GEOG 3a ALL NOTES
GEOG 3a ALL NOTES
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Date Created: 01/31/14
Chapter 6 Ocean Chemistry Chemistry science of matter its composition structure properties and behavior Chemical oceanography involves physics biology and geology of the world ocean Interdisciplinary Figure 64 Classification of Matter Matter is solid material with mass physics mass and energy Mixtures different types of matter separable by physical means Substances elements and compound Elements atoms neutrons protons electrons eg H O Na Molecules two or more atoms united i e H20 where H is hydrogen atom O is oxygen atom inorganic and organic Compounds atoms chemically united like H20 and NaCl Motivation Chemistry affects life in ocean and vice versa i e biochemistry Chemistry is important for climate Physical properties affected by chemistry i e salinity Atmosphere is affected by ocean chemistry and vice versa Pollution is often chemical issue Santa Barbara Oil Spill British ship HMS Challenger 18721876 First oceanography expedition refit warship 200 ft long 2300 tons engine and sail Sailed during the Civil War before Industrial Revolution where CO2 came out Captain Cook made explorations of Alaska Route of the HMS Challenger 713 days at sea out of port 1606 days 69000 nt miles or about 79000 statute miles Went near Antarctica Challenger Facts C Wyville Thomson led expedition John Murray led analyses Captain George Nares and 200 crew onboard Took place just after US Civil War and during early polar exploration through early 190039s British Empire was near its peak Why Challenger Expedition Samplers and Labs Instrument and sampling platform Shallow water dredge Buchanan Water sampler Carbonic acid analysis apparatus Natural history laboratory Chemistry laboratory British ship HMS Challenger 18721876 Why so important quotthe greatest advance in the knowledge of our planet since the celebrated discoveries of the 15th and 16th centuriesquot John Murray in 1895 Provided data concerning composition and structure of the ocean Data are still useful Why Captain James Cook 17281779 Endeavour replica in Cooktown Queensland harbor anchored where the original Endeavour was beached for seven weeks in 1770s Challenger Advances 492 soundings with depth using lead lines 144 miles of sounding rope and 125 miles of piano wire 263 water hydrographic stations 133 otto dredges 151 open water trawls for organisms 4700 new species Measured currents Did excellent chemical analyses i e relevant to carbon etc Discovered Mid Atlantic Ridge and Mariana39s Trench Found life in deep sea disproved azoic dead zone No primordial slime on sea oor postulated by Ernest Haeckel Data stored in UK 50 volumes of reports still used What is in Seawater Composed of H20 and many dissolved elements and compounds Geometry of a water H20 molecule Covalent bonding sharing electrons between H and 0 atoms Important Properties of Water Molecules Water has high surface tension hard to pull molecules apart Capillary waves restoring force depends on polar property of H20 molecules and H bonding H20 is very good at dissolving materials Water exists as solid liquid and gas Water Is An Excellent Solvent Elements like Na with 11 electrons readily donates its quotextraquot outer shell electron while those like Cl with 17 electrons quotmissingquot an outer shell electron readily accepts an electron 0uter shell of electrons wants to be stable i e 2 electrons in 1st 8 electrons in 2nd and 3rd shells etc Periodic Table Na ion and Cl ion together make a stable molecule When together they form NaCl via ionic bonding How does Material Enter Oceans Volcanoes hot springs vents i e chloride Cl Weathering rock i e sodium Na Rivers Rain and atmospheric deposition Biological processes recycling really Meteors from space Age of Earth is estimated to be over 4 Billion years so long time for oceans materials to enter and distribute hence Dittmar39s Principle next Constituents of ocean salinity Note NaCl makes up 86 of dissolved elements Approximate Composition of Open Ocean Seawater Seawater by weight percent Water 965 or 965 ppt Dissolved material 35 or 35 ppt Total 100 or 1000 ppt Ppt parts per thousand like percent but using 1000 for reference base instead of 100 1 What percent by weight is water in the human body 5060 2 What percent of human body is Na Cl 015 015 Definition of Salinity Number of grams of dissolved material in 1 kilogram 1000 gm of seawater Units in parts per thousand ppt or