Does the winter storm-related wind gust intensity in Germany increase under warming climate? – A high-resolution assessment

Abstract. We use high-resolution (4.4 km) numerical simulations of tropical cyclones to produce exceedance probability estimates for extreme wind (gust) speeds over Bangladesh. For the first time, we estimate equivalent return periods up to and including a 1-in-200 year event, in a spatially coherent manner over all of Bangladesh, by using generalised additive models. We show that some northern provinces, up to 200 km inland, may experience conditions equal to or exceeding a very severe cyclonic storm event (maximum wind speeds in ≥64 kn) with a likelihood equal to coastal regions less than 50 km inland. For the most severe super cyclonic storm events (≥120 kn), event exceedance probabilities of 1-in-100 to 1-in-200 events remain limited to the coastlines of southern provinces only. We demonstrate how the Bayesian interpretation of the generalised additive model can facilitate a transparent decision-making framework for tropical cyclone warnings.

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High-Resolution Observations of a Destructive Macroburst

Monthly Weather Review ◽

10.1175/mwr-d-20-0412.1 ◽

2021 ◽

Author(s):

Samuel J. Childs ◽

Russ S. Schumacher ◽

Rebecca D. Adams-Selin

Keyword(s):

High Resolution ◽

Wind Shear ◽

Vertical Wind Shear ◽

Vertical Wind ◽

Convective System ◽

Wind Gust ◽

Damage Survey ◽

Strong Inversion ◽

Radial Outflow ◽

The Town

AbstractShortly after 0600 UTC (midnight MDT) on 9 June 2020, a rapidly intensifying and elongating convective system produced a macroburst and extensive damage in the town of Akron on Colorado’s eastern Plains. Instantaneous winds were measured as high as 51.12 m s−1 at 2.3 m AGL from an eddy covariance (EC) tower, and a 50.45 m s−1 wind gust from an adjacent 10-m tower became the highest official thunderstorm wind gust ever measured in Colorado. Synoptic-scale storm motion was southerly, but surface winds were northerly in a post-frontal airmass, creating strong vertical wind shear. Extremely high-resolution temporal and spatial observations allow for a unique look at pressure and temperature tendencies accompanying the macroburst and reveal intriguing wave structures in the outflow. At 10-Hz frequency, the EC tower recorded a 5-hPa pressure surge in 19 seconds immediately following the strongest winds, and a 15-hPa pressure drop in the following three minutes. Surface temperature also rose 1.5°C in less than one minute, concurrent with the maximum wind gusts, and then fell sharply by 3.5°C in the following minute. Shifting wind direction observations and an NWS damage survey are suggestive of both radial outflow and a gust front passage, and model proximity soundings reveal a well-mixed surface layer topped by a strong inversion and large low-level vertical wind shear. Despite the greatest risk of severe winds forecast to be northeast of Colorado, convection-allowing model forecasts from 6-18 h in advance did show similar structures to what occurred, warranting further simulations to investigate the unique mesoscale and misoscale features associated with the macroburst.

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Upper tropospheric humidity changes under constant relative humidity

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-4159-2016 ◽

2016 ◽

Vol 16 (6) ◽

pp. 4159-4169 ◽

Cited By ~ 2

Author(s):

Klaus Gierens ◽

Kostas Eleftheratos

Keyword(s):

High Resolution ◽

Relative Humidity ◽

Infrared Radiation ◽

Weighting Function ◽

Scale Height ◽

Weighted Mean ◽

Constant Relative Humidity ◽

Warming Climate ◽

Upper Tropospheric Humidity ◽

Peak Emission

Abstract. Theoretical derivations are given on the change of upper tropospheric humidity (UTH) in a warming climate. The considered view is that the atmosphere, which is getting moister with increasing temperatures, will retain a constant relative humidity. In the present study, we show that the upper tropospheric humidity, a weighted mean over a relative humidity profile, will change in spite of constant relative humidity. The simple reason for this is that the weighting function that defines UTH changes in a moister atmosphere. Through analytical calculations using observations and through radiative transfer calculations, we demonstrate that two quantities that define the weighting function of UTH can change: the water vapour scale height and the peak emission altitude. Applying these changes to real profiles of relative humidity shows that absolute UTH changes typically do not exceed 1 %. If larger changes would be observed they would be an indication of climatological changes of relative humidity. As such, an increase in UTH between 1980 and 2009 in the northern midlatitudes, as shown by earlier studies using the High-resolution Infrared Radiation Sounder (HIRS) data, may be an indication of an increase in relative humidity as well.

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Wintersturmschäden im Schweizer Wald von 1865 bis 2014

Schweizerische Zeitschrift fur Forstwesen ◽

10.3188/szf.2015.0184 ◽

2015 ◽

Vol 166 (3) ◽

pp. 184-190 ◽

Cited By ~ 5

Author(s):

Tilo Usbeck

Keyword(s):

Present Article ◽

Forest Area ◽

Wind Gust ◽

Turn Of The Millennium ◽

Storm Events ◽

Winter Storm ◽

Winter Storms ◽

Growing Stock ◽

The Past ◽

Gust Speed

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.

