Structure and dynamics of the Benguela low-level coastal jet

Abstract The characteristics and dynamics of the Chilean low-level coastal jet (CLLCJ) are examined here through diagnosing real-time mesoscale model forecasts in support of the Variability of the American Monsoon System (VAMOS) Ocean–Cloud–Atmosphere Land Study (VOCALS) and additional sensitivity simulations. The forecasted surface winds over the southeast Pacific compare favorably with available observations. According to the forecasts and sensitivity simulations, the Southeast Pacific high pressure system (SEPH) plays a primary role in driving the CLLCJ. The Andes significantly intensify the CLLCJ mainly through interacting with the SEPH and anchoring a baroclinic zone along the Chilean coast. The land–sea differential heating also enhances the CLLCJ by strengthening the coastal baroclinic zone. Based on the location of the SEPH center, the CLLCJ can be separated into two types: a strong-forcing jet, with the SEPH close to the central Chilean coastline; and a weak-forcing jet, with the SEPH centered far away from the coastline. The former is much more intense and associated with stronger interaction between the SEPH and the Andes. The CLLCJ is slightly supergeostrophic within the marine boundary layer top inversion, where weak easterlies develop, and subgeostrophic in the turbulent boundary layer below, where westerlies are present. The inversion easterlies induce strong subsidence along the coast, which contributes to the formation of the coastal low and the coastal baroclinic zone.

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Spatial and vertical structure of precipitating clouds and the role of background dynamics during extreme precipitation event as observed by C-band Polarimetric Doppler Weather Radar at Thumba (8.50° N, 77.00° E)

10.5194/nhess-2020-2 ◽

2020 ◽

Author(s):

Kandula V. Subrahmanyam ◽

K. Kishore Kumar

Keyword(s):

Extreme Precipitation ◽

Vertical Structure ◽

Extreme Rainfall ◽

Weather Radar ◽

Extreme Precipitation Event ◽

Precipitation Event ◽

Doppler Weather Radar ◽

Low Level ◽

Structure And Dynamics ◽

Precipitating Clouds

Abstract. Extreme precipitation events have been cynosure for many meteorologists as well as for common men as it causes severe weather hazards and affects the densely populated regions, especially urban cities. It is now well known that these extreme events have been increasing over the Indian region during the past few years. It becomes very important to understand and assess these events, which is challenging in terms of limited observations. Very recently, the state of Kerala, India experienced extreme rainfall events during August 2018 and led to major flooding, which is regarded as one of the worst natural disasters experienced by Kerala in the last hundred years. This catastrophic event occurred during 12th to 17th August 2018 in which the Kerala state has received 60 % more rainfall than the normal during this period. The present study focuses on investigating the spatial and vertical structure of precipitating clouds and their microphysical properties during this extreme precipitation event using C-band Polarimetric Doppler Weather Radar (DWR) observations over Thumba (8.50° N, 77.00° E). The DWR analyses were carried out during episodes of extreme rainfall, and the time evolution of radar reflectivity structure is examined very closely to understand the structure and dynamics of this unprecedented event. The spatial and vertical structures of precipitating clouds are strongly linked with the background dynamics. Apart from the DWR observations, prevailing dynamics such as tropical easterly jet (TEJ), low-level jet (LLJ) along with vertical velocity also investigated, which showed distant signatures lead to the extreme event. It was observed that the upper level divergence existed associated with low level convergence, which aids to the development of convection. The westward equatorial waves were present in the period of 7–10 days throughout the month of August 2018. The weakening of TEJ at upper troposphere resulted in decrease of vertical shear, which favours the vertical growth of convective clouds leading to the extreme precipitation. The enhanced strength of LLJ is also contributed to the precipitation extreme. Thus, the significance of the present study lies in delineating the structure and dynamics of the extreme precipitation event using indigenously developed DWR.

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Dynamics of the Low-Level Jet off the West Coast of Subtropical South America

Monthly Weather Review ◽

10.1175/mwr3074.1 ◽

2005 ◽

Vol 133 (12) ◽

pp. 3661-3677 ◽

Cited By ~ 90

Author(s):

Ricardo C. Muñoz ◽

RenéD. Garreaud

Keyword(s):

Boundary Layer ◽

South America ◽

Pressure Gradient ◽

West Coast ◽

Marine Boundary Layer ◽

Force Balance ◽

North Central ◽

Central Chile ◽

Low Level ◽

Coastal Jet

Abstract The subtropical west coast of South America is under the influence of the southeast Pacific anticyclone year-round, which induces persistent southerly winds along the coast of north-central Chile. These winds often take the form of a low-level coastal jet, in many aspects similar to the coastal jet existing off the California coast. Extensive diagnostics of mesoscale model results for a case in October 2000 are used here to describe the mean momentum budget supporting the coastal jet. The jet appears to occur when midlatitude synoptic conditions induce a northerly directed pressure gradient force along the coast of north-central Chile. The very steep coastal terrain precludes the development of a significant easterly low-level wind that would geostrophically balance the pressure gradient. Instead, the meridional flow accelerates until turbulent friction in the marine boundary layer balances the meridional pressure gradient. The resulting force balance is semigeostrophic, with geostrophy valid only in the zonal (cross shore) direction. At higher levels, the topographic inhibition of the easterlies relaxes, and a small easterly flow ensues, which turns out to be very important in the temperature and stability budgets of the layer capping the marine boundary layer.

