A New Sea Surface Height–Based Code for Oceanic Mesoscale Eddy Tracking

This paper presents a software tool thatenablesthe identification and automatedtracking ofoceanic eddies observed with satellite altimetry in user-specified regions throughout the global ocean. As input, the code requires sequential maps of sea level anomalies such as those provided by Archiving, Validation, and Interpretationof SatelliteOceanographic (AVISO) data. Outputstake the form of (i) datafiles containing eddy properties,includingposition,radius,amplitude,andazimuthal(geostrophic)speed;and(ii) sequentialimage maps showingseasurface heightmaps withactive eddycenters andtracksoverlaid.The resultsgivenare from a demonstration in the Canary Basin region of the northeast Atlantic and are comparable with a published global eddy track database. Some discrepancies between the two datasets include eddy radius magnitude, and the distributions of eddy births and deaths. The discrepancies may be related to differences in the eddy identification methods, and also possibly to differences in the smoothing of the sea surface height maps. The code is written in Python and is made freely available under a GNU license (http://www.imedea.uib.es/users/ emason/py-eddy-tracker/).

[1]  D. Stammer.  Global Characteristics of Ocean Variability Estimated from Regional TOPEX/POSEIDON Altimeter Measurements , 1997 .

[2]  D. Stammer.  On Eddy Characteristics, Eddy Transports, and Mean Flow Properties , 1998 .

[3]  J. Font,et al.  Identification of Marine Eddies from Altimetric Maps , 2003 .

[4]  P. Tett,et al.  Variability in the Canary Islands area of filament-eddy exchanges , 2004 .

[5]  David Griffin,et al.  Divergent pathways of cyclonic and anti‐cyclonic ocean eddies , 2004 .

[6]  Jorge Tam,et al.  Average circulation, seasonal cycle, and mesoscale dynamics of the Peru Current System: A modeling approach , 2005 .

[7]  Ananda Pascual,et al.  Improved description of the ocean mesoscale variability by combining four satellite altimeters , 2006 .

[8]  John D. Hunter,et al.  Matplotlib: A 2D Graphics Environment , 2007, Computing in Science & Engineering.

[9]  D. Chelton,et al.  Global observations of large oceanic eddies , 2007 .

[10]  Travis E. Oliphant,et al.  Python for Scientific Computing , 2007, Computing in Science & Engineering.

[11]  S. Speich,et al.  Tracking coherent structures in a regional ocean model with wavelet analysis: Application to Cape Basin eddies - art. no. C05043 , 2007 .

[12]  Alexis Chaigneau,et al.  Mesoscale eddies off Peru in altimeter records: Identification algorithms and eddy spatio-temporal patterns , 2008 .

[13]  James C. McWilliams,et al.  The Canary Eddy Corridor: A major pathway for long-lived eddies in the subtropical North Atlantic , 2009 .

[14]  S. Speich,et al.  Mesoscale eddy activity in the southern Benguela upwelling system from satellite altimetry and model data , 2009 .

[15]  Tommy D. Dickey,et al.  A Vector Geometry–Based Eddy Detection Algorithm and Its Application to a High-Resolution Numerical Model Product and High-Frequency Radar Surface Velocities in the Southern California Bight , 2010 .

[16]  Jeffrey J. Early,et al.  The Evolution and Propagation of Quasigeostrophic Ocean Eddies , 2011 .

[17]  D. Chelton,et al.  The Influence of Nonlinear Mesoscale Eddies on Near-Surface Oceanic Chlorophyll , 2011, Science.

[18]  C. D. B. Montégut,et al.  Comparison between three implementations of automatic identification algorithms for the quantification and characterization of mesoscale eddies in the South Atlantic Ocean , 2011 .

[19]  C. Ubelmann,et al.  Vorticity Structures in the Tropical Pacific from a Numerical Simulation , 2011 .

[20]  James C. McWilliams,et al.  Eddy properties in the California Current System , 2011 .

[21]  James C. McWilliams,et al.  Eddy-induced reduction of biological production in eastern boundary upwelling systems , 2011 .

[22]  D. Chelton,et al.  Global observations of nonlinear mesoscale eddies , 2011 .

[23]  R. Blender,et al.  IMILAST: A Community Effort to Intercompare Extratropical Cyclone Detection and Tracking Algorithms , 2013, Bulletin of the American Meteorological Society.

[24]  George Haller,et al.  Objective Detection of Oceanic Eddies and the Agulhas Leakage , 2013 .

[25]  On the role of mesoscale eddies for the biological productivity and biogeochemistry in the eastern tropical Pacific Ocean off Peru , 2013 .

[26]  J. McWilliams.  The Nature and Consequences of Oceanic Eddies , 2013 .

[27]  Valentina Dagienė,et al.  Python for scientific computing education: Modeling of queueing systems , 2014, Sci. Program..

[28]  Björn C. Backeberg,et al.  Eddy properties in the Mozambique Channel: A comparison between observations and two numerical ocean circulation models , 2014 .