Forest damages from winter storms in Switzerland from 1865 to 2014 Winter storms cause the most catastrophic damages in Swiss forests. The present article analyses how these storm damages correspond with wind gust speed, growing stock and forest area, in regard to the whole country and individual cantons, and from 1865 to 2014. During the study period, 26 storm events each totalling a volume of at least 70,000 m3 damaged wood were registered. Winter storm damages were highly variable regarding absolute numbers (volume) and portions per area (m3 per ha) and per growing stock (%). In the past 150 years, the cantons Nidwalden, Freiburg, Aargau, Zurich and Zug were hit most often by storm events, with damages ranging per event in average from 2.2 m3 per ha (Zurich) to 3.1 m3 per ha (Nidwalden). At the turn of the millennium, not only the greatest damages occurred but also growing stock peaked as well did the wind gust speeds.

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.

The most severe damage to forests in central Europe occurs during winter storms that the caused by Northern Hemishperic mid-latitude cyclones. These winter storms have caused several catastrophic windthrows during the past four decades. Amounts of forest storm damage are believed to be a function of both the size of the forest and the storm intensity. To test this hypothesis, the Zurich region (city and canton) was chosed because long-term climate observation data is available for the region. The relationships between forest attributes, wind speed and forest damage were explored by comparing data on forests and wind speed for 107 winters with forest damage. Storm damage was defined as the proportion of damages forests with respect to the growing stock. The variables: daily wind run (91 years), daily maximum hourly average wind speed (107 years) and peak gust wind speed (74 years) were homogenized with respect to high wind speed and related to levels of forest damage.High maximum wind speed at the end of the 19th century and at the beginning of the 20th century was followed by low maximum wind speed in the 1940s, 1960s and 1970s. Since then, maximum values have increased. Gusts (extremes of the maximum wind speed) increased from the beginning of the recordings in 1933 and peaked in the early 1990s.Forest damage due to winter stroms is bes correlated with peak wind spee. Gusts exceeding 40 m/s and resulting in catastrophic windthrow have increased in recent winters. Copyright (C) 2009 Royal Meterological Society.

The most severe damage to forests in Central Europe occurs during winter storms caused by Northern Hemispheric mid-latitude cyclones. Storm events in the winter semesters of the past 150 years were investigated to quantify changes and evaluate whether damage rates, forest properties and climate had changed. Records of damage extent (wind throw/snap/breakage), forest area and growing stock in Switzerland were comparatively analysed. Storm damage (m3) was 17 times greater during the period 1958–2007 than during the period 1908–1957 and 22 times greater than in the period 1858–1907. Forest area in Switzerland has increased by 63% and growing stock by 292% over the past 150 years. The significant recent increase in storm damage could only partially be explained by increased growing stock. Weather reports prior to storms indicated that severe storm damage occurred almost always when soils were unfrozen (96%) and wet (96%). During the observation period mean winter temperature has increased by nearly 2°C and winter precipitation has increased by nearly 50% in the study region. In the Zurich region, daily maximum gust wind speed and storm damage were compared. Maximum gust wind speed above 35ms−1 was associated with extensive storm damage. Catastrophic storm damage and maximum gust wind speed measured during storms have increased during recent decades. In conclusion, increasing growing stock, warm winter temperature and high precipitation, and even more markedly, increasing maximum gust wind speed have all contributed to the recent increase in windstorm damage to forests.

Most natural disturbances to Swiss forests are caused by climatically induced extreme events: winter storms, foehn and thunderstorms predominate in the North of the Alps, and forest fires in the Southern Alps. Many studies predict a general increase of these extreme events under continued climatic change. How resistant are Swiss forests against wind and fire disturbance, and how resilient are they after disturbance? Because in Switzerland most of the severe winds happen in the wintertime, conifers such as Norway spruce and silver fir are the most vulnerable species. Beyond gust speeds of more than 40 m/s, all tree species are damaged. The fire resistance of forests depends on the flammability, which will increase due to increasing drought frequency. Forests in the Ticino will be most affected by this development, and to a lesser extent also forests in the Central Alps and those north of the Alps. After wind and fire disturbance, forest has re-established in almost all regions of Switzerland. Results from various studies in disturbed forests show that the amount of tree regeneration decreases with increasing elevation (R2 = 0.31). After fire, the speed of regeneration depends on various factors such as tree species, drought and the transient absence of mycorrhiza. The natural regeneration process after severe forest disturbances reflects a first step towards a forest more adapted to the future. Trees that establish in big gaps and under repeated drought may resist the future climate.

CryoSat is the first of the ESA Earth Explorer Opportunity Missions within the Earth Observation Envelope Programme (EOEP). It will allow an accurate determination of the marine and land ice mass fluxes at a global scale. The challenge with respect to the Opportunity Missions is to provide the highest scientific return under given limited funding resources and severe planning constraints.This paper gives a brief overview on the CryoSat AOCS, which is. currently under development by Astrium as prime contractor for the CryoSat satellite. It shows how the ambitious CryoSat mission goals can be met by the satellite and AOCS design even under the constraints of limited funding resources. Finally an overview on the CryoSat AOCS control design and performance, sensors and actuators, FDIR and verification approach will be presented.

Most natural disturbances to Swiss forests are caused by climatically induced extreme events: winter storms, foehn and thunderstorms predominate in the North of the Alps, and forest fires in the Southern Alps. Many studies predict a general increase of these extreme events under continued climatic change. How resistant are Swiss forests against wind and fire disturbance, and how resilient are they after disturbance? Because in Switzerland most of the severe winds happen in the wintertime, conifers such as Norway spruce and silver fir are the most vulnerable species. Beyond gust speeds of more than 40 m/s, all tree species are damaged. The fire resistance of forests depends on the flammability, which will increase due to increasing drought frequency. Forests in the Ticino will be most affected by this development, and to a lesser extent also forests in the Central Alps and those north of the Alps. After wind and fire disturbance, forest has re-established in almost all regions of Switzerland. Results from ...