Search Results

You are looking at 61 - 70 of 394 items for :

  • Frontogenesis/frontolysis x
  • Refine by Access: All Content x
Clear All
Mankin Mak
,
Yi Lu
, and
Yi Deng

transverse circulation by the geostrophic flow component in the upper-level jet streak ( Shapiro 1981 ; Shapiro et al. 1984 ). However, ULFs seem to be a part of the synoptic-scale baroclinic waves in general ( Reed 1955 ; Newton 1958 ; Nieman et al. 1998 ). A 2D semigeostrophic model was used by Hoskins (1972) to demonstrate the formation of ULFs driven by an imposed vertically uniform confluent flow. The dynamics of frontogenesis was interpreted as a feedback process in the context of a developing

Full access
Hyun Mee Kim
and
Byoung-Joo Jung

regions of PV gradient changes sign, and the final SV maximum is also collocated with the regions of maximum PV gradient ( Fig. 13b ). To understand the dynamical mechanisms associated with large sensitivities in the lower level in the midlatitude, lower level temperature superposed on streamline at 850 hPa ( Fig. 14a ), and frontogenesis ( Fig. 14b ) and vertical wind ( Fig. 14c ) at 950 hPa superposed on MSLP, are shown. At the initial time of EXP1, a large low-level baroclinic zone and a front were

Full access
Robert Davies-Jones

fronts and jets. The exact solutions are nevertheless useful for revealing relationships between Q vectors and ageostrophic circulations in the various approximations. For example, the exact PE solution tells us which vector ( Q *, R *, or S *) ultimately points in the direction of the true low-level ageostrophic motion during frontogenesis. The other exact solutions quantify the errors of the approximate models [an approach also used by McWilliams and Gent (1980) and Allen et al. (1990) ]. 2

Full access
Weifeng Zhang
and
Dennis J. McGillicuddy Jr.

of subsurface slanted layers on both sides of the warm streamer appears to be consistent with the pattern of frontal subduction at an intensifying density front (e.g., Mahadevan and Tandon 2006 ; Spall 1995 ). Meanwhile, the direction of the flow in the subducting layers is opposite to the double-sided frontal upwelling at cold dense filaments in the Gulf Stream ( Gula et al. 2014 ). As a density front intensifies due to a background convergent flow or lateral stretching, i.e., frontogenesis

Free access
Callum J. Shakespeare
and
John R. Taylor

—that is, α ≡ −∂ x u , where u is the velocity in the x direction, for a front oriented along the y axis—and not the (larger) modulus of the strain-rate tensor, which we will call the “net strain rate.” The straining is considered to arise from a larger-scale background flow—for example, an eddy field—which then acts on the relatively smaller-scale front. A front in such a confluent strain field will sharpen with time in a process known as frontogenesis ( Hoskins and Bretherton 1972 ). Recent

Full access
Sara A. Ganetis
,
Brian A. Colle
,
Sandra E. Yuter
, and
Nicole P. Hoban

scheme of the reflectivity data that included single bands, narrow cold frontal rainbands, and multibands. They compared the environments between single bands and nonbanded cases and found that bands occurred to the northwest of a cyclone associated with a closed midlevel circulation with flow deformation and strong midlevel frontogenesis. The climatological study by Novak et al. (2010) aimed to isolate the role of moist processes in the evolution of the single-banded environment. Using the

Full access
Xiaodong Wu
,
Falk Feddersen
, and
Sarah N. Giddings

grid bathymetry (color shading) and the front study region (white line) to which mean front locations are restricted. Red dots denote the freshwater sources Punta Bandera (PB), Tijuana River Estuary (TJRE), and Sweetwater River. The yellow dot denotes the South Bay Ocean Outfall (SB) mooring site in 30-m depth. San Diego Bay (SDB), Point Loma, and the U.S.–Mexico border are also labeled. Mechanisms for both forced and unforced frontogenesis often have been examined with a frontogenesis tendency

Open access
Esther Capó
,
James C. McWilliams
,
Evan Mason
, and
Alejandro Orfila

1. Introduction A leading mechanism responsible for the emergence of submesoscale currents (SMCs) in the ocean is frontogenesis, a process promoted by the lateral buoyancy gradient in the mixed layer (ML; Hoskins and Bretherton 1972 ; Rudnick and Davis 1988 ; McWilliams 2016 , 2020 ). A prominent, recurrent surface front arises in the western Mediterranean Sea on the eastern edge of the anticyclonic Alboran Gyre(s). In this paper we examine this frontogenesis mechanism. The ocean

Full access
W. R. Geyer
and
D. K. Ralston

estuaries ( Geyer et al. 1998 ) and fjords ( Lavelle et al. 1991 ). Whereas the steady-state dynamics of these fronts have been characterized (e.g., Keulegan 1966 ; Armi and Farmer 1986 , Jirka and Arita 1987 ), their genesis has received scant attention, with the notable exception of the laboratory studies of Simpson and Linden (1989) . Simpson and Linden (1989) were the first to address estuarine frontogenesis, wherein they demonstrated via laboratory experiments that a local enhancement of the

Full access
B. N. Hanstrum
,
K. J. Wilson
, and
S. L. Barrell

frontogenesis within a surface prefrontal trough over southern Australia is presented. Thetrough developed ahead of a surface cold front and, over a period of approximately 24 h, intensified into amature summertime frontal system while the original front underwent total frontolysis. Two-hourly rawinsondeascents at three locations were used to examine the structure of the trough both before and after frontogenesis.Diagnosis of the frontogenetic tendencies showed that horizontal deformation of the potential

Full access