Physical Oceanography and Circulation in the Gulf of Mexico
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Understanding Eddy Field in the Arctic Ocean from High-Resolution Satellite Observations Igor Kozlov1, A
Abstract ID: 21849 Understanding eddy field in the Arctic Ocean from high-resolution satellite observations Igor Kozlov1, A. Artamonova1, L. Petrenko1, E. Plotnikov1, G. Manucharyan2, A. Kubryakov1 1Marine Hydrophysical Institute of RAS, Russia; 2School of Oceanography, University of Washington, USA Highlights: - Eddies are ubiquitous in the Arctic Ocean even in the presence of sea ice; - Eddies range in size between 0.5 and 100 km and their orbital velocities can reach up to 0.75 m/s. - High-resolution SAR data resolve complex MIZ dynamics down to submesoscales [O(1 km)]. Fig 1. Eddy detection Fig 2. Spatial statistics Fig 3. Dynamics EGU2020 OS1.11: Changes in the Arctic Ocean, sea ice and subarctic seas systems: Observations, Models and Perspectives 1 Abstract ID: 21849 Motivation • The Arctic Ocean is a host to major ocean circulation systems, many of which generate eddies transporting water masses and tracers over long distances from their formation sites. • Comprehensive observations of eddy characteristics are currently not available and are limited to spatially and temporally sparse in situ observations. • Relatively small Rossby radii of just 2-10 km in the Arctic Ocean (Nurser and Bacon, 2014) also mean that most of the state-of-art hydrodynamic models are not eddy-resolving • The aim of this study is therefore to fill existing gaps in eddy observations in the Arctic Ocean. • To address it, we use high-resolution spaceborne SAR measurements to detect eddies over the ice-free regions and in the marginal ice zones (MIZ). EGU20 -OS1.11 – Kozlov et al., Understanding eddy field in the Arctic Ocean from high-resolution satellite observations 2 Abstract ID: 21849 Methods • We use multi-mission high-resolution spaceborne synthetic aperture radar (SAR) data to detect eddies over open ocean and marginal ice zones (MIZ) of Fram Strait and Beaufort Gyre regions. -
The General Circulation of the Atmosphere and Climate Change
12.812: THE GENERAL CIRCULATION OF THE ATMOSPHERE AND CLIMATE CHANGE Paul O'Gorman April 9, 2010 Contents 1 Introduction 7 1.1 Lorenz's view . 7 1.2 The general circulation: 1735 (Hadley) . 7 1.3 The general circulation: 1857 (Thompson) . 7 1.4 The general circulation: 1980-2001 (ERA40) . 7 1.5 The general circulation: recent trends (1980-2005) . 8 1.6 Course aim . 8 2 Some mathematical machinery 9 2.1 Transient and Stationary eddies . 9 2.2 The Dynamical Equations . 12 2.2.1 Coordinates . 12 2.2.2 Continuity equation . 12 2.2.3 Momentum equations (in p coordinates) . 13 2.2.4 Thermodynamic equation . 14 2.2.5 Water vapor . 14 1 Contents 3 Observed mean state of the atmosphere 15 3.1 Mass . 15 3.1.1 Geopotential height at 1000 hPa . 15 3.1.2 Zonal mean SLP . 17 3.1.3 Seasonal cycle of mass . 17 3.2 Thermal structure . 18 3.2.1 Insolation: daily-mean and TOA . 18 3.2.2 Surface air temperature . 18 3.2.3 Latitude-σ plots of temperature . 18 3.2.4 Potential temperature . 21 3.2.5 Static stability . 21 3.2.6 Effects of moisture . 24 3.2.7 Moist static stability . 24 3.2.8 Meridional temperature gradient . 25 3.2.9 Temperature variability . 26 3.2.10 Theories for the thermal structure . 26 3.3 Mean state of the circulation . 26 3.3.1 Surface winds and geopotential height . 27 3.3.2 Upper-level flow . 27 3.3.3 200 hPa u (CDC) . -
Pressure-Gradient Forcing Methods for Large-Eddy Simulations of Flows in the Lower Atmospheric Boundary Layer
