Intensity Of Windstorms Research Articles

Changing windstorm characteristics over the US Northeast in a single model large ensemble

Abstract Extreme windstorms pose a significant hazard to infrastructure and public safety, particularly in the highly populated US Northeast (NE). However, the influence climate change and changing land use will have on these events remains unclear. A large ensemble generated using the Max-Planck Institute (MPI) Earth system model is used to generate projections of NE windstorms under different shared socioeconomic pathways (SSPs) and to attribute changes to projected land use land cover (LULC) change, externally forced changes and internal climate variability. To reduce the influence of coarse grid cell resolution and uncertainties in surface roughness lengths, windstorms are identified using simultaneous widespread exceedance of local 99th percentile 10 m wind speeds (U99). Projected declines in forest cover in the NE and the resulting reductions in surface roughness length under SSP3-7.0 lead to projections of large increases in U99 and derived windstorm intensity and scale. However, these projected changes in regional LULC under SSP3-7.0 are unprecedented in a historical context and may not be realistic. After corrections are applied to remove the influence of LULC on wind speeds, regionally averaged U99 exhibit declines for most of the single model initial-condition large ensemble (SMILE) members which are broadly proportional to the radiative forcing and global air temperature increase in the SSPs, with a median value of −0.15 ms−1 °C−1. While weak cyclones are projected to decline in frequency in the NE, intense cyclones and the resulting windstorms and indices of socioeconomic loss do not. Where present, significant trends in these loss indices are positive, and some MPI SMILE members generate future windstorms that are unprecedented in the historical period.

Projected increase in windstorm severity and contribution from sting jets over the UK and Ireland

Extratropical windstorms can lead to extreme impacts in the UK; however, future changes in windstorm frequency and intensity are uncertain due to natural variability and lack of model consensus. Further uncertainty arises due to unresolved or poorly represented processes which can reduce the validity of traditional coarse resolution climate models. This study demonstrates the added value of higher resolution simulations in their representation of extreme windstorms. It also assesses future changes in windstorms in the first ensemble of convection-permitting model (CPM, 2.2 km grid spacing) projections over the UK, released as part of the UKCP18 project, and compares these to changes in the driving 60 km global climate model (GCM) and 12 km regional climate model (RCM). The representation of wind gusts in the CPM and RCM is improved with respect to ERA-Interim reanalysis data compared to observations. Both models are largely similar except over areas with orographic influences where the CPM provides greater detail and simulates higher wind gusts. In contrast, the GCM simulates lower wind gusts and underestimates windstorm intensity; the improvements from the RCM and CPM are partially linked to better representation of cold conveyor belts and sting jets at km-scale. The CPM projects an increase in the frequency of extreme windstorms. In line with a previous study, a large contribution comes from storms that develop sting jets which now seems to be a robust response of windstorms to a warming climate. Similar projected increases are also found in the coarser resolution models, although differences in projections exist at a regional scale in the CPM compared to the RCM and GCM. Overall, higher resolution simulations improve the representation of windstorms, offering greater detail at the local scale which may provide better information for impact modelling, though large-scale projected changes in the assessed storm severity index are insensitive to the model resolutions in the simulations tested here.

Long-term effects of catastrophic wind on southern US coastal forests: Lessons from a major hurricane.

Threats posed by windstorms are an increasing concern to forest managers in the southern United States (US). Studies suggest that the southern US will experience an increase in the occurrence as well as the intensity of windstorms, such as hurricanes, in the future. However, forest managers may have difficulty preparing for this future because there is limited understanding of how windstorms affect the structure and composition of forests over the long term. In this study, we evaluated the impacts of Hurricane Ivan, which made landfall in September 2004 near Gulf Shore, Alabama, impacting forests in the western Florida Panhandle and southwestern Alabama. We acquired the United States Department of Agriculture Forest Inventory and Analysis (FIA) plot data available for the period from 2002 to 2018 for the Ivan-affected area and classified the plots into 4 categories: (1). ND (No Disturbance), (2). NDBH (No Disturbance but Harvested), (3). ID (Disturbance caused by Hurricane Ivan), and (4). IDAH (Disturbance caused by Hurricane Ivan and Harvested). The plots that were damaged by Hurricane Ivan (ID and IDAH plots) had significantly (α = 0.05) (1) higher basal area, (2) higher quadratic mean diameter and height, (3) more diverse tree species composition (species richness and Shannon diversity index), (4) denser stocking of seedling and saplings, (5) lower proportion of dead trees or saplings, and (6) higher live aboveground biomass than the plots that were not damaged by the hurricane (ND and NDBH plots). Diverse stands were not necessarily more windstorm resistant. Species diversity in the overstory may not improve forest resistance to hurricane damage but may improve its resilience following the hurricane. The study suggests that managing stand structure through density management and stand improvement could be critical to windstorm resilience and resistance in the southern US forests.

