Severe Winter Storms Research Articles

FIELD MEASUREMENTS OF VERY OBLIQUE WAVE RUN-UP AND OVERTOPPING WITH LASER SCANNERS

Oosterlo et al. (2019) developed a system using two terrestrial laser scanners, which can measure run-up heights, depths and velocities of waves on a dike in field situations. The system has now been placed next to two overtopping tanks on a dike in the Eems-Dollard estuary in the Netherlands to measure during actual severe winter storms. The goal of the present paper is to further validate this innovative system with data obtained during storm Ciara (10 - 12 February 2020), a severe winter storm with very oblique wave attack. Furthermore, the data gathered during storm Ciara will be compared to the current knowledge on wave overtopping, to possibly gain new insights in the influence of very oblique wave attack on wave overtopping.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/TwSwJuxb-Yo

Sense-making in a Simulated Emergency Operations Centre

This study reports the results of a laboratory experiment in decision-making in an Emergency Operations Centre (EOC) during a crisis. It adapted a validated simulation of a severe winter storm in a fictional city in Canada, during which a variety of serious events caused major disruptions, including loss of life. Participants were naïve individuals, as the focus was on sense-making in unfamiliar dynamic and uncertain environments and situations requiring urgent responses (i.e., conditions that occur during crises). The objective was to assess the impacts of enactment on the retention of memory of recent experiences. The enactment was theorized as the basis for sense-making processes where taking an action is guided by learning through acting. In contrast, predictions based on a simple model, the Zeigarnik effect, indicate the depletion of memory for completed actions, thus indicating their perverse effects on the capacity to learn. This experiment showed that participants in our simulation who played the role of passive observers of EOC activities during a severe storm remembered more of the events than did participants who played the role of trainees in the EOC who had to act on requests for information and decisions. Other results pointed to the conclusion that the role played by participants in the EOC significantly affected which events they remembered, their mood, and their priorities in the EOC. These results imply that having non-acting observers present in the EOC might be a way to better preserve organizational memory.

Estimation of Longshore Sediment Transport Using Video Monitoring Shoreline Data

Video monitoring systems (VMS) have been used for beach status observation but are not effective for examining detailed beach processes as they only measure changes to the shoreline and backshore. Here, we extracted longshore sediment transport (LST) from VMS in order to investigate long- and short-term littoral processes on a pocket beach. LST estimated by applying one-line theory, wave power, and the oblique angle of incident waves were used to understand shoreline changes caused by severe winter storms. The estimated LST showed good agreement with the shoreline changes because the sediments were trapped at one end of the pocket beach and the alongshore direction of transported sediments was corresponded to the direction of LST. The results also showed that the beach that was severely eroded during storms was also rapidly recovered following the evolution of LST, which indicates that the LST may play a role in the recovery process while the erosion was mainly caused by the cross-shore transport due to storm waves. After the beach was nourished, beach changes became more active, even under lower wave energy conditions, owing to the equilibrium process. The analysis presented in this study could be applied to study inhomogeneous beach processes at other sites.

Storm damage at Craig Phadrig hillfort, Inverness

In January 2015 severe winter storms caused substantial damage to Craig Phadrig fort (Scheduled Monument 2892) after two wind-blown trees exposed a section of the inner rampart. Prior to consolidation and reinstatement, Scheduled Monument Consent was granted for an archaeological evaluation of the damaged area. This revealed three principal phases of construction, the earliest a massive timber-laced wall burnt in the 4th–3rd century bc. The upper elements of this ruined structure were incorporated into two secondary phases of refortification comprising construction of a palisade along its crest followed several centuries later by reprofiling of the rampart upper bank. The chronology of the second and third phases is more equivocal, with a single 5th–6th century ad radiocarbon date providing a terminus post quem for the erection of the palisade, while the other features indicate activity in the 11th–13th centuries.