practical salinity units psu or PSU Salinity Determination Given 70 gm of dissolved material i n2 kg or 2000 gm of seawater what is the salinity S 70 gm2000gm o 35 gm1000gm 35gm1000gm gm cancels out o 35 ppt or PSU Dittmar39s Principle In open ocean total amount of dissolved materials may change but ratios of the elements remain very nearly the same Thus we can calculate salinity from chlorinate using formula s 18 x Cl Example Given C1 20 ppt what is the salinity S 18 x Cl 18x20ppt36ppt Where does this method fail o Rivers estuaries bays near coasts Measurements of Salinity Devices Refractometer uses light refraction CTD conductivity temp depth Salinometer Satellite sensors using microwave energy Salinity affects waver conductivity Biologically Important Nutrients for Supporting Phytoplankton Phytoplankton drifting algae are fundamental to life on Earth Biologically important nutrients nitrogen nitrate nitrite silicate phosphate ammonia iron Eutrophic high in macronutrients Oligotrophic low in macronutrients Dittmar39s Principle does not work for rivers bays estuaries and nearshore ocean waters Dittmar39s Principleaka Law of Constant Proportions Why does S 18 X Cl For open ocean we might measure the total mass of our sample of dissolved matter to be 350 gm for our total seawater mass of 1 kg We also determine the mass of the Chlorine ions to be 192 gm Then the ratio of ClS 192 gm 350 gm 055 55 ClS 055 or C1 055 S And by rearranging S Cl 055 and S 18 X Cl Global Carbon Cycle Exchange rate in Gtons Cyr Gtons C stored in each reservoir Note Gtons 109 tons Atmospheric CO2 at Mauna Loa Observatory Keeling curved showing increase of atmospheric CO2 at Mauna Loa Observatory most important curve in science today Higher CO2 leads to lower pH Acid Threat If CO2 continues to rise unchecked computer models show that acidification will deplete carbonate ions in much of the ocean by 2100 turning the waters corrosive for many shell building animals Ocean acidification ongoing decrease in the pH of the Earth39s oceans caused by the uptake of anthropogenic carbon Chapter 7 Ocean Physics Physics study of matter forces motion waves momentum heat radiation and all forms of energy and their transformations exchanges and propagations Physical Oceanography involves chances of energy and matter between atmosphere and ocean and within the ocean Forms of Energy Important to Oceanographers The law of conservation of energy energy can be neither created nor destroyed but it can change forms Thus one form of energy may in principle be converted to another Radiant or solar energy energy in electromagnetic radiation that comes from the Sun important in heating of Earth the ocean and the atmosphere and essential to photosynthesis Example sunlight Kinetic energy energy of motion of moving objects 12 x mass x velocity 2 Example movement of wind across the ocean surface or collisions of water molecules in a glass Thermal energy or heat energy of random motion of molecules which results in the exchange of heat between objects Example ocean warming the overlying air or vice versa Chemical energy energy stored within the chemical bonds of substances Example chemical reactions that occur within the cells of marine organisms Potential energy energy related to the position of objects or the position of atoms in molecules Example a rock sitting on top of a ledge or the spacing between water molecules Temperature of the Ocean Conversions K C 273 F 18 C 32 C 056 F32 Freezing point 0 degrees C 32 degrees F Boiling point 100 degrees C 212 degrees F Room temperature 25 degrees C 77 degrees F Human body temperature 37 degrees C 986 degrees F Absolute zero 27315 degrees C 45958 degrees F where all motion stops CTDRosette for measuring temp salinity pressure and obtain water samples Expendable Bathytermograph XBT measures temperature as function of depth launched from a ship Observational and Modeling Issues Timespace resolution and ranges Sufficient variables to represent processes Synoptic sampling is critical Heat and the Ocean Heat capacity heat needed to raise the entire mass or volume of an object or system Specific heat specific mass or volume Why is heat capacity important for the ocean Thermal inertia ywheel effect for heating and cooling water Stop a spinning bike wheel Temperature swings Concept of Heat Transfer Heat transfer occurs when two systems have different temperatures When two systems reach thermal equilibrium heat transfer stops Heated by conduction convection