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NW Atlantic Sea Height Anomalies and Altimeter-derived Geostrophic Currents

Daily near-real-time sea height anomaly (SHA) data from TOPEX, ERS-2 and GFO altimeters are computed by the NOAA Laboratory for Satellite Altimetry. Data are averaged along 0.2-degree latitude segments of the ground track.
Users can display SHA and geostrophic current maps by using the form below. Check in the proper fields to adjust the visualization parameters.

Last Map (zero contour in red)

Select parameters

SHA

Select Sea Height Anomalies computed by removing linear trends from the along-track data. It also removes the large-scale seasonal level signal. This and the next two fields are mutually exclusive; you can leave the three checkboxes unselected or select one at most

Velocities

Geostrophic velocities are estimated using the SHA values and dynamic topography climatologies (see below).

Velocity Field

This option displays an scalar map where higher velocities are enhanced and the most active areas are clearly visible.

Data Points

Interpolation quality can be checked using this field. Data positions used to generate the products are overlayes on the map. Data from each satellite are displayed using different colors.

Mask Depths

Depths shallower than the selected values are masked.

Climatology

Three different Mean Surface Height references are available if velocity products are generated:

OCCAM_MODEL. This is from a 3 year OCCAM run driven with realistic (ECMWF) winds. OCCAM mssh errors in boundary current separation regions are removed by using climatological dynamic heights based on Levitus (Kuroshio) and Lozier (Gulf Stream) climatologies. Spatial Resolution: 0.25 degree. Additional Information: Alan Fox, Keith Haines, Beverley De Cuevas and David Webb. Altimeter Assimilation in the OCCAM Global Model, Part II: TOPEX/POSEIDON and ERS1 Data. Journal of Marine Systems, 26, 323-347, 2000.
OCCAM_XBT. This is from a 4-year 1992-96 OCCAM run driven by ECMWF winds and with XBT subsurface temperature data assimilated. The assimilation of hydrographic data helps control the biases in the OCCAM mean ssh, so no modifications are made. The mean represents years 1993-95. Spatial Resolution: 0.25 degree. Data Source: Alan Fox, Haines and the OCCAM group.
LEVITUS1000m. Mean Dynamic Topography relative to 1000m depth level. Spatial Resolution: 1 degree.

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