1. Regional Oceanography I
OEAS 604
Lecture Outline
Arctic circulation
Atlantic basin circulation
Indian Ocean circulation
Chapters 8,9 – Knauss
Chapter 12 – Talley et al.

2. Two deep basins
separated by sills
Outlets to North
Atlantic restricted to
Norwegian Sea region
Labrador Sea – water
formation region at
lower latitude

3. Primary Currents EGC, East Greenland Current EIC, East Iceland Current
IC, Irminger Current
IFF, Iceland-Faroe Front
JMC, Jan Mayen Current
NAC, Norwegian Atlantic Current
NIC, North Irminger Current
Grey areas - polynyas

4. Overall schematic of (a) circulation, (b) water mass layers and transformation sites, and (c) water masses in potential temperature-salinity.
EGC, East Greenland Current; WSC, West Spitsbergen Current.
AW, Atlantic Water; AIW, Arctic Intermediate Water; ASW, Arctic Surface Water; DW, Deep Water; PIW, Polar Intermediate Water; PW, Polar Water.
Convective Chimneys – water formation regions

5. Deep Water
Formation
Regions

6. Summer minimum
Winter maximum

10. (a) Potential temperature (°C) and (b) salinity in the Fram Strait.

11. (a) Potential temperature (°C) and (b) salinity across the southern Greenland Sea at 73.5°N.

12. Arctic Ocean: (a) Potential temperature and (b) salinity profiles for the Canadian (dashed) and Eurasian Basins (solid).. (c) Expanded potential temperature and salinity profile in the Canadian Basin

13. (a) Track of the Fram (1893-1896)
(a) Track of the Fram ( ). (b) The ship was intentionally frozen into the ice in 1893 and drifted with the pack until © Source: From Frammuseet (2003).

15. East and west basins
separated by Mid-Atlantic
Ridge
Connection to Arctic and
Southern Ocean
NADW formation in Greenland,
Norwegian and Labrador Seas

16. Antarctic Bottom Water
Pathways
Different varieties along
western and eastern
sides of basin
Limited across basin
exchange
Flow on eastern side
blocked by Walvis Ridge

17. AAIW
Depth of Minimum
Salinity

18. Atlantic Ocean Current Structure
Subtropical gyres in both hemispheres
Eastern and western boundary currents
Subpolar gyre in northern hemisphere
Equatorial current system
Connection to Arctic
Connection to Southern Ocean

19. Western Boundary Currents
Gulf Stream, Brazil Current
Eastern Boundary Currents
Canary Current, Benguela Current
Equatorial Current System
North Equatorial Current
Equatorial Countercurrent
South Equatorial Current
Subpolar Gyre
North Atlantic Current
Irminger Current
East and West Greenland Currents
Labrador Current

20. Gulf Stream
Deep current
High velocity
High transport
Brazil Current

21. Gulf Stream Variability
Branches – North Atlantic Current, Azores Current
Sargasso Sea

22. Gulf Stream rings
Warm core ring
Cold core rings
Cold core ring location

23. Gulf of Mexico
Loop Current – spin off eddies

24. Canary Current – eastern boundary current
Shallower
Lower velocity
Upwelling

25. Mediterranean Outflow
Temperature at 1000 m
Salinity at 1000 m

26. Mediterranean Sea Bathymetry

27. Currents – Mediterranean

28. Water Masses - Mediterranean
LIW - Levantine Intermediate Water

29. Temperature section across
Equator in Atlantic Ocean

30. South
Atlantic
Current
System

31. Indian Ocean
Blocked to north
Wind patterns change direction with season (monsoon)
Circulation in
northern Indian Ocean changes
direction every six
months

32. January – Mean Wind Field

33. Northeast Monsoon
Northern winter (Dec-Feb) cooling of Siberia and Central Asia land mass – greater than cooling of ocean
Atmospheric high pressure forms over land and develops polar continental air mass that sets up pressure gradient that directs winds from land towards sea – cold dry air
Over Africa have trans-equatorial meridional atmospheric pressure gradient (high north, low south) that directs wind into Indian Ocean
Blocks the southward extent of NE monsoon – usually does not cross about 10°S

34. July – Mean Wind Field

35. Southwest Monsoon
Northern summer (June-Aug) warming of southern Eurasia and North Africa land mass
Atmospheric low pressure forms that directs winds from sea to land – pick up moisture
Strong southwest winds blow over the Arabian Sea and Ba of Bengal carrying considerable water vapor – produces the summer rains

36. Indian Ocean – Monsoon System

37. Northeast Monsoon
Southwest Monsoon

39. Agulhas Current
Western boundary
current

40. Leeuwin Current – eastern boundary current

41. Australian
Mediterranean
Sea

42. Australian Mediterranean Sea
February
August

43. Next Class Continue Currents and Water Masses
Pacific Ocean – Chapter 10, Talley et al.
Ocean-atmosphere coupling, Climate change – Chapter 14, Talley et al.