Impacts of Hydrometeor Drift on Orographic Precipitation: Two Case Studies of Landfalling Atmospheric Rivers in British Columbia, Canada

Abstract Two severe winter storms in 2016 and 2017 caused by landfalling atmospheric rivers over British Columbia (BC) are investigated in this study. Our main concern is the impact of hydrometeor drift on the orographic precipitation. It is shown that the dominant contribution to the windward orographic precipitation was from the horizontal moisture convergence. The precipitation distributions across southern BC were also influenced by the convergence/divergence of condensed water due to the wind-driven effect on hydrometeors. Observed hourly and daily precipitation amounts are used to verify the performances of three Canadian numerical weather prediction systems. Our results indicate that these operational systems were capable of predicting the general features of orographic precipitation in BC. However, the two coarse-resolution systems used a diagnostic precipitation scheme that does not fully simulate the hydrometeor drift process. The High-Resolution Deterministic Prediction System (HRDPS) with a prognostic precipitation scheme was substantially more accurate and skillful in predicting the upwind precipitation as well as the spillover of precipitation on the leeward slopes for these two storms. There was evidence suggesting that the spillover effect was overpredicted by the HRDPS due to a systematic bias originating in the model microphysics. This problem has been improved in the current HRDPS with a new microphysics scheme. Based on our atmospheric water balance analysis, we also proposed two postprocessing schemes that could be applied to improve the quantitative precipitation forecasts of the diagnostic precipitation schemes.

Impact of an Extreme Winter Storm Event on the Coagulation/Flocculation Processes in a Prototype Surface Water Treatment Plant: Causes and Mitigating Measures.

Climate change has often caused failure in water treatment operations. In this study, we report a real case study at a major surface water treatment plant in Alabama, USA. Following a severe winter storm, the effluent water turbidity surged to >15.00 Nephelometric Turbidity Units (NTU), far exceeding the 0.30 NTU standard. As a result, the plant operation had to be shut down for three days, causing millions of dollars of losses and affecting tens of thousands of people. Systematic jar tests were carried out with sediment samples from 22 upstream locations. The coagulation and settleability of sediment particles were tested under simulated storm weather conditions, i.e., low temperature (7 °C) and in the presence of various types and concentrations of natural organic matter (NOM) that was extracted from the local sediments. Experimental results proved that elevated NOM (6.14 mg·L−1 as Total Organic Carbon, TOC) in raw water was the root cause for the failure of the plant while the low temperature played a minor but significant role. Pre-oxidation with permanganate and/or elevated coagulant dosage were found effective to remove TOC in raw water and to prevent similar treatment failure. Moreover, we recommend that chemical dosages should be adjusted based on the TOC level in raw water, and a reference dosage of 0.29 kg-NaMnO4/kg-TOC and 19 kg- polyaluminum chloride (PACl) /kg-TOC would be appropriate to cope with future storm water impacts. To facilitate timely adjustment of the chemical dosages, the real time key water quality parameters should be monitored, such as turbidity, TOC, Ultraviolet (UV) absorbance, pH, and color. The findings can guide other treatment operators to deal with shock changes in the raw water quality resulting from severe weather or other operating conditions.

Historical Winter Storm Atlas for Germany (GeWiSA)

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 ( G S ˜ ) of all winter storms was modeled by a least-squares boosting (LSBoost) approach. Orographic features and surface roughness were used as predictor variables. Secondly, the quotient of GS related to each winter storm to G S ˜ , which was defined as storm field factor (STF), was calculated and mapped by a thin plate spline interpolation (TPS). It was found that the mean study area-wide GS associated with the 2007 storm Kyrill is highest (29.7 m/s). In Southern Germany, the 1999 storm Lothar, with STF being up to 2.2, was the most extreme winter storm in terms of STF and GS. The results demonstrate that the variability of STF has a considerable impact on the simulated GS fields. Event-related model validation yielded a coefficient of determination (R2) of 0.786 for the test dataset. The developed GS fields can be used as input to storm damage models representing storm hazard. With the knowledge of the storm hazard, factors describing the vulnerability of storm exposed objects and structures can be better estimated, resulting in improved risk management.