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Nucleosome dynamics

Biochemical Society Symposium ◽

10.1042/bss0730109 ◽

2006 ◽

Vol 73 ◽

pp. 109-119 ◽

Cited By ~ 2

Author(s):

Chris Stockdale ◽

Michael Bruno ◽

Helder Ferreira ◽

Elisa Garcia-Wilson ◽

Nicola Wiechens ◽

...

Keyword(s):

High Resolution ◽

Chromatin Structure ◽

Current Knowledge ◽

Dynamic Properties ◽

Structure And Dynamics ◽

Nucleosome Dynamics ◽

Sharp Focus ◽

Recent Advances ◽

Insight Into ◽

Chromatin Structure And Dynamics

In the 30 years since the discovery of the nucleosome, our picture of it has come into sharp focus. The recent high-resolution structures have provided a wealth of insight into the function of the nucleosome, but they are inherently static. Our current knowledge of how nucleosomes can be reconfigured dynamically is at a much earlier stage. Here, recent advances in the understanding of chromatin structure and dynamics are highlighted. The ways in which different modes of nucleosome reconfiguration are likely to influence each other are discussed, and some of the factors likely to regulate the dynamic properties of nucleosomes are considered.

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The Structure and Dynamics of Cities

10.1017/9781316271377 ◽

2015 ◽

Cited By ~ 51

Author(s):

Marc Barthelemy

Keyword(s):

Structure And Dynamics

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Structure and dynamics of phosphate glasses

Philosophical Magazine B ◽

10.1080/014186398259446 ◽

1998 ◽

Vol 77 (2) ◽

pp. 357-362 ◽

Cited By ~ 1

Author(s):

A. Matic, L. Borjesson

Keyword(s):

Phosphate Glasses ◽

Structure And Dynamics

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Tryptophan-Niacin Metabolism in Rat with Puromycin Aminonucleoside-Induced Nephrosis

International Journal for Vitamin and Nutrition Research ◽

10.1024/0300-9831.76.1.28 ◽

2006 ◽

Vol 76 (1) ◽

pp. 28-33 ◽

Cited By ~ 7

Author(s):

Yukari Egashira ◽

Shin Nagaki ◽

Hiroo Sanada

Keyword(s):

Body Weight ◽

Urinary Excretion ◽

Enzyme Activities ◽

Treated Group ◽

Control Group ◽

Puromycin Aminonucleoside ◽

Low Level ◽

Key Enzyme

We investigated the change of tryptophan-niacin metabolism in rats with puromycin aminonucleoside PAN-induced nephrosis, the mechanisms responsible for their change of urinary excretion of nicotinamide and its metabolites, and the role of the kidney in tryptophan-niacin conversion. PAN-treated rats were intraperitoneally injected once with a 1.0% (w/v) solution of PAN at a dose of 100 mg/kg body weight. The collection of 24-hour urine was conducted 8 days after PAN injection. Daily urinary excretion of nicotinamide and its metabolites, liver and blood NAD, and key enzyme activities of tryptophan-niacin metabolism were determined. In PAN-treated rats, the sum of urinary excretion of nicotinamide and its metabolites was significantly lower compared with controls. The kidneyα-amino-β-carboxymuconate-ε-semialdehyde decarboxylase (ACMSD) activity in the PAN-treated group was significantly decreased by 50%, compared with the control group. Although kidney ACMSD activity was reduced, the conversion of tryptophan to niacin tended to be lower in the PAN-treated rats. A decrease in urinary excretion of niacin and the conversion of tryptophan to niacin in nephrotic rats may contribute to a low level of blood tryptophan. The role of kidney ACMSD activity may be minimal concerning tryptophan-niacin conversion under this experimental condition.

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Studies of the structure and dynamics of theDregion of the polar ionosphere during solar flares in April 2004

International Journal of Geomagnetism and Aeronomy ◽

10.1029/2005gi000107 ◽

2006 ◽

Vol 6 (2) ◽

Author(s):

V. D. Tereshchenko ◽

E. B. Vasil'ev ◽

O. F. Ogloblina ◽

V. A. Tereshchenko ◽

S. M. Chernyakov

Keyword(s):

Solar Flares ◽

Polar Ionosphere ◽

Structure And Dynamics

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