scholarly journals Spontaneous Generated Convective Anticyclones in Low Latitude --- A Model for the Great Red Spot

2021 ◽  
Author(s):  
Tao Cai ◽  
Kwing L. Chan ◽  
Kim-Chiu Chow
Keyword(s):  
Internal Heat ◽  
Critical Value ◽  
Driving Mechanism ◽  
Moist Convection ◽  
Low Latitude ◽  
Deep Model ◽  
Merging Process ◽  
Long Time ◽  
Rotating Turbulent Flow ◽  
Jovian Atmosphere

Abstract The Great Red Spot at about latitude 22oS of Jupiter has been observed for hundreds of years, yet the driving mechanism on the formation of this giant anticyclone still remains unclear. Two scenarios were proposed to explain its formation. One is a shallow model suggesting that it might be a weather feature formed through a merging process of small shallow storms generated by moist convection, while the other is a deep model suggesting that it might be a deeply rooted anticyclone powered by the internal heat of Jupiter. In this work, we present numerical simulations showing that the Great Red Spot could be naturally generated in a deep rotating turbulent flow and survive for a long time, when the convective Rossby number is smaller than a certain critical value. From this critical value, we predict that the Great Red Spot extends at least about 500 kilometers deep into the Jovian atmosphere. Our results demonstrate that the Great Red Spot is likely to be a feature deep-seated in the Jovian atmosphere.

scholarly journals Spontaneous Generated Convective Anticyclones in Low Latitude --- A Model for the Great Red Spot

2021 ◽  
Author(s):  
Tao Cai ◽  
Kwing L. Chan ◽  
Kim-Chiu Chow
Keyword(s):  
Internal Heat ◽  
Critical Value ◽  
Driving Mechanism ◽  
Moist Convection ◽  
Low Latitude ◽  
Deep Model ◽  
Merging Process ◽  
Long Time ◽  
Rotating Turbulent Flow ◽  
Jovian Atmosphere

Abstract The Great Red Spot at about latitude 22oS of Jupiter has been observed for hundreds of years, yet the driving mechanism on the formation of this giant anticyclone still remains unclear. Two scenarios were proposed to explain its formation. One is a shallow model suggesting that it might be a weather feature formed through a merging process of small shallow storms generated by moist convection, while the other is a deep model suggesting that it might be a deeply rooted anticyclone powered by the internal heat of Jupiter. In this work, we present numerical simulations showing that the Great Red Spot could be naturally generated in a deep rotating turbulent flow and survive for a long time, when the convective Rossby number is smaller than a certain critical value. From this critical value, we predict that the Great Red Spot extends at least about 500 kilometers deep into the Jovian atmosphere. Our results demonstrate that the Great Red Spot is likely to be a feature deep-seated in the Jovian atmosphere.

scholarly journals Spontaneous Generated Convective Anticyclones in Low Latitude --- A Model for the Great Red Spot

2021 ◽  
Author(s):  
Tao Cai ◽  
Kwing L. Chan ◽  
Kim-Chiu Chow
Keyword(s):  
Internal Heat ◽  
Critical Value ◽  
Driving Mechanism ◽  
Moist Convection ◽  
Low Latitude ◽  
Deep Model ◽  
Merging Process ◽  
Long Time ◽  
Rotating Turbulent Flow ◽  
Jovian Atmosphere

Abstract The Great Red Spot at about latitude 22oS of Jupiter has been observed for hundreds of years, yet the driving mechanism on the formation of this giant anticyclone still remains unclear. Two scenarios were proposed to explain its formation. One is a shallow model suggesting that it might be a weather feature formed through a merging process of small shallow storms generated by moist convection, while the other is a deep model suggesting that it might be a deeply rooted anticyclone powered by the internal heat of Jupiter. In this work, we present numerical simulations showing that the Great Red Spot could be naturally generated in a deep rotating turbulent flow and survive for a long time, when the convective Rossby number is smaller than a certain critical value. From this critical value, we predict that the Great Red Spot extends at least about 500 kilometers deep into the Jovian atmosphere. Our results demonstrate that the Great Red Spot is likely to be a feature deep-seated in the Jovian atmosphere.

