Dirk Schindler

University of Freiburg | Albert-Ludwigs-Universität Freiburg · Environmental Meteorology

The progress of onshore wind expansion varies globally, as often expressed by a country's installed capacity and capacity factor. However, installed capacity and capacity factor do not allow conclusions about how effectively and efficiently countries use their spatially diverse wind potential. It is unknown how far wind energy expansion is and whet...

Windstorms are among the primary drivers of forest disturbances. Although they are inherent part of the natural ecosystem processes, they severely impact managed forests. Modeling approaches serve as key tools for the evaluation of disturbance risk and different predisposing factors. However, data availability on relevant forest attributes can be p...

Measuring tree response to wind loads is fundamental for the process-based analysis of wind-tree interactions. Comprehensive knowledge of wind-tree interactions enables the further development of decision support tools available for estimating the probability of wind damage to trees. The assessment of critical wind loads that lead to damage is part...

Minimizing the residual load is essential in countries with a high share of variable renewable energies (VRE). Optimally, new wind turbine sites provide high resource availability and the potential for smoothing the temporal course of the residual load. Current high spatial resolution wind atlases are limited to the ability to find high capacity fa...

The success of the German electricity mix transformation depends on the variable renewable energies solar photovoltaics and wind. Their extensive exploitation until 2030 and beyond is a cornerstone on the road to climate neutrality, which Germany aims for in 2045. We use actual electricity generation and consumption data from 2015 to 2021 to analyz...

The Central European 2018 hot drought had severe impacts on many forest ecosystems, including a Scots pine (P. sylvestris) plan- tation at the DE-Har ecosystem site in the Upper Rhine Valley. The co-occurrence of unfavourable site-specific conditions with high air temperatures and dry conditions resulted in massive accelerated tree mortality of P....

This review analyzed 75 studies published 2017–2021 investigating future wind resource evolution. It provides comprehensive information on the studies' specifications and globally summarizes the reported wind resource changes. The studies show substantial differences in design, limiting their comparability. Most studies evaluated a small number of...

Severe drought events negatively affect tree growth and often cause legacy effects, expressed by smaller tree rings in the post-drought recovery years. While the pattern of reduced tree-ring widths is frequently described the processes underlying such legacy effects, i.e., whether it is due to shorter growth periods or lower growth rates, remains u...

The intensified expansion of intermittent onshore wind energy in the European Union raises questions about electricity supply to cover future electricity demand. Complementary wind resource use is considered an option to keep the number of supply-demand mismatches low. Here, the hypothesis is tested that adopting an EU-wide coordinated, complementa...

The capacity factor (cf) is a critical variable for quantifying wind turbine efficiency. Climate change-induced wind resource variations and technical wind turbine fleet development will alter future cfs. Here we define 12 techno-climatic change scenarios to assess regional and global onshore cfs in 2021–2060. Despite a decreasing global wind resou...

The occurrence of hot drought, i.e. low water availability and simultaneous high air temperature, represents a severe threat to ecosystems. Here, we investigated how the 2018 hot drought in Central Europe caused a tipping point in tree and ecosystem functioning in a Scots pine (Pinus sylvestris L.) forest in southwest Germany. Measurements of stres...

Quantifying wind loads acting on forest trees remains a major challenge of wind-tree-interaction research. Under wind loading, trees respond with a complex motion pattern to the external forces that displace them from their rest position. To minimize the transfer of kinetic wind energy, crowns streamline to reduce the area oriented toward the flow....

Previous estimations of the global technical onshore wind energy potential (WEP) range between 64 and 690 PWh/yr. The diversity of WEP estimates is caused by various applied wind resource data sets, geographical restrictions, and wind turbine features. So far, little attention was paid to the wind speed model resolution and hub height influence on...

High wind speed (U) is one of the most dangerous natural hazards in North America and Europe. As a result, spatially explicit, statistical estimation of extreme U is of particular relevance for many sectors. However, the most common sources of wind speed data such as reanalysis data and in situ measurements are limited for this purpose due to their...

This paper reports statistical relationships between measured airflow, air pressure fluctuations, and the wind-induced motion of planted Scots pine trees (Pinus sylvestris L.). The results presented illustrate the potential of low-cost, ground-based air pressure measurements for monitoring wind-induced tree response. It is suggested that air pressu...

The best wind locations are nowadays often occupied by old, less efficient and relatively small wind turbines. Many of them will soon reach the end of their operating lifetime, or lose financial support. Therefore, repowering comes to the fore. However, social acceptance and land use restrictions have been under constant change since the initial ex...