Climatology of extreme downslope windstorms in the Russian Arctic

This paper presents the climatology of downslope windstorms in the Russian Arctic – bora on Novaya Zemlya, windstorms on Spitsbergen, in Tiksi and Pevek, bora on Wrangel Island – in connection with the large-scale circulation. Statistical analysis of wind speed and air temperature during windstorms, the frequency of the phenomenon, as well as analysis of trends in frequency and intensity of downslope windstorms in the late 20th and early 21st centuries were carried out. Similarity of the large-scale background (incoming) flow is evident for all regions; the most frequent features of the incoming flow are elevated inversion and low-tropospheric jet stream. The observed transformation of the incoming flow from weak to strong windstorm along with the relatively weak linear correlation between downslope wind speed and upwind-side flow characteristics suggest that there are nonlinear connections between windstorms and the incoming flow. We found significant negative trends in Wrangel Island bora frequency and intensity, connected largely with the Arctic circulation variability and associated sea-ice loss. A negative trend in intensity of windstorms was also found in Tiksi and Pevek, associated more with midlatitudes circulation patterns.

Communicating the amount of windstorm induced forest damage by the maximum wind gust speed in Finland

Abstract. Windstorms are natural disturbance agents in forests playing a role in natural forest regeneration. In Finland, the most severe individual windstorms have commonly damaged 2–4 million m3 of timber. In addition to financial losses caused to forest owners, windthrown trees have in many cases seriously disrupted the functionality of the national power grid. Communicating windstorm risks in duty forecasting is difficult. In this study, we aimed at developing windstorm impact estimates for forest damage in Finland to help the forecaster to improve communication of the risks of windstorms. We have compared the volume of forest damage caused by the most intense windstorms in Finland during the recent decade to the observed maximum inland wind gust speeds associated with the same windstorms. It was found out that the volume of forest damage follows approximately a power relation as a function of wind gust speed with a power of ∼10. This is a tentative estimate because of a short time series and small number of inspected windstorms. Moreover, also wind direction, location of the affected area and soil properties among other factors have an impact to the amount of damage as illustrated in our inspection. Despite the shortness of the time series, we believe that our results demonstrating the steep increase in the impacts of windstorms with an increasing windstorm intensity are valuable. However, more detailed investigations with longer time series are needed in order to more specifically communicate the windstorm risks and their impacts in boreal forests.

Integrated Approach to Assess the Resilience of Future Electricity Infrastructure Networks to Climate Hazards

Electricity systems are undergoing unprecedented change, with growing capacity for low-carbon generation, and an increasingly distributed approach to network control. Furthermore, the severity of climate related threats is projected to increase. To improve our understanding of the risks from these changes, this paper presents a novel modeling approach to assess the resilience of future electricity networks to climate hazards. The approach involves consideration of the: 1) evolution of electricity networks in response to changes in demand, supply, and infrastructure development policies; 2) implication that these policies have on network configuration and resilience; and 3) impacts of potential changes in climate hazard on network resilience. We demonstrate the research on the National Electricity Transmission System of Great Britain and assess the resilience of this system to changes in the intensity of wind storms under alternative energy futures. The analysis shows that infrastructure policies strongly shape the long-term spatial configuration of electricity networks and consequently this has profound impacts on their resilience. Though the system is resilient to wind storms under the current climate, our analysis shows that the system fails to meet electricity demand after an increase of only 5–10% in the intensity and frequency of wind storms, and a 50% increase could lead to the loss of 85% of peak winter demand. The approach is useful for identifying and communicating potential network risks to wider stakeholders and policy makers seeking to design a transition toward a low-carbon, yet resilient, future electricity systems.

