DOCSLIB.ORG

The Effect of Coastal Upwelling on the Sea-Breeze Circulation at Cabo Frio, Brazil: a Numerical Experiment S

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Effect of Coastal Upwelling on the Sea-Breeze Circulation at Cabo Frio, Brazil: a Numerical Experiment S The effect of coastal upwelling on the sea-breeze circulation at Cabo Frio, Brazil: a numerical experiment S. H. Franchito, V. B. Rao, J. L. Stech, J. A. Lorenzzetti To cite this version: S. H. Franchito, V. B. Rao, J. L. Stech, J. A. Lorenzzetti. The effect of coastal upwelling on the sea-breeze circulation at Cabo Frio, Brazil: a numerical experiment. Annales Geophysicae, European Geosciences Union, 1998, 16 (7), pp.866-871. hal-00316417 HAL Id: hal-00316417 https://hal.archives-ouvertes.fr/hal-00316417 Submitted on 1 Jan 1998 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Ann. Geophysicae 16, 866±881 (1998) Ó EGS ± Springer-Verlag 1998 The eect of coastal upwelling on the sea-breeze circulation at Cabo Frio, Brazil: a numerical experiment S. H. Franchito, V. B. Rao, J. L. Stech, J. A. Lorenzzetti Instituto National de Pesquisas Espaciais, INPE, CP 515, 12201-970, SaÄ o Jose dos Campos, SP, Brazil Received: 20 June 1997 / Revised: 21 January 1998 / Accepted: 12 February 1998 Abstract. The eect of coastal upwelling on sea-breeze circulation in Cabo Frio (Brazil) and the feedback of sea-breeze on the upwelling signal in this region are 1 Introduction investigated. In order to study the eect of coastal upwelling on sea-breeze a non-linear, three-dimensional, The best known regions of coastal upwelling are located primitive equation atmospheric model is employed. The in the eastern margins of the world oceans, e.g. in Peru, model considers only dry air and employs boundary Ecuador, California and Oregon on the Paci®c Ocean layer formulation. The surface temperature is deter- coast, and northwest Africa and southern Benguela mined by a forcing function applied to the Earth's current on the Atlantic Ocean coast. This oceanographic surface. In order to investigate the seasonal variations of phenomenon is of fundamental importance for the the circulation, numerical experiments considering maintenance of the high biological productivity of these three-month means are conducted: January-February- regions. Although less intense, coastal upwelling is also March (JFM), April-May-June (AMJ), July-August- present at some coastal regions located at the western September (JAS) and October-November-December margins of the oceans. For example, during the summer (OND). The model results show that the sea-breeze is period a coastal upwelling is observed at Cape Canav- most intense near the coast at all the seasons. The sea- eral in the southeastern continental shelf of the United breeze is stronger in OND and JFM, when the upwelling States (Lorenzzetti et al., 1987). occurs, and weaker in AMJ and JAS, when there is no Along part of the Brazilian southeast continental upwelling. Numerical simulations also show that when shelf, and particularly near Cabo Frio (22 59 S, the upwelling occurs the sea-breeze develops and attains 0 42020W) (Fig. 1), a seasonal upwelling is present during maximum intensity earlier than when it does not occur. the spring and summer months. During the fall and Observations show a similar behavior. In order to verify winter seasons, there is a relaxation of the upwelling the eect of the sea-breeze surface wind on the upwel- (Stech et al., 1995). The upwelling at Cabo Frio is ling, a two-layer ®nite element ocean model is also another example of this phenomenon occurring on the implemented. The results of simulations using this west coast of oceans. Considering that the surface layers model, forced by the wind generated in the sea-breeze of this region are dominated by warm waters of tropical model, show that the sea-breeze eectively enhances the origin, with low levels of productivity, the observed upwelling signal. coastal upwelling is of great importance for the biolog- ical enrichment of the water and sustaining of the ®shery activities of this region. Studies using ship, coastal Key words. Meteorology and atmospheric dynamics stations data and infrared satellite images have shown (mesoscale meteorology; ocean-atmosphere that strong negative sea surface temperature (SST) interactions) á Oceanography (numerical modeling) anomalies are present during most of the year in this region (Lorenzzetti et al., 1988; Valentin, 1984; Miran- da, 1982). In particular, the infrared images from the NOAA satellites have shown that coastal upwelling occurs from the coast of Espirito Santo state, north of Cabo Frio, to the region near Guanabara Bay, with the largest negative SST anomalies occurring along the coast near the Capes of SaÄ o Tome ,Bu zios and Frio Correspondence to: S. H. Franchito (Humi and Lorenzzetti, 1991). Figure 2 shows a NOAA- S. H. Franchito et al.: The eect of coastal upwelling on the sea-breeze circulation at Cabo Frio, Brazil 867 Fig. 1. Region of Cabo Frio. The coastline considered in the model is indicated by a thick line. The smaller rectangle rep- resents the model domain. The dashed lines represent the iso- baths in m. The line AB indi- cates grid-points along a parallel line 10 km northward from the EW coast; the line CD corresponds to grid-points along a parallel line 10 km westward from the NS coast; the point E represents a grid- point situated 10 km inland from both the EW and NS coastlines; F indicates the inter- ception of the EW and NS coastlines. These lines and points are useful for analyzing the model results 12 AVHRR satellite image that illustrates the presence Central Water (SACW) at the continental slope. Recent of negative SST anomalies in this region. studies have shown that the SACW is the source of the It has been speculated that the seasonality of the cold waters that crop up near the coast in this region Cabo Frio upwelling is associated with the onshore/ (Gaeta et al., 1994; Valentin, 1984). Sometimes when oshore seasonal migration of the South Atlantic strong NE winds persist for several days, strong Fig. 2. Sea surface temperature satellite image showing the coastal upwelling in the Cabo Frio region. The yellow square repre- sents the model domain 868 S. H. Franchito et al.: The eect of coastal upwelling on the sea-breeze circulation at Cabo Frio, Brazil upwelling can develop with surface temperatures drop- mainly in austral summer and it is practically absent in ping to 13±14C near the coast, close to Cabo Frio. winter. Numerical experiments using the atmospheric These temperatures are about 10C cooler than the mid- model will be carried out separately for three-month and outer shelf waters. On the synoptic time scale of 6± mean conditions: January-February-March (JFM), 11 days, as cold fronts pass over the region, the surface April-May-June (AMJ), July-August-September (JAS) winds rotate counterclockwise and blow for a few days and October-November-December (OND), in order to from the southern quadrant, inhibiting the upwelling. study the seasonal variations in the sea-breeze circula- The large-scale atmospheric high pressure center tion of this region. The in¯uence of the breeze on the located over the South Atlantic ocean makes the upwelling is investigated using a numerical ocean model. prevailing surface wind blow from the northeast along These two models are described in Sect. 2; the model the Brazilian coast near Cabo Frio (Stech and Loren- results and comparisons with observations are discussed zzetti, 1992). The southwest-northeast and east-west in Sect. 3; and the summary and conclusions are orientation of the coastline in this region (Fig. 1), favors presented in Sect. 4. the development of a strong alongshore wind stress component, which is the main forcing of this upwelling. Most of the Brazilian coastal regions are in¯uenced 2 The numerical models by the sea-breeze circulation which occurs due to the horizontal temperature dierence between the land and 2.1 The sea-breeze model the ocean. Since the land is warmer than the ocean during the day, the local surface wind blows from sea to The atmospheric model developed for this study is a land (sea-breeze); at higher altitude, there is a weaker three-dimensional, non-linear, primitive equation model return ¯ow, which blows from land to sea. The for dry air. This model is a three-dimensional version of circulation is opposite during the night because the land the two-dimensional model developed by Franchito and is colder than the ocean (land breeze). These local winds Kousky (1982). may have an important role in determining the climate The hydrodynamical equations, the structure of the in coastal regions because they in¯uence the character- horizontal and vertical grids and the temporal integra- istic air ¯ow, the precipitation and the humidity and tion scheme are based on the mesoscale model devel- pollutant transports (Lu and Turco, 1994; Kousky, oped by Anthes and Warner (1978). However, 1980; Anthes, 1978; Ramos, 1975). simpli®cations are made in the parametrizations of the The sea-breeze circulation may be stronger when surface diurnal heating and the planetary boundary coastal upwelling is present because the negative SST layer. Since the model of Franchito and Kousky (1982) anomalies increase the horizontal temperature dierence was published in a journal of limited circulation, a between the ocean and land. The sea-breeze circulation detailed description is given below. in turn modulates the coastal ocean circulation.
