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The Earth Now: The Oceans The Atmosphere The Surface/Crust The Biosphere

PHYS 575/CSI 655: Intro to Atmospheric Physics and Chemistry Lecture Notes #2 - Part 1: The Earth System. The Earth Now: The Oceans The Atmosphere The Surface/Crust The Biosphere Biogeochemical Cycles How the Earth Evolved: Temperature Oxygen Habitability: Life on Earth

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The Earth Now: The Oceans The Atmosphere The Surface/Crust The Biosphere

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  1. PHYS 575/CSI 655: Intro to Atmospheric Physics and ChemistryLecture Notes #2 - Part 1: The Earth System The Earth Now: • The Oceans • The Atmosphere • The Surface/Crust • The Biosphere • Biogeochemical Cycles How the Earth Evolved: • Temperature • Oxygen • Habitability: Life on Earth • The Goldilocks Problem

  2. Announcements: Jan. 31, 2011 Office Hours (with appointment please) • Tuesday: 3:00-4:00 pm • Thursday: 3:00-4:00pm (other times possible) • Homework #1 Due Feb. 7 • Homework #2: Chapter 2: 2.7 (a) through (j), 2.10, 2.15, 2.16 Due February 21 • Feb. 28 – Tentative Term Paper Titles due • Feb. 28 – Exam #1 • March 28 – Term Paper Abstract due

  3. Terminology: The Four Earth Spheres Earth’s four “spheres” include the: • Atmosphere (gaseous envelope) • Geosphere (solid Earth) • Hydrosphere (water portion) • Biosphere (life) Each sphere is composed of many interrelated parts and is physically and chemically intertwined with all other spheres. Although each of Earth’s four spheres can be studied separately, they are all related in a complex and continuously interacting whole that we call the "Earth System." "Earth system science" uses an interdisciplinary approach to integrate the knowledge of several academic fields in the study of our planet and its global environmental problems.

  4. Earth System Science A "system" is a group of interacting parts that form a complex whole. • Closed systems are those in which energy moves freely in and out, but matter does not enter or leave the system. • In an open system, both energy and matter flow into and out of the system.

  5. The Energy that Drives the Earth System The two sources of energy that power the Earth system are: (1) the Sun, which drives the external processes that occur in the atmosphere, hydrosphere, and at Earth’s surface, and (2) heat from Earth’s interior that powers the internal processes that produce volcanoes, earthquakes, and mountains.

  6. The Earth’s Geosphere: Surface http://www.umich.edu/~gs265/geosp2.gif

  7. The Earth’s Geosphere:Surface to the Center of the Earth

  8. The “Ring of Fire” – Driven by Plate Tectonics http://nzphoto.tripod.com/volcano/PacificPlate.gif

  9. Mantle Convection: Driver of Plate Tectonics http://www.cas.muohio.edu/limpermuseum/InvestigateConceptsInGeology/_images/Forces%20that%20Cause%20PT.jpg

  10. Plate Subduction at Plate Boundaries

  11. Redoubt Volcano: 1990

  12. Plate Tectonics and Climate Plate tectonics drives a long term (60-100 MY) cycle of carbon through the biosphere. This regulates climate changes. http://dilu.bol.ucla.edu/

  13. Why is water so special? • Water (H2O) is one of three essential requirements for life (energy, carbon, liquid water), and is made up of two of the six most abundant elements in the universe. • Floats when it freezes. • Superb solvent for transporting raw materials for metabolism and waste products. • Water is liquid over temperature range at which organic reactions are robust. • It is the major greenhouse gas on Earth. • Forms cloudswhich influence Earth’s albedo. • Has a large effect on the thermodynamics of Earth’s atmosphere through its phase changes and large heat capacity.

  14. Water Vapor Water vapor (H2O) qualifies as a major gas, but its percentage abundance varies with location and time. • A typical percentage abundance for atmospheric water vapor is ~2%. • Observed abundances vary from a fraction of a percent to several percent. • Changes in phase between gas, liquid and solid influence the abundance of atmospheric water vapor.

  15. The Oceans • Oceans cover 72% of Earth’s surface. • Equivalent to 2.6 km average depth. • 250 times mass of atmosphere. • Heat capacity over 1000 times that of the atmosphere. • 34-35 g of dissolved salts per kg of water.

