Evidence of the coexistence of upstream and downstream solitary wavetrains in the real atmosphere (original) (raw)
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International Journal of Remote Sensing, 2004
From a true colour image of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) onboard the Orbview-2 satellite, we observed two packets of orderly wave clouds on two sides of Hainan Island in the South China Sea. A packet of 23 wave clouds stretches southward from the island. A second packet of more than 20 wave clouds stretches north-eastward off the north-east coast of the island. The concave orientation of the wave cloud lines implies that both packets are propagating away from the island. A chart of geopotential height and velocity at 850 mbar shows a south-westerly air flow over the island; hence the two wave cloud packets propagate upstream and downstream, simultaneously. Thus, we have found new evidence of the coexistence of both upstream and downstream solitary wavetrains generated in the real atmosphere by land topographic disturbances. Comparison with theoretical results supports this conclusion.
A solitary wave packet in the atmosphere observed from space
Geophysical Research Letters, 1998
A group of paralld cloud lines was identified in seven successive space shuttle photographs taken over the Pakistani offshore zone in the northern Arabian Sea on April 29, 1993. There are a total of 19 lines aligned with the length of the leading line longer than 250 km and an average separation distance (wavelength) of 1 km. We suggest that the lines are generated by an atmospheric solitary wave packet characterized by decreases in amplitudes and wavelengths from the front to the rear. These features are comparable with the dnoidal soliton solution to the Korteweg-de Vries (KdV)equation. The land breeze and katabatic flow are proposed as a possible generation mechanism.
A Case Study of Internal Solitary Wave Propagation During ASIAEX 2001
IEEE Journal of Oceanic Engineering, 2004
During the recent Asian Seas International Acoustics Experiment (ASIAEX), extensive current meter moorings were deployed around the continental shelf-break area in the northeastern South China Sea. Thirteen RADARSAT SAR images were collected during the field test to integrate with the in situ measurements from the moorings, ship-board sensors, and conductivity/temperatire/depth (CTD) casts. Besides providing a synoptic view of the entire region, satellite imagery is very useful for tracking the internal waves, locating surface fronts, and identifying mesoscale features. During ASIAEX in May 2001, many large internal waves were observed at the test area and were the major oceanic features studied for acoustic volume interaction. Based on the internal wave distribution maps compiled from satellite data, the wave crests can be as long as 200 km with an amplitude of 100 m. Environmental parameters have been calculated based on extensive CTD casts data near the ASIAEX area. Nonlinear internal wave models have been applied to integrate and assimilate both synthetic aperture radar (SAR) and mooring data. Using SAR data in deep water as an initial condition, numerical simulations produced the wave evolution on the continental shelf and compared reasonably well with the mooring measurements at the downstream station. The shoaling, turning, and dissipation of large internal waves at the shelf break have been studied and are very important issues for acoustic propagation.
Nonlinear internal wave spirals in the northern East China Sea
Scientific reports, 2018
Oceanic internal waves are known to be important to the understanding of underwater acoustics, marine biogeochemistry, submarine navigation and engineering, and the Earth's climate. In spite of the importance and increased knowledge of their ubiquity, the wave generation is still poorly understood in most parts of the world's oceans. Here, we use satellite synthetic aperture radar images, in-situ observations, and numerical models to (1) show that wave energy (having relatively high amplitude) radiates from a shallow sill in the East China Sea in all directions, but with a significant time lag dependent on background conditions, (2) reveal that wave fronts are locally formed with often favorable conditions for re-initiation, and (3) demonstrate the resulting variety of wave patterns. These findings would be the case for any broad shelf having shallow sills with time-varying conditions, and therefore have significant implications on the redistribution of energy and materials ...