A study of Holocene Asian summer and winter monsoon change by an analog of climate factors between millennial and modern interannual scales

2019 ◽  
Vol 44 (3) ◽  
pp. 315-337
Author(s):  
Yu Li ◽  
Yichan Li ◽  
Wangting Ye ◽  
Simin Peng
Keyword(s):  
Asian Monsoon ◽  
East Asian Monsoon ◽  
East Asian ◽  
Driving Mechanism ◽  
Climatic Data ◽  
Low Latitude ◽  
Global Circulation ◽  
Asian Summer ◽  
Winter Insolation ◽  
Monsoon Indices

The East Asian monsoon exerts a profound influence on environmental change in the East Asian region. Various factors have been hypothesized as the dominant Asian monsoon forcings, however, the forcings can change from interannual to millennial timescales. The linkages between monsoon forcings at different timescales remain unclear. To better understand the connection of the variabilities and mechanisms of the East Asian monsoon at various timescales, we present a modern analog. Various climatic data, monsoon indices, and circulation factor calculations were used to identify the variabilities and controlling factors of the modern East Asian summer and winter monsoons. Paleo-climatic proxies from a region sensitive to both summer and winter monsoons were used in concert with monsoon simulation data to reconstruct and analyze paleo-monsoon variations and mechanisms. Results showed that the weakening of the Holocene Asian summer and winter monsoons is closely linked to low-latitude summer insolation and mid-latitude winter insolation, while modern summer and winter monsoons are related to global circulation, sea surface temperature, and sea ice change. We confirm that the driving mechanism of the monsoon was dependent on timescale.

Experimental Study on Stabilization of Chromium Contaminated Soil

2011 ◽  
Vol 414 ◽  
pp. 273-279
Author(s):  
Ji Da Chen ◽  
Li Liu ◽  
Li Wei Zhang ◽  
Shi Guo Liao ◽  
Yong Ting Song ◽  
...  
Keyword(s):  
Experimental Study ◽  
Contaminated Soil ◽  
Critical Value ◽  
Polluted Soil ◽  
Pyrrolidine Dithiocarbamate ◽  
Stabilization Method ◽  
Toxicity Assay ◽  
Long Time ◽  
Stabilization Effect ◽  
Ammonium Pyrrolidine Dithiocarbamate

To develope a practicable stabilization method for remediation chromium contaminated soil, reductant and chelate reagent were investigated for stabilization artificical chromium contaminated soil, and the stabilization effect was tested through extraction toxicity assay after stablized soil was oxidized at pH 12. The experimental results showed that the composition of sodium bisulfite & ammonium pyrrolidine dithiocarbamate was an ideal stabilizer of chromium in soil, and the extraction toxicity was much less than that of classical stabilized chromium polluted soil with only reductant or the maximum critical value in GB16889-2008, which suggested that the composition of reductant & compound of dithiocarbamate might be practically appllied for remediation chromium contaminated soil because it was likely to remain chromium much more stable in soil for a long time and significantly decrease Cr mobility.

scholarly journals Dynamical properties of vortical structures on the beta-plane

1994 ◽  
Vol 268 ◽  
pp. 103-131 ◽  
Author(s):  
G. G. Sutyrin ◽  
J. S. Hesthaven ◽  
J. P. Lynov ◽  
J. Juul Rasmussen
Keyword(s):  
Rossby Wave ◽  
Potential Vorticity ◽  
Fluid Transport ◽  
Numerical Solutions ◽  
Critical Value ◽  
Wave Radiation ◽  
Approximate Theory ◽  
Initial Direction ◽  
Vortical Structures ◽  
Long Time