X-Band Dual-Polarization Radar Observations of Snow Growth Processes of a Severe Winter Storm: Case of 12 December 2013 in South Korea

AbstractThe characteristics of microphysical processes of a severe winter storm that occurred on the Korean Peninsula on 12 December 2013 was studied in this work for the first time via X-band dual-polarization weather radar observations. A new range–height indicator (RHI) scan-based quasi-vertical profile methodology, in which polarimetric radar variables were averaged at each height of the RHI scan, was introduced to investigate the snow microphysics, and the obtained polarimetric radar signatures served as fingerprints of the dendritic growth, aggregation, and riming processes. Enhanced differential reflectivity (Zdr) and specific differential phase shift (Kdp) bands were detected near the −15°C isotherm, which signified the growth of dendrites or platelike crystals. The observed correlation between the increases in the reflectivity factor at horizontal polarization Zh and copolar correlation coefficient ρhv and the decreases in Zdr and Kdp magnitudes at lower heights suggested the occurrence of the aggregation process. The combination of high Zh and low Zdr values with turbulent atmospheric conditions observed at the ground level indicated the occurrence of the riming process. In addition, the negative Kdp and Zdr values combined with high Zh and ρhv magnitudes (observed near the end of the snow event) indicated the formation of graupel particles. The polarimetric radar signatures obtained for the snow growth processes were evident from ground observations and agreed well with the results of the Weather Research and Forecasting Model and Modern-Era Retrospective Analysis for Research and Applications data. Furthermore, the spatial variability of Zh methodology was implemented to describe both aggregates and rimed ice particles.

Factors Influencing the Seasonal Predictability of Northern Hemisphere Severe Winter Storms

AbstractWe investigate the role of the tropics, the stratosphere, and atmosphere‐ocean coupling for seasonal forecasts of strong, potentially damaging, Northern Hemisphere extratropical winter wind storm frequencies. This is done by means of relaxation experiments with the European Centre for Medium‐Range Weather Forecasts model, which allow us to prescribe perfect forecasts for specific parts of the coupled atmosphere‐ocean system. We find that perfect predictions of the Northern Hemisphere stratosphere significantly enhance winter storm predictive skill between eastern Greenland and Northern Europe. Correct seasonal predictions of the occurrence of stratospheric sudden warmings play a decisive role. The importance of correctly predicting the tropics and of two‐way atmosphere‐ocean coupling, both for forecasting stratospheric sudden warming risk and, correspondingly, severe winter storm frequency, is noted.

Beach-fill equilibration and dune growth at two large-scale nourishment sites

Natural dune growth after nourishment is often observed, and such growth plays an important role in beach management for coastal communities. Nourishment sand equilibration after construction is another important topic for project planning and design. Large-scale nourishment projects at Nags Head (NC, USA) (completed in 2011) and Bridgehampton–Sagaponack (NY, USA) (completed in 2014) are under comparatively high-wave energy conditions and offer new insight regarding these topics. After nourishment, a natural beach and inshore morphology were produced with high rates of dune growth by eolian transport. At Nags Head, volumetric dune growth averaged 8 m3/m/yr over the first 5 years following project completion, while Bridgehampton–Sagaponack averaged 9 m3/m/yr over the first 3 post-project years. Results are compared with the Bagnold (1941) analytical model predictions of dune growth and are shown to correlate and decay closely with dry-sand beach width as the nourished profile equilibrates. The extra volume and elevation in the dunes have provided a higher level of storm protection and have helped the sites avoid any major damage to oceanfront properties during hurricanes or numerous severe winter storms.

Euro-Atlantic winter storminess and precipitation extremes under 1.5 °C vs. 2 °C warming scenarios

