scholarly journals Atmospheric circulation patterns associated with strong wind events in Catalonia

2011 ◽  
Vol 11 (1) ◽  
pp. 145-155 ◽  
Author(s):  
J. C. Peña ◽  
M. Aran ◽  
J. Cunillera ◽  
J. Amaro
Keyword(s):  
Principal Component ◽  
Strong Wind ◽  
Atmospheric Circulation Patterns ◽  
Synoptic Weather ◽  
Weather Events ◽  
Circulation Patterns ◽  
Discriminant Analyses ◽  
High Impact Weather ◽  
Strong Winds ◽  
Wind Events

Abstract. The benefit of having a daily synoptic weather type catalogue and even more, a detailed catalogue for high impact weather events is well recognised by both climatologist and meteorologist communities. In this way the Meteorological Service of Catalonia (SMC) has produced some accurate classifications for extreme events, such as hailstorms or strong winds (SW). Within the framework of the MEDEX project, the SMC has been collaborating to increase the level of awareness about these events. Following this line of work, the aim of this study is to characterise the SW events in Catalonia. According to the guidelines of the MEDEX project we worked with its SW event database for the period June 1995 to May 2004. We also used the period 2005–2009 to test the methodology. The methodology is based on principal component, cluster and discriminant analyses and applied to four variables: SLP, temperature at 850 hPa and geopotential at 500 hPa on a synoptic-scale and local gust wind. We worked with ERA-Interim reanalysis and applied discriminant analysis to test the quality of the methodology and to classify the events of the validation period. We found seven patterns for the SW events. The strongest event corresponds to NW-Flow with the Azores Anticyclone and the passing of a low pressure through the Pyrenees. This methodology has distinguished the summer events in an independent cluster. The results obtained encourage us to follow this line of work.

scholarly journals A methodology to conduct wind damage field surveys for high-impact weather events of convective origin

2020 ◽  
Vol 20 (5) ◽  
pp. 1513-1531 ◽  
Author(s):  
Oriol Rodríguez ◽  
Joan Bech ◽  
Juan de Dios Soriano ◽  
Delia Gutiérrez ◽  
Salvador Castán
Keyword(s):  
Field Studies ◽  
High Impact ◽  
Strong Wind ◽  
Field Surveys ◽  
Weather Events ◽  
Straight Line ◽  
High Impact Weather ◽  
Strong Winds ◽  
Wind Events ◽  
The One

Abstract. Post-event damage assessments are of paramount importance to document the effects of high-impact weather-related events such as floods or strong wind events. Moreover, evaluating the damage and characterizing its extent and intensity can be essential for further analysis such as completing a diagnostic meteorological case study. This paper presents a methodology to perform field surveys of damage caused by strong winds of convective origin (i.e. tornado, downburst and straight-line winds). It is based on previous studies and also on 136 field studies performed by the authors in Spain between 2004 and 2018. The methodology includes the collection of pictures and records of damage to human-made structures and on vegetation during the in situ visit to the affected area, as well as of available automatic weather station data, witness reports and images of the phenomenon, such as funnel cloud pictures, taken by casual observers. To synthesize the gathered data, three final deliverables are proposed: (i) a standardized text report of the analysed event, (ii) a table consisting of detailed geolocated information about each damage point and other relevant data and (iii) a map or a KML (Keyhole Markup Language) file containing the previous information ready for graphical display and further analysis. This methodology has been applied by the authors in the past, sometimes only a few hours after the event occurrence and, on many occasions, when the type of convective phenomenon was uncertain. In those uncertain cases, the information resulting from this methodology contributed effectively to discern the phenomenon type thanks to the damage pattern analysis, particularly if no witness reports were available. The application of methodologies such as the one presented here is necessary in order to build homogeneous and robust databases of severe weather cases and high-impact weather events.

scholarly journals A methodology to conduct wind damage field surveys for high impact weather events from convective origin