Load more

Recommended publications
  • How the Ocean Affects Weather & Climate
    Ocean in Motion 6: How does the Ocean Change Weather and Climate? A. Overview 1. The Ocean in Motion -- Weather and Climate In this program we will tie together ideas from previous lectures on ocean circulation. The students will also learn about the similarities and interactions between the atmosphere and the ocean. 2. Contents of Packet Your packet contains the following activities: I. A Sea of Words B. Program Preparation 1. Focus Points OThe oceans and the atmosphere are closely linked 1. the sun heats the atmosphere as well as the oceans 2. water evaporates from the ocean into the atmosphere a. forms clouds and precipitation b. movement of any fluid (gas or liquid) due to heating creates convective currents OWeather and climate are two different things. 1. Winds a. Uneven heating and cooling of the atmosphere creates wind b. Global ocean surface current patterns are similar to global surface wind patterns c. wind patterns are analogous to ocean currents 2. Four seasons OAtmospheric motion 1. weather and air moves from high to low pressure areas 2. the earth's rotation also influences air and weather patterns 3. Atmospheric winds move surface ocean currents. ©1998 Project Oceanography Spring Series Ocean in Motion 1 C. Showtime 1. Broadcast Topics This broadcast will link into discussions on ocean and atmospheric circulation, wind patterns, and how climate and weather are two different things. a. Brief Review We know the modern reason for studying ocean circulation is because it is a major part of our climate. We talked about how the sun provides heat energy to the world, and how the ocean currents circulate because the water temperatures and densities vary.
    [Show full text]
  • Chapter 7 100 Years of the Ocean General Circulation
    CHAPTER 7 WUNSCH AND FERRARI 7.1 Chapter 7 100 Years of the Ocean General Circulation CARL WUNSCH Massachusetts Institute of Technology, and Harvard University, Cambridge, Massachusetts RAFFAELE FERRARI Massachusetts Institute of Technology, Cambridge, Massachusetts ABSTRACT The central change in understanding of the ocean circulation during the past 100 years has been its emergence as an intensely time-dependent, effectively turbulent and wave-dominated, flow. Early technol- ogies for making the difficult observations were adequate only to depict large-scale, quasi-steady flows. With the electronic revolution of the past 501 years, the emergence of geophysical fluid dynamics, the strongly inhomogeneous time-dependent nature of oceanic circulation physics finally emerged. Mesoscale (balanced), submesoscale oceanic eddies at 100-km horizontal scales and shorter, and internal waves are now known to be central to much of the behavior of the system. Ocean circulation is now recognized to involve both eddies and larger-scale flows with dominant elements and their interactions varying among the classical gyres, the boundary current regions, the Southern Ocean, and the tropics. 1. Introduction physical regimes, understanding of the ocean until relatively recently greatly lagged that of the atmo- In the past 100 years, understanding of the general sphere. As in almost all of fluid dynamics, progress circulation of the ocean has shifted from treating it as an in understanding has required an intimate partnership essentially laminar, steady-state, slow, almost geological, between theoretical description and observational or flow, to that of a perpetually changing fluid, best charac- laboratory tests. The basic feature of the fluid dynamics terized as intensely turbulent with kinetic energy domi- of the ocean, as opposed to that of the atmosphere, has nated by time-varying flows.
