Summer-Winter Hemispheric Asymmetry of Sudden Increase in Ionospheric Total Electron Content

Details Summer-Winter Hemispheric Asymmetry of Sudden Increase in Ionospheric Total Electron Content Summer-Winter Hemispheric Asymmetry of Sudden Increase in Ionospheric Total Electron Content

Dec 2006

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2006agufmsa23a..05t&link_type=abstract

American Geophysical Union, Fall Meeting 2006, abstract #SA23A-05

Other

2419 Ion Chemistry And Composition (0335), 2423 Ionization Processes (7823), 2427 Ionosphere/Atmosphere Interactions (0335), 2479 Solar Radiation And Cosmic Ray Effects, 7519 Flares

Scientific paper

Sudden increases in total electron content (SITEC) induced by intense solar flares and their relation to O/N2 density ratio were statistically studied using data of GPS networks, TIMED/GUVI, and NRLMSISE-00 model. SITEC is one of sudden ionospheric disturbances induced by solar flares, which emit extreme ultraviolet and X rays in short time interval. The recently developed imaging technique using TEC data from GPS receiver networks has been applied to study SITEC and have clarified some of global-scale characteristics of SITEC phenomena [e.g., Afraimovich et al., 2001; Zhang and Xiao, 2003, 2005]. However, seasonal, local-time, and solar-cycle dependencies of SITEC have been still in dispute. In this study, we investigated 91 SITEC events associated with solar flares larger than M5 X-ray class during January 2000 and May 2005 global TEC data from SOPAC GPS networks. The global TEC maps revealed that the SITEC value basically depends on the cosine of solar zenith angle (SZA). However, we found that there were significant residuals (delta) from the linear fitting to the SZA for almost all the flare events. The value of delta is statistically larger in the winter hemisphere than in the summer hemisphere. The strength of summer-winter hemispheric asymmetry becomes weaker as the solar cycle declines toward its minimum. On the other hand, there is not a clear statistical difference in delta between the morning and evening sectors. Some similarity of summer-winter asymmetry is also seen in the dayside distribution of the O/N2 density ratio from both the NRLMSISE-00 model and the TIMED/GUVI observation. The latitudinal gradient of GUVI O/N2 at the solstice becomes smaller to follow the increasing solar activity in the same way as that of the residual SITEC delta. These results indicate that the SITEC phenomena induced by intense solar flares depend on not only the SZA, but also the O/N2 density ratio.

Affiliated with

Also associated with

No associations

Rating

Summer-Winter Hemispheric Asymmetry of Sudden Increase in Ionospheric Total Electron Content does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Summer-Winter Hemispheric Asymmetry of Sudden Increase in Ionospheric Total Electron Content, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Summer-Winter Hemispheric Asymmetry of Sudden Increase in Ionospheric Total Electron Content will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-965306