atmosphere Article Pressure-Gradient Forcing Methods for Large-Eddy Simulations of Flows in the Lower Atmospheric Boundary Layer François Pimont 1,* , Jean-Luc Dupuy 1 , Rodman R. Linn 2, Jeremy A. Sauer 3 and Domingo Muñoz-Esparza 3 1 Department of Forest, Grassland and Freshwater Ecology, Unité de Recherche des Forets Méditerranéennes (URFM), French National Institute for Agriculture, Food, and Environment (INRAE), CEDEX 9, 84914 Avignon, France; [email protected] 2 Earth and Environmental Sciences Division, Los Alamos National Lab, Los Alamos, NM 87545, USA; [email protected] 3 Research Applications Laboratory, National Center for Atmospheric Research, Boulder, CO 80301, USA; [email protected] (J.A.S.); [email protected] (D.M.-E.) * Correspondence: [email protected]; Tel.: +33-432-722-947 Received: 26 October 2020; Accepted: 9 December 2020; Published: 11 December 2020 Abstract: Turbulent flows over forest canopies have been successfully modeled using Large-Eddy Simulations (LES). Simulated winds result from the balance between a simplified pressure gradient forcing (e.g., a constant pressure-gradient or a canonical Ekman balance) and the dissipation of momentum, due to vegetation drag. Little attention has been paid to the impacts of these forcing methods on flow features, despite practical challenges and unrealistic features, such as establishing stationary velocity or streak locking. This study presents a technique for capturing the effects of a pressure-gradient force (PGF), associated with atmospheric patterns much larger than the computational domain for idealized simulations of near-surface phenomena. Four variants of this new PGF are compared to existing forcings, for turbulence statistics, spectra, and temporal averages of flow fields. -
The Vertical Structure of a Loop Current Eddy 10.1029/2018JC013801
Journal of Geophysical Research: Oceans RESEARCH ARTICLE The Vertical Structure of a Loop Current Eddy 10.1029/2018JC013801 T. Meunier1 , E. Pallás-Sanz1 , M. Tenreiro1 , E. Portela1 , J. Ochoa1 , A. Ruiz-Angulo2 , Key Points: 1 • The thermohaline and kinematic and S. Cusí vertical structure of a recently 1 2 detached Loop Current Eddy is Departamento de Oceanografía, CICESE, Ensenada, B.C., Mexico, UNAM, Ciudad de México, CDMX, Mexico revealed in details • This structure results from conservative advection of Caribbean Abstract The vertical structure of a recently detached Loop Current Eddy (LCE) is studied using in water below 200 m and surface fluxes situ data collected with an underwater glider from August to November 2016. Altimetry and Argo data are and mixing above • Heat and salt excess carried by the analyzed to discuss the context of the eddy shedding and evolution as well as the origin and transformation eddy requires important heat fluxes of its thermohaline properties. The LCE appeared as a large body of nearly homogeneous water between and fresh water input for balance to 50 and 250 m confined between the seasonal and main thermoclines. A temperature anomaly relative be reached in the Gulf of Mexico to surrounding Gulf’s water of up to 9.7∘ C was observed within the eddy core. The salinity structure had a double core pattern. The subsurface fresh core had a negative anomaly of 0.27 practical salinity unit, while Correspondence to: T. Meunier, the deeper saline core’s positive anomaly reached 1.22 practical salinity unit. Both temperature and salinity [email protected] maxima were stronger than previously reported. -
Predictability of the Loop Current Variation and Eddy Shedding Process in the Gulf of Mexico Using an Artificial Neural Network Approach
1098 JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY VOLUME 32 Predictability of the Loop Current Variation and Eddy Shedding Process in the Gulf of Mexico Using an Artificial Neural Network Approach XIANGMING ZENG,YIZHEN LI, AND RUOYING HE Department of Marine, Earth, and Atmospheric Sciences, North Carolina State University, Raleigh, North Carolina (Manuscript received 15 September 2014, in final form 8 January 2015) ABSTRACT A novel approach based on an artificial neural network was used to forecast sea surface height (SSH) in the Gulf of Mexico (GoM) in order to predict Loop Current variation and its eddy shedding process. The em- pirical orthogonal function analysis method was applied to decompose long-term