Abstract. Severe winter storms in combination with precipitation extremes pose a serious threat to Europe. Located at the southeastern exit of the North Atlantic's storm track, European coastlines are directly exposed to impacts by high wind speeds, storm floods and coastal erosion. In this study we analyze potential changes in simulated winter storminess and extreme precipitation, which may occur under 1.5 or 2 ∘C warming scenarios. Here we focus on a first simulation suite of the atmospheric model CAM5 performed within the HAPPI project and evaluate how changes of the horizontal model resolution impact the results regarding atmospheric pressure, storm tracks, wind speed and precipitation extremes. The comparison of CAM5 simulations with different resolutions indicates that an increased horizontal resolution to 0.25∘ not only refines regional-scale information but also improves large-scale atmospheric circulation features over the Euro-Atlantic region. The zonal bias in monthly pressure at mean sea level and wind fields, which is typically found in low-resolution models, is considerably reduced. This allows us to analyze potential changes in regional- to local-scale extreme wind speeds and precipitation in a more realistic way. Our analysis of the future response for the 2 ∘C warming scenario generally confirms previous model simulations suggesting a poleward shift and intensification of the meridional circulation in the Euro-Atlantic region. Additional analysis suggests that this shift occurs mainly after exceeding the 1.5 ∘C global warming level, when the midlatitude jet stream manifests a strengthening northeastward. At the same time, this northeastern shift of the storm tracks allows an intensification and northeastern expansion of the Azores high, leading to a tendency of less precipitation across the Bay of Biscay and North Sea. Regions impacted by the strengthening of the midlatitude jet, such as the northwestern coasts of the British Isles, Scandinavia and the Norwegian Sea, and over the North Atlantic east of Newfoundland, experience an increase in the mean as well as daily and sub-daily precipitation, wind extremes and storminess, suggesting an important influence of increasing storm activity in these regions in response to global warming.

Aggregated responses of human mobility to severe winter storms: An empirical study.

Increasing frequency of extreme winter storms has resulted in costly damages and a disruptive impact on the northeastern United States. It is important to understand human mobility patterns during such storms for disaster preparation and relief operations. We investigated the effects of severe winter storms on human mobility during a 2015 blizzard using 2.69 million Twitter geolocations. We found that displacements of different trip distances and radii of gyration of individuals’ mobility were perturbed significantly. We further explored the characteristics of perturbed mobility during the storm, and demonstrated that individuals’ recurrent mobility does not have a higher degree of similarity with their perturbed mobility, when comparing with its similarity to non-perturbed mobility. These empirical findings on human mobility impacted by severe winter storms have potential long-term implications on emergency response planning and the development of strategies to improve resilience in severe winter storms.

Revisiting the synoptic-scale predictability of severe European winter storms using ECMWF ensemble reforecasts

Abstract. New insights into the synoptic-scale predictability of 25 severe European winter storms of the 1995–2015 period are obtained using the homogeneous ensemble reforecast dataset from the European Centre for Medium-Range Weather Forecasts. The predictability of the storms is assessed with different metrics including (a) the track and intensity to investigate the storms' dynamics and (b) the Storm Severity Index to estimate the impact of the associated wind gusts. The storms are well predicted by the whole ensemble up to 2–4 days ahead. At longer lead times, the number of members predicting the observed storms decreases and the ensemble average is not clearly defined for the track and intensity. The Extreme Forecast Index and Shift of Tails are therefore computed from the deviation of the ensemble from the model climate. Based on these indices, the model has some skill in forecasting the area covered by extreme wind gusts up to 10 days, which indicates a clear potential for early warnings. However, large variability is found between the individual storms. The poor predictability of outliers appears related to their physical characteristics such as explosive intensification or small size. Longer datasets with more cases would be needed to further substantiate these points.

Characteristics of different convective parameterization schemes on the simulation of intensity and track of severe extratropical cyclones over North Atlantic

The role of the convective parameterization schemes (CPSs) in the ARW-WRF (WRF) mesoscale model is examined for extratropical cyclones (ETCs) over the North Atlantic Ocean. The simulation of very severe winter storms such as Xynthia (2010) and Gong (2013) are considered in this study. Most popular CPSs within WRF model, along with Yonsei University (YSU) planetary boundary layer (PBL) and WSM6 microphysical parameterization schemes are incorporated for the model experiments. For each storm, four numerical experiments were carried out using New Kain Fritsch (NKF), Betts-Miller-Janjic (BMJ), Grell 3D Ensemble (Gr3D) and no convection scheme (NCS) respectively. The prime objectives of these experiments were to recognize the best CPS that can forecast the intensity, track, and landfall over the Iberian Peninsula in advance of two days. The WRF model results such as central sea level pressure (CSLP), wind field, moisture flux convergence, geopotential height, jet stream, track and precipitation have shown sensitivity CPSs. The 48-hour lead simulations with BMJ schemes produce the best simulations both regarding ETCs intensity and track than Gr3D and NKF schemes. The average MAE and RMSE of intensities are least that (6.5hPa in CSLP and 3.4ms−1 in the 10-m wind) found in BMJ scheme. The MAE and RMSE for and intensity and track error have revealed that NCS produces large errors than other CPSs experiments. However, for track simulation of these ETCs, at 72-, 48- and 24-hour means track errors were 440, 390 and 158km respectively. In brevity, BMJ and Gr3D schemes can be used for short and medium range predictions of the ETCs over North Atlantic. For the evaluation of precipitation distributions using Gr3D scheme are good agreement with TRMM satellite than other CPSs.