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Improving our understanding of wind extremes from Bangladesh tropical cyclones: insights from a high-resolution convection-permitting numerical model

10.5194/nhess-2020-299 ◽

2020 ◽

Author(s):

Hamish Steptoe ◽

Theo Economou

Keyword(s):

High Resolution ◽

Tropical Cyclones ◽

Additive Model ◽

Additive Models ◽

Exceedance Probability ◽

Storm Event ◽

Wind Gust ◽

Storm Events ◽

Generalised Additive Model ◽

Cyclonic Storm

Abstract. We use high resolution (4.4 km) numerical simulations of tropical cyclones to produce exceedance probability estimates for extreme wind (gust) speeds over Bangladesh. For the first time, we estimate equivalent return periods up to and including a 1-in-200 year event, in a spatially coherent manner over all of Bangladesh, by using generalised additive models. We show that some northern provinces, up to 200 km inland, may experience conditions equal to or exceeding a very severe cyclonic storm event (maximum wind speeds in ≥ 64 knots) with a likelihood equal to coastal regions less than 50 km inland. For the most severe super cyclonic storm events (≥ 120 knots), event exceedance probabilities of 1-in-100 to 1-in-200 events remain limited to the coastlines of southern provinces only. We demonstrate how the Bayesian interpretation of the generalised additive model can facilitate a transparent decision-making framework for tropical cyclone warnings.

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Mean and extreme temperatures in a warming climate: EURO CORDEX and WRF regional climate high-resolution projections for Portugal

Climate Dynamics ◽

10.1007/s00382-018-4124-4 ◽

2018 ◽

Vol 52 (1-2) ◽

pp. 129-157 ◽

Cited By ~ 24

Author(s):

Rita M. Cardoso ◽

Pedro M. M. Soares ◽

Daniela C. A. Lima ◽

Pedro M. A. Miranda

Keyword(s):

High Resolution ◽

Regional Climate ◽

Extreme Temperatures ◽

Warming Climate

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Expected Recurrence of Extreme Winds in Northwestern Sahara and Associated Uncertainties

Energies ◽

10.3390/en14216913 ◽

2021 ◽

Vol 14 (21) ◽

pp. 6913

Author(s):

Elena García García Bustamante ◽

J. Fidel González González Rouco ◽

Jorge Navarro ◽

Etor E. Lucio Lucio Eceiza ◽

Cristina Rojas Rojas Labanda

Keyword(s):

High Resolution ◽

Large Body ◽

Return Level ◽

Wind Gust ◽

Return Levels ◽

Uncertainty Space ◽

Simulation Based ◽

Regional Simulation ◽

Extreme Winds ◽

Selection Of

Estimating the probability of the occurrence of hazardous winds is crucial for their impact in human activities; however, this is inherently affected by the shortage of observations. This becomes critical in poorly sampled regions, such as the northwestern Sahara, where this work is focused. The selection of any single methodological variant contributes with additional uncertainty. To gain robustness in the estimates, we expand the uncertainty space by applying a large body of methodologies. The methodological uncertainty is constrained afterward by keeping only the reliable experiments. In doing so, we considerably narrow the uncertainty associated with the wind return levels. The analysis suggest that not necessarily all methodologies are equally robust. The highest 10-min speed (wind gust) for a return period of 50 years is about 45 ms−1 (56 ms−1). The intensity of the expected extreme winds is closely related to orography. The study is based on wind and wind gust observations that were collected and quality controlled for the specific purposes herein. We also make use of a 12-year high-resolution regional simulation to provide simulation-based wind return level maps that endorse the observation-based results. Such an exhaustive methodological sensitivity analysis with a long high-resolution simulation over this region was lacking in the literature.

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Tunnel valley infill and genesis revealed by high-resolution 3-D seismic data

Geology ◽

10.1130/g49048.1 ◽

2021 ◽

Author(s):

James D. Kirkham ◽

Kelly A. Hogan ◽

Robert D. Larter ◽

Ed Self ◽

Ken Games ◽

...

Keyword(s):

High Resolution ◽

Seismic Data ◽

Three Dimensional ◽

Ice Sheets ◽

Ice Dynamics ◽

The North ◽

Warming Climate ◽

Internal Structures ◽

The North Sea ◽

Glacial Landforms

Landforms produced beneath former ice sheets offer insights into inaccessible subglacial processes and present analogues for how current ice masses may evolve in a warming climate. Large subglacial channels cut by meltwater erosion (tunnel valleys [TVs]) have the potential to provide valuable empirical constraints for numerical ice-sheet models concerning realistic melt rates, water routing, and the interplay between basal hydrology and ice dynamics. However, the information gleaned from these features has thus far been limited by an inability to adequately resolve their internal structures. We use high-resolution three-dimensional (HR3-D) seismic data (6.25 m bin size, ~4 m vertical resolution) to analyze the infill of buried TVs in the North Sea. The HR3-D seismic data represent a step-change in our ability to investigate the mechanisms and rates at which TVs are formed and filled. Over 40% of the TVs examined contain buried glacial landforms including eskers, crevasse-squeeze ridges, glacitectonic structures, and kettle holes. As most of these landforms had not previously been detected using conventional 3-D seismic reflection methods, the mechanisms that formed them are currently absent from models of TV genesis. The ability to observe such intricate internal structures opens the possibility of using TVs to reconstruct the hydrological regimes of former mid-latitude ice sheets as analogues for contemporary ones.

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