. Seven existing
parameterizations for estimating new snow densities were tested against
these data, and most calculations overestimate the hourly automated
measurements. Two of the tested parameterizations were capable of simulating
low new snow densities observed at sheltered inner-alpine stations. The
observed variability in new snow density from the automated measurements
could not be described with satisfactory statistical significance by any of
the investigated parameterizations. Applying simple linear regressions
between new snow density and wet bulb temperature based on the measurements'
data resulted in significant relationships (r2 > 0.5 and p ≤ 0.05)
for single periods at individual stations only.
Higher new snow density was calculated for the highest elevated and most
wind-exposed station location. Whereas snow measurements using ultrasonic
devices and snow pillows are appropriate for calculating station mean new
snow densities, we recommend instruments with higher accuracy e.g. optical
devices for more reliable investigations of the variability of new snow
densities at sub-daily intervals.
The application of numerical modelling of the snowpack in support of avalanche hazard prediction is increasing. Modelling, in complement to direct observations and weather forecasting, provides ...information otherwise unavailable on the present and future state of the snowpack and its mechanical stability. However, there is often a perceived mismatch between the capabilities of modelling tools developed by research organizations and implemented by some operational services, and the actual operational use of those by avalanche forecasters. This causes frustration on both sides. By summarizing currently implemented modelling tools specifically designed for avalanche forecasting, we intend to diminish and contribute to bridging this gap. We highlight specific features and potential added value, as well as challenges preventing a more widespread use of these modelling tools. Lessons learned from currently used methods are explored and provided, as well as prospects for the future, including a list of the most critical issues to be addressed.
Tourismus und Klimawandel Pröbstl-Haider, Ulrike; Lund-Durlacher, Dagmar; Olefs, Marc ...
2021, 2020-11-30
eBook
Open access
Diese Open-Access-Publikation beleuchtet die komplexen Beziehungen zwischen Tourismus und Klimawandel für die Tourismusdestination Österreich und basiert auf einer umfassenden Erhebung, ...Zusammenfassung und Bewertung des aktuellen Standes der Forschung zu diesem Thema. Für diesen Bericht haben 40 Wissenschaftler*innen führender Forschungseinrichtungen, unterstützt durch ein internationales Team an Begutachter*innen, mehr als zwei Jahre intensiv zusammengearbeitet. Die dargestellten Forschungsarbeiten zum Einfluss des Klimawandels auf den Tourismus gehen davon aus, dass sich die in den nächsten Jahrzehnten zu erwartenden Veränderungen des Klimas sehr stark auf die österreichische Tourismusbranche auswirken werden. Allerdings fällt dem Sektor auch eine nicht unerhebliche Rolle als Mitverursacher des Klimawandels zu. Aktuellen Untersuchungen zufolge verursacht der Tourismus rund 8% aller globalen CO2-Emissionen. Vor diesem Hintergrund werden für die verschiedenen Teilaspekte des touristischen Angebots geeignete Minderungs- und Anpassungsmaßnahmen vorgestellt und diskutiert. Der Bericht verdeutlicht insbesondere die spezifische Betroffenheit der touristischen Outdoor-Aktivitäten vom Wintersport bis zum Golftourismus, beschreibt die neuen Herausforderungen für den Städtetourismus und die Organisation von Events und beleuchtet ausführlich, wie Anpassungsmöglichkeiten, insbesondere im Bereich der Mobilität, der Beherbergung, touristischer Indoor-Angebote, sowie der Gastronomie und Kulinarik, ausgestaltet und umgesetzt werden können. Dabei werden die Verantwortung und die Möglichkeiten des Reisenden ebenso dargestellt, wie die Handlungsoptionen von Betrieben, Destinationen und der rahmensetzenden nationalen Politik. Das Buch macht deutlich, dass, um die Pariser Klimaziele erreichen zu können, ein veränderter Lebensstil und rasche Umsetzungsschritte notwendig sind. Wie dieser „Paris-Lifestyle“ erreicht werden könnte und welche Herausforderungen auf diesem Weg bewältigt werden müssen, verdeutlichen die zusammenfassenden Schlusskapitel. Die vorliegende differenzierte Aufbereitung des Themas für alle Reisenden, die Tourismusbranche und die Politik war nur durch eine gezielte Förderung aus Mitteln des Klima- und Energiefonds im Rahmen des Programms „Austrian Climate Research Programme – ACRP“ möglich.