A simple wind–tree interaction model predicting the probability of wind damage at stand level

Forest wind damage occurs under the passage of strong intermittent wind gusts at tree level. In order to predict the probability of tree damage of a forest, a simple statistical wind speed model was developed and coupled to a tree swaying model. The wind model is based on a stochastic approach and on some universal characters of normalized wind statistics at canopy top. This model aims at generating high frequency (10Hz) time series of the three wind velocity components at canopy top knowing only the wind intensity from a nearby meteorological station and the height and cumulative plant area index of the forest. Compared to field measurements and large-eddy simulations over different canopy structures and densities, the wind model was able to reproduce accurately the main features of canopy-top wind dynamics, in particular the signature of the mixing-layer type coherent eddy structures developing at canopy top. Coupled with a tree swaying model, the model has allowed to predict the probability of wind damage of forest following the windstorm intensity and duration, and following the main tree characteristics resulting from silvicultural scenarios. By responding to some weaknesses of existing mechanistic wind risk models, this simple wind–tree interaction model may represent the first step toward a new generation of mechanistic wind risk models based on a probabilistic approach.

Wave climate projections for Ireland for the end of the 21st century including analysis of EC‐Earth winds over the North Atlantic Ocean

ABSTRACTThis study aims to quantify the potential impact of global climate change on Ireland's marine resource, which is of significant economic and social importance. Global climate models predict warming of the Earth's atmosphere and oceans, which will consequently affect mean sea levels, the frequency and severity of extreme weather events, winds and ocean waves. Such changes need to be carefully assessed for long‐term marine and coastal planning. We derived future wave climate projections for Ireland using the EC‐Earth global climate model and the WAVEWATCH III wave model, by comparing the future 30‐year period 2070–2099 to 1980–2009 for the RCP4.5 and the RCP8.5 forcing scenarios. This data set is currently the highest resolution wave projection data set available for Ireland. EC‐Earth predicts decreases in means (up to 3%) and extremes (up to 14% for the 95th percentile) of 10 m wind speeds over the North Atlantic Ocean (5–75°N, 0–80°W) by the end of the century. Similarly, the model projections show decreases in the frequency and intensity of wind storms crossing Ireland but these changes are not statistically significant. The WAVEWATCH III model predicts an overall decrease in mean (up to 15%) and extreme (up to 15% for the 95th percentile) annual, boreal winter and summer significant wave heights around Ireland.

Loss potentials associated with European windstorms under future climate conditions

Possible changes in the frequency and intensity of windstorms under future climate conditions during the 21st century are investigated based on an ECHAM5 GCM multi-scenario en- semble. The intensity of a storm is quantified by the associated estimated loss derived with using an empirical model. The geographical focus is 'Core Europe', which comprises countries of Western Europe. Possible changes of losses are analysed by comparing ECHAM5 GCM data for recent (20C, 1960 to 2000) and future climate conditions (B1, A1B, A2; 2060 to 2100), each with 3 ensemble members. Changes are quantified using both rank statistics and return periods (RP) esti- mated by fitting an extreme value distribution using the peak over threshold method to potential storm losses. The estimated losses for ECHAM5 20C and reanalysis events show similar statistical features in terms of return periods. Under future climate conditions, all climate scenarios show an increase in both frequency and magnitude of potential losses caused by windstorms for Core Eu- rope. Future losses that are double the highest ECHAM5 20C loss are identified for some countries. While positive changes of ranking are significant for many countries and multiple scenarios, signif- icantly shorter RPs are mostly found under the A2 scenario for return levels correspondent to 20 yr losses or less. The emergence time of the statistically significant changes in loss varies from 2027 to 2100. These results imply an increased risk of occurrence of windstorm-associated losses, which can be largely attributed to changes in the meteorological severity of the events. Additionally, fac- tors such as changes in the cyclone paths and in the location of the wind signatures relative to highly populated areas are also important to explain the changes in estimated losses.

