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Giovanni-3 User's ManualChapter 6:A-Train

What is the A-Train?

The A-Train of satellites circles Earth in a "formation flying" configuration. About 8 minutes pass between the time the first satellite (Aqua) and the last (Aura) passes over any given spot. Overall, the string of satellites stretches across 3,000 kilometers (1,864 miles) in space, with each traveling about 7 kilometers per second . CloudSat radar trails Aqua by an average of about 60 seconds. CloudSat flies approximately 460 kilometers (286 miles) behind Aqua and much closer in front of CALIPSO-only around 93.8 kilometers (58.3 statute miles) away, which corresponds to 12.5 seconds average delay between lidar and radar measurements from CloudSat and CALIPSO.

What data are currently available for the A-Train satellites in Giovanni-3?

Currently, data from the Cloud Profiling Radar (CPR) instrument on CloudSat and data from MODIS-Aqua are available in Giovanni-3.

What data parameters from CloudSat are available in Giovanni-3?

Reflectivity(dBz) and Received Echo Powers from Cloudsat
Temperature and humidity from MODIS-Aqua.

How does Giovanni-3 display the A-Train data?

Giovanni-3 generates the data output for CloudSat as a "Curtain Plot". A Curtain Plot creates a two-dimensional representation of data parameter values plotted against pressure (in the vertical dimension) and
distance along the satellite ground track (in the horizontal dimension). The data parameter values in the Curtain Plot are displayed using a color palette.

How are dates and region of interest selected for the A-Train instance?

The user initially specifies a date of interes using the calendar menu, and the orbital tracks are displayed. Ascending or descending orbits may be selected. A point on the orbital track is designated with the Java applet map,, and the range along the track (with this point at the center of the range) is designated. The minimum range is 350 kilometers.

How is the output generated for the A-Train instance?

Once the date and range have been selected, the Curtain Plot can now be generated by clicking the "Run Service" button. All four parameters can be plotted together on a single output page, or individual parameters can be displayed. (To remove a parameter from the display, depress the "Ctrl" button and click on the parameter. To add a deleted parameter, click on the deleted parameter.  Selected parameters will be highlighted in blue.).

Why is this called a "beta" instance?

Development of the instance and the addition of more parameters and plotting options is continuing.

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Last updated: Sep 09, 2009 02:30 PM ET