http://www.ssec.wisc.edu/data/sst/

TYPICAL TEMPERATURE PROFILES Thermocline is a range of depths (from Pinet, 1998) Thermocline is a range of depths

CTD – Conductivity-Temperature-Depth Recorder thermistor CTD – Conductivity-Temperature-Depth Recorder

Celsius Temperature = Thermodynamic Temperature – 273.15ºK (from Pinet, 1998) Celsius Temperature = Thermodynamic Temperature – 273.15ºK Measured with International Temperature Scale ( ITS-90) T68 = 1.00024 T90 T68 = International Practical Temperature Scale 1968 (ITPS-68)

(from Pinet, 1998) (NORTHERN HEMISPHERE) 4

(from Pinet, 1998) (NORTHERN HEMISPHERE) 4

Pressure = Mass * Gravity / Area Pressure = Force / Area Pressure = Mass * Gravity / Area Mass = Density * Volume Pressure = Density * Volume * Gravity / Area Volume/ Area = Depth Pressure = Density * Gravity * Depth

DENSITY VARIES CONINUOUSLY PRESSURE z - z Pz Pz = - g z DENSITY CONSTANT z1 - z Pz z2 z3 Pz = -Σ13 ng zn DENSITY STRATIFIED Pycno- cline - z Pz Mixed Layer DENSITY VARIES CONINUOUSLY WITH DEPTH Units: N/m2 = Pa 1 m depth ~ 1 db ~ 104 Pa

Major Constituents Cl- 18.98/34.4 = 55% Na+ 10.556/34.4 = 31% The concentrations of these major constituents are conservative. They are unaffected by most biological and chemical processes. This is related to the principle of constant proportion The MAJOR constituents of seawater are conservative. Conservative means that they are not affected by chemical or biological processes. Discuss. You can mix two ocean waters and get a third mixture. That is a conservative process. The major constituents are sodium and chloride. Note that salt is similar to blood. The concentration of salts is nearly the same. What else is in seawater? Cl- 18.98/34.4 = 55% Na+ 10.556/34.4 = 31%

Residence Time = Concentration (mass/vol)/Rate of supply (mass/vol/time) Residence time is important. The easy way to calculate it is to divide the amount of the material (say lithium) in the ocean by the rate that it is coming in from the rivers. Of course sodium and chloride stay around a long time. But not long on geological time scales. Many are reactive and don’t stay in the ocean very long. Calcium builds shells. Barium, cobalt, chromium and aluminum react and precipitate. Strontium is absorbed along with calcium in shells. The ocean mixes on scales of 100 to 1000 years but the major constituents are around for millions of years. The ocean is well mixed.

8.

Reference Composition Salinity SR does have units! TEOS-10 Manual “Thermodynamic properties of seawater are more accurately represented as functions of SA than of SP.” Reference Composition Salinity SR does have units! SR = 35.16504/35 Sp (g/kg)

----- cannot be measured in practice. Absolute Salinity SA : “ratio of the mass of dissolved material in sea water to the mass of sea water.” ----- cannot be measured in practice. Reference Salinity SR gives our best estimate of SA SA = SR + SA SR = 35.16504/35 Sp (g/kg) (From TEOS-10 Manual) Still much work to be done on SA

Where do the Salts come from? Let’s go over the sources of the salts.

high temperate subtropical 7. (from Pinet, 1998)

TEMPERATURE Salinity Temperature 37 34 31 30 20 10

density anomaly (kg/m3) WATER DENSITY density anomaly (kg/m3) 23 24 25 26 27 Equator Density Profiles in the Open Ocean 1000 Tropics depth (m) 2000 High Latitude 3000 4000 Density Anomaly σt = Density - 1000 Specific Volume = Inverse of Density

11. (from Pinet, 1998)

TEOS-10

TEOS-10

Effects of Salinity on the Properties of Seawater Lowers freezing point Lowers temperature of maximum density Lowers evaporation rate Seawater freezes before reaching max density -1.33 Now we see how the salt content changes the properties of seawater. Recall how salt ions sit amongst the water molecule clusters as the salts are hydrated. Freezing point depression: typically salt water freezes at -1.9C. Salt keeps the molecules from forming the crystal lattice until enough heat is removed to slow things down. Density: The salts are heavier than water molecules and thus the salty water is heavier. The salts cause the temperature of maximum density to be decreased. Above salinity 27 seawater density decreases with increasing temperature. What does this mean to lakes and oceans? A lake turns over as it freezes The ocean remains stratified as it freezes 24.7 (from Pinet, 1998)

90 % of Ocean Water Greater influence of salinity on density Mean T & S for World Ocean Greater influence of salinity on density

Sound Speed: C = 1449 + 4. 6 T – 0. 055 T 2 + 1. 4 (S – 35) + 0 Sound Speed: C = 1449 + 4.6 T – 0.055 T 2 + 1.4 (S – 35) + 0.017 D (m/s) Cair = 330 m/s ~ 660 kn

SOFAR Channel and Acoustic Shadow Zone (SOund Fixing And Ranging ) Depth (m) (From Tomczak’s Web Site)

k = vertical attenuation coefficient (m-1) clear ocean water turbid coastal water Light Penetration in Sea Water Iz = Io e –k z k = vertical attenuation coefficient (m-1) (fraction of that entering at the surface)

Water absorbs reds and oranges (long wavelength light – warm colors) scatters blue (short wavelength light – cool colors)

Coriolis Deflection Animated illustration 1 Animated illustration 2 http://nsidc.org/cryosphere/arctic-meteorology/factors_affecting_climate_weather.html Animated illustration 1 Animated illustration 2

Atmospheric Processes Air pressure differences create the global wind field. Coriolis deflection causes winds to blow in the direction in which they do. Air Pressure: P = density x g x height

Equatorial atmospheric circulation – Walker cell isobaric surfaces Walker Cell Strong convection in W Pac, Congo, Amazon

Meridional air circulation cells Trades - return flow in the Hadley/Walker cell system Meridional air circulation cells

Note the strong convection in: a) the western tropical Pacific, b) along ~5-10ºN (ITCZ), and c) along 40-50º (Polar Fronts) http://www.ssec.wisc.edu/data/

Rotating Globe

Global Wind Fields

Global Air Pressure Distribution Icelandic Low Aleutian Low

Summer/Winter Pressure Variations Permanent Highs over Indian S Pac, S Atl, Permanent Low over Southern Ocean High over N Pac and N Atl modified by Aleutian Low and Icelandic Low

Global wind speeds

Seasonal Variations of ITCZ and generation of Tropical Depressions

Seasonal excursion of the ITCZ Mats Halldin

SE trades become SW when crossing the Equator to the N (Coriolis) This generates a Tropical Depression

Location of formation of tropical storms/hurricanes Steered by oceanic tropical anticyclone – Trades / Westerlies