11:45 〜 12:00
[PEM11-11] Simultaneous measurement of ion drift and neutral wind using Ba/Sr chemical releases of CHI sounding rocket experiment
キーワード：電離圏、熱圏、ケミカルリリース、カスプ領域、観測ロケット
The CHAMP satellite observations suggest that neutral up-welling due to Joule heating of the ionospheric E layer in the cusp region causes neutral density enhancement above 400 km [Lühr et al., 2004]. In the heating process, small-scale electric field seems to play an important role. Hurd and Larsen [2016] showed that the small-scale electric field estimated from drift of Barium ion (Ba+) and the neutral winds contributed the heating.
To measure the Joule heating and find the neutral up-welling in the cusp region, in November 2014, the sounding rocket campaign which was a chemical release experiment of Barium (Ba) and Strontium (Sr) named Cusp Region Experiment 1 (C-REX-1) was conducted. The sounding rocket was launched from Andøya Space Center, Norway. In this experiment, we measured ion drift and neutral wind using Ba+ as ion tracers and Sr as neutral tracers. However, no signatures of the up-welling and small-scale electric field were observed at the C-REX-1 experiment. In December 2019, the Joint Japan-U.S. Cusp Heating Investigation (CHI) rocket was launched from Svalbard Rocket Range, Norway, and released Ba/Sr from all 8 canisters. Another sounding rocket C-REX-2 was also planned at the same window of CHI; however, it was postponed due to the low magnetospheric activity and weather conditions.
We newly developed band-pass filters for Ba+ (614.2 nm) and Sr (460.7 nm) with 6 nm bandwidth. These wavelengths correspond to the resonance scattering emissions of Ba+/Sr, respectively. We successfully observed Ba+/Sr separately and simultaneously with band-pass filters from Longyearbyen and Ny-Ålesund until about 25 minutes after the launch of the CHI rocket.
The measurement results of the ion drift and neutral wind are shown in Figures 1 and 2. The horizontal velocities of the ion drift were 170-1200 m/s to east-northeast direction approximately. In only one case of 3rd ion tracer, a vertical velocity of 323 m/s was obtained at 324 km altitude, although the data was only available for about one minute for analysis. Neutral tracers moved to the northwest or west direction at 100-170 m/s horizontally. We analyzed two of the eight clouds but we could not find neutral up-welling which could cause the enhancement of neutral density above 400 km.
References:
Lühr, H., M. Rother, W. Köhler, P. Ritter, L. Grunwaldt, Thermospheric up-welling in the cusp region: Evidence from CHAMP observations, Geophys. Res. Lett., 31, L06805, 2004.
Hurd, L. D., and M. F. Larsen, Small-scale fluctuations in barium drifts at high latitudes and associated Joule heating effects, J. Geophys. Res. Space Physics, 121, 779–789, 2016.
To measure the Joule heating and find the neutral up-welling in the cusp region, in November 2014, the sounding rocket campaign which was a chemical release experiment of Barium (Ba) and Strontium (Sr) named Cusp Region Experiment 1 (C-REX-1) was conducted. The sounding rocket was launched from Andøya Space Center, Norway. In this experiment, we measured ion drift and neutral wind using Ba+ as ion tracers and Sr as neutral tracers. However, no signatures of the up-welling and small-scale electric field were observed at the C-REX-1 experiment. In December 2019, the Joint Japan-U.S. Cusp Heating Investigation (CHI) rocket was launched from Svalbard Rocket Range, Norway, and released Ba/Sr from all 8 canisters. Another sounding rocket C-REX-2 was also planned at the same window of CHI; however, it was postponed due to the low magnetospheric activity and weather conditions.
We newly developed band-pass filters for Ba+ (614.2 nm) and Sr (460.7 nm) with 6 nm bandwidth. These wavelengths correspond to the resonance scattering emissions of Ba+/Sr, respectively. We successfully observed Ba+/Sr separately and simultaneously with band-pass filters from Longyearbyen and Ny-Ålesund until about 25 minutes after the launch of the CHI rocket.
The measurement results of the ion drift and neutral wind are shown in Figures 1 and 2. The horizontal velocities of the ion drift were 170-1200 m/s to east-northeast direction approximately. In only one case of 3rd ion tracer, a vertical velocity of 323 m/s was obtained at 324 km altitude, although the data was only available for about one minute for analysis. Neutral tracers moved to the northwest or west direction at 100-170 m/s horizontally. We analyzed two of the eight clouds but we could not find neutral up-welling which could cause the enhancement of neutral density above 400 km.
References:
Lühr, H., M. Rother, W. Köhler, P. Ritter, L. Grunwaldt, Thermospheric up-welling in the cusp region: Evidence from CHAMP observations, Geophys. Res. Lett., 31, L06805, 2004.
Hurd, L. D., and M. F. Larsen, Small-scale fluctuations in barium drifts at high latitudes and associated Joule heating effects, J. Geophys. Res. Space Physics, 121, 779–789, 2016.