Search

Your search keyword '"Fan, Daidu"' showing total 309 results
Start Over Author "Fan, Daidu"
309 results on '"Fan, Daidu"'

14. Shear Instability and Turbulent Mixing by Kuroshio Intrusion Into the Changjiang River Plume.

Author

Tu, Junbiao, Wu, Jiaxue, Fan, Daidu, Liu, Zhiyu, Zhang, Qianjiang, and Smyth, William

Abstract

Shear instability is a dominant mechanism for mixing in the stratified oceans and coastal seas. For the first time, we present fine‐scale, direct measurements of shear instabilities in the bottom front generated by the Kuroshio intrusion into the Changjiang (Yangtze) river plume. Shear instabilities were identified using a shipboard echo‐sounder and the resulting turbulent mixing was quantified using a turbulence microstructure profiler. The shear instabilities generate vigorous turbulent mixing with dissipation rate and vertical diffusivity up to O (10−4 m2 s−3) and O (10−1 m2 s−1), respectively, comparable to values associated with shear instabilities observed in river plumes and western boundary currents but several orders of magnitude larger than typical values in the open ocean. The enhanced turbulence may contribute significantly to mixing between the Kuroshio water and coastal water and thereby alter the coastal biogeochemistry cycles. Plain Language Summary: Strong velocity shear across a density interface can produce instability, causing the interface to roll up to form a train of vortices ("billows") that subsequently break down into turbulence. This process is important in the vertical mixing of the oceanic interior and coastal seas. Using acoustic images, we find that this flow instability is induced by the interaction between the Kuroshio current and the Yangtze river plume. We also quantify the resulting turbulent mixing using high‐resolution measurements. The turbulence efficiently mixes the Kuroshio and river plume‐influence water and can change biogeochemistry cycles in the coastal seas. Key Points: Interaction between Kuroshio and river plume‐influenced coastal waters generates shear instabilityShear instability elevates turbulence level by 2–3 orders of magnitude compared to the fluid above and belowThe enhanced turbulence effectively mixes oceanic and coastal waters [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

47. Study of Coastal Morphological Changes by Tsunamis in Aceh (Indonesia) Using Satellite Images

Author

Faiez, Ziadul, Fan, Daidu, Faiez, Ziadul, and Fan, Daidu

Abstract

This study identified the coastal morphological changes caused by tsunamis that occurred in Banda Aceh, Lampuuk-Lhoknga, and Meulaboh. The morphology of study areas was drastic changes during the 2004 tsunami and followed by the 2005, 2010, and 2012 tsunamis. Time series of Landsat satellite images and tidal data were collected during the period 1988-2020 and analyzed using DSAS (Digital Shoreline Analysis System) analysis method. The main aim of this study is to monitor recovery, trend development, and controlling factors of the coastal morphology before and after fifteen years of the 2004 tsunami. In Banda Aceh, the shoreline shift in the 2004-2005 period shows an inland retreat trend, with an average NSM (net shoreline movement) value of -644.69 m. The EPR (end point rate) value for the 2005-2020 period reached 21.31 m/year, but the recovery of the 2020 shoreline position has not returned to the original position before the 2004 tsunami. The significant shoreline retreat and land loss with an average NSM value of -40.59 m in the period 2004-2005 occurred on the Lampuuk and Lhoknga beaches. The 2020 shoreline of Lampuuk beach underwent a recovery with accretion. Nevertheless, Lhoknga beach is still experiencing apparent erosion. The recovery of the Meulaboh east coast was fast as evidenced by the development of the annual growth of spit features. The coastal morphological changes are influenced by complex interactions between natural and anthropogenic processes. The 2004 tsunami was the major factor to change the coastal morphology in the study areas.

Published
2023

Catalog

Books, media, physical & digital resources
See catalog results