Revitalizing Global Environmental Governance for Climate Change

Whether the December 2009 negotiations in Copenhagen produce or real success (1)--that is to say, merely a foundation for further negotiations or a full-blown new post-Kyoto Protocol climate change agreement--the world seems headed for a period of extraordinary international environmental activity with implications for every nation, community, business, and individual on the planet. The scale, complexity, and potential cost of responding to the threat of climate change make this a policy challenge of unprecedented proportions. And it is becoming increasingly clear that the worldwide effort to reduce greenhouse gas emissions and mitigate the threat of global warming and related problems, including changed rainfall patterns, melting polar ice, sea-level rise, and increased intensity of windstorms, will not be successful without significant institutional support at the global scale. The existing global environmental governance system, centered on the UN Environment Programme (UNEP) in Nairobi, is by almost all accounts not up to the task of managing the response to climate change. UNEP suffers from a vague mandate, severe budget constraints, limited analytic capacity, and other human resource challenges as well as a lack of political support. UNEP has a record of success in some respects, notably in shepherding the process that led to the Montreal Protocol and a series of subsequent amendments that helped phase out chlorofluorocarbons (CFCs) and other chemicals that threatened the world's protective ozone layer. But in recent years, UNEP has not been a major player on climate change. Indeed, fragmentation is one of the fundamental problems of our current regime of global environmental Dozens of organizations have some degree of environmental responsibility, including the UN Commission on Sustainable Development, UN Development Programme (UNDP), the World Bank and other multilateral development banks, and numerous environmental treaty secretariats. But these various entities often do not play well together. There has been little attempt to set consistent priorities, achieve a systematic division of labor, rationalize budgets, or pursue synergies across issues. Moreover, there has been little policy coordination between global-scale economic decisionmaking and parallel efforts at worldwide environmental protection. A successful global response to climate change will therefore require broad-scale revitalization of the global environmental governance regime. (2) In fact, the urgent need for strengthened environmental cooperation across the world in response to climate change offers an opportunity to rethink global governance more broadly. In this regard, now may be the time to launch a Global Environmental Organization (GEO), based on a new international organization model. Rather than a ramped-up UNEP, I envision a GEO that is leaner and more focused, and which subsumes existing environmental treaty secretariats and consolidates within it the UN Commission on Sustainable Development. It would have a small permanent staff in Geneva and a substantial virtual presence, drawing in expertise from around the world in an evolving set of global public policy networks. To be effective, the new international organization would need clear goals, a compelling set of core principles, carefully specified functions and capacities, and a strong commitment to good governance. Goals Any reform of the global environmental governance structure needs to emphasize effectiveness, efficiency, and equity. These goals seem straightforward, yet past international environmental policy cooperation efforts have fallen short on all three of these elements. With a few notable exceptions (such as the Montreal Protocol), the existing regime has produced many meetings and some agreements, but few concrete improvements in environmental performance. Principles Successful international organizations have clear guiding principles. …

Application of an Adiabatic WRF Adjoint to the Investigation of the May 2004 McMurdo, Antarctica, Severe Wind Event

The tangent linear and adjoint of an adiabatic version of the Weather Research and Forecasting (WRF) Model with its Advanced Research WRF (ARW) dynamic core have been developed. The source-to-source automatic differentiation tool [i.e., the Transformation of Algorithm (TAF) in FORTRAN] was used in the development. Tangent linear and adjoint checks of the developed adiabatic WRF adjoint modeling system (WAMS) were conducted, and all necessary correctness verification procedures were passed. As the first application, the adiabatic WAMS was used to study the adjoint sensitivity of a severe windstorm in Antarctica. Linearity tests indicated that an adjoint-based sensitivity study with the Antarctic Mesoscale Prediction System (AMPS) 90-km domain configuration for the windstorm is valid up to 24 h. The adjoint-based sensitivity calculation with adiabatic WAMS identified sensitive regions for the improvement of the 24-h forecast of the windstorm. It is indicated that the windstorm forecast largely relies on the model initial conditions in the area from the south part of the Trans-Antarctic Mountains to West Antarctica and between the Ross Ice Shelf and the South Pole. Based on the sensitivity analysis, the southerly or southeasterly wind at lower levels in the sensitivity region should be larger, the cyclone should be stronger, and the atmospheric stratification should be more stable over the north slope of the Trans-Antarctic Mountain to the Ross Ice Shelf, than the AMPS analyses. By constructing pseudo-observations in the sensitivity region using the gradient information of forecast windstorm intensity around McMurdo, the model initial conditions are revised with the WRF three-dimensional variational data assimilation, which leads to significant improvement in the prediction of the windstorm. An adjoint sensitivity study is an efficient way to identify sensitivity regions in order to collect more observations in the region for better forecasts in a specific aspect of interest.

