Wind and Other Data Added to OMNI

Volume 14, Number 1, March 1998
By Joseph King and Natasha Papitashvili

The logo of the Wind project.

NSSDC's multispacecraft hourly compilation of nearby solar Wind magnetic field and plasma parameters has mostly consisted of Interplanetary Monitoring Platform (IMP) 8 data since the 1983 departure of the International Sun-Earth Explorer (ISEE) 3 (International Cometary Explorer [ICE]) from the Earth's vicinity. The November 1994 launch of the Wind spacecraft as part of the International Solar-Terrestrial Physics (ISTP) program enables a much more complete OMNI solar Wind record.

NSSDC has just added its first Wind data to OMNI, definitive magnetic field data for May 1995 through June 1996. Because Wind is sometimes an hour or so upstream of the Earth and up to 50 Earth radii transverse to the Earth-Sun line, NSSDC staff had to time shift 1-min data from Wind observation times to expected Earth arrival times, using Wind-observed solar wind flow speeds and the assumption that interplanetary variations are aligned with the ideal Parker spiral angle. Staff then built hourly Wind averages from the shifted 1-min values falling within Earth- arrival hour-boundary times.

For the 14 months of available overlapping Wind and IMP interplanetary magnetic field (IMF) data, staff found 4,331 common hours. The mean values of Wind and IMP differences (IMP minus Wind) Bx, By, Bz, and Bt (t = total; geocentric solar ecliptic [GSE] coordinates) values are -0.06+/-1.03, 0.00+/-0.96, -0.01+/-0.92, -0.05+/ -0.44. For hours when both IMP and Wind data were available, staff retained IMP data in OMNI if IMP coverage was continuous for at least four hours; otherwise, staff added Wind data to OMNI. This addition yielded 4,354 IMP hours, 5,660 Wind hours, and 234 no-coverage hours for the 14-month interval. IMP data were used in preference to Wind data since the IMP data are typically acquired closer to Earth and hence are a somewhat more reliable indicator of solar wind variations impinging on the magnetosphere.

Definitive Wind magnetic field data will be added to OMNI for the first six months of the Wind mission and for the period after June 1996 as they become available from the Goddard Space Flight Center (GSFC) magnetometer team. Definitive Wind solar wind plasma parameters from the GSFC/Massachusetts Institute of Technology (MIT) Solar Wind Experiment (SWE) will also be added as they become available. Staff expect additions on the time scale of a small number of months. At the same time, staff have also been able to update the IMP magnetic field, plasma, and energetic particle data on OMNI to late 1997.

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Miranda Beall, beall@nssdca.gsfc.nasa.gov, (301) 286-0162
Raytheon STX, Code 633, NASA Goddard Space Flight Center
Greenbelt, MD 20771, U.S.A.

Erin D. Gardner, gardner@nssdca.gsfc.nasa.gov, (301) 286-0163
Raytheon STX, Code 633, NASA Goddard Space Flight Center
Greenbelt, MD 20771, U.S.A.



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Author:Miranda Beall
Curators: Erin Gardner and Miranda Beall
Responsible Official: Dr. Joseph H. King, Code 633
Last Revised: 16 APR 98 [EDG]