TY - JOUR
T1 - Daytime e-region irregularities during the 22 July 2009 solar eclipse over Chung-Li (24.9°N, 121.2°E), a moderate mid-latitude station
AU - Brahmanandam, Potula Sree
AU - Chu, Yen Hsyang
AU - Su, Ching Lun
AU - Lin, Ting Han
PY - 2013/12
Y1 - 2013/12
N2 - The 22 July 2009 solar eclipse with an obscuration of > 83% at Chung-Li (24.9°N, 121.2°E, Dip 35°N) in Taiwan during noon hours has provided a unique opportunity for us to examine its impact on E-region irregularities which were observed simultaneously by the 52 MHz coherent radar and a co-located ionosonde. Significant observations revealed that the daytime E-region strong backscatter echoes at multiple heights and a sudden intensification of the weak sporadic E-layer during the 22 July 2009 solar eclipse. These results follow the research findings of Patra et al. (2009). As the incident solar radiation suddenly blocked by intruding Moon during solar eclipse events that would generally create night-like ionospheric conditions, it is surmised that the E-region irregularities were indeed induced by the eclipse associated effects. The induced effects resulted in faster recombination of molecular ions, generation of gravity waves and electric fields that could have created a conducive environment to excite plasma irregularities through a gradient-drift instability mechanism. The vertical shears of radar Doppler velocity and the peak radar backscatter at the node of Doppler velocity shear, as resolved by the coherent scatter radar with interferometer technique, were possibly due to the upward propagating gravity waves and wave-induced polarization electric fields. The present observational results should not only be highly useful to ascertain plausible mechanisms responsible for nighttime E-region irregularities, but also provided evidence that a solar eclipse could generate E-region plasma irregularities over temperate mid-latitudes for the first time.
AB - The 22 July 2009 solar eclipse with an obscuration of > 83% at Chung-Li (24.9°N, 121.2°E, Dip 35°N) in Taiwan during noon hours has provided a unique opportunity for us to examine its impact on E-region irregularities which were observed simultaneously by the 52 MHz coherent radar and a co-located ionosonde. Significant observations revealed that the daytime E-region strong backscatter echoes at multiple heights and a sudden intensification of the weak sporadic E-layer during the 22 July 2009 solar eclipse. These results follow the research findings of Patra et al. (2009). As the incident solar radiation suddenly blocked by intruding Moon during solar eclipse events that would generally create night-like ionospheric conditions, it is surmised that the E-region irregularities were indeed induced by the eclipse associated effects. The induced effects resulted in faster recombination of molecular ions, generation of gravity waves and electric fields that could have created a conducive environment to excite plasma irregularities through a gradient-drift instability mechanism. The vertical shears of radar Doppler velocity and the peak radar backscatter at the node of Doppler velocity shear, as resolved by the coherent scatter radar with interferometer technique, were possibly due to the upward propagating gravity waves and wave-induced polarization electric fields. The present observational results should not only be highly useful to ascertain plausible mechanisms responsible for nighttime E-region irregularities, but also provided evidence that a solar eclipse could generate E-region plasma irregularities over temperate mid-latitudes for the first time.
KW - Ionospheric irregularities
KW - Mid-latitude ionosphere
KW - Solar eclipse
KW - Wave propagation
UR - http://www.scopus.com/inward/record.url?scp=84890332825&partnerID=8YFLogxK
U2 - 10.3319/TAO.2013.07.08.01(AA)
DO - 10.3319/TAO.2013.07.08.01(AA)
M3 - 期刊論文
AN - SCOPUS:84890332825
SN - 1017-0839
VL - 24
SP - 1021
EP - 1032
JO - Terrestrial, Atmospheric and Oceanic Sciences
JF - Terrestrial, Atmospheric and Oceanic Sciences
IS - 6
ER -