other (t = 0 and t = 15), the jet vanishes, and the flow rounds the region of the
hugged loops, like one solid body.
Figures 4 and 8 show that, despite the external anticyclonic rotation, a cyclonic
Taylor column can be formed over the depression during a specific interval of the
anticyclone intensity. This column is capable to capture and twist
counter-clockwise passive liquid particles as well as vortices inside it. This gives an
explanation to the seemingly strange cyclonic direction of the observed lens motion
in the works by Ivanov and Korablev [6, 7]. In the case where the initial location of
the lens center is outside the Taylor column, the lens leaves the vicinity of the LB.
Conclusions
The formation, drift, and destruction of mesoscale vortices within the LB occur
against a background of the large-scale processes in the study site. Hence, the PS is
a buffer zone of the water exchange between the North Atlantic and the Arctic
Ocean [11]. The complex character of their interaction determines the seasonal and
multi-year variability of the hydrological regime and dynamics of the PS and, in
particular, the LB. Raj et al. [15] note the inter-annual and seasonal variability of
the number of observed vortices in the investigated basin and their relationship to
these external processes. It should be kept in mind that it is almost impossible
to recreate in the model experiment the complete similarity with the real ocean
conditions. However, such modeling, in spite of some assumptions, allows us to
trace all the stages of the influence of the external parameters on the behavior of the
intrathermocline lens. In this contribution based on the results of various experimental observations, the existence of a quasi-permanent intratermocline lens in the
vicinity of the deep part of the LB is postulated as a fact. Within the framework of
the numerical model, we model various scenarios of the lens motion, which can
take place in the ocean. In particular, it is clearly shown that (1) the lens not
captured by the quasi-stationary Taylor column leaves the LB region, (2) the lens
located in the vicinity of the hyperbolic point can remain for a long time in the
quasistatic state, (3) the lens belonging to the inner part of the Taylor column,
which is associated with the separatrix loop of the stream function, performs closed
periodic rotations in the cyclonic direction. The latter can occur even in presence of
a large-scale anticyclonic vortex of moderate intensity. The model conclusions
about the behavior of the quasi-constant anticyclonic vortex in the LB coincide with
the main observed results. They also give an idea of the physical processes that
determine the various conditions of its cyclonic drift depending on the variability of
the velocity field characteristics and the topographic effect.
Acknowledgements The work was supported by Russian Science Foundation (grant
14-50-00095) (analysis of the ocean data) and Ministry of Education and Science of the Russian
Federation (grant 14.W03.31.0006, (numerical simulation), and Russian Foundation of Basic
Research (grant 16-55-150001) (vortex dynamics).
Evolution of an Intrathermocline Lens …
345
hugged loops, like one solid body.
Figures 4 and 8 show that, despite the external anticyclonic rotation, a cyclonic
Taylor column can be formed over the depression during a specific interval of the
anticyclone intensity. This column is capable to capture and twist
counter-clockwise passive liquid particles as well as vortices inside it. This gives an
explanation to the seemingly strange cyclonic direction of the observed lens motion
in the works by Ivanov and Korablev [6, 7]. In the case where the initial location of
the lens center is outside the Taylor column, the lens leaves the vicinity of the LB.
Conclusions
The formation, drift, and destruction of mesoscale vortices within the LB occur
against a background of the large-scale processes in the study site. Hence, the PS is
a buffer zone of the water exchange between the North Atlantic and the Arctic
Ocean [11]. The complex character of their interaction determines the seasonal and
multi-year variability of the hydrological regime and dynamics of the PS and, in
particular, the LB. Raj et al. [15] note the inter-annual and seasonal variability of
the number of observed vortices in the investigated basin and their relationship to
these external processes. It should be kept in mind that it is almost impossible
to recreate in the model experiment the complete similarity with the real ocean
conditions. However, such modeling, in spite of some assumptions, allows us to
trace all the stages of the influence of the external parameters on the behavior of the
intrathermocline lens. In this contribution based on the results of various experimental observations, the existence of a quasi-permanent intratermocline lens in the
vicinity of the deep part of the LB is postulated as a fact. Within the framework of
the numerical model, we model various scenarios of the lens motion, which can
take place in the ocean. In particular, it is clearly shown that (1) the lens not
captured by the quasi-stationary Taylor column leaves the LB region, (2) the lens
located in the vicinity of the hyperbolic point can remain for a long time in the
quasistatic state, (3) the lens belonging to the inner part of the Taylor column,
which is associated with the separatrix loop of the stream function, performs closed
periodic rotations in the cyclonic direction. The latter can occur even in presence of
a large-scale anticyclonic vortex of moderate intensity. The model conclusions
about the behavior of the quasi-constant anticyclonic vortex in the LB coincide with
the main observed results. They also give an idea of the physical processes that
determine the various conditions of its cyclonic drift depending on the variability of
the velocity field characteristics and the topographic effect.
Acknowledgements The work was supported by Russian Science Foundation (grant
14-50-00095) (analysis of the ocean data) and Ministry of Education and Science of the Russian
Federation (grant 14.W03.31.0006, (numerical simulation), and Russian Foundation of Basic
Research (grant 16-55-150001) (vortex dynamics).
Evolution of an Intrathermocline Lens …
345