SynthETC: A Statistical Model for Severe Winter Storm Hazard on Eastern North America.

We develop, evaluate, and apply "SynthETC," a statistical-stochastic model of winter extra-tropical cyclones (ETCs) over eastern North America. SynthETC simulates the life cycle of ETCs from formation to termination, and it can be used to estimate the probability of extreme ETC events beyond the historical record. Two modes of climate variability are used as independent covariates: El Niño/Southern Oscillation (ENSO) Niño3.4 and the monthly North Atlantic Oscillation (NAO). We use SynthETC to estimate the annual occurrence rate over sites in eastern North America of intense ETC passage in different ENSO and NAO states. Positive NAO is associated with increased rates over the North Atlantic, while negative NAO is associated with decreased rates over the North Atlantic and increased rates over northern Quebec. Positive ENSO is associated with decreased rates over the North Atlantic, Ontario, and the Canadian Maritime, while negative ENSO is associated with increased rates over those regions, as well as the Great Lakes region.

Shoreline management plans in England and Wales: A scientific and transparent process?

Coastal change, including severe winter storms, requires decision-makers to understand the nature of coastal hazards so they can manage the risks and protect coastal communities. This study has provided the first structured quantitative analysis of the scientific underpinning and transparency associated with key policies dictating the future of the coastline in England and Wales. Based on a content analysis of first and second generation shoreline management plans, it has queried the visibility, clarity and transparency of evidence. Results point to improved evidence and understanding at the regional-scale, but issues associated with the transparency of the science informing policy at local levels. Inconsistencies in performance appear to relate to differing approaches of the consultancies preparing the plans rather than the nature of the coasts, the types of policies or the government guidance informing plan development. The study points to a need for a more thorough quality assurance process at national level and calls for clearer guidance on how these regional coastal adaptation plans and their supporting science should be read and interpreted by relevant stakeholder audiences. There are clear lessons from this study for planning processes elsewhere, especially those involving the downscaling of regionally based data and information. There are also potential applications of our criteria-based approach to other planning systems which require scientific scrutiny and transparency.

Mobility of maerl-siliciclastic mixtures: Impact of waves, currents and storm events

Maerl beds are free-living, non-geniculate coralline algae habitats which form biogenic reefs with high micro-scale complexity supporting a diversity and abundance of rare epifauna and epiflora. These habitats are highly mobile in shallow marine environments where substantial maerl beds co-exist with siliciclastic sediment, exemplified by our study site of Galway Bay. Coupled hydrodynamic-wave-sediment transport models have been used to explore the transport patterns of maerl-siliciclastic sediment during calm summer conditions and severe winter storms. The sediment distribution is strongly influenced by storm waves even in water depths greater than 100 m. Maerl is present at the periphery of wave-induced residual current gyres during storm conditions. A combined wave-current Sediment Mobility Index during storm conditions shows correlation with multibeam backscatter and surficial sediment distribution. A combined wave-current Mobilization Frequency Index during storm conditions acts as a physical surrogate for the presence of maerl-siliciclastic mixtures in Galway Bay. Both indices can provide useful integrated oceanographic and sediment information to complement coupled numerical hydrodynamic, sediment transport and erosion-deposition models.