2019 ◽  
Author(s):  
Oriol Rodríguez ◽  
Joan Bech ◽  
Juan de Dios Soriano ◽  
Delia Gutiérrez ◽  
Salvador Castán
Keyword(s):  
High Impact ◽  
Strong Wind ◽  
Field Surveys ◽  
Weather Events ◽  
Damage Field ◽  
High Impact Weather ◽  
Strong Winds ◽  
Wind Events ◽  
The One

Abstract. Post-event damage assessments are essential to document the effects of high-impact weather events such as floods or strong wind events. Moreover, evaluating the damage and characterizing its extension and intensity can be helpful for further analysis such as completing a diagnostic meteorological case study. This paper presents a methodology to perform field surveys of damage caused by strong winds of convective origin, i.e. tornado, downburst and other types of convective winds. It is based on previous studies and also on 136 fieldworks performed by the authors in Spain from 2004 to 2018. The methodology includes the systematic collection of pictures and records of damages on man-made structures and on vegetation, as well as collection of any available Automatic Weather Station data, witness reports and images of the phenomenon and their location and orientation. Three final deliverables are proposed to synthesize the data recorded: (i) A summary of the fieldwork; (ii) A table consisting of detailed geolocated information about each damage, and (iii) A map or a .kml file containing the previous information ready for graphical display and further analysis. This methodology has been applied by the authors in the past, sometimes only a few hours after the event occurrence and, in many occasions, when the type of convective phenomenon (e.g. tornado, downburst) was uncertain. In the latter case the information resulting from this methodology has proofed very useful to discern the phenomenon type, based on the damage patterns particularly if no witness reports were available. The application of systematic methodologies as the one presented here is necessary in order to build homogeneous databases of severe weather cases and high impact weather events.

Statistical Summary and Case Studies of Strong Wind Damage in China

2013 ◽  
Vol 8 (6) ◽  
pp. 1096-1102 ◽  
Author(s):  
Shuyang Cao ◽  
◽  
Jin Wang ◽  
Keyword(s):  
Case Studies ◽  
Low Cost ◽  
Wind Damage ◽  
Strong Wind ◽  
Severe Damage ◽  
Engineering Measures ◽  
Strong Winds ◽  
Wind Events ◽  
Forestry Products ◽  
Statistical Summary

Strong wind events, such as typhoons and tornados, have caused severe damage to buildings and other structures as well as agricultural and forestry products in China. This paper analyzes statistical data on typhoons and tornados in China, and it reports case studies on strong wind damage. Lessons from past damage from strong winds, as well as engineering measures against potential wind damage to low-cost houses, are presented for the purpose of wind-related disaster risk reduction.

Climatology of High Wind Events in the Owens Valley, California

2008 ◽  
Vol 136 (9) ◽  
pp. 3536-3552 ◽  
Author(s):  
Shiyuan Zhong ◽  
Ju Li ◽  
C. David Whiteman ◽  
Xindi Bian ◽  
Wenqing Yao
Keyword(s):  
Sierra Nevada ◽  
Blow Up ◽  
Common Belief ◽  
Strong Wind ◽  
High Wind ◽  
Owens Valley ◽  
Reanalysis Dataset ◽  
Strong Winds ◽  
Wind Events ◽  
Upper Level

Abstract The climatology of high wind events in the Owens Valley, California, a deep valley located just east of the southern Sierra Nevada, is described using data from six automated weather stations distributed along the valley axis in combination with the North American Regional Reanalysis dataset. Potential mechanisms for the development of strong winds in the valley are examined. Contrary to the common belief that strong winds in the Owens Valley are westerly downslope windstorms that develop on the eastern slope of the Sierra Nevada, strong westerly winds are rare in the valley. Instead, strong winds are highly bidirectional, blowing either up (northward) or down (southward) the valley axis. High wind events are most frequent in spring and early fall and they occur more often during daytime than during nighttime, with a peak frequency in the afternoon. Unlike thermally driven valley winds that blow up valley during daytime and down valley during nighttime, strong winds may blow in either direction regardless of the time of the day. The southerly up-valley winds appear most often in the afternoon, a time when there is a weak minimum of northerly down-valley winds, indicating that strong wind events are modulated by local along-valley thermal forcing. Several mechanisms, including downward momentum transfer, forced channeling, and pressure-driven channeling all play a role in the development of southerly high wind events. These events are typically accompanied by strong south-southwesterly synoptic winds ahead of an upper-level trough off the California coast. The northerly high wind events, which typically occur when winds aloft are from the northwest ahead of an approaching upper-level ridge, are predominantly caused by the passage of a cold front when fast-moving cold air behind the surface front undercuts and displaces the warmer air in the valley. Forced channeling by the sidewalls of the relatively narrow valley aligns the wind direction with the valley axis and enhances the wind speeds.

