arXiv subjects

Jin-Liang Wang

Publications and source records attributed to Jin-Liang Wang.

5 recordsLinked to original sources

arXiv2019

Key Modes for Time-Space Evolutions of ENSO and PDO by ESMD Method

The relation between El Niño-Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) perplexes the researchers. Probably, this is due to the default choice on empirical orthogonal function (EOF) method whose outputs are merely static maps without evolution characteristics. To change this situation, the new extreme-point symmetric mode decomposition (ESMD) method is tried. It reveals that: (1) As the ENSO concerned, the key modes are the quarter-decadal and half-decadal ones; (2) As the PDO concerned, the key modes are the half-decadal, decadal and interdecadal ones; (3) The half-decadal mode can be seen as a mutual component for ENSO and PDO and it plays a key part in the so-called "ENSO-like" variation of PDO. In addition, an integrated version of ESMD is developed for time-space evolution. Its outputs have verified the warm-cold shiftings of ENSO and PDO for the most typical episode during 1997-2000.

physics.ao-ph↗

arXiv2019

Current-Generating Mechanism for El Niño & La Niña, an Data Evidence from Integrated ESMD Method

Different to classical theories which emphasize east--west feedback along the equator, data analyses via the extreme-point symmetric mode decomposition (ESMD) method support a new viewpoint that the El Niño--Southern Oscillation (ENSO) cycle is horizontally dependent, rather than vertically dependent. The consistency between the ocean current changes and sea-surface temperature anomalies results in a current-generating mechanism for El Niño and La Niña events. The corresponding new findings are as follows: (1) The appearance of the Central Equatorial Countercurrent (CECC) and the enhancement of the North Equatorial Countercurrent (NECC) are primary causes for the occurrences of positive anomalies in the central and eastern Pacific, respectively. (2) In addition to the contribution from the CECC, initiations of the eastern and central Pacific types of El Niño events are mainly caused by the southward transport of warm water from the high-temperature sea-area off Central America, and from the eastern low-speed gap of the NECC, respectively. (3) The northern and southern branches of the South Equatorial Current contribute to the negative anomalies in the eastern and central Pacific, respectively. Particularly, the later transfers cold water from the southeast to the central equatorial Pacific in a direct way, and this implies the crack of the ENSO-asymmetry problem.

physics.ao-ph↗

arXiv2017

Modeling the Propagation, Breaking and Drift of Ocean Surface Wave

A new model other than the classical ones given by Airy, Stokes and Gerstner for the ocean surface wave is constructed. It leads to new understandings for the wave mechanisms: (1) A wave with bigger amplitude or smaller steepness travels faster; (2) The wave breaks when the front angle is bigger than 46.3 degree; (3) The magnitude of the wave drift should be smaller than that of the known Stokes drift.

physics.gen-ph↗

arXiv2017

Wave Model and Wave Drift Caused by the Asymmetry of Crest and Trough

It follows from the review on classical wave models that the asymmetry of crest and trough is the direct cause for wave drift. Based on this, a new model of Lagrangian form is constructed. Relative to the Gerstner model, its improvement is reflected in the horizontal motion which includes an explicit drift term. On the one hand, the depth-decay factor for the new drift accords well with that of the particle's horizontal velocity. It is more rational than that of Stokes drift. On the other hand, the new formula needs no Taylor expansion as for Stokes drift and is applicable for the waves with big slopes. In addition, the new formula can also yield a more rational magnitude for the surface drift than that of Stokes.

physics.ao-ph↗

arXiv2013

Extreme-Point Symmetric Mode Decomposition Method for Data Analysis

An extreme-point symmetric mode decomposition (ESMD) method is proposed to improve the Hilbert-Huang Transform (HHT) through the following prospects: (1) The sifting process is implemented by the aid of 1, 2, 3 or more inner interpolating curves, which classifies the methods into ESMD_I, ESMD_II, ESMD_III, and so on; (2) The last residual is defined as an optimal curve possessing a certain number of extreme points, instead of general trend with at most one extreme point, which allows the optimal sifting times and decompositions; (3) The extreme-point symmetry is applied instead of the envelop symmetry; (4) The data-based direct interpolating approach is developed to compute the instantaneous frequency and amplitude. One advantage of the ESMD method is to determine an optimal global mean curve in an adaptive way which is better than the common least-square method and running-mean approach; another one is to determine the instantaneous frequency and amplitude in a direct way which is better than the Hilbert-spectrum method. These will improve the adaptive analysis of the data from atmospheric and oceanic sciences, informatics, economics, ecology, medicine, seismology, and so on.

physics.gen-ph↗