  16. The Oceans Vertical Structure - temperature

  17. Characterizing Ocean Water Ocean SalinityDensity Contours (0/00) Ocean water has an equation of state, just as the atmosphere. However, the density of sea water depends upon both temperature and salinity. Typically, sea water has a density about 1.02-1.03 times that of fresh water. Thus the relative density of sea water has a dramatic effect upon buoyancy. Variations in the density of sea water drive currents, known as the thermohaline circulation. (# along sounding denotes depth in 100m) Density: 26.0  1.026 g/cm3 AABW – Antarctic Bottom Water NADW – North Atlantic Deep Water

  18. Ocean Circulation:Driven by wind stress (momentum transfer)and density gradient (thermohaline circulation) Heating Cooling Thermocline = level where temperature increase with height is largest.

  19. Global Thermohaline Circulation Downwelling Shading denotes downwelling of ocean water. This occurs in the N. Atlantic, and in two large areas off the coast of Antarctica. Blue = Bottom Water Red = Surface Water The global thermohaline circulation represents a “conveyor belt” of energy. Downwelling Downwelling

  20. Ocean Surface Currents – Driven by Wind Stress (annual mean ocean surface currents) G – Gulf Stream K – Kuroshio Current H – Humboldt Current S – South Equatorial Current N – North Equatorial Countercurrent

  21. Ocean Eddiesare dynamical in nature and a manifestation of turbulence generated by instabilities. Color enhanced image of the Gulf Stream off the eastern US. Colors denote temperature range from ~6oC to 20oC. http://www.jhu.edu/~eps/faculty/waugh/gallery/gulf_stream_rings.jpg

  22. The Marine Biosphere Dissolved Carbon and Oxygen Virtually all sunlight that reaches the surface of the ocean is absorbed in the topmost 100m – the Euphotic Zone. In this region life abounds where there is sufficient nutrients such as phosphorous and Iron. These regions are also enriched in oxygen (a product of photosynthesis) and depleted in carbon (consumed by metabolism).

  23. The Marine Biosphere Primary Productivity (photosynthesis) Photosynthesis:(+sunlight) Water + carbon dioxide  glucose + oxygen 6 H2O + 6 CO2  C6H12O6 + O2 Phytoplankton are capable of consuming the nutrients in the euphotic zone in a matter of days, requiring continual replenishment.

  24. “Ideal” Thermohaline Circulation & Nutrients Nutrients consumed in the euphotic zone by phytoplankton are returned to the deep ocean when the organisms die, sink, and decompose. This cycle of nutrients plays an important role in the carbon cycle of the biosphere. Regions of upwelling of deep ocean water supply large amounts of nutrients to photosynthetic life and lead to high primary productivity.

  25. Primary Productivity

  26. Sea Surface Temperature (SST) SST is determined by both radiative (solar heating) and dynamical (wind stress and ocean currents) factors. Annual Mean SST (Total) Departure of local SST from zonal average. This reveals the influence of winds on the SST.

  27. NH Cryosphere The Cryosphere is the portion of the Earth system comprised of water in its solid state, or for which frozen water is an essential component. The cryosphere influences the Earth’s albedo, ocean level, heat capacity, and circulation of ocean waters.

  28. Continental ice sheets, mainly on Greenland and Antarctica, dominate the mass of the cryosphere. The mass balance is maintained by snowfallas the source, and sublimation, calving of icebergs, and edge meltingas the major losses of ice mass. Ice creep transfers mass to the rim of the ice caps and loss regions.

  29. Antarctica http://members.ozemail.com.au/~slacey/images/antarctica_map.gif

  30. The Antarctic Ice Sheet

  31. Ice Creep

  32. Ice Creep, and Flows

  33. Permafrost at High Northern Latitudes Permafrost embedded in soils has a major impact on the ecology and human activities in Siberia, Alaska, and northern Canada.The figure shows the vertical profile of summer and wintertemperatures in a region ofpermafrost. The depth of the permafrost layer varies from as little as a few meters in zones of intermittent perma-frost, to as much as 1km over the coldest regions of Siberia.

  34. Permafrost at High Northern Latitudes The permafrost layer varies depending upon terrain. http://www.bgrg.org/pages/education/alevel/coldenvirons/Permafrost%20Structure.gif

  35. Drunken Forrests

  36. Melting of Permafrost

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