OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions SPECIAL DATES: MPA meeting…6 Jul R/V Pt Sur Cruise…14 Jul R/V Pt Sur Cruise…25 Jul Exam-1 (definite)...2 Aug Exam-2 (Tentative)…1 Sep Labor Day Holiday...5 Sep Final Exam...19 Sep (Sp-226, ) EX 1 OC3230 Calendar, Summer 2005 version 7 August 2005 S.D. trip

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Distributions of properties (“Taxonomy” of T-S) T: 0-6 ˚C S: ‰ T ave : 3.5 ˚C S ave : 34.7 ‰ Mostly “zonal” but with important variations Vert. Grad >> Horz. Grad Presentation types: Horizontal maps or plan views (contours) Vertical Profiles Vertical Sections (contours) 75% by volume

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions “Summer” (N.H.) “Winter” (N.H.)

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Annual range is maximum in mid latitudes

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions T follows the sun  follows 1/T S follows ? ? (Zonal) Sea Surface T, , S

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions (Zonal) Sea Surface Salinity

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Sea Surface Salinity (cm)

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Sea Surface Salinity “Fresh”“Salty”

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Temperature Salinity thermocline halocline Profiles

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Profiles

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions pycnocline Density Note how curves join at depth: Deep water conditions are less variable Top-to-bottom contrast is most extreme at the equator Profiles

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Seasonal cycle of upper ocean temperature in mid latitudes Note: different methods of displaying the same data 50˚N, 145˚W (“Station P”) Profiles and Contours

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Sections-Temperature (Vertical) Temperature section through Atlantic Ocean Note bowl-shaped isotherms Note iso-thermal (constant temperature) conditions at high latitudes, particularly in the southern hemisphere

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Sections-Temperature ? ? Which profile comes from which latitude?

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Sections-Temperature A review: Which section is in situ temperature and which section is potential temperature,  ?

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Sections-Temperature & Salinity Fresh Salty ?

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Sections-Temperature & Salinity version from text (note opposite view from west) T (˚C) S (‰) Atlantic

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Sections-Temperature & Salinity T (˚C) S (‰) Pacific S-minS-min

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Sections-Oxygen (ml/l) Atlantic Pacific “Young” “Old” Surface values are ~8 ml/l

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Sections-WOCE (80s-90s) The World Ocean Circulation Experiment (WOCE) Decade-long, major international program to map T-S (and other) properties Section A-16 along 25W Longitude provides a good look at the water mass structure of the Atlantic Ocean

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Sections-WOCE (80s-90s) Potential Temperature

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Sections-WOCE (80s-90s) Salinity

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Sections-WOCE (80s-90s) Oxygen

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Other Tracers Known Source Functions OC Distributions Chlorofluorocarbons (e.g., Freon) and their ratios

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Other Tracers Today’s CFC distributions in the Atlantic Ocean Note the high values in the northeast surface waters consistent with a deep-water source region

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Other Tracers Helium and “Bomb” carbon or heavy water (tritium)

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Water Masses What’s going on? Interleaving and mixing of “water masses” created near the surface in particular areas Deepest layers originate from far N and S in Atlantic

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Water Masses Step 1: Subduction Step 2: Mixing as water flows along isopycnals… N-S surface gradient vertical gradient

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Water Masses S T Water Type: point on the T-S diagram Water Mass: line on the T-S diagram Water formed as a mixture of two water types must have T-S values that fall along the line between the two original points

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Water Masses S T Water formed as a mixture of three water types must have T-S values that fall within the triangle be- tween the original points Water Type: point on the T-S diagram

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Water Masses TST-S ***Critical Figure*** This illustrates changes in the shape of profiles and T-S curves as mixing occurs between distinct water types The example mimics the low- salinity layer observed at mid depths in the Atlantic

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Water Masses Thermohaline Circulation is Inferred from T-S Distributions

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Water Masses

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Water Masses S T ***Critical*** Classic T-S curve observed in the S. Atlantic Ocean It provides evidence of 4 different source water types AAIW: Antarctic Intermediate Water NADW: North Atlantic Deep Water AABW: Antarctic Bottom Water

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions S T Water Masses (< 4˚C) World Ocean ? ? ?

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions S T Water Masses (< 4˚C) World Ocean Indian Pacific Atlantic

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Water Masses Deep water masses originate from the Southern Ocean around Antarctica or from the north Atlantic Ocean.

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Water Masses Intermediate waters are dominated by AAIW, which originates along the subpolar front in the Southern Ocean

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Water Masses

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Water Masses Value and depth of the salinity minimum layers in the Atlantic Ocean Evidence for northward spreading of AAIW with a concentration of flow along the western boundary AAIW ?

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Water Masses Surface water masses are many and have T-S characteristics of the region

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Water Masses Mediterranean Outflow

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Thermohaline “Conveyor Belt” Thermohaline circulation influences and buffers the climate system through the slow circula- tion of the deep currents and the exchange between surface and deep water that takes place over several thousand years

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Thermohaline “Conveyor Belt”

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions Thermohaline “Conveyor Belt”

OC3230-Paduan images Copyright © McGraw Hill Chap 7-8: Distributions O.T.E.C. concept system closedsystem opensystem