Die Einbindung der Solarenergie in den deutschen Energiemix hat sich in den vergangenen zwei Jahrzehnten vervielfacht. Daher wird es immer wichtiger, die räumlich-zeitlichen Schwankungen der Sonnenenergie zu quantifizieren, um die Ausbau von Photovoltaikanlagen in der Fläche effizient zu fördern und damit die Stromnetze zu stabilisieren. Nur umfass...

The best wind locations are nowadays often occupied by old, less efficient and relatively small wind turbines. Many of them will soon reach the end of their operating lifetime, or lose financial support. Therefore, repowering comes to the fore. However, social acceptance and land use restrictions have been under constant change since the initial ex...

The integration of solar energy into Germany's energy mix has multiplied over the last two decades. Therefore, it becomes increasingly important to quantify the spatiotemporal variations of solar energy to efficiently promote photovoltaic systems’ spatial spreading and strengthen the stability of power grids. Only comprehensive information on surfa...

Wind energy is crucial in German energy and climate strategies as it substitutes carbon intensive fossil fuels and achieves substantial greenhouse gas (GHG) reductions. However, wind energy deployment currently faces several problems: low expansion rates, wind turbines at the end of their service life, or the end of remuneration. Repowering is a vi...

Destructive winter storms cause recurring major damage to physical, biological, human, and managed systems in Central Europe. Therefore, detailed knowledge of their future development in many areas of human life is of great importance for planning strategic management decisions. One feature to characterise the winter storm intensity is the daily ma...

Interactions between wind and trees control energy exchanges between the atmosphere and forest canopies. This energy exchange can lead to the widespread damage of trees, and wind is a key disturbance agent in many of the world's forests. However, most research on this topic has focused on conifer plantations, where risk management is economically i...

To reduce the negative implications associated with the use of conventional energies on the environment and human health, intensified renewable energy expansion is inevitable. Wind energy is one of the most promising renewable energies since the theoretical technical wind energy potential is far enough to cover the global electricity consumption. H...

An important metric for quantifying the greenhouse gas saving potential of wind turbine types is the greenhouse gas payback time. Previous studies revealed that wind speed and wind turbine size are negatively correlated with greenhouse gas payback times. However, so far, payback times were mostly estimated for wind turbine types with a hub height o...

The preconditions for wind farm installation and operation are high energy yields and accessibility. However, so far, no attempts were made to develop a global scale index integrating energy yields and accessibility of wind farms. Thus, the goal of this study was to create a universally applicable wind farm potential index that enables finding prod...

Among the renewable energy sources, the highest share of European net electricity generation comes from wind power. However, the European onshore wind resource's volatile nature is a significant challenge in ensuring a constant national electricity supply. Therefore, this study examined the potential of complementary use of national wind resources...

Severe storms caused the largest amount of damaged timber in European forests in the past 70 years. Storm damage occurs when wind loads exceed the failure limits of trees. A decisive factor in assessing storm damage is comprehensive knowledge of interactions between the aerial parts of trees and the high-impact airflow. This paper describes the ine...

Severe storms caused the largest amount of damaged timber in European forests in the past 70 years. Storm damage occurs when wind loads exceed the failure limits of trees. A decisive factor in assessing storm damage is comprehensive knowledge of interactions between the aerial parts of trees and the high-impact airflow. This paper describes the ine...

Wind energy in Germany is awarded a crucial role in increasing the share of renewable energies in the electricity mix to 65% until 2030, especially in light of the federal government's recent decision to phase out coal-based electricity until 2038. In addition to the targeted expansion of wind energy, Germany will be struggling with thousands of wi...

The power law is most often applied to extrapolate the near-surface wind speed to the wind turbine hub height. Due to variations of the meteorological conditions , the power law exponent varies over time. Usually, no long-term wind speed measurements from multiple heights are available which would allow time-dependent and spatially explicit power l...

1. Interactions between wind and trees control energy exchanges between the atmosphere and forest canopies. This energy exchange can lead to the widespread damage of trees and wind is a key disturbance agent in many of the world’s forests. However, most research on this topic has focused on conifer plantations, where risk management is economically...

The intermittent nature of wind energy is a major challenge transforming the energy sector from fossil fuels to renewables. Depending on the location, results from previous studies show that the availability of wind energy can strongly vary over a year. However, although global temporal wind speed fluctuations are complex on the monthly and seasona...

