deformation radius (a length measure derived from the
depth, stratification strength, and Coriolis parameter).
Eddies are mainly generated by the instability of largescale currents, and these motions follow the law of potential vorticity conservation that counts variations of
Coriolis parameter with latitude (beta effect) and depth
variation (topographic effect). Vorticity balance as derived
in special cases by Sverdrup and Stommel explains also
existence of strong narrow-band currents near the western
coasts of the oceans: Gulf Stream in the Atlantic, Kuroshio
in the Pacific, etc.
Surface and deep currents in the ocean
Surface currents in the ocean follow the global wind patterns, forming the basin-wide gyres with stronger western
boundary currents. Many descriptions of surface currents
can be found in the literature (e.g., Talley et al., 2011).
Modern views have been created with the help of remote
sensing and numerical modeling. We refer to the recent
paper by Dohan and Maximenko (2010), from where we
have adopted the schematic of circulation in the Northern
Atlantic (Figure 1). In the Southern Hemisphere, the continents do not cut the ocean flow path; Antarctic Circumpolar Current flows clockwise through all the oceans and
provides the global link of water masses of different
oceans.
When warm surface waters move toward the polar
regions, they cool down. As the water density increases,
the waters sink toward greater depths and can move
toward tropical regions. Sinking waters are modified by
freshwater flux. When the latter exceeds some critical
level, the “new” water in the polar region may not be dense
Currents, Figure 2 (a) Schematic of Northern Atlantic circulation with the rapid monitoring array at 26
N. From http://www.noc.
soton.ac.uk/rapidmoc/. (b) Gulf Stream (blue curves), meridional overturning circulation (MOC; red curves), Ekman (black curves) and
upper mid-ocean (purple curves) transports (10 days and 3 months, low-pass filtered) April 2004 to March 2011 as measured by the
rapid array. Transports are in Sverdrups (1 Sv ¼ 10
6 m
3 s
À1 ). From http://www.noc.soton.ac.uk/rapidmoc/ (Bryden et al., 2012).
CURRENTS
141
depth, stratification strength, and Coriolis parameter).
Eddies are mainly generated by the instability of largescale currents, and these motions follow the law of potential vorticity conservation that counts variations of
Coriolis parameter with latitude (beta effect) and depth
variation (topographic effect). Vorticity balance as derived
in special cases by Sverdrup and Stommel explains also
existence of strong narrow-band currents near the western
coasts of the oceans: Gulf Stream in the Atlantic, Kuroshio
in the Pacific, etc.
Surface and deep currents in the ocean
Surface currents in the ocean follow the global wind patterns, forming the basin-wide gyres with stronger western
boundary currents. Many descriptions of surface currents
can be found in the literature (e.g., Talley et al., 2011).
Modern views have been created with the help of remote
sensing and numerical modeling. We refer to the recent
paper by Dohan and Maximenko (2010), from where we
have adopted the schematic of circulation in the Northern
Atlantic (Figure 1). In the Southern Hemisphere, the continents do not cut the ocean flow path; Antarctic Circumpolar Current flows clockwise through all the oceans and
provides the global link of water masses of different
oceans.
When warm surface waters move toward the polar
regions, they cool down. As the water density increases,
the waters sink toward greater depths and can move
toward tropical regions. Sinking waters are modified by
freshwater flux. When the latter exceeds some critical
level, the “new” water in the polar region may not be dense
Currents, Figure 2 (a) Schematic of Northern Atlantic circulation with the rapid monitoring array at 26
N. From http://www.noc.
soton.ac.uk/rapidmoc/. (b) Gulf Stream (blue curves), meridional overturning circulation (MOC; red curves), Ekman (black curves) and
upper mid-ocean (purple curves) transports (10 days and 3 months, low-pass filtered) April 2004 to March 2011 as measured by the
rapid array. Transports are in Sverdrups (1 Sv ¼ 10
6 m
3 s
À1 ). From http://www.noc.soton.ac.uk/rapidmoc/ (Bryden et al., 2012).
CURRENTS
141