and radiation Convection transfers heat through movements of molecules Radiation transfers heat through radiation of electromagnetic energy which may travel through a vacuum Review of Properties of Seawater Density mass over volume What affects density of seawater Pressure p increase gives density increase p decrease gives density decrease Salinity S increase gives density increase S decrease gives density decrease Temperature T increase gives density decrease T decrease gives density increase What processes affect seawater density in the ocean Processes that increase density processes that decrease density Hydrostatic Pressure P p g h p density massvolume g acceleration of gravity h water depth Note 10 m of water depth is equivalent of 1 atmos Of pressure Concept of Buoyancy Positive oats negative sinks neutral stays same depth Archimede s Principle Buoyant force weight of uid displaced by object o If object is more dense than water it sinks less dense rises same density stays put Argo Floats use of buoyancy to collect CTD data Principle used for submarines profiling moorings gliders AUVs The electromagnetic energy spectrum including light Note 1 nanometer 1 nm 10 A 9 meters Wein s Law is represented as kmax 2890T Where T is in K with K C 273 Example Where is the hottest part of the volcano s lava Note kmax and T are inversely proportional Yellow has shorter wavelength than red And rearranging Wein s Law equation T 2890 A Blackbody Radiation Stefan Boltzmann E 0 TA4 Earth is cooler than Sun so wavelengths of Earth radiation IR are longer than those of Sun visible We call these Earth s emitted longwave and Sun s emitted shortwave radiation What Happens to Light That Enters the Ocean Wavelength is important light energy is critical for photosynthesis life incl phytoplankton and heating of the upper ocean Light is re ected scattered and absorbed Beer s Law light intensity decreases exponentially with depth in the ocean o Most of life in ocean exists down to depth where light is at least 1 of surface value euphotic zone o Phytoplankton are major absorbers and scatterers of light in the ocean Coccolithophorid Blooms these are important scatterers of light and produce DMS a major green gas As aerosols DMS provides seeds for clouds Chalk cliffs of Dover and elsewhere are massive deposits of coccoliths Radiation Fluxes in the Atmosphere and Ocean Greenhouse Gases carbon dioxide CO2 Methane CH4 Water vapor H20 Nitrous oxide N20 Dimethylsulfide DMS CH32S Halocarbons CFC Schloro uorocarbons Shortwave radiations makes it through green house glass while longwave radiation are trapped within the green house glass leading to heating Seasons What are seasons o a subdivision of the year marked by changes in weather ecology and hours of daylight Why do we care o Affects our atmosphere climate daily lives Why are there seasons Changes in the overhead position of the Sun causes variations in the amount of solar radiation incident on a unit area of the Earth s surface Thus on a seasonal basis the area of the Earth s surface heated most directly changes day to day What is the tilt of the Earth s axis of rotation o 235 Color Vision Do sea lions have color vision o They do but very limited see only blue green area of the spectrum o Likely an adaptation for living in marine coastal habitats Do dogs have color vision Dichromats and have color vision but limited can see blue and yellow but difficult to differentiate red and green They have two spectral types of cones photoreceptors while normal humans have three cones Use color instead of brightness to differentiate light or dark blueyellow Midnight Sun Effect The apparent solar path across the sky as viewed by observers at different latitudes Note height of the sun in the sky decreases as an observer moves towards the poles Seasonal changes in solar path are less than regional differences but their effects are pronounced Sun remains below the visible horizon for observers at the poles during winter months All of these patterns result solely from the orbit of a tilted Earth around the sun Chapter 8 Ocean Atmosphere Definitions Fluids substances that ow air and seawater Weather for both the atmosphere and ocean weather describes the physical conditions at a particular time and place Study meteorology Climate for both geophysical uids climate is the average weather for specified time periods and geographic areas or locations Study climatology o Note We have both atmospheric and oceanic weather and climate o Global