    [Show full text]
  • Climate and Atmospheric Circulation of Mars
    Climate and QuickTime™ and a YUV420 codec decompressor are needed to see this picture. Atmospheric Circulation of Mars: Introduction and Context Peter L Read Atmospheric, Oceanic & Planetary Physics, University of Oxford Motivating questions • Overview and phenomenology – Planetary parameters and ‘geography’ of Mars – Zonal mean circulations as a function of season – CO2 condensation cycle • Form and style of Martian atmospheric circulation? • Key processes affecting Martian climate? • The Martian climate and circulation in context…..comparative planetary circulation regimes? Books? • D. G. Andrews - Intro….. • J. T. Houghton - The Physics of Atmospheres (CUP) ALSO • I. N. James - Introduction to Circulating Atmospheres (CUP) • P. L. Read & S. R. Lewis - The Martian Climate Revisited (Springer-Praxis) Ground-based observations Percival Lowell Lowell Observatory (Arizona) [Image source: Wikimedia Commons] Mars from Hubble Space Telescope Mars Pathfinder (1997) Mars Exploration Rovers (2004) Orbiting spacecraft: Mars Reconnaissance Orbiter (NASA) Image credits: NASA/JPL/Caltech Mars Express orbiter (ESA) • Stereo imaging • Infrared sounding/mapping • UV/visible/radio occultation • Subsurface radar • Magnetic field and particle environment MGS/TES Atmospheric mapping From: Smith et al. (2000) J. Geophys. Res., 106, 23929 DATA ASSIMILATION Spacecraft Retrieved atmospheric parameters ( p,T,dust...) - incomplete coverage - noisy data..... Assimilation algorithm Global 3D analysis - sequential estimation - global coverage - 4Dvar .....? - continuous in time - all variables...... General Circulation Model - continuous 3D simulation - complete self-consistent Physics - all variables........ - time-dependent circulation LMD-Oxford/OU-IAA European Mars Climate model • Global numerical model of Martian atmospheric circulation (cf Met Office, NCEP, ECMWF…) • High resolution dynamics – Typically T31 (3.75o x 3.75o) – Most recently up to T170 (512 x 256) – 32 vertical levels stretched to ~120 km alt.
    [Show full text]
  • El Niño and La Niña
    About the Images What are El Niño and La Niña? The images show El Niño, neutral, and La Niña sea surface The naturally occurring El Niño and La Niña phenomenon rep- heights (SSHs) relative to a reference state established in resents a “dance” between the atmosphere and ocean in the 1992. In the equatorial region of the Pacific Ocean, the SSH equatorial Pacific Ocean. Sometimes the atmosphere leads the during El Niño was higher by more than 18 cm over a large ocean and causes ocean conditions, and sometimes the ocean longitudinal region. The warmer water associated with El Niño leads the atmosphere and produces atmospheric motions that— displaces colder water in the upper layer of the ocean causing when strong enough—influence global atmospheric circulation. an increase in SSH because of thermal expansion. During La Sea surface temperature (SST) is the critical variable connecting Niña the temperature of the upper ocean is lower than normal, the atmosphere and ocean. Since SSH measurements yield criti- causing SSH to decrease because of thermal contraction. The cal information about the depth of the subsurface temperatures, neutral condition occurs when the upper-ocean temperature e.g., the thermocline, they provide key information on the onset, is “normal.” Red and white shades indicate high SSHs relative maintenance, and dissipation of El Niño and La Niña events. to the reference state, while blue and purple shades indicate SSHs lower than the reference state. Neutral conditions appear The 2015 El Niño Event green. The El Niño and neutral images are derived using data After five consecutive months with SSTs 0.5 °C above the acquired by the Ocean Surface Topography Mission (OSTM)/Jason-2 long-term mean, the National Oceanic and Atmospheric Admin- satellite.
    [Show full text]
  • Atmospheric General Circulation
    LectureLecture 5:5: AtmosphericAtmospheric GeneralGeneral CirculationCirculation JS JP HadleyHadley CellCell FerrelFerrel CellCell PolarPolar CellCell (driven by eddies) LHL H Basic Structures and Dynamics General Circulation in the Troposphere General Circulation in the Stratosphere Wind-Driven Ocean Circulation ESS55 Prof. Jin-Yi Yu SingleSingle--CellCell Model:Model: ExplainsExplains WhyWhy ThereThere areare TropicalTropical EasterliesEasterlies Without Earth Rotation With Earth Rotation Coriolis Force (Figures from Understanding Weather & Climate and The Earth System) ESS55 Prof. Jin-Yi Yu BreakdownBreakdown ofof thethe SingleSingle CellCell ÎÎ ThreeThree--CellCell ModelModel Absolute angular momentum at Equator = Absolute angular momentum at 60°N The observed zonal velocity at the equatoru is ueq = -5 m/sec. Therefore, the total velocity at the equator is U=rotational velocity (U0 + uEq) The zonal wind velocity at 60°N (u60N) can be determined by the following: (U0 + uEq) * a * Cos(0°) = (U60N + u60N) * a * Cos(60°) (Ω*a*Cos0° - 5) * a * Cos0° = (Ω*a*Cos60° + u60N) * a * Cos(60°) u60N = 687 m/sec !!!! This high wind speed is not observed! ESS55 Prof. Jin-Yi Yu PropertiesProperties ofof thethe ThreeThree CellsCells thermally indirect circulation thermally direct circulation JS JP HadleyHadley CellCell FerrelFerrel CellCell PolarPolar CellCell (driven by eddies) LHL H Equator 30° 60° Pole (warmer) (warm) (cold) (colder) ESS55 Prof. Jin-Yi Yu AtmosphericAtmospheric Circulation:Circulation: ZonalZonal--meanmean ViewsViews Single-Cell Model Three-Cell Model (Figures from Understanding Weather & Climate and The Earth System) ESS55 Prof. Jin-Yi Yu TheThe ThreeThree CellsCells ITCZ Subtropical midlatitude High Weather system (Figures from Understanding Weather & Climate and The Earth System) ESS55 Prof. Jin-Yi Yu ThermallyThermally Direct/IndirectDirect/Indirect CellsCells Thermally Direct Cells (Hadley and Polar Cells) Both cells have their rising branches over warm temperature zones and sinking braches over the cold temperature zone.
