scholarly journals The evolution of second mode internal solitary waves over variable topography

2017 ◽  
Vol 836 ◽  
pp. 238-259 ◽  
Author(s):  
C. Yuan ◽  
R. Grimshaw ◽  
E. Johnson
Keyword(s):  
Solitary Wave ◽  
General Circulation ◽  
Transition Point ◽  
Lower Layer ◽  
Nonlinear Coefficient ◽  
Circulation Model ◽  
Internal Solitary Wave ◽  
Layer System ◽  
Mode 2 ◽  
Polarity Change

A study of the propagation of a mode-2 internal solitary wave over a slope-shelf topography is presented. The methodology is based on a variable-coefficient Korteweg–de Vries (vKdV) equation, using both analysis and numerical simulations, and simulations using the MIT general circulation model (MITgcm). Two configurations are considered. One is a mode-2 internal solitary wave propagating up the slope, from one three-layer system to another three-layer system. Depending on the height of the shelf, which determines the variation of the nonlinear coefficient of the vKdV equation, this can be classified into two cases. First, the case of a polarity change, in which the coefficient of the quadratic nonlinear term changes sign at a certain critical point on the slope, and second, the case with no such polarity change. In both these cases there is a small transfer of energy from the mode-2 wave to mode-1 waves. The other configuration is when the lower layer in the three-layer system goes to zero at a transition point on the slope, and beyond that point, there is a two-layer fluid system. A mode-2 internal solitary wave propagating up the slope cannot exist past this transition point. Instead it is extinguished and replaced by a mode-1 bore and trailing wave packet which moves onto the shelf.

scholarly journals Transformation of mode-2 internal solitary wave over a pseudo slope-shelf

AIP Advances ◽  
2017 ◽  
Vol 7 (9) ◽  
pp. 095309 ◽  
Author(s):  
Ming-Hung Cheng ◽  
Chih-Min Hsieh ◽  
John R.-C. Hsu ◽  
Robert R. Hwang
Keyword(s):  
Solitary Wave ◽  
Internal Solitary Wave ◽  
Mode 2

On the breaking of internal solitary waves at a ridge

2002 ◽  
Vol 469 ◽  
pp. 161-188 ◽  
Author(s):  
J. KRISTIAN SVEEN ◽  
YAKUN GUO ◽  
PETER A. DAVIES ◽  
JOHN GRUE
Keyword(s):  
Solitary Wave ◽  
Wave Breaking ◽  
Lower Layer ◽  
Fluid Layer ◽  
Fluid Velocity ◽  
Internal Solitary Wave ◽  
Layer Thickness Ratio ◽  
Transmitted Waves ◽  
Ridge Height ◽  
Experimental Laboratory

An experimental laboratory study has been carried out to investigate the propagation of an internal solitary wave of depression and its distortion by a bottom ridge in a two-layer stratified fluid system. Wave profiles, density fields and velocity fields have been measured at three reference locations, namely upstream, downstream and over the ridge. Experiments have been performed with wave amplitudes in the range 0.2– 1.9 times the depth of the upper layer, and a ratio between the lower and the upper layer in the range 3.0–8.5. The ridge slope was varied from 0.1 to 0.33 and the maximum ridge height was two-thirds of the thicker fluid layer. Over the ridge, the flow has been classified into: (i) cases when the bottom ridge has little influence on the propagation and spatial structure of the internal solitary wave, (ii) cases where the internal solitary wave is significantly distorted by the blocking effect of the ridge (though no wave breaking occurs), and (iii) cases for which the internal solitary wave is broken as it encounters and passes over the bottom ridge. A detailed description of the processes leading to wave breaking is given. Breaking has been found to take place when the fluid velocity in the lower layer exceeds 0.7 of a local nonlinear wave speed, defined at the top of the ridge. The breaking condition is also expressed in terms of the amplitude of the incident wave, the layer thickness ratio and the relative height of the ridge. The wave breaking can be determined from the input parameters of the experiment. The transmitted waves have been found to always consist of a leading pulse (solitary wave) followed by a dispersive wavetrain. The (solitary) wave amplitude is significantly reduced only when breaking takes place at the ridge. Internal waves of mode two are generated in cases with strong breaking.

scholarly journals Observationally derived transport diagnostics for the lowermost stratosphere and their application to the GMI chemistry and transport model

2007 ◽  
Vol 7 (9) ◽  
pp. 2435-2445 ◽  
Author(s):  
S. E. Strahan ◽  
B. N. Duncan ◽  
P. Hoor
Keyword(s):  
General Circulation ◽  
Transport Model ◽  
Lower Layer ◽  
Potential Temperature ◽  
Circulation Model ◽  
Chemical Mechanism ◽  
Data Sets ◽  
Extratropical Tropopause ◽  
Stratospheric Composition ◽  
The Impact

