A High-Resolution Modeling Study of the 24 May 2002 Dryline Case during IHOP. Part II: Horizontal Convective Rolls and Convective Initiation

2006 ◽  
Vol 134 (1) ◽  
pp. 172-191 ◽  
Author(s):  
Ming Xue ◽  
William J. Martin
Keyword(s):  
Acute Angle ◽  
Shear Instability ◽  
Mature Stage ◽  
The West ◽  
West Side ◽  
Convective Initiation ◽  
Boundary Shear ◽  
Aspect Ratios ◽  
Localized Forcing ◽  
Convective Rolls

Abstract In Part I of this paper, the timing and location of convective initiation along a dryline on 24 May 2002 were accurately predicted, using a large 1-km-resolution nested grid. A detailed analysis of the convective initiation processes, which involve the interaction of the dryline with horizontal convective rolls, is presented here. Horizontal convective rolls (HCRs) with aspect ratios (the ratio of roll spacing to depth) between 3 and 7 develop in the model on both sides of the dryline, with those on the west side being more intense and their updrafts reaching several meters per second. The main HCRs that interact with the primary dryline convergence boundary (PDCB) are those from the west side, and they are aligned at an acute angle with the dryline. They intercept the PDCB and create strong moisture convergence bands at the surface and force the PDCB into a wavy pattern. The downdrafts of HCRs and the associated surface divergence play an important role in creating localized maxima of surface convergence that trigger convection. The downward transport of westerly, southwesterly, or northwesterly momentum by the HCR downdrafts creates asymmetric surface divergence patterns that modulate the exact location of maximum convergence. Most of the HCRs have a partially cellular structure at their mature stage. The surface divergence flows help concentrate the background vertical vorticity and the vorticity created by tilting of environmental horizontal vorticity into vortex centers or misocyclones, and such concentration is often further helped by cross-boundary shear instability. The misocyclones, however, do not in general collocate with the maximum updrafts and, therefore, the points of convective initiation, but can help enhance surface convergence to their south and north. Sequences of convective cells develop at the locations of persistent maximum surface convergence, then move away from the source with the midlevel winds. When the initial clouds propagate along the convergence bands that trigger them, they grow faster and become more intense. While the mesoscale convergence of dryline circulation preconditions the boundary layer by deepening the mixed layer and lifting moist air parcels to their LCL, it is the localized forcing by the HCR circulation that determines the exact locations of convective initiation. A conceptual model summarizing the findings is proposed.

scholarly journals La datation du choeur de l’église de Vaucelles reproduit en plan par Villard de Honnecourt

2018 ◽  
Vol 81 (3) ◽  
pp. 411-417
Author(s):  
Laurence Terrier Aliferis
Keyword(s):  
Nineteenth Century ◽  
Historical Sources ◽  
The West ◽  
West Side ◽  
Villard De Honnecourt ◽  
The Church

Abstract The ruined Cistercian church of Vaucelles is known only by a few preserved fragments and a plan of the choir reproduced by Villard of Honnecourt. Historical sources provide three key dates: 1190 (start of construction), 1215 (entry into the new church), 1235 (date of the dedication). From the nineteenth century until now, it was considered that the foundations were laid in 1190 and that the construction started on the west side of the church. In 1216, the nave would have been completed, and the choir would have been built between 1216 and 1235. Consultation of the historical sources and examination of the historiographic record changes this established chronology of the site. In fact, the construction proceeded from east to west. The choir reproduced in 1216 or shortly before by Villard de Honnecourt presents the building as it then appeared, with the eastern part of the building totally completed.

St Audrie's Bay, Somerset, England: a candidate Global Stratotype Section and Point for the base of the Jurassic System

1994 ◽  
Vol 131 (2) ◽  
pp. 191-200 ◽  
Author(s):  
G. Warrington ◽  
J. C. W. Cope ◽  
H. C. Ivimey-Cook
Keyword(s):  
Type Locality ◽  
International Commission ◽  
The West ◽  
West Side ◽  
Type Area ◽  
Jurassic System ◽  
Stratotype Section

AbstractIn 1967 the Somerset coastline near Watchet was proposed as the type area of the basal (Planorbis) chronozone of the Hettangian Stage and thus of the Jurassic System. Neither at that time nor subsequently, however, has a type locality and section been nominated from those available in the area. There is urgent need to select a Global Stratotype Section and Point (GSSP) for the base of the Hettangian, and of the Jurassic System. The cliff forming the headland at the west side of St Audrie's Bay, three kilometres east of Watchet, Somerset, is here proposed as the type locality and section, with the base of the Hettangian Stage, at the base of the Planorbis Chronozone, being placed at the horizon currently recognized as that at which ammonites of the genus Psiloceras appear. In this section the base of the Planorbis Chronozone corresponds with the base of the Psiloceras planorbis Biozone. The proposal of this section is conditioned by the availability of comprehensive litho- and biostratigraphic information, and the ability of the section to fulfil International Commission on Stratigraphy (ICS) requirements for a candidate GSSP.

