The EK drift velocities and radii are shown in Fig. 15a versus the maximal wind
velocity and in Fig. 15b versus the sea surface tilt. Blue and pink colors correspond
to anticyclonic ice drift and cyclonic ice drift. The absolute values of the EK drift
velocity increase proportionally to the maximal wind speed. Ice drift speeds |v ek | in
the anticyclonic gyre are slightly higher than the drift speeds in the cyclonic gyre.
The EK radii R ek in the anticyclonic gyres are also slightly greater than the EK radii
in the cyclonic gyres. The EK radii decrease with the increase of the maximal wind
speed. The EK radii are slightly greater than the value of the r-coordinate where the
absolute wind velocity is maximal. The EK radii and ice drift speeds |v ek |
insignificantly increase as the sea surface tilt increases.
Conclusions
Analytical solutions describing steady-state wind drift of sea ice with elastic-plastic
rheology are constructed and analyzed. Solutions describing zonal ice drift consist
of the elastic ice strip with the solid body motion and the plastic ice strip where pure
shear drift are realized. There is the only solution describing the ice drift to the
“north” when the wind is parallel to the shoreline and the shoreline is on the
“eastern” side of the drift ice. If the wind has onshore component then there
are solutions describing both zonal ice drifts in the “northern” and “southern”
directions. Depending on the sea surface tilt and onshore wind component the width
of the elastic strip changes from 1 to 100 km. The drift speed of the elastic strip is
below 45 cm/s, when the wind speed is 20 m/s, and below 25 cm/s, when the wind
speed is 10 cm/s. The mean thickness of the ice rubble in the shear zone of 20 km
width exceeds 6 m when the speed of onshore wind is 20 m/s.
The analytical solutions describing circular wind drift of ice are investigated in
the case when velocity profile of the wind gyre is described by the polynomial
function considered in [9]. The solutions describing cyclonic and anticyclonic drift
are constructed taking into account sea surface tilt. The solutions consist of elastic
circular kernel with the solid body rotation and plastic shear zone of the ring shape.
The solutions are localized in the region of the wind gyre. Solutions with the plastic
shear zone exist when the maximal wind velocity is greater than the critical value.
The general property of the solutions is the increase of the elastic kernel radius, and
the decrease of the shear zone width with the decrease of the maximal wind
velocity. It is shown that cyclonic and anticyclonic solutions with the plastic shear
zone exist both when the maximal wind velocity is greater than the critical value.
The influence of the sea surface tilt on the characteristics of the ice drift is much
smaller than the influence of the wind velocity. The maximal drift speed at the
periphery of the elastic kernel is below 45 cm/s, when the maximal wind speed is
20 m/s, and below 25 cm/s when the maximal wind speed is 10 cm/s.
The comments for the future analysis are as follows. Rheological constants
P* = 5 kPa and γ = 3 give reasonable characteristics of the constructed solutions.
More detailed comparison of analytical solutions and observed features of ice drift
556
A. Marchenko
velocity and in Fig. 15b versus the sea surface tilt. Blue and pink colors correspond
to anticyclonic ice drift and cyclonic ice drift. The absolute values of the EK drift
velocity increase proportionally to the maximal wind speed. Ice drift speeds |v ek | in
the anticyclonic gyre are slightly higher than the drift speeds in the cyclonic gyre.
The EK radii R ek in the anticyclonic gyres are also slightly greater than the EK radii
in the cyclonic gyres. The EK radii decrease with the increase of the maximal wind
speed. The EK radii are slightly greater than the value of the r-coordinate where the
absolute wind velocity is maximal. The EK radii and ice drift speeds |v ek |
insignificantly increase as the sea surface tilt increases.
Conclusions
Analytical solutions describing steady-state wind drift of sea ice with elastic-plastic
rheology are constructed and analyzed. Solutions describing zonal ice drift consist
of the elastic ice strip with the solid body motion and the plastic ice strip where pure
shear drift are realized. There is the only solution describing the ice drift to the
“north” when the wind is parallel to the shoreline and the shoreline is on the
“eastern” side of the drift ice. If the wind has onshore component then there
are solutions describing both zonal ice drifts in the “northern” and “southern”
directions. Depending on the sea surface tilt and onshore wind component the width
of the elastic strip changes from 1 to 100 km. The drift speed of the elastic strip is
below 45 cm/s, when the wind speed is 20 m/s, and below 25 cm/s, when the wind
speed is 10 cm/s. The mean thickness of the ice rubble in the shear zone of 20 km
width exceeds 6 m when the speed of onshore wind is 20 m/s.
The analytical solutions describing circular wind drift of ice are investigated in
the case when velocity profile of the wind gyre is described by the polynomial
function considered in [9]. The solutions describing cyclonic and anticyclonic drift
are constructed taking into account sea surface tilt. The solutions consist of elastic
circular kernel with the solid body rotation and plastic shear zone of the ring shape.
The solutions are localized in the region of the wind gyre. Solutions with the plastic
shear zone exist when the maximal wind velocity is greater than the critical value.
The general property of the solutions is the increase of the elastic kernel radius, and
the decrease of the shear zone width with the decrease of the maximal wind
velocity. It is shown that cyclonic and anticyclonic solutions with the plastic shear
zone exist both when the maximal wind velocity is greater than the critical value.
The influence of the sea surface tilt on the characteristics of the ice drift is much
smaller than the influence of the wind velocity. The maximal drift speed at the
periphery of the elastic kernel is below 45 cm/s, when the maximal wind speed is
20 m/s, and below 25 cm/s when the maximal wind speed is 10 cm/s.
The comments for the future analysis are as follows. Rheological constants
P* = 5 kPa and γ = 3 give reasonable characteristics of the constructed solutions.
More detailed comparison of analytical solutions and observed features of ice drift
556
A. Marchenko