climate change re ects evolution of weather conditions over longer time scales Motivation Weather affects daily lives politics agriculture Extreme weather and climate change take lives and affect national and world economics Atmosphere drives ocean s currents waves and thermodynamics heating and cooling Goal prediction of future oceanic and atmospheric conditions using data and models Meteorological Measurements Instrumentation Wind speed Wind direction Barometric pressure Solar SW radiation Longwave radiation Air temperature Relative humidity Rainfall Heat Momentum and Mass Fluxes Wind stress at sea surface causes exchange of momentum energy and mass Cause waves and currents as well as turbulent mixing Cooking at ocean surfaces causes convective mixing and vertical currents Ice and Its Effects Affects heat exchangebiology Produces fresh water Production of brine as sea ice forms causes convection Ice has high albedo Ice melting on land leads to raised sea level Ice formation lowers sea level Critical factor for global climate change Albedo Re ected Radiation Incident Radiation Which of the objects in the picture have the highest albedo Surfer GirlKiki Lowest albedo Theodore Nansen If there were more Great Pyrs in the world what would happen to Earth s albedo Increase Could they reduce global warming Doubt it Climate warming decreases ice which decreases albedo and albedo and leads to even more warming positive feedback Climate cooling causes more ice which causes greater albedo which causes even more cooling positive feedback Coriolis Effect occurs because Earth is spherical and rotates Angular momentum is conserved Need a component of velocity toward or away from axis of rotation Note the different speeds of a person standing still at the North Pole at 40 N and one at the equator As a cloud moves northward in the NH it moves the location which has slower tangential velocity than where it came from resulting in a deflection rightward from its path Try for southward cloud movement Satellite launches at equator Why o Southward goes faster till you pass the equator Coriolis Effect Accounts for rotation of Earth when we study motions of the Atmosphere and the Ocean from Earth reference frame From our fixed frame of reference moving objects such as winds and currents de ect to thright of their trajectories in the NH and to the left of their trajectories in the SH Increases with latitude For horizontal motion is zero at the equator Proportional to the velocity of the parcel of seawater or air faster moving objects experience greater e ections due to Coriolis Effect Most important for large scale motions that is over scale greater than tens of kilometers tens of milse such as the circulation of the ocean and atmosphere Newton s 2 Law F ma applies for inertial reference frame Need to account for rotational effects on Earth Baseball train problem General Circulation of the Atmosphere Horizontal Pressure Gradients A key to understanding atmospheric and oceanic motions in the forms of winds and currents What would atmospheric circulation look like if the Earth stopped rotating and the Earth were only water covered Halley s Theory would work Ferrel s 3 cell model of atmosphere circulation Models and theories simplify and conceptualize but they are not perfect Why are there 3 cells of meridional circulation in each hemisphere How many cells for faster a rotating planet assume same heating For a slower rotating or non rotating planet Note waves in these flow fields Flow patterns of a uid in a rotating annulus when the inner and outer cylinders are at different temperatures Lines correspond to isotherms at mid depth Transition from laminar to turbulent flow in this sequence of figures starting at the top left is a consequence of an increase in the rate of rotation from one figure to the next Figure 8 19 Rossby waves encircle the whole Earth and are important for the weather patterns we observe especially in the NH mid latitudes which are highly in uenced by these waves Waves can allow very cold dry air masses to move south and warm moist air masses to move north Rossby waves are planetary waves as they have very long wavelengths and wrap around the Earth in the atmosphere also waves in the ocean which propagate west Rossby waves result from variation In the Coriolis effect with latitude and conservation of angular momentum Jet Stream Jet Stream brings cold air to the central US warm air to the eastern seaboard effecting a poleward transport of