ATOC 1060 1nd EditionBased on Chapter 6 Lecture 10Outline of Last Lecture I. Ocean CirculationA. Surface Ocean Circulation driven by windB. Deep Ocean Circulation- Driven by differences in Water DensityII. Coupled Climate VariabilityA. El Nino Southern OscillationB. Tropical Pacific East West Ocean Atmospheric circulationC. How does it workD. Impacts on the Extra Tropics?Outline of Current Lecture Intro to the CryosphereI. SnowII. PermafrostIII. GlaciersIV. Sea IceCurrent LectureI. Snow We measure snow by using Snow Water Equivalent (SWE) SWE: height of snow if you melted it to form water, Units cm 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. Depth = SWE * (waterdensity/snow density) Depth = SWE * 5 Depth and SWE in same unitsComposite Analysis 1. Find largest ENSO events 2. Average snow during those events 3. Assess impact of ENSO on snow Snow Formation:1. Freeze super cooled liquid drops, often aided by “ice nuclei” 2. Grow ice crystals by vapor diffusion. 3. Grow ice crystals by collecting other ice crystals or other super cooled liquid drops. The shape of snow is formed by air temperature and humidityDuring winter, snow covers ~ half of the land surface north of 20ºNClimate impacts of Snow1. Snow cover increases albedo (cooling effect).2. Snow cover insulates the underlying surface (warming effect). - Snow is a poor conductor of heat. Snow caves keep you warm- Snow slows the progression from winter to spring providing regional thermal inertia (reluctance to change current temperature).- It takes energy to melt snow! Snow reflects energyII. PermafrostPermafrost: Rock or soil material remains below freezing (0ºC) for 2+ years. (frozen ground)o May contain up to 30% water or none atall o 18% of Northern Hemisphere haspermafrost underground - Permafrost is cooled at surface and heated frombelow (geothermal)Active layer: layer, which thaws during summer and freezes during winter Unstable terrain: when permafrost has a high water content and melts - When you have an unstable terrain, Methane is released.- Melting permafrost creates an anaerobic environment where methane-producing organisms can thrive. Methane is greenhouse gas.Greenhouse potential: increase in greenhouse effect caused by gas as compared to an equivalent amount of carbon dioxide III. GlaciersGlacier: ice that moves- Crevasses are evidence that glaciers move- Glaciers move under their own weight- Glaciers become glacial Ice with compression- 15 times as dense as snow- Once ice forms, air bubbles are sealed allowing us to take ice cores and directly measure atmospheric composition Ice Cores: Show temperature changes (measured using isotopes) with CO2 changes (direct measurement) - Gain mass from snow- Lose mass by melting and calvingGlacial Calving: formation of icebergFlow of Glaciers- Pressure due to ice weight makes the deep ice deformable. This ‘plastic deformation’ increases with depth (more ice above=more pressure) - If the ice is frozen to rough ground there is lots of friction at base, and the maximum flow will be well above the base - Friction with valley sides, ice flows fastest in the middle of mountain glaciers.- Near the surface, ice is ‘taken for a ride’ by the flow beneath. - Changes in flow rate in the lower ‘plastic’ zone can lead to fractures (crevasses) of the brittle ice near the surface (above 50m depth line). IV. Sea IceSea Ice: Forms when ocean water freezesAffects deep ocean circulation- When sea ice forms, only the fresh water turns into to ice, leaving most of the salt behind. - Ocean water that didn’t freeze becomes more saline. - Cold salty water sinks. - Sea ice formation helps drive the deep ocean circulation.-Sea ice acts as a barrier for communication between the Ocean and the Atmosphere! -Sea Ice moves because of the