Trees and their response to wind: mid Flandrian strong winds, Severn Estuary and inner Bristol Channel, southwest Britain

1992 ◽  
Vol 338 (1286) ◽  
pp. 335-364 ◽  
Keyword(s):  
Field Studies ◽  
Acute Angle ◽  
Strong Wind ◽  
Early Maturity ◽  
General Direction ◽  
Severn Estuary ◽  
Constant Variance ◽  
Strong Winds ◽  
Wind Events ◽  
Fall Direction

The response of contemporary trees to strong winds (gale force and greater) is repeatable and well defined, as shown by field studies in south east Britain after the October 1987 and January 1990 events, combined with awide-ranging literature survey. It involves the general processes of windprune, windsnap, windtilt and windthrow. Windprune depends on a range of physical and physiological mechanisms and leads to the loss of axial symmetry by a tree, especially where open-grown at an exposed site. Windsnap, windtilt and windthrow see the fall of a tree, as the result of either the breaking of the trunk or partial to full uprooting. Damage of this sort in a forest or woodland ranges from single trees, to scattered groups (swathes), to general devastation. In the main, perfectly healthy trees in youth or early maturity are affected by windsnap, windtilt and windthrow during strong wind events. Their fall-direction is readily established using the position of the rootball or snapped end of the trunk, the alignment of a broken trunk and stump, the taper of the trunk, the position on the trunk of relatively crowded branches (tree crown), and the position of the typically upward acute angle between branch and trunk. Contemporary trees overthrown by wind fall in a direction close to the wind. The variance of fall-directions in a sample due to a single wind event is observed to increase with the size of the woodland area from which the sample is drawn, but appears to become constant for sample areas in excess of 10 2 - 10 3 ha. Because this constant variance is relatively small, the mean fall-direction becomes, in contemporary woodlands and forests, a trustworthy indicator of the general direction of the strong wind which felled the trees. Rooted peats of mid Flandrian age ( ca . 6000-2500 conventional radiocarbon years) which include prostrate trees are widely present among the post-glacial estuarine silts exposed along the shores of the Severn Estuary and the inner Bristol Channel. The trees when overthrown appear in the main to have been perfectly healthy and in youth to early maturity. Oak and alder are the predominant species, and their fall-directions, as judged from the criteria listed from contemporary forests and woodlands, and measured at 18 horizons distributed over 14 sites, are highly coherent both locally and over the area as a whole. Using a model in which the variance of fall-directions observed for a single event is combined with a probability density for event mean directions, it appears that the trees fossilized in the peats were felled by strong winds which blew chiefly toward a range of directions from N.N.W . clockwise to S.S.E. A westerly zonal air-flow is indicated but, compared to the contemns than now, with a greater emphasis on both southerly and westerly to northwesterly blows.