Climate Change and Global Environmental Governance

Elizabeth R. DeSombre, Global Environmental Institutions (New York: Routledge, 2006). James Gustave Speth and Peter M. Haas, Global Environmental Governance (Washington, DC: Island Press, 2006). Pamela S. Chasek, David L. Downie, and Janet Welsh Brown, Global Environmental Politics, 4th ed. (Boulder: Westview Press, 2006). Richard E. Saunier and Richard A. Meganck, Dictionary and Introduction to Global Environmental Governance (London: Earthscan, 2007). Global environmental governance has emerged as a hot topic in scholarly circles. The manifest inadequacy of international policy cooperation in response to transboundary pollution problems and the need for better management of shared natural resources has led to a flurry of academic writing. Scholars in environmental studies, political science, international relations, and law are now critically analyzing the structure and effectiveness of the international environmental regime and efforts to address change, declining fisheries, deforestation, loss of biodiversity, the spread of toxic chemicals, and other issues. These problems have also captured attention in the public arena. Al Gore won the Nobel Peace Prize for his efforts to focus the public on the climate crisis. His book An Inconvenient Truth and related movie have won numerous awards. Adding to this arc of interest, a number of scholarly books that seek to illuminate the institutions, legal structures, and politics that shape global-scale environmental policymaking have been released over the past several years. The logic of collective action in the international environmental arena is clear. Absent cooperation, the spillover of pollution from one country onto its neighbors or into the shared space of the global commons, as well as the over-exploitation of shared natural resources, promise not just environmental degradation but also economic inefficiency, political instability, and diminished social welfare. Ecological interdependence, expanded economic inter-linkages, and tensions at the trade-environment interface have also made environmental cooperation an important element in the process of establishing the terms of engagement for international commerce. (1) The world community's failure to stem the buildup of greenhouse gas emissions in the atmosphere and resulting fears that the world is suffering the effects of change--global warming, sea level rise, increased intensity of windstorms, changed rainfall patterns, and other problems--add urgency to the quest for a better-functioning international environmental regime. All of the books surveyed in the following paragraphs find negative trend lines with regard to environmental cooperation, with the exception of efforts to phase out chlorofluorocarbons (CFCs) and other chemicals that destroy the ozone layer. Understanding which international environmental efforts are effective--and why--thus takes on a degree of urgency among issues of global policymaking. Unfortunately, these recent books, while beginning to explore the contours of this important question, do too little to help us understand how to move forward and build a more effective international environmental regime. Nevertheless, the works reviewed provide an important starting point for this critical inquiry. Elizabeth DeSombre's Global Environmental Institutions offers a thorough tour of the existing structure of environment-related international organizations. As part of the Global Institutions Series, edited by Thomas Weiss and Rorden Wilkinson, the book provides a useful history of the UN Environment Programme (UNEP), although some of the details of her analysis have been disputed. (2) DeSombre illuminates the governance, financing, and scientific efforts of UNEP and also reviews the Earth Summits, (3) which have helped structure the international community's thinking about environmental challenges over the past forty years. …

Geoinformation Analysis of Factors Affecting Wind Damage in the Šumava National Park

Geoinformation Analysis of Factors Affecting Wind Damage in the Šumava National ParkThis project forms part of the "Remotely Accessed Decision Support System for Transnational Environmental Risk Management" (STRiM) project undertaken within the framework of the European Union's INTERREG IIIB CADSES programme. The test took place in a 70 km2test area within the western part of the Šumava National Park. It is commonly known that windthrow occurs frequently in the Šumava Mountains, and it tends to occur in particular areas. The intensity of windstorms and the amount of damage caused appear to be relatively constant. In the case of Šumava, such meteorological hazards frequently become biotic hazards as they are often followed by bark beetle infestations. We hypothesise that, in particular areas, the incidence of windthrow, the amount of harm done, and the cost of alleviating that damage are in close relationship with natural factors prevalent in the area and with previous human intervention (forestry) in the landscape. Analysis of such factors, and a comparison with actual data on windthrow, showed that a) the most damaged stands were generally found on gently sloping sites of 8-15 degrees; b) the leeward side of elevations were more heavily damaged; c) non-natural forest stands were subject to more damage; d) damage increased with increasing stand density; e) middle-aged stands of around 12 years were at greatest risk; and f) the most damaged portions of the test area were located at sites with normally drained and deep soils. Further, landscape relief and active surface character appeared to play an important role in modifying wind speed and direction, thereby increasing the wind's devastating power.

