GEO-SCI 103 Lecture 8Outline of Last Lecture 7: Solar Heating of Earth and transfer of HeatI. Solar Energy, Winds, and Ocean CurrentsII. The Seasons: Behind the Wheel of Climate ChangeOutline of Current Lecture 8: Seawater Density and Ocean Stratification (p. 120-123)I. Density Layering in the OceanA. ThermoclineB. High LatitudesC. Mid LatitudesD. Low LatitudesE. PycnoclineF. CTD DeploymentII. Seawater Density and the Role of HeatA. Density Stratification B. How salt changes physical properties of waterC. Salinity in relationship to environmentD. Water massE. DensityCurrent LectureI. Density Layering in the Ocean*The world ocean is well stratified (layered) in the low to mid latitudes due to solar heating of surface waters and the formation of a permanentthermocline. *The thermocline separates the warm (less dense) surface waters from the icy cold (more dense) deep waters.*The pycnocline represents this density barrier between surface and deep waters. Insufficient solar heating in the high latitudes inhibits the formation of a permanent thermocline and pycnocline. These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.A. The Thermocline: solar energy heats the surface waters in the low to mid latitudes (net solar gain in the tropics and subtropicsa. This creates a warm, less dense surface layer over very cold and dense deep waters. b. Permanent thermocline: the interval through which temperature decreases rapidly with increasing water depth. 1. Extends from the base of the mixed layer (depth from 50-100 m toapprox. 900-1000 m) 2. The depth of the surface mixed layer depends upon the mixing (homogenization) of the warmed surface waters by day-to-day wind/storms/waves/surface currents. (Mixed layer tends to be bigger in winter season)3. Absent in Polar Regions because surface waters and deep-waters are very cold. Therefore, there is little temperature contrast/gradient between polar surface and deep-waters4. Effective barrier that prevents the mixing of cold deep water with the surface mixed layer. This limits the amount of nutrients that can be brought up from below for use by organisms B. High Latitudes: Polar Watersa. Seasonal summer thermoclineb. No permanent thermocline (500-1000 m): surface waters are cold and so are deep waters C. Mid Latitudes (Temperate Waters)a. Seasonal summer thermoclineb. Permanent thermocline (-100-1000m)c. Cold deep waters below thermocline (below pycnoline) D. Low Latitudes: Tropical Watersa. Seasonal summer thermoclineb. Permanent thermocline (-100-1000m) c. Cold deep waters below thermoclineE. Pycnoclinea. The vertical interval in the ocean where density increases rapidly with water depth. It is very well developed in the tropics but almost absent in the polar oceanF. CTD Deployment (Conductivity Temperature Depth): instrument package that is lowered through the water and gathers environmental data.II. Seawater Density and the Role of Heat A. Density Stratificationa) Temperature and salinity together with pressure, control the density of waterb) Cold Water with more salinity=more densec) Warm water with less salinity = less densed) Therefore, warm water floats on cold water e) When water becomes denser by cooling or by processes of the hydrologic cycle such as evaporation or sea ice formation, it may sink to become a distinct intermediate water mass B. How salt changes physical properties of water a) Lowers the freezing point, such that water with the salinity of the oceancan exist as a liquid down to temperatures as low as -2 degrees Celsius b) Changes temperature of maximum density, making the coldest water the densest so it naturally settles to bottom of ocean basinC. Salinity in relationship to Environmenta) In tropic areas, where there is abundant rainfall, surface water salinities are diluted (less amount of salt)b) In the subtropics (where evaporation is high), surface water salinities are typically higher (ex: Mediterranean Seawarm salty water) D. Water Mass a) Body of water that can be identified by its physical and chemical characteristics (temperature, salinity, density, dissolved gasses, dissolved nutrients)b) When water becomes denser by cooling or by processes of the hydrologic cycle such as evaporation or sea ice formation, it may sink to become a distinct intermediate water mass c) Intermediate and deep-water sink to their level of neutral buoyancy (equilibrium) below the sun warmed surface waters. E. Densitya) Grams per cubic centimeter or kilograms per cubic meter b) Pure Water= temperature of 25 degrees Celsius and has a density of 1.000 g/cm^3. c) Seawater= density varies between 1.022 g/cm^3 (warm tropical surface waters) and 10.28 g/cm^3 (cold polar surface waters and deep waters d) Sigma Tee: (density, (g/cm^3)-1.000) x 1000.1. Therefore, ocean density values range between