CDAWeb Provides New Access to ISTP's KP Data

Volume 12, Number 2, June 1996
By Ramona Kessel, Richard Burley, Robert McGuire, and Mauricio Peredo

The NASA/Goddard Space Flight Center (GSFC) Space Physics Data Facility (SPDF) and NSSDC have just released a new World Wide Web-based system for accessing the public International Solar-Terrestrial Physics (ISTP) Key Parameter (KP) data base: CDAWeb, the Coordinated Data Analysis (Workshop) Web.

The system is tied to a complete and current data base of the full public ISTP KPs presently in production. At this time there are about 400 data variables from GEOTAIL, WIND, INTERBALL, ancillary spacecraft, and ground-based investigations. More variables will be added in the near future from POLAR, the Solar and Heliospheric Observatory (SOHO) and Cluster. CDAWeb supports interactive plotting of variables from multiple instruments on multiple investigations simultaneously on arbitrary, user-defined time scales. It also supports digital data retrieval in both Common Data Format (CDF) and ASCII format.

ISTP spacecraft Key Parameters supply particle and field measurements at approximately one-minute resolution. GEOTAIL KPs include low-energy electron and ion fluxes at 32 energies and four look directions; plasma density, pressure, and bulk flow velocity; energetic particle differential and integral fluxes, abundance ratios, anisotropies; and magnetic and electric field components, spacecraft potential, and bias current. WIND KPs include ion and electron density, velocity and temperature, ion (proton, He, CNO, Iron) and electron fluxes, electric field background, transients, and average values at 76 frequency values, and magnetic field components. Additional particle and field KPs are provided by ancillary spacecraft such as the Interplanetary Monitoring Platform (IMP 8) and the Los Alamos National Laboratory (LANL) and the Geostationary Operational Environment Satellite (GOES) geosynchronous satellites. Ground-based investigations such as HF Radars, VLF/ELF/ULF Radars, Magnetometers, Riometers, Sounders, Photometers and Imagers provide data at anywhere from 1-minute resolution to 30-minute resolution depending on the type of measurement. In many cases the data are more complicated than can be displayed in simple time series plots and thus are displayed as, for example, spectrograms, images, or ionospheric convection patterns.

The easiest paths to CDAWeb access to the full set of ISTP Key Parameters are from either the Space Physics Data Facility Home Page at URL or the NSSDC Space Physics Home Page at URL

This is a powerful new capability to better leverage the combined KP data base to accomplish the coordinated science objectives of ISTP. Readers are invited to take this opportunity to look for events in the Key Parameter data sets, possibly events that they have found already through analyzing other data. Resident with the data is the necessary information (metadata) on labels, time tags, dependencies, display types, etc., so that the steps needed to actually display the data are minimal.

To use CDAWeb, readers should follow these steps:

  1. 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).

  2. Choose from a list of variables for each selected data set. Specify the time range and specify whether a plot or a listing/ASCII file is desired.

The data are then processed and returned (as plots or listings). The plots are in fact a set of GIF image(s) that can be easily downloaded for local save if desired. The listings can be displayed to the screen, saved directly as (an) ASCII file(s) (as an option of the reader's local browser/use "source" mode), or readers can download the CDF data files themselves. At this time the type of plot used for a particular variable is pre-selected and cannot be changed. Other plot types and functionality will be added in the future. (Note that the powerful underlying plot software is in Interactive Data Language [IDL], and plans are to make this software accessible in the fairly near future.)

Additionally, the SPDF Home Page has links for access to SPyCAT (NSSDC/SPDF's Space Physics Catalog Web interface to the more comprehensive NASA Data Archive and Distribution Service [NDADS] near-line archive), access to other CDAWeb data bases (such as the Inter-Agency Consultative Group [IACG] 1st Campaign, the GEOTAIL-WIND Magnetopause Skimming Campaign, and an Education testbed data base of select Coordinated Data Analysis Workshop [CDAW] 9 data), and access to other useful information and tools. One such tool (Gif_walk) aids access to a data base of orbit plots created by the ISTP Science Planning and Operations Facility (SPOF) based from the SPDF/NSSDC Satellite Situation Center software and data base. Gif_walk is also configured for access to the SPOF's data base of existing standard summary plots of Key Parameters being used to check Key Parameter data quality and to identify events.

The platforms supporting these large data bases are being upgraded now, but response may be somewhat slow until these upgrades are complete. 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 data base. Readers are invited to report any anomalies or problems as they are seen in their testing and use.

The authors hope readers like what has been done. For questions or comments on CDAWeb, please contact either Ramona Kessel (telephone: [301] 286-6595; E-mail: or Robert McGuire (telephone: [301] 286-7794; E-mail:

An overview of CDAWeb, a WWW-based display and retrieval system supporting correlative science with a data base spanning nearly four years (and growing). This figure includes the initial Source Selector, some example plots with CDAWeb capabilities highlighted, and some complimentary user responses to the system.

Top row from left to right: Gregory Galiardi, Robert McGuire, and Richard Baldwin. Second row from left to right: Robert Candey, Ramona Kessel, and Jason Mathews. Bottom row from left to right: Mauricio Peredeo, Karen Horrocks, Emily Greene, and Richard Burley.

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Author:Miranda Beall (
Curators: Erin Gardner ( and Miranda Beall (beall@g
Responsible Official: Dr. Joseph H. King, Code 633
Last Revised: 21 Nov 1996 [EDG]