heat Northern Hemisphere Polar Stream can reach 100200 knots in core Located about 10 km Actual weather patterns are more complicated than simple theories depict Why Mountains Continent ocean ice contrasts NH more land SH more ocean Seasonality What causes temperature distributions map color images Warmest equatorial regions low latitudes Less radiation more radiation Radiation exposure is much greater in lower latitudes than higher latitudes Seasonal contrasts Salinity the amount of dissolved minerals in a gram of water What affects sea surface salinity SSS Rainprecipitation decrease salinity because diluting salt water with fresh water Evaporation causes salinity increases as H20 leaves sfc and salts remain behind If P gt E decrease SSS If P lt E increase SSS If P E no change in SSS P E and SSS distributions as function of latitude How are they related o Inversely related Why are there seasonal differences Distributions of temperature and salinity across the Atlantic Ocean Cooler water is heavier Average depth of the ocean is 4000 meters Where is the thermocline and pycnocline o Thermocline between warmer and cooler water line o Pycnocline density change o Change in temperature leads to change in density What affects deep distributions Hurricanes Typohoons Cyclones WillyWilly s Hurricane for Atlantic Can we infer Hadley cell from this map of rising or sinking air YES Lots of rising air and convection close to the equator inner tropical convergence zone air is converging moving towards the equator and rising Heated air rises up ows with circulation pattern Where do tropical storms hurricanes and typhoons generally form Near equator where air convects strongly What is the ITCZ intertropical convergence zone air is converging moving towards the equator and rising Why more cyclones in the northern hemisphere Bias towards northern hemisphere because there is more land mass Typhoon Phailin Strikes India October 2013 160 mph winds Cat 5 1 million evacuated from low areas death toll so far is 43 Cyclone Odisha made landfall in the same region in 1999 and killed 10000 people At the peak of Phailin s power Recipe for a Hurricane a Whirling Heat Engine 1 Heat 200 ft of ocean water about 80F required for enough water to evaporate 2 Converge winds near surface and with cyclonic counterclockwise rotation 3 Make air unstable allow to rise 4 Humidify about 18000 ft of air as you pull it into storm Extra water vapor supplies more latent heat energy 5 Avoid ripping storm apart maintain pre eXisting winds those not created by storm at same direction and speed at all altitudes 6 Pump away air rising in the storm with a high pressure area in the upper atmosphere a Note These ingredients are rare fewer than 10 of tropical weather disturbances become tropical storms Keep trying How Powerful is a Hurricane A severe storm may have a total power to 10 15 Equivalent to exploding 500000 atomic bombs per day Named by both men and women names in alphabetical order Hurricanes Continued Category 15 depending on wind speeds interior pressure and damage Hurricane Fabian Hit Bermuda as Category 3 hurricane on September 5 2003 Worst hurricane to strike Bermuda since 1926 winds 100 kts 50 ms 8 people died 300 million damage to Bermuda Hurrican Sandy Perfect Storm Also known as Super StormFrankenstorm Oct 2012 Sandy moved few mph northward as Cat 2 hurricane Merging of an extra tropical low over NYC with Hurricane Sandy Fujiwhara Effect 192123 Cat 1Definition Problem Lowest bar Press Of 930 mb Largest in diameter in history 1100 mi No model had attempted to predict such a phenomenon but it had occurred in 1954 1972 and 1989 Bad or biased news reporting 13 foot storm surge 45 million people were affected loss of power to 10 million peoplestill out some places FEMA issues government promises like during Katrina unkept 66 billion in damage initial est 1B only Katrina more at 108 billion affected 24 states plus Caribbean Islands 253 people killed in 11 countriesKatrina had over 1835 deaths Hurricanes Continued Are hurricanes and typhoons becoming more frequent and more intense because of global warming Argument severe loss of summertime Arctic sea ice attributed to greenhouse warming appears to enhance NH jet stream meandering intensity Arctic air mass invasions toward middle latitudes and increase the frequency of atmospheric blocking events like the one that steered Hurricane Sandy west into the densely populated NYC
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