Companion Notes for Oceanography, Study notes of Oceanography

Download Companion Notes for Oceanography and more Study notes Oceanography in PDF only on Docsity! Companion Notes for OCEAN STUDIES: Chapter 1 – Ocean in the Earth System Central Question: What is the Earth System perspective for studying the ocean? ❖ 1.1 Case-in-Point: Earth system interaction: The Japan & Indian Tsunamis ➢ Overview of tsunamis ▪ What is a tsunami? ▪ How, in general, do tsunamis originate? ▪ In which ocean basin do most tsunamis occur? ➢ March 11, 2011, a tsunami struck the Honshu region of Japan ▪ Produced by fourth largest earthquake since 1900; approximately 15,890 deaths and 2500 missing ➢ December 26, 2004, a tsunami struck the Banda Aceh region of Indonesia ▪ Produced by a 9.1 magnitude earthquake; approximately 227,898 dead and missing ▪ You should view these catastrophic events as examples of the interaction between Earth systems, and see the value of using an Earth system approach to planning human structures and activities. Why do you suppose that prevention of similar devastation in the future must rely upon a perspective that takes into account oceanographic and geologic processes as well as human settlement patterns? A concept map might help you keep track of the many interactions within this complex system. ❖ 1.2 Earth as a System ▪ A system consists of an interacting set of components that behave in an orderly way according to the laws of nature. In the context of this course, we can view the Earth System as an integrated and comprehensive system that includes all components of the following subsystems (any of which can also be described as a ‘system’ in its own right). • Hydrosphere, Cryosphere, Atmosphere, Geosphere, and Biosphere ▪ Be able to describe the meaning of an Earth system perspective, identify and describe the major subsystems of the Earth system, and provide some examples of how Earth’s major subsystems interact with one another. ➢ 1.2.1 Hydrosphere ▪ Includes the movement of water among its three phases: solid (sleet, snow, hail, ice), liquid (rain, water) and gas (water vapor). ▪ Be able to describe the global water cycle as an interactive system, including the processes whereby water cycles between Earth’s surface and atmosphere. ▪ As you read, consider the major implications of the global water budget for the flow of water between land and ocean. ▪ Be able to answer the following: • Approximately how much of Earth’s water is contained in the oceans?  Which reservoir is the next largest?  Be able to name four additional hydrologic reservoirs. • What atmospheric feature drives many surface ocean currents? • How and why does deep ocean circulation differ from surface circulation? • How and where do surface waters interact with deep ocean waters?  Deposits those materials elsewhere – some will form sedimentary rocks • Note how weathering and erosion relate to one another. One implies the other. ▪ Internal Geological Processes – powered primarily by Earth’s internal; heat engine • Plate tectonics: movement of lithospheric plates across the planet’s surface  Learn what sorts of landform features can be created along tectonic plate boundaries  Hot spots need not occur along plate boundaries. How do they relate to plate movement?  Supercontinent: one large landmass on the planet ➢ Pangaea (Greek for “all land”) – most recent supercontinent ➢ 1.2.4 Biosphere ▪ Encompasses all living organisms on Earth ▪ Range in size of organisms  Bacteria  Blue whales, giant fungal complexes ▪ Photosynthesis: process by which green plants, algae, and photosynthetic microbes use light energy to combine carbon dioxide from the atmosphere with water and nutrients to produce sugars • Consumes carbon dioxide from the atmosphere • Releases oxygen to the atmosphere ▪ Figure 1.6 shows chlorophyll concentrations in the world’s oceans. In upcoming chapters we’ll learn the importance of available nutrients and dissolved gasses in determining this fundamental biological distribution. ▪ Cellular respiration: convert organic matter into energy for life processes – maintenance, growth, reproduction, and waste. • Consumes oxygen • Releases carbon dioxide ▪ Chemosynthesis: use chemical energy rather than light as an energy source to produce organic carbon • Grow in areas were light is not available • Use energy from substances such as hydrogen sulfide (H2S) or methane (CH4) ▪ Ecosystems • Communities of living organisms that interact with one another and with their non-living environment. ‘Communities’ include populations of all species of living organisms within a defined region. • Producers (autotrophs) harness energy through photosynthesis or chemosynthesis • Consumers (heterotrophs) receive energy by consuming other organisms - autotrophs or heterotrophs (or decomposers). • Decomposers receive energy when they return nutrients by breaking down organic material, typically releasing it to the non-living environment. ▪ Food chain: transfer of food and energy from producer to consumer to another consumer ▪ Food web: more complex food chain • Consumer may eat both consumers and producers or consumers from two or more different levels ▪ Trophic Level • Steps in a food chain or food web  1st Trophic Level = Producers  2nd Trophic Level = Consumers  3rd Trophic Level = Consumers that eat 2nd trophic level consumers • 10% of the energy at one trophic level is transferred to the next higher level • Remaining 90% used for growth, respiration, reproduction, and mobility or lost as waste ▪ Biomass: the total weight or mass of organisms used to describe the transfer of energy in food chains. Decreasing amount of biomass from one trophic level to the next reflects inefficiencies of energy transfer. ▪ Estuary • Forms where fresh and salt water mix • Some of Earth’s most productive ecosystems • Influenced by tides (periodic rise and fall of sea level) ▪ Biogeochemical Cycles • Pathways of solids, liquids, and gases among the reservoirs of Earth’s spheres. Examples of such cycles include:  Global water cycle  Carbon cycle  Oxygen cycle  Rock cycle • Cycles follow the law of energy conservation – Energy is required/transferred when moving material from one reservoir to another. • These cycles do follow the law of conservation of matter, which states that matter may be converted, but it is neither created nor destroyed. • Residence time is used to describe the average length of time that a molecule of a substance will remain in a reservoir. ❖ 1.3 The Global Water Cycle ➢ Ceaseless movement of water among its various reservoirs at the planetary scale ▪ Water vaporizes from the ocean or land ▪ Water vapor condenses to form clouds ▪ Clouds produce rain, snow, and other forms of precipitation ▪ Precipitation recharges the ocean and the terrestrial reservoirs ▪ Water flows back to the ocean ➢ Know the following terms well: ▪ Evaporation: process where water absorbs heat energy and changes from a liquid to a vapor ▪ Transpiration: water in the plant escapes as vapor through the leaves invisible infrared radiation emitted by the surface. Figure 1.16 depicts a map created using data from passive satellite monitoring. Examples include: ➢ Sea-surface temperatures (SST) ➢ Ocean color (distribution and abundance of chlorophyll) • Active Satellites  Radar instruments that emit pulses of microwave radiation, then records the reflected signal. Measurements include: ➢ Surface roughness ➢ Variations in ocean surface elevation ➢ Velocity and direction of surface currents ➢ Some data available on deep ocean currents ❖ 1.5 Modeling the Ocean ➢ Model: approximate representation or simulation of a real system. Know the definitions of each of these types of models. What are the advantages and potential shortcomings of using models to advance scientific understanding? ▪ Conceptual – statement of a fundamental law or relationship • Organize data, describe interactions among components of any system ▪ Graphical – compiles and displays data in a format that readily conveys meaning • Bathymetric charts, maps of sea floor elevations. Figure 1.17 is an example of a graphical model. ▪ Physical – small-scale representation of system, such as a wave tank ▪ Numerical – consists of mathematical equations that simulate the process  Use observational data for initial conditions and to guide and verify model predictions  Projects future state of a complex system and the probability that the projection  Tested and validated using a completely different set of data  They have reduced (but not eliminated) the need for physical models in investigating the Earth system.