Estimating Regional Precipitation Trends Comparison of two Methods

1997 ◽  
Vol 28 (1) ◽  
pp. 21-36 ◽  
Author(s):  
I. Hanssen-Bauer ◽  
E. J. Førland ◽  
O.E. Tveito ◽  
P.Ø Nordli
Keyword(s):  
Regional Differences ◽  
Principal Component ◽  
Distinct Region ◽  
Precipitation Trend ◽  
Homogeneous Precipitation ◽  
Precipitation Series ◽  
Atmospheric Circulation Patterns ◽  
Circulation Patterns ◽  
Precipitation Trends

Two different methods were applied to estimate long-term precipitation trends representative for regions in Norway. A new method, comparative trend analysis (CTA), was applied on 142 homogeneous precipitation series of 70-100 years. In this way 12 precipitation trend regions were identified. Principal component analysis (PCA) was applied on a subset of 30 series during the period 1896-1994 The results from both analyses were used to estimate precipitation trend series at several locations. The estimates based upon the PCA were of same quality as the estimates based upon the CTA. However, by CTA it is possible to visualize the trend in a distinct region by using just one trend curve, while trend curves based on PCA are composed of contributions from 5 principal components. The resulting trend curves document that the annual precipitation level has increased by 8-14% throughout this century in most Norwegian regions. The increase occurred not simultaneously all over the country. The regional differences in precipitation trends and variability are probably connected to variations in the atmospheric circulation patterns.

scholarly journals Response of an Antarctic Peninsula Fjord to Summer Katabatic Wind Events

2019 ◽  
Vol 49 (6) ◽  
pp. 1485-1502 ◽  
Author(s):  
Øyvind Lundesgaard ◽  
Brian Powell ◽  
Mark Merrifield ◽  
Lisa Hahn-Woernle ◽  
Peter Winsor
Keyword(s):  
Antarctic Peninsula ◽  
Upper Ocean ◽  
Katabatic Wind ◽  
Strong Wind ◽  
Deep Basin ◽  
Wind Event ◽  
Salinity Increase ◽  
Strong Winds ◽  
Wind Events ◽  
Passive Tracers

AbstractFjords along the western Antarctic Peninsula are episodically exposed to strong winds flowing down marine-terminating glaciers and out over the ocean. These wind events could potentially be an important mechanism for the ventilation of fjord waters. A strong wind event was observed in Andvord Bay in December 2015, and was associated with significant increases in upper-ocean salinity. We examine the dynamical impacts of such wind events during the ice-free summer season using a numerical model. Passive tracers are used to identify water mass pathways and quantify exchange with the outer ocean. Upwelling and outflow in the model fjord generate an average salinity increase of 0.3 in the upper ocean during the event, similar to observations from Andvord Bay. Down-fjord wind events are a highly efficient mechanism for flushing out the upper fjord waters, but have little net impact on deep waters in the inner fjord. As such, summer episodic wind events likely have a large effect on fjord phytoplankton dynamics and export of glacially modified upper waters, but are an unlikely mechanism for the replenishment of deep basin waters and oceanic heat transport toward inner-fjord glaciers.

scholarly journals Evaluating the Ability of FARSITE to Simulate Wildfires Influenced by Extreme, Downslope Winds in Santa Barbara, California

Fire ◽  
2020 ◽  
Vol 3 (3) ◽  
pp. 29 ◽  
Author(s):  
Katelyn Zigner ◽  
Leila M. V. Carvalho ◽  
Seth Peterson ◽  
Francis Fujioka ◽  
Gert-Jan Duine ◽  
...  
Keyword(s):  
Fire Spread ◽  
Strong Wind ◽  
Santa Barbara ◽  
Spread Model ◽  
Sensitivity Tests ◽  
Wildfire Spread ◽  
Fire Area ◽  
Strong Winds ◽  
Wind Events ◽  
In Fire

Extreme, downslope mountain winds often generate dangerous wildfire conditions. We used the wildfire spread model Fire Area Simulator (FARSITE) to simulate two wildfires influenced by strong wind events in Santa Barbara, CA. High spatial-resolution imagery for fuel maps and hourly wind downscaled to 100 m were used as model inputs, and sensitivity tests were performed to evaluate the effects of ignition timing and location on fire spread. Additionally, burn area rasters from FARSITE simulations were compared to minimum travel time rasters from FlamMap simulations, a wildfire model similar to FARSITE that holds environmental variables constant. Utilization of two case studies during strong winds revealed that FARSITE was able to successfully reconstruct the spread rate and size of wildfires when spotting was minimal. However, in situations when spotting was an important factor in rapid downslope wildfire spread, both FARSITE and FlamMap were unable to simulate realistic fire perimeters. We show that this is due to inherent limitations in the models themselves, related to the slope-orientation relative to the simulated fire spread, and the dependence of ember launch and land locations. This finding has widespread implications, given the role of spotting in fire progression during extreme wind events.

