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Aucun titre de diapositive

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First systematic model/current meter comparison study at basin scale ... Future Work. Investigate the origin of problems. Same exercice on low-passed velocity ... – PowerPoint PPT presentation

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Title: Aucun titre de diapositive


1
Temporal and spatial structure of the Atlantic
eddy flow between 1980 and 2000 WOCE current
meter database versus 1/6 CLIPPER model
Thierry Penduff, Bernard Barnier, Christel Le
Delliou LEGI, Grenoble, France
APPROACH Observed EKEs Gather 1980-2000 WOCE
velocity data Selection / filtering /
interpolation EKE estimates over 6-months
intervals Model EKEs are Mirror images of
observed EKE estimates
OBJECTIVES Rigorously compare model and WOCE EKE
estimates over the Atlantic during 20 years
(Horizontal, vertical, and temporal structure)
  • CLIPPER MODEL SIMULATION
  • OPA 8.1 z-level code
  • Primitive equations
  • 68oS-65oN, 4 open boundaries
  • 1/6o mercator grid, 42 levels
  • 8-year spinup (Mean ERA15)
  • 1980-2000 (ECMWF reanalysis
  • analysis)
  • WOCE CURRENT METER
  • DATASET
  • 1300 velocity time series

2
Processing of the WOCE and CLIPPER databases
1300 raw WOCE velocity time series
CLIPPER 1980-2000 database
Quality tests gap filling or not, Tgt6 months, ...
Same locations and time intervals
31.5 rejected
891 velocity time series
5 day low-pass filter - Detrending - Variance
computation
891 WOCE and CLIPPER EKE estimates at the same
(x,y,z,t)
CLUSTERS
3
Intensity of the mean EKE field within clusters
Gulf Stream Cluster Model EKE field is too
strong and baroclinic
4
Baroclinicity of the mean EKE field
Baroclinicity B(EKEupper-EKElower)/EKElower
Shown Bmodel / BWOCE.
Model EKE too baroclinic
Model EKE too barotropic
Summary First systematic model/current meter
comparison study at basin scale Criteria
time-averaged EKE levels and baroclinicity In
most areas Model EKE levels somewhat too
weak (resolution) Model EKE too baroclinic
(spurious bottom friction in z-level
models) Model EKE level and baroclinicity
especially realistic in the NECC Future
Work Investigate the origin of problems Same
exercice on low-passed velocity timeseries
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