TY - JOUR
T1 - Satellite observed new mechanism of Kuroshio intrusion into the northern South China Sea
AU - Lin, Jia Yi
AU - Zheng, Zhe Wen
AU - Zheng, Quanan
AU - Wu, Ding Rong
AU - Gopalakrishnan, Ganesh
AU - Ho, Chung Ru
AU - Pan, Jiayi
AU - Lin, Yu Chun
AU - Xie, Ling Ling
N1 - Funding Information:
The satellite-observed SSHA from January 1993 to December 2018 were used to identify the occurrences and distributed characteristics of EIET. Satellite-derived absolute geostrophic currents (AGCs) for the same period were used to map the upper layer characteristics of LSKI. SSHA and AGCs are gridded products obtained from Archiving, Validation, and Interpretation of Satellite Oceanographic Data (AVISO) and distributed by the Copernicus Marine and Environment Monitoring Service (CMEMS). These products were obtained by mapping altimetry data from various satellite missions covering the time period from 1993 to present, with 0.25° spatial resolution and 7-day temporal resolution (https://www.aviso.oceanobs.com/). As noted in Chelton et al. (2011), eddies may disappear temporarily and reappear a few time-steps later, due to the sampling errors and noise in the AVISO product. Based on visual inspections on the eddy trajectories, Faghmous et al. (2015) indicated that an eddy tracking procedure would terminate eddy trajectories prematurely if without accounting for this bias. In particular, the tracks were being prematurely terminated at a higher rate in the daily SSHA data relative to the rates reported by Chelton et al. (2011) using weekly SSHA field. Thus, the weekly AVISO data are applied here to elucidate the relationship between EIET and consequential LSKI. The SSHA dataset was improved significantly by using atmospheric barometric and tidal corrections relative to the original version (Volkov et al., 2007). Additionally, as noted in Zhang et al. (2017), a systematic comparison of the surface currents retrieved from drifters and altimeter observations of AGCs showed very consistent velocity magnitudes and current patterns that surrounded the Luzon Strait, implying the good quality of the altimetry datasets for this study area.
Publisher Copyright:
© 2022 The Authors
PY - 2022/12
Y1 - 2022/12
N2 - In addition to existing theories, this study proposes a new mechanism of Kuroshio Intrusion passing through the Luzon Strait (LSKI) on the basis of the satellite observed sea surface height anomaly from January 1993 to December 2018. First, 11 events of westward propagating cyclonic Eddy Impingement on the Kuroshio on the Eastern side of Taiwan (EIET) were recognized. Statistical results indicate that approximately 82% of EIET led to consequential LSKI. Systematic analysis indicates a reduction in northward inertial advection, which is responsible for connecting EIET to consequential LSKI. Dynamic diagnosis further unveils the detailed physical exchange processes therein. Squeezing of the planetary vorticity and advection of negative relative vorticity in response to the collision of the EIET with downstream Kuroshio current (KC) contribute to LSKI. Although the beta-term is relatively weak, for the left flank of LSKI, where the influences of advection and flow divergence largely reduce, it plays a dominant role in forcing the KC to intrude farther west into the northern SCS. Aforementioned results identify the possibility of the downstream Kuroshio changes might modify the upstream LSKI critically. More interestingly, this mechanism is a backward feedback sourcing from the Kuroshio downstream region (east of Taiwan) to the upstream region (Luzon Strait).
AB - In addition to existing theories, this study proposes a new mechanism of Kuroshio Intrusion passing through the Luzon Strait (LSKI) on the basis of the satellite observed sea surface height anomaly from January 1993 to December 2018. First, 11 events of westward propagating cyclonic Eddy Impingement on the Kuroshio on the Eastern side of Taiwan (EIET) were recognized. Statistical results indicate that approximately 82% of EIET led to consequential LSKI. Systematic analysis indicates a reduction in northward inertial advection, which is responsible for connecting EIET to consequential LSKI. Dynamic diagnosis further unveils the detailed physical exchange processes therein. Squeezing of the planetary vorticity and advection of negative relative vorticity in response to the collision of the EIET with downstream Kuroshio current (KC) contribute to LSKI. Although the beta-term is relatively weak, for the left flank of LSKI, where the influences of advection and flow divergence largely reduce, it plays a dominant role in forcing the KC to intrude farther west into the northern SCS. Aforementioned results identify the possibility of the downstream Kuroshio changes might modify the upstream LSKI critically. More interestingly, this mechanism is a backward feedback sourcing from the Kuroshio downstream region (east of Taiwan) to the upstream region (Luzon Strait).
KW - Absolute geostrophic currents
KW - Eddy impingement
KW - Kuroshio intrusion
KW - Luzon Strait
KW - Sea surface height anomaly
UR - http://www.scopus.com/inward/record.url?scp=85142171013&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85142171013&partnerID=8YFLogxK
U2 - 10.1016/j.jag.2022.103119
DO - 10.1016/j.jag.2022.103119
M3 - Article
AN - SCOPUS:85142171013
SN - 1569-8432
VL - 115
JO - International Journal of Applied Earth Observation and Geoinformation
JF - International Journal of Applied Earth Observation and Geoinformation
M1 - 103119
ER -