TY - JOUR
T1 - Correlation between electron density and temperature in the topside ionosphere
AU - Kakinami, Yoshihiro
AU - Watanabe, Shigeto
AU - Liu, Jann Yenq
AU - Balan, Nanan
PY - 2011
Y1 - 2011
N2 - The correlation between the electron temperature (Te) and electron density (Ne) at 600 km height at magnetic dip latitudes (MLat) less than about ±40° measured by the Hinotori satellite from February 1981 to June 1982 is presented. The results show the well-known negative correlation between daytime Ne and Te when N e is low. However, when the daytime Ne is significantly high (>106 cm-3), the correlation turns positive irrespective of latitude, longitude, season, solar flux levels, and magnetic activity levels. The positive correlation is most clear during 1100-1500 local time and around the magnetic dip equator (MLat < 10°) where high values of Ne with high Te are most abundant. Te also increases with increasing MLat in the same Ne range. Since the cooling through Coulomb collisions increases with the increase of Ne, the results suggest that an additional heat source(s) is involved for the positive correlation between Ne and Te. The additional heat source seems to be related to the integrated Ne along the magnetic field lines from the ground to 600 km altitude in one hemisphere, which is found to decrease with increasing MLat. Although the mechanism for the positive correlation is not well understood, the results imply that the T e in the topside ionosphere is controlled more by the integrated Ne than by in situ Ne or F2 peak N e..
AB - The correlation between the electron temperature (Te) and electron density (Ne) at 600 km height at magnetic dip latitudes (MLat) less than about ±40° measured by the Hinotori satellite from February 1981 to June 1982 is presented. The results show the well-known negative correlation between daytime Ne and Te when N e is low. However, when the daytime Ne is significantly high (>106 cm-3), the correlation turns positive irrespective of latitude, longitude, season, solar flux levels, and magnetic activity levels. The positive correlation is most clear during 1100-1500 local time and around the magnetic dip equator (MLat < 10°) where high values of Ne with high Te are most abundant. Te also increases with increasing MLat in the same Ne range. Since the cooling through Coulomb collisions increases with the increase of Ne, the results suggest that an additional heat source(s) is involved for the positive correlation between Ne and Te. The additional heat source seems to be related to the integrated Ne along the magnetic field lines from the ground to 600 km altitude in one hemisphere, which is found to decrease with increasing MLat. Although the mechanism for the positive correlation is not well understood, the results imply that the T e in the topside ionosphere is controlled more by the integrated Ne than by in situ Ne or F2 peak N e..
UR - http://www.scopus.com/inward/record.url?scp=84855431741&partnerID=8YFLogxK
U2 - 10.1029/2011JA016905
DO - 10.1029/2011JA016905
M3 - 期刊論文
AN - SCOPUS:84855431741
SN - 2169-9380
VL - 116
JO - Journal of Geophysical Research: Space Physics
JF - Journal of Geophysical Research: Space Physics
IS - 12
M1 - A12331
ER -