Monitoring the mesoscale eddies of the Lofoten Basin: <b>i</b>mportance, progress, and challenges

Raj, Roshin P.; Halo, Issufo

doi:10.1080/01431161.2016.1201234

Cited by 14 publications

(16 citation statements)

References 56 publications

(98 reference statements)

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“…Eddy sizes also show an inverse relation with the frequency of occurrence, and eddy radii varied between 6 and 49 km. Typically, long‐lived eddies show larger radius compared to eddies of shorter lifespan (Raj & Halo, ); our study also showed the similar pattern (Figure c). The mean radius of cyclonic (20 km) and anticyclonic eddies (21 km) does not show much difference, but the lifetime of cyclonic eddies exceeded that of the anticyclonic.…”

Section: Resultssupporting

confidence: 84%

Variability in Eddy Distribution Associated With East India Coastal Current From High‐Frequency Radar Observations Along Southeast Coast of India

et al. 2018

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Surface current observations from Indian Coastal Ocean Radar Network installed along the Tamil Nadu coast (southeast India) was used to quantify the mesoscale eddies associated with East India Coastal Current (EICC) during 2014–2017. A flow geometry‐based eddy detection algorithm has been applied to the daily averaged surface current maps and was able to detect and track mesoscale eddies of variable temporal and spatial scales. A total of 51 (27 cyclonic and 24 anticyclonic) eddy events, which lasted for more than 4 days, were identified during this period. Total count of cyclonic eddies exceeded the anticyclonic eddies with a clear seasonal pattern concurrent with the mean flow of EICC. The number of anticyclonic eddies leads in southwest monsoon and spring transition period; however, in fall transition and northeast monsoon period number of cyclonic eddies dominates in line with the poleward and equatorward phase of EICC, respectively. Monthly eddy kinetic energy maps showed a seasonal cycle with highest values in November and April. Monthly maps of the surface current vectors provide the broader picture of the seasonal reversal of currents in February and October and low magnitude offshore flow in the summer monsoon period. The Rossby number distribution along a transect perpendicular to the coast was in the order of O(1) shows the presence of strong submesoscale dynamics in the study domain. A case study of an eddy event conferred significant changes in the biological and physical properties of the coastal ocean derived from satellite data.

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Section: Resultssupporting

confidence: 84%

Variability in Eddy Distribution Associated With East India Coastal Current From High‐Frequency Radar Observations Along Southeast Coast of India

et al. 2018

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“…Several eddy detection schemes are available for the automated detection of eddies (Raj & Halo, 2016). The most commonly used methods are based on the geometric criteria (Chelton et al, 2011), dynamical criteria (Isern‐Fontanet et al, 2006) and the hybrid method, which combined the use of geometric as well as the dynamical criteria (Raj et al, 2016).…”

Section: Methodsmentioning

confidence: 99%

“…The most commonly used methods are based on the geometric criteria (Chelton et al, 2011), dynamical criteria (Isern‐Fontanet et al, 2006) and the hybrid method, which combined the use of geometric as well as the dynamical criteria (Raj et al, 2016). In order to identify eddies in the Lofoten Basin, we use an automatic hybrid eddy detection algorithm that has been used successfully in several oceanic basins (Halo, 2012; Halo et al, 2014), especially in the Lofoten Basin (Raj et al, 2015, 2016; Raj & Halo, 2016). To avoid the influence of the land contamination on altimeter data, the detection of eddies is limited to 30 km offshore of the Lofoten coast.…”

Section: Methodsmentioning

confidence: 99%

“…The tracking of eddies in space and consecutive time steps is done with reference to the centers of each eddy observation, in a generalized nondimensional property space, following the method proposed by Penven et al (2005). More details of tracking of Lofoten Basin eddies from altimeter data are presented in Raj et al (2015, 2016) and Raj and Halo (2016). A limitation of the eddy tracking method used here is the premature termination of eddy tracks due to an absence of surface eddy signatures for a short period, which can influence the estimation of eddy life.…”

Section: Methodsmentioning

confidence: 99%

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Interaction Between Mesoscale Eddies and the Gyre Circulation in the Lofoten Basin

et al. 2020

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The interaction between the mesoscale eddies and the cyclonic gyre circulation of the Lofoten Basin is studied using a suite of satellite altimeters, a regional coupled ocean‐sea‐ice data assimilation system (the TOPAZ reanalysis) and Argo float data. An automated method identified 5,373/5,589 individual anticyclonic/cyclonic eddies in the Lofoten Basin from more than 65,000 altimeter‐based eddy observations, of which 70–85% are found to be nonlinear. The nonlinearity of eddies is estimated from its translational and rotational velocities. The study found clustering of highly intense nonlinear eddies on either side of the Lofoten Basin. Further, we show the distinct cyclonic drift of the anticyclonic and cyclonic eddies, both confined to the western side of the basin, and its similarity to the middepth gyre circulation also confined to the same region. A well‐defined cyclonic drift pattern of eddies is found during the time period when the gyre circulation of the basin is strengthened, while a clear cyclonic drift of eddies is absent during a weakened gyre. Analysis of barotropic energy conversion in the reanalysis data shows maximum transfer of energy from the eddy field to the mean flow in the Lofoten Vortex region. Even though comparatively smaller (roughly 9 times) there is also notable transfer of energy from the mean flow to the eddies in the region located outside the Lofoten Vortex. Our study shows that the gyre circulation when strengthened, receives more energy from the Lofoten Vortex and loses less energy to those eddies circulating around the Lofoten Vortex.

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“…Two examples of such events have been recorded in the bay in summer 2008 (Prymnesium polylepis bloom) and 2006 (failure in the local sewage treatment plant), both of which produced an intense chlorophyll bloom. Regional ocean dynamics has been investigated, considering the Lofoten Basin as a test case, using altimeter data to detect mesoscale eddies and to follow their evolution (Raj and Halo 2016) 1 . The exercise was repeated using the AVISO altimeter data set at different temporal resolution and demonstrated the need of high temporal resolution data to better detect trajectory evolution of eddies in the Lofoten Basin.…”

Section: Remote Sensing Of the Coastal Zonementioning

confidence: 99%

European Remote Sensing: progress, challenges, and opportunities

Ban

Marullo

Eklundh

2017

International Journal of Remote Sensing

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Monitoring the mesoscale eddies of the Lofoten Basin: importance, progress, and challenges

Cited by 14 publications

References 56 publications

Variability in Eddy Distribution Associated With East India Coastal Current From High‐Frequency Radar Observations Along Southeast Coast of India

Variability in Eddy Distribution Associated With East India Coastal Current From High‐Frequency Radar Observations Along Southeast Coast of India

Interaction Between Mesoscale Eddies and the Gyre Circulation in the Lofoten Basin

European Remote Sensing: progress, challenges, and opportunities

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