TY  - JOUR
A1  - Kim, Kyung-Chan
A1  - Shprits, Yuri Y.
T1  - Survey of the Favorable Conditions for Magnetosonic Wave Excitation
T2  - Journal of geophysical research : Space physics
N2  - The ratio of the proton ring velocity (VR) to the local Alfven speed (VA), in addition to proton ring distributions, plays a key factor in the excitation of magnetosonic waves at frequencies between the proton cyclotron frequency fcp and the lower hybrid resonance frequency fLHR in the Earth's magnetosphere. Here we investigate whether there is a statistically significant relationship between occurrences of proton rings and magnetosonic waves both outside and inside the plasmapause using particle and wave data from Van Allen Probe-A during the time period of October 2012 to December 2015. We also perform a statistical survey of the ratio of the ring energy (ER, corresponding to VR) to the Alfven energy (EA, corresponding to VA) to determine the favorable conditions under which magnetosonic waves in each of two frequency bands (fcp < f ≤ 0.5 fLHR and 0.5 fLHR < f < fLHR) can be excited. The results show that the magnetosonic waves in both frequency bands occur around the postnoon (12–18 magnetic local time, MLT) sector outside the plasmapause when ER is comparable to or lower than EA, and those in lower-frequency bands (fcp < f ≤ 0.5 fLHR) occur around the postnoon sector inside the plasmapause when ER/EA > ~9. However, there is one discrepancy between occurrences of proton rings and magnetosonic waves in low-frequency bands around the prenoon sector (6–12 MLT) outside the plasmapause, which suggests either that the waves may have propagated during active time from the postnoon sector after being excited during quiet time, or they may have locally excited in the prenoon sector during active time.
Y1  - 2018
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/54602
SN  - 2169-9380
SN  - 2169-9402
VL  - 123
IS  - 1
SP  - 400
EP  - 413
PB  - American Geophysical Union
CY  - Washington
ER  -