Bellwork 2/2 What causes surface circulation? How is surface circulation in the Southern Hemisphere different from the Northern Hemisphere? How do gyres play a role in the creation of the Great Pacific Garbage Patch?

Gyres & The GPGP Circular moving ocean currents trap material within the North Pacific basin.

Sometimes, the material is not confined to one basin. This simulation stops at 10 years…plastic & other materials don’t “go away” after 10 years

Which currents are easier to observe on the real data? Why might the Canary Current be more difficult to observe?

2. Deep Ocean Circulation accounts for thorough mixing of deep water masses formed by differences in salinity & temperature “thermohaline” currents Begin forming in high latitudes as cold, salty water sinks

So, what causes these Thermohaline Currents? As the name suggests…differences in water Temperature & Salinity (salt content) Let’s take a closer look at the composition of this ocean water…

Composition of Seawater What is in Seawater? Salt! Sodium Chloride (NaCl) But also…magnesium, sulfate, calcium, and potassium

Salinity Total amount of solid material dissolved in water Expressed in “parts per thousand” (ppt) Is the salinity of our oceans equal throughout? What might contribute to this?

Temperature: Ocean water is not the same temperature throughout… Latitude affects surface water temperatures

We’re going to investigate in our lab today  Density: The density of our seawater is also not equal throughout each basin! WHY??? WHO CARES??? We’re going to investigate in our lab today 

Quick review…Density: What is meant by “Density”? How much matter is in a given volume D= m/v Less dense material floats on top of more dense material

Ocean Water Density Lab: How does temperature & salinity affect ocean water density? How does this lead to layering & deep currents in the ocean?

Bellwork 1/30 In Part 1 of your lab…what happened to the blue (cold) water melting off the ice cube when it was in warm water? What about cold water? What sorts of observations did you make?

Ocean Water Density Lab: How does temperature & salinity affect ocean water density? How does this lead to layering in the ocean?

Part 2: Salinity & Density You are trying to observe how the fresh, slightly salty, and very salty water layers You do not need to stir the different waters together…just gently pipet a few drops into the beaker

Bellwork 2/1 Please, turn in your Ocean Water Density lab…if you haven’t already  1. What sorts of factors can change ocean water density? 2. How might ocean water density play a role in ocean currents?

Coming up… Monday 2/13: Today 2/1: Friday 2/3: Tuesday 2/7: Finish ocean water properties (density) Intro to Sediments Begin sediment lab Friday 2/3: Finish sediment lab Discuss ocean sediments Tuesday 2/7: Ocean Acidification Thursday 2/9: Wrap up loose ends Review time Monday 2/13: -- Unit 1 Oceans Test…and begin Unit 2: The Atmosphere!

Sources of Sea Salts Chemical weathering of rocks Volcanic eruptions

Relative proportions of water and dissolved components in seawater

The ocean’s salinity has been relatively stable for millions of years So, if these salts are constantly being put into the ocean, is the water getting saltier?! Nope! The ocean’s salinity has been relatively stable for millions of years Why not? Organisms using the salts Salts are chemically precipitated out as sediments

Processes affecting seawater salinity Processes that decrease salinity (add water) Precipitation Runoff from land Icebergs melting Sea ice melting Processes that increase salinity (remove water) Evaporation Formation of sea ice

Variations in the ocean’s surface temperature and salinity with latitude What’s going on here?

Change in salinity = halocline

Temperature vs. Depth Density vs. Depth

Ocean temperature Temperature variation with depth Low-latitudes High temperature at the surface Rapid decrease in temperature with depth (thermocline) High-latitudes Cooler surface temperatures No rapid change in temperature with depth

Variations in ocean water temperature with depth

Ocean density Density is mass per unit volume - how heavy something is for its size Determines the water’s vertical position in the ocean Creating layers in the ocean Factors affecting seawater density Salinity Temperature Which has a greater influence—temperature or salinity?

Ocean density Density variations with depth Low-latitudes Low density at the surface Density increases rapidly with depth (pycnocline) because of colder water High-latitudes High-density (cold) water at the surface Little change in density with depth

Variations in ocean water density with depth

Quick Practice Draw graph of Temperature VS Depth at: Hawaii

Draw graph of Temperature VS Depth at: Bering Strait

Draw graph of Density VS Depth at: New Zealand

Draw graph of Density VS Depth at: Varangerhalvoya National Park (Botsfjord, Norway)

Why does any of this matter?!?! Ocean Currents Weather Climate