Summary Goal: Determine Te solar cycle variation for inclusion in IRI.
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Transcript of Summary Goal: Determine Te solar cycle variation for inclusion in IRI.
Solar Cycle Variations of Solar Cycle Variations of Topside Electron Density and Topside Electron Density and
Temperature: Altitudinal, Temperature: Altitudinal, Latitudinal, and Seasonal Latitudinal, and Seasonal
Differences. Differences.
D. Bilitza(1), P. Richards(2), V. Truhlik(3), T. Abe(4), L. Triskova(3)
(1)Raytheon ITSS, GSFC, SPDF, Greenbelt, USA
(2)NASA, Earth-Sun Systems Division, Washington DC, USA(3) Institute of Atmospheric Physics, Praha, Czech Republic
(4) Aerospace Exploration Agency (JAXA), Sagamihara, Japan
Summary
- Goal: Determine Te solar cycle variation for inclusion in IRI.
- Source: Data base of satellite insitu measurements and FLIP model
- This Study: Solar activity variation of Ne and Te at 550, 900, and 2000 km, for MLT= 2, and 13, during all seasons
Previous Studies – Balan et al., 2001- MU Radar
Balance of gain, loss,and transport processes for thermal energy can result in increase or decrease with solar activity.
Previous Studies – Oyama et al., 2002 - Akebono
At high altitudes the heat transport from the plasmasphere results in an increase with solar activity.
Previous Studies – Zhang, Holt, 2004 – Millstone Hill
Database
Akebono, since Feb 1989, 700 – 10,000 km, -75 - 75
Altitudinal Differences – Jicamarca latitude
Altitudinal Differences – Jicamarca:
Altitudinal Differences – Millstone Hill:
Midnight Noon
Averages of Akebono electron temperatures versus solar flux for different altitude ranges during daytime for summer (top) and winter (right) conditions seem to indicate an increase with solar flux at higher altitudes and a decrease for the lower height range and no significant seasonal changes.
Equinox, mid-latitude, noon
550
km90
0 km
2000
km
Log(Ne) Te
Winter, mid-latitude, midnight55
0 km
900
km20
00 k
m
Log(Ne) Te
600 kmNoon, Mid-lat
900 km1500 km
2200 kmMidnight, Mid-latMidnight, EquatorNoon, Equator
Seasonal Differences
Mid-latitude, noon, 550 km
Equ
inox
Sum
mer
Win
ter
Mid-latitude, noon, 900 km
Equ
inox
Sum
mer
Win
ter
Mid-latitude, noon, 2000 kmE
quin
oxS
umm
erW
inte
r
Summer
EquinoxWinter
Results
-Ne increases with solar activity for all cases.
-Solar cycle effects are strongest at low altitudes.
- Te changes over the solar cycle are generally much smaller than those of Ne and show a seasonal dependence during daytime: increases in summer, constant or small decrease in winter, decrease in equinox.
-FLIP generally confirms the Ne trends seen in our data base.
-FLIP agrees well with the Te daytime values. - During nighttime FLIP overestimates the winter values and underestimates the summer and equinox data