Overview of the OMNI 2 data set and the OMNIWeb interface

The OMNIWeb interface provides access to the multi-source OMNI 2 data set, to the individual data sets contributing to OMNI 2 and to detailed documentation about OMNI 2.

The OMNI 2 data set

The OMNI 2 data set was created at NSSDC in 2003 as a successor to the OMNI data set first created in the mid-1970's. The OMNI 2 data set contains hourly resolution solar wind magnetic field and plasma data from many spacecraft in geocentric orbit and in orbit about the L1 Lagrange point ~225 Re in front of the Earth. The data set also contains hourly fluxes of energetic protons, geomagnetic activity indices (AE, Dst, etc.) and sunspot numbers. The data set is periodically updated. Details about the contents and preparation of OMNI 2 are found in the two other options of the "About OMNI 2 data and OMNIWeb interface" section of the top OMNIWeb page.

The OMNIWeb interface

The OMNIWeb interface provides multi-modal access to the OMNI 2 data set, to data contributing to OMNI 2 as well as to other solar wind data not used in OMNI 2, and detailed documentation about OMNI 2 and its OMNI predecessor.

In the "Browse and Retrieve Data" section of the OMNIWeb interface, the basic data access functionality (1) allows users to generate intensity-time plots, screen listings or downloadable ASCII files of any subset of OMNI 2 parameters for any time span. The data may be basic hourly data or daily or 27-day averages thereof. In addition, (2) users may generate screen listings or ASCII files of any parameter subset limited to hours when values of any (same or other) subset of parameters fall within user-specified minima and maxima. (This is "filtering.") Another option (3) allows users to build scatter plots for any pair of OMNI 2 parameters for any time span, again using filtering by values of any parameter subset. In addition to the scatter plot, this option also computes a linear regression fit between the parameter pair plotted. A fourth option (4) lets users generate distributions of parameter values for any OMNI parameter for any time span, with filtering against any parameter subset. This option also computes means and standatd deviations for the data selected for the distribution. The final option (5) of the "Browse and Retrieve Data" section of the OMNIWeb interface yields a static (but periodically NSSDC-updated) daily-resolution IMF polarity plot covering the entire OMNI 2 time span.

A separate section of the OMNIWeb interface delivers the user to ftp areas of the Space Physics Data Facility at NASA/GSFC where hourly, daily and 27-day OMNI 2 ASCII files are ftp-accessible. Also ftp- accessible are CDF-formatted versions of the hourly files and ASCII files whose records are formatted for COHOWeb compatibility. (COHOWeb data cover the heliospheric regions visited by Pioneer, Voyager, Ulysses, Earth, etc.)

Another OMNIWeb interface section links users (1) to SPDF or other web pages from which higher resolution magnetic field and plasma data contributing to the hourly OMNI 2 averages are accessible, (2) to various merged hourly data sets created at NSSDC as part of OMNI 2 preparation and (3) to some other currently important solar wind data which have not (yet) been folded into OMNI 2.

Finally, the "About ." section links users to two major descriptive texts about OMNI 2 data set contents and preparation. The text labelled "OMNI 2 data" is an update of an equivalent text which long described the OMNI data set. Among other things, it gives (1) the time spans of each type of data in OMNI 2, (2) the detailed list of words in the OMNI 2 records with units and formats (e.g., F6.1), (3) a discussion of the creation of daily and 27-day averages and (4) links to (4a) field and plasma coverage-vs-time plots and to (4b) scanned pages from early Interplanetary Medium Data Books describing the preparation of the original OMNI data set in detail.

The other text labelled "OMNI 2 preparation" gives detailed information on data sources, cleaning, time-shifting, cross comparisons, normalizations and prioritizations. This text is at a level of detail closer to that of the early Data Books than to that of the "OMNI 2 data" text file.

[November, 2011. The above text uses "OMNIWeb" as the name of the primary interface to OMNI 2 and closely related material. "OMNIWeb now carries a broader meaning, such that the above text is specifically related to http://omniweb.gsfc.nasa.gov/ow.html.]



If you have any questions/comments about OMNIWEB system, contact: Dr. Natalia Papitashvili, National Space Science Data Center, Mail Code 672, NASA/Goddard Space Flight Center, Greenbelt, MD 20771

NASA Official: Dr. Robert McGuire, Head of the Space Physics Data Facility