The anticipated climate change during the next decades is posing crucial challenges to ecosystems. In order to decrease the vulnerability of forests, introducing tree species' mixtures are a viable strategy, with deep-rooting native Silver fir (Abies alba) being a primary candidate for admixture into current pure stands of European beech (Fagus syl...

An important aspect of planning the future expansion of wind energy is the consideration of changes in available wind resources due to climate change. In previous studies simulations of the future behavior of wind resources were derived from regional climate models at coarse spatial resolutions not suitable for wind energy potential assessment at t...

In recent decades, winter storms have caused the largest amount of damaged wood in European forests due to their large-scale extent and the characteristics of their near-surface gust fields. The hazard of forests from winter storms is associated with the occurrence of high- impact gust speed. Therefore, a high-resolution (25 m × 25 m) winter storm...

Background Sarcoidosis is a multisystemic granulomatous disorder of unknown origin. The central role of macrophages and granuloma formation, the predominant involvement of lung and skin, and certain risk populations (e.g. firefighters 1, 2 ) might be explained by causative airborne antigen(s) ³ . Whether air pollution is involved in pathogenesis an...

The anticipated greater penetration of the variable renewable energies wind and solar in the future energy mix could be facilitated by exploiting their complementarity, thereby improving the balance between energy supply and demand. Based on the hypothesis that a complementary use of wind and solar is possible, this investigation provides informati...

A new model for mapping the near-surface wind speed L-moments on a high spatial resolution scale (250 m × 250 m) is introduced (GloWiSMo). The target variables are the first five L-moments of 6146 globally distributed wind speed time series. ERA5 reanalysis wind speed available on a 0.25° × 0.25° grid was used as predictor representing the large-sc...

The parameterization of hybrid-mechanistic storm damage models is largely based on the results of tree pulling tests. The tree pulling tests are used for imitating the quasi-static wind load associated with the mean wind speed. The combined effect of dynamic and quasi-static wind loads associated with wind load maxima is considered by either linear...

A new approach for modeling daily precipitation (RR) at very high spatial resolution (25 m × 25 m) was introduced. It was used to develop the Precipitation Atlas for Germany (GePrA). GePrA is based on 2357 RR time series measured in the period 1981-2018. It provides monthly percentiles (p) of the large-scale RR patterns which were mapped by a thin...

which compared the goodness-of-fit of different theoretical parametric distributions, were evaluated. The evaluation scheme considered three aspects: (1) distributions, (2) parameter estimations methods, and (3) goodness-of-fit metrics. It was found that the two-parameter Weibull distribution is by far the most frequently (in 44 out of 46 studies)...

Based on 12 global circulation models, the simulated changes in empirical 10 m wind speed distributions under the representative concentration pathway RCP8.5 were quantified. It is demonstrated that climate change leads to significant wind speed distribution changes around the world. It is very likely that mean wind speed increases in most parts of...

While gas transport in soil is commonly assumed to be driven by molecular diffusion, pressure-pumping due to small air pressure fluctuations was identified to enhance the gas transport rate during periods of high wind speed. A possible explanation is related to the vertical oscillating movement of gas in the air-filled pore-space due to these air p...

Long-term gust speed (GS) measurements were used to develop a winter storm atlas of the 98 most severe winter storms in Germany in the period 1981-2018 (GeWiSa). The 25 m × 25 m storm-related GS fields were reconstructed in a two-step procedure: Firstly, the median gust speed (GS) of all winter storms was modeled by a least-squares boosting (LSBoos...

Small air pressure fluctuations (amplitudes: <10 Pa, frequency range: 0.01‐0.1 Hz) were simultaneously measured using an inexpensive differential air pressure sensor system and a significantly more expensive high‐precision absolute air pressure sensor reference. The measured air pressure fluctuations were compared and analyzed in the time domain an...

In a large number of previous studies, the technical wind energy potential was estimated from national to global scale. Usually, it was assumed that the underlying meteorological potential remains constant over time. However, the wind resource greatly varies on different temporal scales including inter-annual and multi-decadal scales. In this study...

The statistical air density distribution was modeled on a high-spatial resolution scale (200 m × 200 m) and the error by using constant standard air density was estimated using Germany as study area. Daily mean air temperature and air pressure time series of 144 meteorological measuring stations operated in the period 1979-2014 were used to calcula...

