CDAWeb has a WWW-based user interface (HTML and CGI front-end) that accepts
user requests and generates HTML, ASCII, and GIF output that is viewed by your
WWW browser (e.g. Netscape
, Internet Explorer
, etc). To use CDAWeb
you must have a browser capable of filling out forms and displaying inline GIF images.
For general information see the following articles that describe CDAWeb:
Note: Accessing large amounts of data may take up to several minutes so
please be patient, otherwise try selecting data from smaller time periods. This full
ISTP KP data access will be the largest-scale user exposure to the system to date,
and the first wide exposure of the system combined with this database. Please report
any anomalies or problems as they are seen in your testing and use.
We hope you like what we've done!
For each database accessible via CDAWeb, the system consists of three major components,
a series of WWW pages (Home Page, Data Selector, Data Explorer), as depicted in
Figure 1 below.
Figure 1. CDAWeb System Diagram
- HOME PAGE -- choose a mission group (e.g., Wind,
Geosynchronous spacecraft, ground-based investigations) and/or instrument type
(e.g., Magnetic Fields (space,) Particles (space), Ground-Based HF-Radars).
- DATA SELECTOR -- submit or deselect and then
submit the instruments that resulted from the first step.
- DATA EXPLORER -- choose from a list of variables
for each selected data set, specify the time range, and specify whether you want
a plot or a listing/ASCII file.
HOME PAGE (known as the CDAWeb Source Selector Form)
- This is typically the starting point in using the system.
- From this form, choose a mission group source and/or instrument to get a list
- Mission groups and instruments are logically combined in a query such
that selecting "Geotail" mission and "Magnetic Fields" instrument will
only match Geotail Magnetic Field datasets as in a logical "AND" operation.
Selection of multiple missions and multiple instruments becomes a
logical "OR" operation; e.g., selecting Geotail and Wind missions and
Electric Fields and Magnetic field instruments will match against
all Geotail and Wind datasets that have either electric field or magnetic field
- Press the "submit" button to find matching datasets.
- Datasets matching your query are pre-selected in a list and may
be unselected by clicking on the checkboxes.
- The list includes the data set name, source name, PI and affiliation.
- Make your selections and press "submit" button to view the variables/parameters
in those datasets.
- Parameters for each dataset are displayed on the data explorer form.
- Select start and stop time, which is pre-populated with the last-most
- Select activity (Download, List, or Plot) to perform the appropriate operation.
- Select variables only to List or Plot (download option lists all CDF data files
for selected times including all variables).
- Press "submit" button to perform the action.
The data are then processed and displayed (as plots or listings),
or you can download the CDF data files themselves.
The plots are in fact a set of GIF image(s) that can be easily downloaded and saved
locally if desired. At this time, the type of plot used for a particular variable is
automatically determined. Other plot types and functionality will be added in the
future. (Note that the powerful underlying
IDL plotting software is available
for download to further analyze the datasets.)
The listings are displayed as hyperlinks that can be displayed on
the browser and/or saved directly as an ASCII file (which is an option of your
local browser using "Source" (AS-IS) as the format for the saved document.)
- Download CDFs
Selecting this option will generate a list of CDF data sets for the
particular time period. Each file can be downloaded by clicking on the
All databases listed as public
are available to anyone
with no prior permission. However,
CDAWeb databases are password protected (please send all access
questions to Bob McGuire, (301) 286-7794, Robert.E.McGuire@nasa.gov )
A number of error messages are displayed when user input is invalid or missing
required fields, system resources are unavailable, and other situations occur.
Most of these error messages are explained in the
There is a
of restrictions and problems with individual data sets available through CDAWeb.