Abstract. Transport from the surface to the lowermost stratosphere (LMS) can occur on timescales of a few months or less, making it possible for short-lived tropospheric pollutants to influence stratospheric composition and chemistry. Models used to study this influence must demonstrate the credibility of their chemistry and transport in the upper troposphere and lower stratosphere (UT/LS). Data sets from satellite and aircraft instruments measuring CO, O3, N2O, and CO2 in the UT/LS are used to create a suite of diagnostics for the seasonally-varying transport into and within the lowermost stratosphere, and of the coupling between the troposphere and stratosphere in the extratropics. The diagnostics are used to evaluate a version of the Global Modeling Initiative (GMI) Chemistry and Transport Model (CTM) that uses a combined tropospheric and stratospheric chemical mechanism and meteorological fields from the GEOS-4 general circulation model. The diagnostics derived from N2O and O3 show that the model lowermost stratosphere has realistic input from the overlying high latitude stratosphere in all seasons. Diagnostics for the LMS show two distinct layers. The upper layer begins ~30 K potential temperature above the tropopause and has a strong annual cycle in its composition. The lower layer is a mixed region ~30 K thick near the tropopause that shows no clear seasonal variation in the degree of tropospheric coupling. Diagnostics applied to the GMI CTM show credible seasonally-varying transport in the LMS and a tropopause layer that is realistically coupled to the UT in all seasons. The vertical resolution of the GMI CTM in the UT/LS, ~1 km, is sufficient to realistically represent the extratropical tropopause layer. This study demonstrates that the GMI CTM has the transport credibility required to study the impact of tropospheric emissions on the stratosphere.

scholarly journals Interaction of a mode-2 internal solitary wave with narrow isolated topography

2017 ◽  
Vol 29 (7) ◽  
pp. 076601 ◽  
Author(s):  
David Deepwell ◽  
Marek Stastna ◽  
Magda Carr ◽  
Peter A. Davies
Keyword(s):  
Solitary Wave ◽  
Internal Solitary Wave ◽  
Mode 2

scholarly journals Observationally derived transport diagnostics for the lowermost stratosphere and their application to the GMI chemistry and transport model

2007 ◽  
Vol 7 (1) ◽  
pp. 1449-1477 ◽  
Author(s):  
S. E. Strahan ◽  
B. N. Duncan ◽  
P. Hoor
Keyword(s):  
General Circulation ◽  
Transport Model ◽  
Lower Layer ◽  
Circulation Model ◽  
Chemical Mechanism ◽  
Data Sets ◽  
Global Modeling ◽  
Upper Troposphere ◽  
Stratospheric Composition ◽  
The Impact

Abstract. Transport from the surface to the lowermost stratosphere can occur on timescales of a few months or less, making it possible for short-lived tropospheric pollutants to influence stratospheric composition and chemistry. Models used to study this influence must demonstrate the credibility of their chemistry and transport in the upper troposphere and lower stratosphere (UT/LS). Data sets from satellite and aircraft instruments measuring CO, O3, N2O, and CO2 in the UT/LS are used to create a suite of diagnostics of the seasonally-varying transport into and within the lowermost stratosphere, and of the coupling between the troposphere and stratosphere in the extratropics. The diagnostics are used to evaluate a version of the Global Modeling Initiative (GMI) Chemistry and Transport Model that uses a combined tropospheric and stratospheric chemical mechanism and meteorological fields from the GEOS-4 general circulation model. The diagnostics derived from N2O and O3 show that the model lowermost stratosphere (LMS) has realistic input from the overlying high latitude stratosphere in all seasons. Diagnostics for the LMS show two distinct layers. The upper layer (~350 K–380 K) has a strong annual cycle in its composition, while the lower layer, just above the tropopause, shows no seasonal variation in the degree of tropospheric coupling or composition. The GMI CTM agrees closely with the observations in both layers and is realistically coupled to the UT in all seasons. This study demonstrates the credibility of the GMI CTM for the study of the impact of tropospheric emissions on the stratosphere.

Pemanfaatan CFSRv2 untuk Statistical Downscaling menggunakan Principal Component Regression dan Partial Least Square

2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Khairunnisa Khairunnisa ◽  
Rizka Pitri ◽  
Victor P Butar-Butar ◽  
Agus M Soleh
Keyword(s):  
Statistical Downscaling ◽  
General Circulation ◽  
Principal Component Regression ◽  
Circulation Model ◽  
Principal Component ◽  
Meteorological Station ◽  
Grid Size ◽  
Partial Least Square ◽  
Least Square ◽  
Output Data

This research used CFSRv2 data as output data general circulation model. CFSRv2 involves some variables data with high correlation, so in this research is using principal component regression (PCR) and partial least square (PLS) to solve the multicollinearity occurring in CFSRv2 data. This research aims to determine the best model between PCR and PLS to estimate rainfall at Bandung geophysical station, Bogor climatology station, Citeko meteorological station, and Jatiwangi meteorological station by comparing RMSEP value and correlation value. Size used was 3×3, 4×4, 5×5, 6×6, 7×7, 8×8, 9×9, and 11×11 that was located between (-40) N - (-90) S and 1050 E -1100 E with a grid size of 0.5×0.5 The PLS model was the best model used in stastistical downscaling in this research than PCR model because of the PLS model obtained the lower RMSEP value and the higher correlation value. The best domain and RMSEP value for Bandung geophysical station, Bogor climatology station, Citeko meteorological station, and Jatiwangi meteorological station is 9 × 9 with 100.06, 6 × 6 with 194.3, 8 × 8 with 117.6, and 6 × 6 with 108.2, respectively.

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