    [Show full text]
  • The Earth's Rotation and Atmospheric Circulation, from 1963 to 1973 Kurt
    Geophys. J. R. astr. Soc. (1981) 64,67-89 The Earth’s rotation and atmospheric circulation, from 1963 to 1973 Kurt Lambeck and Peter Hopgood Research School of Earth Sciences, Australian National University, Canberra 2600, Australia Received 1980 June 13; in original form 1980 March 17 ‘If everybody minded their own business, the world would go round a deal faster than it does.’ Alice’s Adventures in Wonderland Lewis Carroll Summary. The zonal angular momentum of the atmospheric circulation has been evaluated month-by-month and compared with astronomical observa- tions of the length-of-day for the 10 years from 1963 May to 1973 April. The reason for undertaking this study is to enable the astronomical observa- tions to be ‘corrected’ for the zonal wind effect and to investigate the residual excitation function for solid-Earth contributions. The principal conclusions reached are the following: (i) The annual change in length-of-day is almost entirely due to the seasonal changes in the zonal circulation with tidal, oceanographic and hydrologic phenomena contributing together at most 10 per cent of the total excitation. (ii) The semi-annual term is pre- dominantly due to the zonal wind and the body tide, with oceanic and hydrologic terms contributing about 10 per cent. (iii) The atmospheric circulation plays a dominant role in length-of-day changes in the period range from 1 to about 4 yr. This is partly associated with the quasi-biennial oscilla- tion and its harmonics. Both the period and amplitude of these fluctuations are very variable. (iv) At longer periods the atmosphere may still contribute to the total excitation but other excitation functions begin to rise above the spectrum of the meteorological excitation.
    [Show full text]
  • Atmospheric Circulation and Weather Systems
    CHAPTER ATMOSPHERIC CIRCULATION AND WEATHER SYSTEMS arlier Chapter 9 described the uneven pressure is measured with the help of a distribution of temperature over the mercury barometer or the aneroid barometer. Esurface of the earth. Air expands when Consult your book, Practical Work in heated and gets compressed when cooled. This Geography — Part I (NCERT, 2006) and learn results in variations in the atmospheric about these instruments. The pressure pressure. The result is that it causes the decreases with height. At any elevation it varies movement of air from high pressure to low from place to place and its variation is the pressure, setting the air in motion. You already primary cause of air motion, i.e. wind which know that air in horizontal motion is wind. moves from high pressure areas to low Atmospheric pressure also determines when pressure areas. the air will rise or sink. The wind redistributes the heat and moisture across the planet, Vertical Variation of Pressure thereby, maintaining a constant temperature In the lower atmosphere the pressure for the planet as a whole. The vertical rising of decreases rapidly with height. The decrease moist air cools it down to form the clouds and amounts to about 1 mb for each 10 m bring precipitation. This chapter has been increase in elevation. It does not always devoted to explain the causes of pressure decrease at the same rate. Table 10.1 gives differences, the forces that control the the average pressure and temperature at atmospheric circulation, the turbulent pattern selected levels of elevation for a standard of wind, the formation of air masses, the atmosphere.