The long-time evolution of monopolar and dipolar vortices influenced by the largescale gradient of the ambient potential vorticity (the β-effect) is studied by direct numerical solutions of the equivalent barotropic quasi-geostrophic equation. Translation and reorganization of vortical structures are shown to depend strongly on their intensity. Transport of trapped fluid by vortical structures is illustrated by calculating particle trajectories and by considering closed isolines of potential vorticity and the streamfunction in a co-moving reference frame.The initial behaviour of strong monopoles is found to be well described by a recent approximate theory for the evolution of azimuthal mode one, even for times longer than the linear Rossby wave period. In the long-time limit, strong monopoles transport particles mainly westward, although the meridional displacement is several times larger than the initial vortex size. The appearance of an annulus with opposite radial gradient of the potential vorticity around the vortex core is demonstrated. This annulus forms owing to the meridional vortex drift on the β-plane and results in reorganization of a strong monopolar vortex into a rotating tripole. A critical value of the vortex intensity is found, below which the tripolar structure does not appear even in the case of an initially shielded vortex. Weak monopolar vortices are able to trap particles and provide some west-meridional fluid transport, even in the case when they decay like a linear Rossby wave packet.The evolution of initial f-plane dipoles on the β-plane is strongly dependent on the initial direction of propagation. Strong dipoles adjust to steadily propagating modon solutions either accelerating (westward case), decelerating (eastward case) or oscillating with a decaying amplitude (meridional case), thereby carrying trapped particles predominantly eastward. A steady state is not reached if the dipole intensity is below a critical value which depends on the initial direction of propagation. Weak dipoles either decay and shrink owing to Rossby wave radiation (westward case), gradually separate and split (eastward case), or disintegrate (meridional case) without longdistance fluid transport. Thus, on the β-plane monopoles provide mainly westward transport of trapped fluid, whereas dipoles provide mainly eastward transport. Only strong monopoles are found to provide significant meridional fluid transport.

Study on Cruise Control System for Two Wheelers using Pawl and Ratchet Mechanism

2019 ◽  
Vol 1 (4) ◽  
pp. 17-21
Author(s):  
Manoj MTR
Keyword(s):  
Motor Vehicle ◽  
Driving Mechanism ◽  
Cruise Control ◽  
Long Distance ◽  
Ratchet Mechanism ◽  
Cruise Control System ◽  
Servo Mechanism ◽  
Ir Sensors ◽  
Control Concept ◽  
Long Time

Cruise control is a system to control the speed of motor vehicle automatically at certain speed. This is a servo mechanism that takes over the throttle of the vehicle to maintain a steady speed set by the driver, as it is an optional feature for high end variant cars. In this project we are going to implement cruise control concept for two wheelers, In order to avoid continuous acceleration for very long time when we are for long distance rides. We have planned to invoke this concept using electro-mechanical components like IR sensors, Driving mechanism (motor linkages) and pawl ratchet.

A nonlinear instability burst in plane parallel flow

1972 ◽  
Vol 51 (4) ◽  
pp. 705-735 ◽  
Author(s):  
L. M. Hocking ◽  
K. Stewartson ◽  
J. T. Stuart ◽  
S. N. Brown
Keyword(s):  
Differential Equation ◽  
Reynolds Number ◽  
Critical Value ◽  
Three Dimensions ◽  
Parabolic Differential Equation ◽  
Nonlinear Instability ◽  
Two Dimensional ◽  
Slowly Varying Function ◽  
Plane Poiseuille Flow ◽  
Long Time

An infinitesimal centre disturbance is imposed on a fully Ldveloped plane Poiseuille flow at a Reynolds numberRslightly greater than the critical valueRcfor instability. After a long time,t, the disturbance consists of a modulated wave whose amplitudeAis a slowly varying function of position and time. In an earlier paper (Stewartson & Stuart 1971) the parabolic differential equation satisfied byAfor two-dimensional disturbances was found; the theory is here extended to three dimensions. Although the coefficients of the equation are coinples, a start is made on elucidating the properties of its solutions by assuming that these coefficients are real. It is then found numerically and confirmed analytically that, for a finite value of (R-Rc)t, the amplitudeAdevelops an infinite peak at the wave centre. The possible relevance of this work to the phenomenon of transition is discussed.