A comprehensive assessment of twenty-first century climate change in the European Alps is presented. The analysis is based on the EURO-CORDEX regional climate model ensemble available at two grid ...spacings (12.5 and 50 km) and for three different greenhouse gas emission scenarios (RCPs 2.6, 4.5 and 8.5). The core simulation ensemble has been subject to a dedicated evaluation exercise carried out in the frame of the CH2018 Climate Scenarios for Switzerland. Results reveal that the entire Alpine region will face a warmer climate in the course of the twenty-first century for all emission scenarios considered. Strongest warming is projected for the summer season, for regions south of the main Alpine ridge and for the high-end RCP 8.5 scenario. Depending on the season, medium to high elevations might experience an amplified warming. Model uncertainty can be considerable, but the major warming patterns are consistent across the ensemble. For precipitation, a seasonal shift of precipitation amounts from summer to winter over most parts of the domain is projected. However, model uncertainty is high and individual simulations can show change signals of opposite sign. Daily precipitation intensity is projected to increase in all seasons and all sub-domains, while the wet-day frequency will decrease in the summer season. The projected temperature change in summer is negatively correlated with the precipitation change, i.e. simulations and/or regions with a strong seasonal mean warming typically show a stronger precipitation decrease. By contrast, a positive correlation between temperature change and precipitation change is found for winter. Among other indicators, snow cover will be strongly affected by the projected climatic changes and will be subject to a widespread decrease except for very high elevation settings. In general and for all indicators, the magnitude of the change signals increases with the assumed greenhouse gas forcing, i.e., is smallest for RCP 2.6 and largest for RCP 8.5 with RCP 4.5 being located in between. These results largely agree with previous works based on older generations of RCM ensembles but, due to the comparatively large ensemble size and the high spatial resolution, allow for a more decent assessment of inherent projection uncertainties and of spatial details of future Alpine climate change.
Ski resorts increasingly rely on snow making to ensure good quality skiing regardless of the variability of the natural snow cover. This study aims to quantify past changes in snow making conditions ...based on an analysis of long-term wet bulb temperature time series from 20 weather stations in Germany and Austria. The weather stations are located at a range of altitudes from 267 m to 3109 m, in the vicinity of ski resorts. The lengths of the time-series range from 54 to 83 years. Using a threshold mean daily wet bulb temperature of −2 °C we define ‘potential snow making days’ and track changes in the number of snow making days in the months of the early skiing season (October, November, December) by computing linear trends, comparing consecutive 20 year periods, and Mann-Kendall trend testing of overlapping sub-periods. The number of snow making days changes least in October and most in December when averaged over all stations. Very high stations show more change in October and less change in December than the lower stations. Several stations show a significant decrease of snow making days per month, particularly in more recent sub-periods, but trends vary strongly between stations and for different sub-periods. Sub-periods with positive trends are present in earlier phases of the time series at some stations and inter-annual variability is generally 1–2 orders of magnitude greater than detected trends. Detailed microclimatic studies are necessary to determine potential future effects of changes in snow making conditions on the scale of a ski resort.
•We use daily wet bulb temperature time series as a measure for snow making conditions.•Inter-annual variability is large compared to detected trends.•Significant trends for snowmaking days are largely negative in recent years, varying with altitude and location.
Seasonal snow is an essential water resource in many mountain regions. However, the spatio-temporal variability in mountain snow depth or snow water equivalent (SWE) at regional to global scales is ...not well understood due to the lack of high-resolution satellite observations and robust retrieval algorithms. We investigate the ability of the Sentinel-1 mission to monitor snow depth at sub-kilometer (100 m, 500 m, and 1 km) resolutions over the European Alps for 2017–2019. The
Sentinel-1 backscatter observations, especially in cross-polarization, show a high correlation with regional model simulations of snow depth over Austria and Switzerland. The observed changes in radar backscatter with the
accumulation or ablation of snow are used in an empirical change detection
algorithm to retrieve snow depth. The algorithm includes the detection of dry and wet snow conditions. Compared to in situ measurements at 743 sites in the European Alps, dry snow depth retrievals at 500 m and 1 km resolution have a spatio-temporal correlation of 0.89. The mean absolute error equals 20 %–30 % of the measured values for snow depths between 1.5 and 3 m. The performance slightly degrades for retrievals at the finer 100 m spatial resolution as well as for retrievals of shallower and deeper snow. The results demonstrate the ability of Sentinel-1 to provide snow estimates in mountainous regions where satellite-based estimates of snow mass are currently lacking. The retrievals can improve our knowledge of seasonal snow mass in areas with complex topography and benefit a number of applications, such as water resource management, flood forecasting, and numerical weather prediction. However, future research is recommended to
further investigate the physical basis of the sensitivity of Sentinel-1
backscatter observations to snow accumulation.