satellite-observed SSH into spatial patterns (EOFs) and time-dependent principal components (PCs). The nonlinear autoregressive network was then developed to predict major PCs of the GoM SSH in the future. The prediction of SSH in the GoM was constructed by multiplying the EOFs and predicted PCs. Model sensitivity experiments were conducted to determine the optimal number of PCs. Validations against independent satellite observations indicate that the neural network–based model can reliably predict Loop Current variations and its eddy shedding process for a 4-week period. In some cases, an accurate forecast for 5–6 weeks is possible. 1. Introduction critical importance for both scientific research and so- cietal benefit. For example, in order to mitigate the ad- Originating at the Yucatan Channel and exiting verse impacts of the Deepwater Horizon oil spill in 2010, through the Florida Straits, the Loop Current (LC) is a intensive research on the LC and LC eddies was per- dominant circulation feature in the Gulf of Mexico formed during and after the incident (e.g., Liu et al. -
SWASHES: a Compilation of Shallow Water Analytic Solutions For
SWASHES: a compilation of Shallow Water Analytic Solutions for Hydraulic and Environmental Studies O. Delestre∗,‡,,† C. Lucas‡, P.-A. Ksinant‡,§, F. Darboux§, C. Laguerre‡, T.N.T. Vo‡,¶, F. James‡ and S. Cordier‡ January 22, 2016 Abstract Numerous codes are being developed to solve Shallow Water equa- tions. Because there are used in hydraulic and environmental studies, their capability to simulate properly flow dynamics is critical to guaran- tee infrastructure and human safety. While validating these codes is an important issue, code validations are currently restricted because analytic solutions to the Shallow Water equations are rare and have been published on an individual basis over a period of more than five decades. This article aims at making analytic solutions to the Shallow Water equations easily available to code developers and users. It compiles a significant number of analytic solutions to the Shallow Water equations that are currently scat- tered through the literature of various scientific disciplines. The analytic solutions are described in a unified formalism to make a consistent set of test cases. These analytic solutions encompass a wide variety of flow conditions (supercritical, subcritical, shock, etc.), in 1 or 2 space dimen- sions, with or without rain and soil friction, for transitory flow or steady state. The corresponding source codes are made available to the commu- nity (http://www.univ-orleans.fr/mapmo/soft/SWASHES), so that users of Shallow Water-based models can easily find an adaptable benchmark library to validate their numerical methods. Keywords Shallow-Water equation; Analytic solutions; Benchmarking; Vali- dation of numerical methods; Steady-state flow; Transitory flow; Source terms arXiv:1110.0288v7 [math.NA] 21 Jan 2016 ∗Corresponding author: [email protected], presently at: Laboratoire de Math´ematiques J.A. -
Lecture 7: Atmospheric General Circulation
The climatological mean circulation Deviations from the climatological mean Synthesis: momentum and the jets Lecture 7: Atmospheric General Circulation Jonathon S. Wright [email protected] 11 April 2017 The climatological mean circulation Deviations from the climatological mean Synthesis: momentum and the jets The climatological mean circulation Zonal mean energy transport Zonal mean energy budget of the atmosphere The climatological mean and seasonal cycle Deviations from the climatological mean Transient and quasi-stationary eddies Eddy fluxes of heat, momentum, and moisture Eddies in the atmospheric circulation Synthesis: momentum and the jets Vorticity and Rossby waves Momentum fluxes Isentropic overturning circulation The climatological mean circulation Zonal mean energy transport Deviations from the climatological mean Zonal mean energy budget of the atmosphere Synthesis: momentum and the jets The