Using reflection seismic method to estimate the fluid dynamics parameters related to wakes

2021 ◽  
Author(s):  
Wenhao Fan ◽  
Haibin Song ◽  
Kun Zhang ◽  
Yi Gong ◽  
Shun Yang ◽  
...  
Keyword(s):  
Potential Vorticity ◽  
Negative Potential ◽  
Distribution Area ◽  
The West ◽  
West Side ◽  
Reflection Seismic ◽  
Vorticity Distribution ◽  
Positive Vorticity ◽  
Coherent Vortices ◽  
Survey Line

<p>In this study, when using reflection seismic data to study the wakes of the Batan Islands, a method for estimating the fluid dynamics parameters such as the relative vorticity (relative Rossby number) and the relative potential vorticity is proposed. Although the relative Rossby number estimation method proposed in this study cannot guarantee absolute accuracy in the calculation value, this method is more accurate in describing the positive and negative vorticity distribution for the wakes, and the resolution of the positive and negative vorticity distribution described by this method is higher than the result of the reanalysis data. For the wakes developed in the Batan Islands, the reflection events in the wake development area have the larger inclination than the reflection events in the western Pacific water distribution area. It is also found that the negative vorticity wakes are mainly distributed on the west side of the island/ridge, and the positive vorticity wakes are mainly distributed on the east side of the island/ridge. This is consistent with the understanding of previous wakes simulations. The strong vorticity values in the study area are mainly distributed at depths above 300m, and the maximum impact depth of wakes can reach 600m. At the downstream position of the wake on the survey line 7, it can be seen that the bottom boundary layer has separated, and there is the negative vorticity wakes on the west side intruding into the positive vorticity wakes on the east side , which is presumed to be caused by the disturbance of the small anticyclone existing near the Batan Islands. For the survey line 7, the negative potential vorticity is mainly distributed on the west side of the island/ridge, and the influence range can reach the sea depth of 600m. In the negative potential vorticity region, there is strong energy dissipation and vertical shear. In this study, we don’t find the existence of submesoscale coherent vortices on the survey line 7, but find the reflection structure similar to filaments on the seismic section. Combined with the analysis of the balanced Richardson number angle of survey line 7, we speculate that the wake in the negative potential vorticity distribution area has the characteristics of symmetrical instability, and the symmetrical instability may destroy the process of filaments forming submesoscale coherent vortices.</p>

A Romano-British Interment, with Bucket and Sceptres, from Brough, East Yorkshire

1938 ◽  
Vol 18 (1) ◽  
pp. 68-74 ◽  
Author(s):  
Philip Corder ◽  
I. A. Richmond
Keyword(s):  
Present Note ◽  
Fourth Century ◽  
The Other ◽  
The West ◽  
West Side ◽  
The Road ◽  
The Subject ◽  
Chief Interest ◽  
Roman Age ◽  
The Way

The Roman Ermine Street, having crossed the Humber on the way to York from Lincoln, leaves Brough Haven on its west side, and the little town of Petuaria to the east. For the first half-mile northwards from the Haven its course is not certainly known: then, followed by the modern road, it runs northwards through South Cave towards Market Weighton. In the area thus traversed by the Roman road burials of the Roman age have already been noted in sufficient quantity to suggest an extensive cemetery. The interment which is the subject of the present note was found on 10th October 1936, when men laying pipes at right angles to the modern road, in the carriage-drive of Mr. J. G. Southam, having cut through some 4 ft. of blown sand, came upon a mass of mixed Roman pottery, dating from the late first to the fourth century A.D. Bones of pig, dog, sheep, and ox were also represented. Presently, at a depth of about 5 ft., something attracted closer attention. A layer of thin limestone slabs was found, covering two human skeletons, one lying a few feet from the west margin of the modern road, the other parallel with the road and some 8 ft. from its edge. The objects described below were found with the second skeleton, and the first to be discovered was submitted by Mr. Southam to Mr. T. Sheppard, F.S.A.Scot., Director of the Hull Museums, who visited the site with his staff. All that can be recorded of the circumstances of the discovery is contained in the observations then made, under difficult conditions. ‘Slabs of hard limestone’, it was reported, ‘taken from a local quarry of millepore oolite and forming the original Roman road, were distinctly visible beneath the present roadway—one of the few points where the precise site of the old road has been located. On the side of this… a burial-place has been constructed. What it was like originally it is difficult to say, beyond that a layer of thin … slabs of limestone occurred over the skeletons. This had probably been kept in place or supported by some structure of wood, as several large iron nails, some bent at right angles, were among the bones.’ If this were all that could be said about the burials, they would hardly merit a place in these pages. The chief interest of the record would be its apparent identification of the exact course of the Roman road at a point where this had hitherto been uncertain. Three objects associated with the second skeleton are, however, of exceptional interest.

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