A distributed snow model is applied to simulate the spatiotemporal evolution of the Austrian snow cover at 1 km × 1 km spatial and daily temporal resolution for the period 1948–2009. After a ...comprehensive model validation, changes in snow cover conditions are analyzed for all of Austria as well as for different Austrian subregions and elevation belts focusing on the change in snow cover days (SCDs). The comparison of SCDs for the period 1950–79 to those achieved for 1980–2009 for all of Austria shows a decrease in SCDs with a maximum of >35 SCDs near Villach (Carinthia). The analysis of SCD changes in different subregions of Austria reveals mean changes between −11 and −15 days with highest absolute change in SCDs for southern Austria. Two decrease maxima could be identified in elevations of 500–2000 m MSL (between −13 and −18 SCDs depending on the subregion considered) and above 2500 m MSL (over −20 SCDs in the case of central Austria). The temporal distribution of SCD change in the Austrian subregions is characterized by a reduction of SCDs in midwinter and at the end of winter rather than by fewer SCDs in early winter. With respect to the temporal distribution of SCD change in different elevation belts, changes in elevations below 1000 m MSL are characterized by a distinct reduction of SCDs in January. With increasing elevation the maximum change in SCDs shifts toward the summer season, reaching a maximum decrease in the months of June–August above 2500 m MSL.
A rapid sequence of cascading events involving thermokarst lake outburst, local rock glacier front failure, debris flow development, and river blockage hit Radurschl Valley (Ötztal Alps, Tyrol) on ...13 August 2019. Compounding effects from permafrost degradation and drainage network development within the rock glacier initiated the complex process chain. The debris flow dammed the main river of the valley, impounding a water volume of 120 000 m3 that was partly drained by excavation to prevent a potentially catastrophic outburst flood. We present a systematic analysis of destabilizing factors to deduce the failure mechanism. The identification and evaluation of individual factors reveals a critical combination of topographical and sedimentological disposition, climate, and weather patterns driving the evolution of a thermokarst drainage network. Progressively changing groundwater flow and storage patterns within the frozen sediment accumulation governed the slope stability of the rock glacier front. Our results demonstrate the hazard potential of active rock glaciers due to their large amount of mobilizable sediment, dynamically changing internal structure, thermokarst lake development, and substantial water flow along a rapidly evolving channel network.
In this paper future changes of surface water availability in Austria are investigated. We use an ensemble of downscaled and bias-corrected regional climate model simulations of the EURO-CORDEX ...initiative under moderate mitigation (RCP4.5) and Paris Agreement (RCP2.6) emission scenarios. The climatic water balance and its components (rainfall, snow melt, glacier melt and atmospheric evaporative demand) are used as indicators of surface water availability, and we focus on different altitudinal classes (lowland, mountainous and high alpine) to depict a variety of processes in complex terrain. Apart from analysing the mean changes of these components, we also pursue a hazard risk approach by estimating future changes in return periods of meteorological drought events of a given magnitude as observed in the reference period. The results show, in general, wetter conditions over the course of the 21st century over Austria on an annual basis compared to the reference period 1981–2010 (e.g. RCP4.5 +107 mm, RCP2.6 +63 mm for the period 2071–2100). Considering seasonal differences, winter and spring are getting wetter due to an increase in precipitation and a higher fraction of rainfall as a consequence of rising temperatures. In summer only little changes in the mean of the climatic water balance conditions are visible across the model ensemble (e.g. RCP4.5 ±0 mm, RCP2.6 −2 mm for the period 2071–2100). On the contrary, by analysing changes in return periods of drought events, an increasing risk of moderate and extreme drought events during summer is apparent, a signal emerging within the climate system along with increasing warming.
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