A Flex-Model for long-term assessment of community-residing older adults following disasters

For the rapidly growing older adult population, disaster consequences are frequently life disruptive and even life threatening. By 2050, it is estimated that the global older adult population will reach 22 percent of the total. With declining health, this population poses a particular risk needing to be addressed in emergency preparedness and disaster recovery. The purpose of this article is to describe a Flex-Model (F-M) for the long-term assessment of older adults following a disaster. An F-M is a series of three-dimensional representations of an archetype with flexible components, both linear and parallel, that can be adapted to situations, time, place, and needs. The model incorporates the Life Patterns Model and provides a template that can be adjusted to meet the needs of a local community, healthcare providers, and emergency management officials, regardless of the country or region, during the months after a disaster. The focus is on changes resulting from the disaster including roles, relationships, support systems, use of time, self-esteem, and life structure. Following a baseline assessment, each of these life patterns is assessed through the model with options for interventions over time. A pilot study was conducted in Georgia to gain information that would be helpful in developing a more specific assessment tool following a severe winter storm. While this is a local study, the findings can nevertheless be used to refine and focus the F-M for future implementation. Results indicated that older adults used high-risk heating and lighting sources and many were totally responsible for their own welfare. Findings have implications for emergency preparedness and long-term recovery.

Sprouting response of an evergreen broad‐leaved forest to a 2008 winter storm in Nanling Mountains, southern China

AbstractA severe winter storm from January to February 2008 caused considerable damage to the Nanling evergreen broad‐leaved forest. The sprout vigor of each species during postdisaster recovery plays a very important role in the succession trends of disturbed forests. In April 2008, four plots (50 × 30 m) were established in the Shierdushui Nature Reserve of Guangdong Province, China, to examine the damage status by the dominant species and diameters at breast height (DBHs), and the sprout response (indicated by the number of sprouts per stem) of the evergreen broad‐leaved forest to the severe winter storm. In contrast with freezing damage, the percentage of trees killed by mechanical damage from the mass of snow and ice was significantly higher (10% vs. 90%). More than 70% of the total dead trees had DBHs less than 4 cm. The impact of the severe winter storm in the tree layer was much more serious than in the shrub layer. Stem bending killed the highest percentage of trees, accounting for 59.53% of the total number of dead trees. The sprout number per stem differed significantly among damage types. The more severe damage induced a higher sprout number. Without considering the damage extent, significant differences in the sprout response were also found at both the dominant species and family levels. The tree layer exceeded the shrub layer in the mean number of sprouts (35.87 vs. 15.92). A bivariate correlation indicated that the sprout response was positively related to DBH and annual stem radial growth of the mother trees, implying that DBH and the growth rate of plant species most likely control the sprout response to disturbance in the subtropical evergreen broad‐leaved forests in the Nanling Mountains, southern China.

Eco-engineered rock pools: a concrete solution to biodiversity loss and urban sprawl in the marine environment

In coastal habitats artificial structures typically support lower biodiversity and can support greater numbers of non-native and opportunistic species than natural rocky reefs. Eco-engineering experiments are typically trialed to succeed; but arguably as much is learnt from failure than from success. Our goal was to trial a generic, cost effective, eco-engineering technique that could be incorporated into rock armouring anywhere in the world. Artificial rock pools were created from manipulated concrete between boulders on the exposed and sheltered sides of a causeway. Experimental treatments were installed in locations where they were expected to fail and compared to controls installed in locations in which they were expected to succeed. Control pools were created lower on the structure where they were immersed on every tidal cycle; experimental pools were created above mean high water spring tide which were only immersed on spring tides. We hypothesised that lower and exposed pools would support significantly higher taxon and functional diversity than upper and sheltered pools. The concrete pools survived the severe winter storms of 2013/14. After 12 months, non-destructive sampling revealed significantly higher mean taxon and functional richness in lower pools than upper pools on the exposed side only. After 24 months the sheltered pools had become inundated with sediments, thus failing to function as rock pools as intended. Destructive sampling on the exposed side revealed significantly higher mean functional richness in lower than upper pools. However, a surprisingly high number of taxa colonised the upper pools leading to no significant difference in mean taxon richness among shore heights. A high number of rare taxa in the lower pools led to total taxon richness being almost twice that of upper pools. These findings highlight that even when expected to fail concrete pools supported diverse assemblages, thus representing an affordable, replicable means of enhancing biodiversity on a variety of artificial structures.