    [Show full text]
  • Chapter 7 100 Years of the Ocean General Circulation
    CHAPTER 7 WUNSCH AND FERRARI 7.1 Chapter 7 100 Years of the Ocean General Circulation CARL WUNSCH Massachusetts Institute of Technology, and Harvard University, Cambridge, Massachusetts RAFFAELE FERRARI Massachusetts Institute of Technology, Cambridge, Massachusetts ABSTRACT The central change in understanding of the ocean circulation during the past 100 years has been its emergence as an intensely time-dependent, effectively turbulent and wave-dominated, flow. Early technol- ogies for making the difficult observations were adequate only to depict large-scale, quasi-steady flows. With the electronic revolution of the past 501 years, the emergence of geophysical fluid dynamics, the strongly inhomogeneous time-dependent nature of oceanic circulation physics finally emerged. Mesoscale (balanced), submesoscale oceanic eddies at 100-km horizontal scales and shorter, and internal waves are now known to be central to much of the behavior of the system. Ocean circulation is now recognized to involve both eddies and larger-scale flows with dominant elements and their interactions varying among the classical gyres, the boundary current regions, the Southern Ocean, and the tropics. 1. Introduction physical regimes, understanding of the ocean until relatively recently greatly lagged that of the atmo- In the past 100 years, understanding of the general sphere. As in almost all of fluid dynamics, progress circulation of the ocean has shifted from treating it as an in understanding has required an intimate partnership essentially laminar, steady-state, slow, almost geological, between theoretical description and observational or flow, to that of a perpetually changing fluid, best charac- laboratory tests. The basic feature of the fluid dynamics terized as intensely turbulent with kinetic energy domi- of the ocean, as opposed to that of the atmosphere, has nated by time-varying flows.
    [Show full text]
  • Atmospheric Circulation
    Atmospheric circulation Trade winds http://science.nasa.gov/science-news/science-at-nasa/2002/10apr_hawaii/ Atmosphere (noun) the envelope of gases (air) surrounding the earth or another planet Dry air: Argon, 0.98% O2, 21% N2, 78% CO2, >400ppm & rising Water vapor can be up to 4% 50% below 5.6 km (18,000 ft) 90% below 16 km (52,000 ft) http://mychinaviews.com/2011/06/into-thin-air.html Drivers of atmospheric circulation Uneven solar heating At poles sun’s energy is spread over a larger region Uneven solar heating At poles sun’s energy is spread over a larger region Uneven solar heating At poles sun’s energy is spread over a larger region Ways to transfer heat Conduction: Transfer of heat by direct contact. Heat goes from warmer areas to colder areas. Ways to transfer heat Radiation: Any object radiates heat as electromagnetic radiation (light, infrared) based on temperature of the object. Ways to transfer heat Convection: Heat carried by a fluid (air, water, etc) from a region of high temperature to a region of lower temperature. Convection cell Warm air rises, then as it cools it sinks back down Thermal (heat) balance Heat in = Heat out, for earth as a whole ! Heat in = Heat out, for latitude bands " Heat out t r o p s n a r Heat in t t a e h t e N RedistributionIncreasing heat of heat drive atmospheric circulation So, might expect Cool air sinking near the poles Warm air rising at equator Lutgens and Tarbuk, 2001 http://www.ux1.eiu.edu/~cfjps/1400/circulation.html Turns out a 3 cell modelis better Polar cell Ferrel cell (Mid-latitude
    [Show full text]
  • Atmospheric Circulation and Tides Of" 51Peg B-Like" Planets
    A&A manuscript no. ASTRONOMY (will be inserted by hand later) AND Your thesaurus codes are: ASTROPHYSICS 08 Atmospheric Circulation and Tides of “51Pegb-like” Planets Adam P. Showman1 and Tristan Guillot2 1 University of Arizona, Department of Planetary Sciences and Lunar and Planetary Laboratory, Tucson, AZ 85721; show- [email protected] 2 Observatoire de la Cˆote d’Azur, Laboratoire Cassini, CNRS UMR 6529, 06304 Nice Cedex 4, France; [email protected] Submitted 23 March 2001; Accepted 18 January 2002 Abstract. We examine the properties of the atmo- the similar brown dwarfs, for which theoretical models spheres of extrasolar giant planets at orbital distances now reproduce the observations well, even in the case of smaller than 0.1 AU from their stars. We show that these low-temperature objects (Teff ∼ 1000K or less) (e.g. Mar- “51 Peg b-like” planets are rapidly synchronized by tidal ley et al. 1996; Allard et al. 1997; Liebert et al. 2000; interactions, but that small departures from synchronous Geballe et al. 2001; Schweitzer et al. 2001 to cite only a rotation can occur because of fluid-dynamical torques few). However, an important feature of extrasolar plan- within these planets. Previous radiative-transfer and evo- ets is their proximity to a star: The irradiation that they lution models of such planets assume a homogeneous at- endure can make their atmospheres significantly different mosphere. Nevertheless, we show using simple arguments than those of isolated brown dwarfs with the same ef- that, at the photosphere, the day-night temperature dif- fective temperature. This has been shown to profoundly ference and characteristic wind speeds may reach ∼ 500K alter the atmospheric vertical temperature profile (Sea- and ∼ 2kmsec−1, respectively.