climatological mean and seasonal cycle 400 Outgoing longwave radiation 350 net energy loss in Incoming solar radiation ] 2 − 300 the extratropics m 250 W [ x 200 u l f y 150 net energy gain g r e n 100 E in the tropics 50 0 90°S 60°S 30°S 0° 30°N 60°N 90°N 6 4 2 0 2 Energy flux [PW] 4 JRA-55 6 90°S 60°S 30°S 0° 30°N 60°N 90°N data from JRA-55 The climatological mean circulation Zonal mean energy transport Deviations from the climatological mean Zonal mean energy budget of the atmosphere Synthesis: momentum and the jets The climatological mean and seasonal cycle 400 Outgoing longwave radiation 350 Incoming solar radiation ] 2 − 300 -
Patterns of the Loop Current System and Regions of Sea Surface Height Variability in the Eastern Gulf of Mexico Revealed by the Self-Organizing Maps
University of South Florida Scholar Commons Marine Science Faculty Publications College of Marine Science 4-2016 Patterns of the Loop Current System and Regions of Sea Surface Height Variability in the Eastern Gulf of Mexico Revealed by the Self-Organizing Maps Yonggang Liu University of South Florida, [email protected] Robert H. Weisberg University of South Florida, [email protected] Stefano Vignudelli Consiglio Nazionale delle Ricerche, Area Ricerca CNR Gary T. Mitchum University of South Florida, [email protected] Follow this and additional works at: https://scholarcommons.usf.edu/msc_facpub Scholar Commons Citation Liu, Yonggang; Weisberg, Robert H.; Vignudelli, Stefano; and Mitchum, Gary T., "Patterns of the Loop Current System and Regions of Sea Surface Height Variability in the Eastern Gulf of Mexico Revealed by the Self-Organizing Maps" (2016). Marine Science Faculty Publications. 273. https://scholarcommons.usf.edu/msc_facpub/273 This Article is brought to you for free and open access by the College of Marine Science at Scholar Commons. It has been accepted for inclusion in Marine Science Faculty Publications by an authorized administrator of Scholar Commons. For more information, please contact [email protected]. PUBLICATIONS Journal of Geophysical Research: Oceans RESEARCH ARTICLE Patterns of the loop current system and regions of sea surface 10.1002/2015JC011493 height variability in the eastern Gulf of Mexico revealed by the Key Points: self-organizing maps A combined space- and time-domain Self-Organizing Map analysis is Yonggang Liu1, Robert H. Weisberg1, Stefano Vignudelli2, and Gary T. Mitchum1 performed The extracted spatial patterns 1College of Marine Science, University of South Florida, St. -
Upwelling and Isolation in Oxygen-Depleted
Biogeosciences Discuss., doi:10.5194/bg-2016-34, 2016 Manuscript under review for journal Biogeosciences Published: 11 March 2016 c Author(s) 2016. CC-BY 3.0 License. Upwelling and isolation in oxygen-depleted anticyclonic modewater eddies and implications for nitrate cycling Johannes Karstensen1, Florian Schütte1, Alice Pietri2, Gerd Krahmann1, Björn Fiedler1, Damian Grundle1, Helena Hauss1, Arne Körtzinger1,3, Carolin R. Löscher1, Pierre Testor2, Nuno Viera4, Martin 5 Visbeck1,3 1GEOMAR, Helmholtz Zentrum für Ozeanforschung Kiel, Düsternbrooker Weg 20, 24105 Kiel, Germany 2LOCEAN, UMPC; Paris, France 3Kiel University, Kiel Germany 4Instituto Nacional de Desenvolvimento das Pescas (INDP), Cova de Inglesa, Mindelo, São Vicente, Cabo Verde 10 Correspondence to: Johannes Karstensen ([email protected]) Abstract. The physical (temperature, salinity, velocity) and biogeochemical (oxygen, nitrate) structure of an oxygen depleted coherent, baroclinic, anticyclonic mode-water eddy (ACME) is investigated using high-resolution autonomous glider and ship data. A distinct core with a diameter of about 70 km is found in the eddy, extending from about 60 to 200 m depth and. The core is occupied by fresh and 15 cold water with low oxygen and high nitrate concentrations, and bordered by local maxima in buoyancy frequency. Velocity and property gradient sections show vertical layering at the flanks and underneath the eddy characteristic for vertical propagation (to several hundred-meters depth) of near inertial internal waves (NIW) and confirmed by direct current measurements. A narrow region exists at the outer edge of the eddy where NIW can propagate downward. NIW phase speed and mean flow are of 20 similar magnitude and critical layer formation is expected to occur. -