Structure, microphysics, and surface area of the Arctic snowpack near Alert during the ALERT 2000 campaign

The seasonal snowpack at Alert (North coast of Ellesmere Island, 82°29.94′N, 62°20.55′W) was studied in February and April 2000, on land and on sea ice. The stratigraphy was studied, and the density and specific surface area (SSA) of each snow layer were measured. SSA was measured by CH 4 adsorption at 77 K using a volumetric method. On land, the snowpack was 10–50 cm thick and consisted of a depth hoar layer covered by one or more hard wind-packed layers with densities between 0.35 and 0.52. These were sometimes separated by soft layers of more or less faceted crystals. The surface was covered by recent precipitation and surface hoar. The stratigraphy on sea ice was more variable, with numerous hard wind-packed layers alternating with soft layers of depth hoar or faceted crystals. SSA values ranged from 125 cm 2/g for depth hoar to 1500 cm 2/g for diamond dust and dendritic snow. The total surface area of the snowpack was calculated from the thickness, density, and SSA of each layer, and ranged from 1160 to 3710 m 2 of snow surface area per m 2 of ground. These values were used to estimate the potential impact of the snowpack on atmospheric chemistry, by adsorption/desorption of trace gases. Using the example of acetone, whose adsorption behavior on ice is estimated, it is found that the snowpack may sequester most of the acetone of the (snow+boundary layer) system most of the year. The release during metamorphism of trace gases dissolved in snow is also discussed. We propose that the frequency and intensity of wind storms will strongly affect the release of trace gases, as this will determine whether intense metamorphism leading to depositional depth hoar can happen.

Subalpine forest damage from a severe windstorm in northern Colorado

As windstorm intensity increases above some threshold, disturbance spread and damage patterns are expected to be less strongly shaped by preblowdown forest composition and structure than by the pattern of the storm itself. We examined this generalization by analyzing differences in wind damage among tree species and stands following a severe blowdown in 1997 affecting over 10 000 ha of subalpine forest in the Routt Divide area of northern Colorado, U.S.A. Individual tree traits such as species, height, and status as standing dead or alive strongly influenced the amount and type (uprooting vs. snapping) of wind damage. Populus tremuloides Michx. exhibited much less uprooting and overall damage than the conifers. Among the canopy trees of the conifer species, Pinus contorta Dougl. ex. Loud and Abies lasiocarpa (Hook.) Nutt. sustained the lowest and highest rates of snapping, respectively. Standing dead conifers were more likely to be snapped than uprooted, and taller trees were more likely to be damaged than shorter trees. Stand-level characteristics such as stand density, amount of dead basal area, and species composition were predictive of the amount of wind damage for areas of moderate- but not high-severity blowdown. Even in such an extreme windstorm as the Routt blowdown, which had estimated wind speeds of 200–250 km/h, individual tree attributes and stand-level characteristics significantly influenced the severity and type of wind damage.

The Campaign Against Windstorms in the Banana Plantations Near Santa Marta, Colombia, 1956–57

Windstorms do great damage in banana plantations near the Sierra Nevada de Santa Marta in Colombia. These plantations, which owe their location to the rainfall maximum caused by convergence in the trade winds as they flow around the mountain massif, suffer most damage from the few most violent tempests and relatively little from the frequent milder squalls, offering the prospect that even slight mitigation of severe storms would be economically rewarding. Most damage was found to be triggered by easterly waves and similar large-scale disturbances, though the windstorms themselves remained purely local. Cloud seeding to attempt reduction of windstorm intensity was undertaken during the 1956 and 1957 seasons on the hypothesis that stimulation of showers early in the diurnal build-up of instability would dissipate some of the instability and reduce insolation at the ground, thus diminishing the intensity of later convective overturning. Comparison of damages during these seeded seasons with those of preceding and subsequent seasons showed a marked reduction in the ratio of severe windstorms to mild ones during the campaign and a reduction perhaps as much 39 per cent in damages, worth several million dollars annually.