    [Show full text]
  • 3.4 Land-Sea-Atmosphere Interactions Exacerbating Ocean
    3.4 Land-sea-atmosphere interactions exacerbating ocean deoxygenation in Eastern Boundary Upwelling Systems (EBUS) Véronique Garçon, Boris Dewitte, Ivonne Montes and Katerina Goubanova 3.4 Land-sea-atmosphere interactions exacerbating ocean deoxygenation in Eastern Boundary Upwelling Systems (EBUS) Véronique Garçon1, Boris Dewitte1,2,3,4, Ivonne Montes5 and Katerina Goubanova2 1 Laboratoire d’Etudes en Géophysique et Océanographie Spatiales- LEGOS, UMR5566-CNRS /IRD/UT/CNES, Toulouse, France 2 Centro de Estudios Avanzados en Zonas Áridas, La Serena, Chile 3 Departamento de Biología Marina, Facultad de Ciencias del Mar, Universidad Católica del Norte, Coquimbo, Chile SECTION 3.4 SECTION 4 Millennium Nucleus for Ecology and Sustainable Management of Oceanic Islands (ESMOI), Coquimbo, Chile 5 Instituto Geofísico del Perú, Lima, Perú Summary • While the biogeochemical and physical changes associated with ocean warming, deoxygenation and acidification occur all over the world’s ocean, the imprint of these global stressors have a strong regional and local nature such as in the Eastern Boundary Upwelling Systems (EBUS). EBUS are key regions for the climate system due to the complex of oceanic and atmospheric processes that connect the open ocean, troposphere and land, and to the fact that they host Oxygen Minimum Zones (OMZs), responsible for the world’s largest fraction of water column denitrification and for the largest estimated emission (0.2-4 Tg N yr-1) of the greenhouse gas nitrous oxide (N2O). • Taking into account mesoscale air-sea interactions in regional Earth System models is a key requirement to realistically simulate upwelling dynamics, the characteristics of turbulence and associated offshore transport of water mass properties.
    [Show full text]
  • What Caused the Accelerated Sea Level Changes Along the United States East Coast During 2010-2015?
    What caused the accelerated sea level changes along the United States East Coast during 2010-2015? Ricardo Domingues1,2, Gustavo Goni2, Molly Baringer2, Denis Volkov1,2 1Cooperative Institute for Marine and Atmospheric Studies, University of Miami, Florida 2Atlantic Oceanographic and Meteorological Laboratory, NOAA, Miami, Florida Corresponding author: Ricardo Domingues ([email protected]) Key points: Accelerated sea level rise recorded between Key West and Cape Hatteras during 2010-2015 was caused by warming of the Florida Current Warming of the Florida Current provided favorable baseline conditions for occurrence of nuisance flooding events recorded in 2015 Temporary sea level decline in 2010-2015 north of Cape Hatteras was mostly caused by changes in atmospheric conditions Abstract: Accelerated sea level rise was observed along the U.S. eastern seaboard south of Cape Hatteras during 2010-2015 with rates five times larger than the global average for the same time-period. Simultaneously, sea levels decreased rapidly north of Cape Hatteras. In this study, we show that accelerated sea level rise recorded between Key West and Cape Hatteras was predominantly caused by a ~1°C (0.2°C/year) warming of the Florida Current during 2010-2015 that was linked to large-scale changes in the Atlantic Warm Pool. We also show that sea level decline north of Cape Hatteras was caused by an increase in atmospheric pressure combined with shifting wind patterns, with a small contribution from cooling of the water column over the continental shelf. Results presented here emphasize that planning and adaptation efforts may benefit from a more thorough assessment of sea level changes induced This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record.
    [Show full text]