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TAMU OCNG 251 - Lect4b(Oceano)-(WindPatterns)

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“OK, so what’s the speed of dark?”“When everything is coming your way,you're obviously in the wrong lane”“Who laughs last,thinks slowest”i. Earth Heat Balanceii.The Ocean/Atmosphere couplingOCNG 251: OceanographyOCNG 251: OceanographyTuesday, Sept. 30Tuesday, Sept. 30thth, 2008, 2008Part 2Part 2ReviewFigure from: The Earth Radiation Budget Experiment (ERBE)Global Radiation Balance EquationTemperaturesTemperaturesDeficitDeficitSurplusSurplusOur AtmosphereOur Atmosphere• Extremely dynamic ! system driven by solarheating. Composed of different air packets atdifferent temperatures.• Warm gas expands, lowering density and leading topressure differences (! wind)Our Atmosphere• Warm gas expands, lowering density and leadingto pressure differencesSea BreezeWarm gas expands, lowering density and leading topressure differencesThe Central American Smoke Event of May 1998The Central American Smoke Event of May 1998Atmospheric Regional TransportSince we are dealing with ultra-fine particles Since we are dealing with ultra-fine particles !! we weare bound to see some wide geographical distributionare bound to see some wide geographical distributionHadley et al. (2007) J. Hadley et al. (2007) J. GeophysGeophys. . ResRes. . VolVol. 112.. 112.North American emissions of BC: 41.5 G/MonthNorth American emissions of BC: 41.5 G/MonthInput transport: Input transport: 32 G/Month (75% originates from Asia!)32 G/Month (75% originates from Asia!)Combustion and Global TransportEarth’s energy budget is initially at disequilibrium!Amount of solar radiationreceived annually at the Earth’ssurfaceEarth’s Heat BudgetQs>Qb Qs<Qb Qs<Qb The Atmosphere starts Moving: Simplified Global Circulation PatternsNS• Equator: Low-pressure zone• Poles: High-pressure zonesSimple circulation cell in eachhemisphere with:" Surface winds directedtowards the Equator" Upper-level winds directedtowards the poles" That’s it!!" That’s it????Coriolis Coriolis Acceleration on EarthAcceleration on EarthAt the North and South Poles At the North and South Poles !! is vertical to the surface and is vertical to the surface andanywhere else it is slanted to the surface with an angle equal toanywhere else it is slanted to the surface with an angle equal tothe local the local colatitude colatitude (90 - the latitude angle,(90 - the latitude angle,ΦΦ).).The local angular velocity component vertical to the surface is:The local angular velocity component vertical to the surface is:!!sinsinΦΦ..It describes the rotation of the local surface around the radiusIt describes the rotation of the local surface around the radiusconnecting it to the center of the Earthconnecting it to the center of the EarthThe Coriolis Effect:" The Earth rotates upon its axis" The vertical angular velocity increases from 0 km/h at theequator to a maximum value at the poleshttp://www.classzone.com/books/earth_science/terc/content/visualizations/es1904/es1904page01.cfm?chapter_no=19 N SGeostrophic Flow with FrictionAtmospheric – Wind patternsHigh/Low Pressure systems: Heat capacity!JulyAtmospheric – Wind patternsHigh/Low Pressure systems: Heat capacity!JanuaryAtmospheric – Wind patternsHigh/Low Pressure systems: Wind generationJanuaryEasterliesWesterliesWesterliesEasterlies Global Circulation Patterns:1) AtmosphereAtmospheric circulation results from1) Earth’s rotation and2) differential heating at surface andin atmosphere!this produces prevailing winds andlatitudinal belts of high/low pressure!Earth is essentially divided intotwo atmospheric sections (red line)!So, is this it?NS Global Circulation Patterns:2) OceansSurface oceanic circulationresults from• 1) Prevailing winds(differential heating atsurface and in atmosphere)and• 2) Earth’s rotation! this produces prevailingcurrents and heat transfer(High Heat Capacity =Delayed Response Time)! Evaporation is the largesttransfer flux of energy(heat) from the ocean to theatmosphereThe Gulf Stream Global Circulation Patterns:3) Atmosphere-Ocean “coupling”!Low latitudes: Oceans!High latitudes: AtmosphereAtmosphere-Ocean “coupling”!Atmosphere – Transfer of moisture to the atmosphere(heat released in higher latitudes as water condenses!)Atmosphere-Ocean “coupling”!Atmosphere – Transfer of moisture to theatmosphere: Hurricanes!www.weather.comHurricane formationHurricanes are commonly formed by easterly waves. In theAtlantic, the waves are kinks in the African Easterly Jet, a strongwind that blows over the Atlantic from the West African coast.The easterly waves trigger strongthunderstorms that move westward.Over the warm waters of the Atlantic,the thunderstorms embedded in theeasterly wave can grow into a hurricaneunder the right conditions.Rule of thumb:" If hurricanes form before 40ºW,then get tend to miss the U.S.A." If hurricanes form beyond 70ºW,then there is a greater chance thatthey’ll hit the U.S.A.Atmosphere-Ocean “coupling”!Atmosphere – Transfer of moisture to theatmosphere: Hurricanes!““ValidityValidity”” vsvs. . ““ValueValue”” of Forecasts of ForecastsClimate of (un)certaintyClimate of (un)certainty……GustavGustav’’s forecast was s forecast was ““spot onspot on”” 3-4 days in advance 3-4 days in advanceDid it help that it wasnDid it help that it wasn’’t as t as ““destructivedestructive”” as announced? as announced?Seasonal ActivitySeasonal Activity20052005Forecasting hurricanesForecasting hurricanesClimate of (un)certaintyClimate of (un)certainty……"Based on a range of models, it is likely that future tropical"Based on a range of models, it is likely that future tropicalcyclones (typhoons and hurricanes) will become more intense,cyclones (typhoons and hurricanes) will become more intense,with larger peak wind speeds and more heavy precipitationwith larger peak wind speeds and more heavy precipitationassociated with ongoing increases of tropical SSTs (IGPCC)associated with ongoing increases of tropical SSTs (IGPCC)Hurricane incidenceHurricane incidence & Intensity:& Intensity:"" El El Niño Niño (inverse)(inverse)"" Storms in western Africa (direct)Storms in western Africa (direct)"" SST Atlantic (direct)SST Atlantic (direct)((UnivUniv.. of Colorado)of Colorado)Next Class…Physical properties of (sea)waterDensity structure of


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TAMU OCNG 251 - Lect4b(Oceano)-(WindPatterns)

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