Empirical forest storm damage models can assist in identifying the key factors of the occurrence of storm damage in order to develop locally adapted measures to minimize damage in forests. Yet, there is a significant lack of knowledge in these models concerning the correlation between storm damage and high-impact near-surface airflow. To improve ou...

Molecular diffusion is commonly assumed as main physical process of gas transport in soils. However, non-diffusive gas transport processes like the so-called pressure-pumping effect can affect soil gas transport significantly. The pressure-pumping effect has only been detected indirectly and the underlying mechanisms remain unclear. Using a novel i...

The response of four Scots pine trees to wind excitation was measured and analyzed. We investigated whether wind-induced tree sway in the fundamental mode is affected and enhanced by resonance effects between cyclic wind loading and oscillatory tree response. By combining results from wavelet analysis and analysis of phase- amplitude coupling, we d...

Wind-to-hydrogen (WH) is a promising option for reducing greenhouse gas emissions in the transport sector. Therefore, the reduction potential of fossil fuels by WH was estimated taking meteorological, geographical, and technical constraints into account. The wind resource estimation is based on the application of the high-resolution (200 m × 200 m)...

The goals of this study were to develop and to evaluate wind turbine siting scenarios for achieving a share of about 40% (250 TWh/yr) wind energy in Germany's gross electricity consumption. The scenarios were developed to quantify the influence of (1) available technology and repowering, (2) resource distribution, and (3) siting strategy on five si...

The fitting of empirical wind speed distributions is an important component in wind turbine energy yield assessment. Its accuracy depends on both the adequacy of the fitting function and the quality of the fitted wind speed data. Therefore, the system of wind speed distributions was recently introduced to further improve the statistical estimation...

The intermittent and stochastic nature of the wind resource complicates constant electricity supply in countries with high wind energy share in the electricity mix. Therefore, the goal of this study was to quantify the inter-annual variability of wind energy generation on the national scale by estimating upper and lower limits of annual wind energy...

The mixed Burr-Generalized Extreme Value distribution (BGEV) and Gaussian copulas were used in a two-step procedure for estimating the directional wind energy yield in 100 m above ground level in Germany. In a first step, BGEV was fitted to the marginal distributions of ERA-5 reanalysis horizontal wind vector component data available from the Europ...

The response of four trees in a Scots pine (Pinus sylvestris L.) plantation to wind loading was studied using time series decomposition methods. For this purpose, wind speed and stem displacement time series recorded on a windy day were divided into intervals adjusted according to stem displacement. The real wind load acting on the sample trees dur...

The goal of this study was to model Germany’s 3D wind resource using the wind speed-wind shear model (WSWS) on a high spatial resolution grid (200 m × 200 m). The model is based on near-surface wind speed data and reanalysis wind speed data. Furthermore, terrain and land use features were used to develop predictor variables for statistical mapping...

Based on ERA-20C data available for the period 2008–2010, the potential of six onshore wind turbine installation scenarios to cover current electricity consumption at the national and global scale was studied. The technical wind energy potential was estimated using the recently developed, highly accurate Burr-Generalized Extreme Value mixture distr...

Based on ERA-20C data available for the period 2008–2010, the potential of six onshore wind turbine installation scenarios to cover current electricity consumption at the national and global scale was studied. The technical wind energy potential was estimated using the recently developed, highly accurate Burr-Generalized Extreme Value mixture distr...

Assessment of future precipitation responses is crucial for various sectors which include tourism, agriculture, and energy yield. The study is focused on south Germany and aims to analyse the future spatio-temporal responses of annual and seasonal precipitation. Future precipitation data were derived and analysed from a number of Regional Climate M...

The goal of this study was to develop a statistical bivariate wind speed-wind shear model (WSWS). The development of WSWS is based on near surface wind speed data available from 397 measurement stations distributed over Germany, as well as on ERA-Interim reanalysis wind speed data available in 1000 m above ground level (a.g.l.). These data were use...

Strong gusts negatively affect wind turbines in many ways. They (1) harm their structural safety; (2) reduce their wind energy output; and (3) lead to a shorter wind turbine rotor blade fatigue life. Therefore, the goal of this study was to provide a global assessment of the gust climate, considering its influence on wind turbines. The gust charact...

Small air pressure fluctuations in the atmosphere are responsible for the pressure pumping effect, which leads to an enhancement of soil gas transport. To investigate the spatial variability of these air pressure fluctuations, several high-precision differential pressure sensors were installed at the floor of a Scots pine forest. The alignment of t...

