Near Real-Time Altimeter-GTS Data: Applet Usage

Altimeter Applet Usage

Position the mouse over each component on the image below to learn more about it.

This interface displays near-real time sea height anomalies (SHA) derived from JASON-1, TOPEX, ERS-2, ENVISAT and GFO altimeters, processed by the NRL site at the Stennis Space Center, and GTS data provided by NOAA/NOS. The maps are generated by interpolating SHA data corresponding to a 10-day period up to the selected date. The SHA is the default parameter displayed, with contour values drawn every 10 cm. The dynamic height maps are displayed by activating the field labelled 'currents', with contour values drawn every 50 cm of dynamic height. The data spatial distribution can be observed by overlaying the data points used to generate the SHA map. To identify the data source, the ground-track for each sensor is displayed with different colors: blue-JASON-1,black-TOPEX, red-ERS-2, brown-ENVISAT, pink-GFO.

Three different Mean Surface Heights are available:

OCCAM_MODEL. This field is derived from a 3-year OCCAM run driven with realistic (ECMWF) winds. The 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 field is derived from a 4-year 1992-96 OCCAM run driven by ECMWF winds and assimilated with XBT subsurface temperature data. This assimilation of hydrographic data helps control the biases in the OCCAM mean ssh. 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. Spatial Resolution: 1 degree.

The GTS controls are located in the applet's upper area. Four types of GTS headers are routinely processed and ingested into the database:

BUOY - Reports from buoy observations
TRACKOB - Reports of marine surface observations along ship's tracks
BATHY - Reports of bathythermal observations
TESAC - Temperature, salinity and current reports from sea stations

Using the 'Days' scrollbar, you can select the number of days prior to the chosen ending date as the temporal range to extract the GTS data. The oldest measurement for each WMO code is displayed as a square. The output type is selected by using a drop-down list which comes with the 'Graphics' default.

You can click and drag the mouse on either of the displayed maps to select the area of interest. The button labelled 'Go!' launches the CGI routine that generates the results.

Acknowledgements:
Thanks to Alan Fox for providing the OCCAM mean surfaces.
This applet is based on the TMAPapplet developed by Jonathan Callahan at NOAA/PMEL.

Please, address your questions or comments to Joaquin A. Trinanes

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