The Atmospheric General Circulation and Its Variability Dennis L
The Atmospheric General Circulation and its Variability Dennis L. Hartmann Department of Atmospheric Sciences, University of Washington, Seattle, Washington USA Abstract Progress in understanding the general circulation of the atmosphere during the past 25 years is reviewed. The relationships of eddy generation, propagation and dissipation to eddy momentum fluxes and mean zonal winds are now sufficiently understood that intuitive reasoning about momentum based on firm theoretical foundations is possible. Variability in the zonal-flow can now be understood as a process of eddy, zonal-flow interaction. The interaction of tropical overturning circulations driven by latent heating with extratropical wave-driven jets is becoming a fruitful and interesting area of study. Gravity waves have emerged as an important factor in the momentum budget of the general circulation and are now included in weather and climate models in parameterized form. Stationary planetary waves can largely be explained with linear theory. 1. Introduction: I attempt here to give a summary of progress in understanding the general circulation of the atmosphere in the past 25 years, in celebration of the 125th anniversary of the Meteorological Society of Japan. This is a daunting task, especially within the confines of an article of reasonable length. I will therefore concentrate on a few areas that seem most interesting and important to me and with which I am relatively familiar. I will not attempt to give a full list of references, but will attempt to pick out a few important early references and some more recent references. Interested readers can use these data points to fill in the intervening developments. -
Ocean Surface Current Climatology in the Northern Gulf of Mexico
Ocean Surface Current Climatology in the Northern Gulf of Mexico by Donald R. Johnson Center for Fisheries Research and Development Gulf Coast Research Laboratory University of Southern Mississippi Project funded by the Marine Fisheries Initiative (MARFIN) program of NMFS/NOAA Published by Gulf Coast Research Laboratory Ocean Springs, Mississippi 39564 May 2008 Table of Contents List of Figures ………………………………………1 Abstract ………………………………………2 I. Introduction ………………………………………3 II. Data and Statistics ………………………………………4 A. Scalar ………………………………………6 B. Vector ……………………………………..10 III. Wind Stress Climatology ……………………………………14 IV. Surface Current Patterns ..….....……………………………20 A. Methodology ………...…………………………...20 B. Monthly Averaged Currents .......................................21 Acknowledgements ……………………………………..36 References ……………………………………..37 ii List of Figures: Figure Page 1. Sea Surface Temperature in the Gulf of Mexico 3 2. Location of daily current vectors in data set 4 3. Grid distribution 5 4. Average Speed (Savg) 6 5. Standard Deviation of Speed (Sstd) 7 6. Maximum Speed (Smax) 8 7a. Scatter plot U/V(Dog Key Pass) 9 7b. Scatter plot U/V (South of Petit Bois Island) 9 8. Vector Resultant Speed (Sr) 11 9. Vector Resultant Direction 12 10. Correlation U/V (r) 13 11. Monthly climatological wind stress for the northern Gulf of Mexico. Taken from Harrison(1989). 15-18 12. Climatological wind stress averages for non-summer (upper) And summer (lower) months. 19 13. Example of observed daily currents between year-days 172-192 and within 50 km of a single grid point (red square). The inner red circle is 20 km from the grid point and the outer red circle is 50 km away. 20 14. Weight of current observation vs distance from each grid point. -
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.