scholarly journals Observations of convection in the giant planets: results from space missions

2006 ◽  
Vol 2 (S239) ◽  
pp. 196-196
Author(s):  
A. P. Ingersoll
Keyword(s):  
Giant Planet ◽  
Internal Heat ◽  
Internal Field ◽  
Giant Planets ◽  
The Sun ◽  
Moist Convection ◽  
Convective Storms ◽  
Zonal Winds ◽  
Zonal Jets ◽  
Inverse Energy Cascade

AbstractThe giant planets are fluid objects; their solid cores occupy much less than half of their volumes. The largest planet, Jupiter, is over ten times the size of Earth. The giant planet atmospheres are powered in roughly equal parts by sunlight and by internal heat, which is left over from planetary formation. In most cases, the winds are measured by tracking clouds relative to the internal magnetic fields. Saturn is the exception, since the internal field is axisymmetric and therefore provides no evidence of rotation. In all four giant planets, the winds blow mainly in the east-west (zonal) direction, and the coloured cloud bands are aligned with the winds. The patterns are organized by rotation and not by the energy sources, since the sun at zenith moves from one pole to the other during the course of a year on Uranus, and yet the winds do not change. Although the power per unit area - the sum of absorbed sunlight and internal heat - is 20 times greater at Jupiter than at Neptune, the winds at Neptune are stronger. In fact Jupiter has the weakest winds of all the giant planets, although it is closest to the sun. Besides the zonal winds, the giant planets have long-lived vortices that have the same sign of vorticity as the latitude bands in which they sit. These large vortices exhibit a variety of behaviours, including oscillation in shape, position, and orientation, merging and splitting, and filament ejection. The anticyclones have a compact, oval shape; the cyclones are more elongated and diffuse. The cyclones contain lightning, which is a sign of moist convection. The cyclones therefore have a more disturbed appearance, since the convective storms are vigorous and chaotic. The convective storms are more frequent on Jupiter, but they are apparently more energetic on Saturn. The convective storms maintain a Reynolds stress that pumps momentum into the zonal jets in what is known as an inverse energy cascade. The depth to which the zonal winds extend is largely unknown. The winds could be confined to the outer 1 percent of the planets radii, or they could extend down into the fluid interiors, where the electrical conductivity and magnetic field become important.

scholarly journals Discovering the Low-Latitude Ionospheric Trough Associated With the Inner Radiation Belt

2021 ◽  
Author(s):  
Alexander Karpachev
Keyword(s):  
Geomagnetic Storm ◽  
Radiation Belt ◽  
Ring Current ◽  
Recovery Phase ◽  
Low Latitude ◽  
Champ Satellite ◽  
Main Ionospheric Trough ◽  
Long Time ◽  
Late Recovery ◽  
First Time

Abstract The dynamics of ionospheric troughs during great geomagnetic storm on April 11–13, 2001 is considered. An analysis is based on measurements of electron density at altitudes of the CHAMP satellite 410–465 km. The subauroral, mid-latitude and low-latitude troughs were observed at nighttime, sometimes simultaneously. The subauroral trough is usually defined as the main ionospheric trough. The mid-latitude trough is associated with the magnetospheric ring current. It appears at the beginning of the storm recovery phase at latitudes of 40–45° GMLat (L=1.7–2.0) and exists for a long time at the late recovery phase at latitudes of the residual ring current 50–55° GMLat (L~2.4–3.0). The low-latitude trough was revealed for the first time. It is developed at the latitudes of the inner radiation belt 34–45° GMLat (L=1.45–2.00). This trough is associated with the precipitation of energetic particles from the inner radiation belt.

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