Accurate modeling of empirical wind speed distributions is a crucial step in the estimation of average wind turbine power output. For this purpose, the Weibull distribution has often been fitted to empirical wind speed distributions. However, the Weibull distribution has been found to be insufficient to reproduce many wind speed regimes existing ar...

Wind energy in Germany has experienced high growth rates over the last few years. The set political target in the German federal state of Baden-Wuerttemberg is to raise the share of wind energy in the overall electricity supply to 10% by 2020. To achieve this goal, detailed information on wind energy potential in Baden-Wuerttemberg is necessary. Th...

The exchange of greenhouse gases between the soil and the atmosphere is highly relevant for the climate of the Earth. Recent research suggests that wind-induced air pressure fluctuations can alter the soil gas transport and therefore soil gas efflux significantly. Using a newly developed method, we measured soil gas transport in situ in a well aera...

Soil gas transport is commonly assumed to be governed by molecular diffusion. However, non-diffusive transport processes such as wind-induced pressure-pumping can significantly enhance soil gas transport during periods of high wind speed. During a field campaign at a forest site, we combined methods to measure soil gas transport, air pressure and a...

The aim of this study was evaluating the goodness-of-fit of 24 one-component probability density functions and 21 mixture probability density functions to empirical wind speed probability density functions on a global scale. Era-Interim reanalysis wind speed data for the period 2011-01-01 to 2015-12-31 with a spatial resolution of 1�° x 1°� were us...

This study deals with high spatial resolution modelling of near-surface gust speed distributions in a complex region. The database on which gust speed distributions were modelled includes 69 daily maximum gust speed time series provided by the German Weather Service (DWD) for the period 1979–2013. Comparability of the time series was achieved by ga...

High-precision differential air pressure measurements were conducted in the below-canopy space of a Scots pine forest and in the forest soil to investigate small air pressure fluctuations and their effect on soil gas flux. In addition to air pressure measurements, tracer gas concentration in the soil and airflow characteristics above and below the...

Results from a newly available empirical maximum gust speed model were evaluated for their predictive power of forest storm damage caused by the high-impact winter storm 'Lothar' in the German federal state of Baden-Wuerttemberg. In this state, Lothar was the most severe storm event of the last decades, causing nearly 30 million m 3 of damaged timb...

This is an overview of the results from previously published climate modeling studies reporting on projected aspects of future storminess over the North Atlantic European region (NAER) in the period 2020-2190. Changes in storminess are summarized for seven subregions in the study area and rated by a categorical evaluation scheme that takes into acc...

Biorthogonal decomposition (BOD) is used to detect and study synchronous coherent structures occurring at multiple levels in the vertical momentum flux (u'w') within and above a planted Scots pine forest during a 12-week continuous measurement period. In this study, the presented method allowed for the simultaneous detection and quantification of t...

Routinely collected booking records of salvaged timber from the period 1979–2008 were used to empirically model the (1) storm damage probability; (2) proportions of storm-damaged timber and (3) endemic storm damage risk in the forest area of the German federal state of Baden-Wuerttemberg by applying random forests. Results from cross-validated pred...

Biorthogonal decomposition (BOD) is used to detect and study synchronous coherent structures occurring at multiple levels in the vertical momentum flux (u′w′) within and above a planted Scots pine forest during a 12-week continuous measurement period. In this study, the presented method allowed for the simultaneous detection and quantification of t...

In this paper a methodology is presented that can be used to statistically model characteristics of near-surface wind speed in complex terrain at high spatial resolution. It was developed based on daily mean wind speed time series provided by the German Weather Service for 65 stations located in southwest Germany. After comprehensive preparation of...

Gas transport in soil is mainly governed by molecular diffusion and is usually modelled using the first Fick's law. However, mass flow of air due to pressure differences can play a significant role in gas transport. Soil can be considered as a „high-filter“ for pressure waves i.e. only pressure waves with low frequencies (day-1 to h-1) can deeply...

This study concerns the role of short-and long-wave radiant flux densities from different directions in complex urban settings for human thermal comfort on clear-sky summer days. The aims of the investigation are to quantify the importance of the sky view factor as an urban design-dependent variable for the 3-D radiant flux densities absorbed by th...

Although responses of aerial tree parts to wind excitation are of crucial importance for deciduous broadleaved tree stability against wind loading, only a few field studies have been conducted that explore wind–tree part interactions. Therefore, responses of aerial parts of an individual Norway maple tree (Acer platanoides) to wind excitation were...