scholarly journals Daily Atmospheric Circulation Patterns and Their Influence on Dry/Wet Events in Iran

Atmosphere ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 81
Author(s):  
Zahra Ghassabi ◽  
Ebrahim Fattahi ◽  
Maral Habibi
Keyword(s):  
Atmospheric Circulation ◽  
Red Sea ◽  
Principal Component ◽  
Moisture Flux ◽  
The South ◽  
Flux Divergence ◽  
Atmospheric Circulation Patterns ◽  
Pressure Surface ◽  
Pi Index ◽  
Circulation Patterns

Analyzing atmospheric circulation patterns characterize prevailing weather in a region. The method of principal component analysis and clustering was used to classify daily atmospheric circulation patterns. The average daily geopotential height of 500 hPa with 0.5° resolution of the ECMWF (1990–2019) were extracted from the Middle East. The S array was used to identify air types, and k-means clustering was used to classify daily air types. All days were divided into eighteen groups. Then, the surface maps and moisture flux divergence at the 850-hPa level of each pattern were studied. The, the connection between circulation patterns and precipitation occurrence is investigated by the PI index. The existence of a variety of precipitation and temperature regimes and consequent dry/wet periods is related to the type and frequency of the circulation patterns. In patterns with south to southwesterly currents, the low-pressure surface center extends from the south of the Red Sea to southern Turkey and is associated with the mid-level trough, where the moisture fluxes converge in the south of the Red Sea, southwest/south of Iran, and east of the Mediterranean Sea. Therefore, according to the intensity of the patterns, the most precipitation falls in the country’s western half, and the Zagros Mountain’s wind side. With the eastward movement of the Cyclonic patterns, the rainfall area extends to the eastern half of the country. With the pattern that the thermal low surface pressure extends to 35 °N latitude and is associated with the mid-level subtropical high, almost no rain occurs in the country.

scholarly journals THE DESIGN CONCEPT OF DUAL BREAKWATERS AND ITS APPLICATION TO TOWNSVILLE, AUSTRALIA

1980 ◽  
Vol 1 (17) ◽  
pp. 115 ◽  
Author(s):  
W. Bremner ◽  
D.N. Foster ◽  
C.A. Miller ◽  
B.C. Wallace
Keyword(s):  
Wind Band ◽  
Cost Savings ◽  
Storm Surges ◽  
Time Interval ◽  
Strong Wind ◽  
Storm Waves ◽  
Weather Events ◽  
Long Time ◽  
Wave Heights ◽  
Strong Winds

In Central and North Queensland the coastline is protected by the Great Barrier Reef over a length of some 1900km from Gladstone in the south to the tip of Cape York (Fig. 1). The fetch distance from the reef to the coastline is very variable from about 15km to 140km. Hence the coastal areas north of Gladstone have moderate to low wave climates except during abnormal weather events such as cyclones or long time interval bands of strong winds. In these events larger storm waves of significant wave heights of 10m may be superimposed, in the case of cyclones, on storm surges several metres in height. The design of breakwaters and shoreline structures for protection against all except cyclonic and strong wind band effects requires, in the main, readily available sizes of armour rock and relatively low crest elevations. To offer similar protection against cyclonic weather events often requires the use of artificial armour units of concrete and a substantial increase in crest heights. The resulting increase in costs makes many of the small projects uneconomic. In this paper the concept of using an offshore breakwater which is designed to fail under extreme wave conditions to protect an inner breakwater or revetment is examined and the results applied to Townsville Harbour where cost savings of the order of 40 percent were achieved over a conventional design.

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