Radio tomographic imaging of sporadic-<i>E</i> layers during SEEK-2

Abstract

Abstract. During the SEEK-2 Rocket Campaign in August 2002, a Dual Band Beacon (DBB) transmitting to GroundReceivers provided unique data on E-Region electron densities. Information from two rocket beacons and four ground receivers yielded multiple samples of E-region horizontal and vertical variations. The radio beacon measurements were made at four sites (Uchinoura, Tarumizu, Tanegashima, Takazaki) in Japan for two rockets (S310-31 and S310-32) launched by the Institute of Space and Aeronautical Science (ISAS). Analysis was completed for four sets of beacon data to provide electron density images of sporadic-E layers. Signals from the two-frequency beacons on the SEEK-2 rockets were processed to yield total electron content (TEC) data that was converted into electron density measurements. Wide variations in layer structures were detected. These included horizontal sporadic-E variations, vertical profiles of double, single, and weak layers. The radio beacon measurements were shown to be in agreement with the in-situ SEEK-2 sensors. The first tomographic image of a sporadic-E layer was produced from the data. The rocket beacon technique was shown to be an excellent tool to study sporadic-E layers because absolute TEC accuracy of 0.01 TEC Units can be easily obtained and, with proper receiver placement, electron density images can be produced using computerized ionospheric tomography with better than 1 km horizontal and vertical resolution.

SEEK-2 (Sporadic-<i>E</i> Experiment over Kyushu 2) − Project Outline, and Significance

“…The large spatiotemporal variations of the E s -peaks were confirmed from the findings of the DBB experiment. Bernhardt et al (2005) successfully obtained the first tomographic imaging of the E s -layers by analyzing the TEC from Uchinoura and Tarumizu. The analysis retrieved double-layered structures and spatial variability of densities with a horizontal scale of about 30 km.…”

Electron density and plasma waves in mid-latitude sporadic-<i>E</i> layer observed during the SEEK-2 campaign

“…In addition, we compare the results with those from the Dual Band Beacon experiment (Bernhardt et al, 2005), to estimate the horizontal extent of the E s layer. In the electron density profiles obtained by the NEI on board the S310-31, there are two sharp peaks in the ascending phase, although there is only one peak in the descending phase.…”

“…The DBB observation is to survey the horizontal distribution of the electron density by the measurement of Total Electron Content (TEC) value along the path between the rocket and ground-based receiver sites (located on Uchinoura, Tarumizu, and Takasaki). Bernhardt et al (2005) reported slant TEC values obtained by the S310-31 and S310-32 rockets. The slant TEC value rapidly increased when the rocket passed the E s layer and reached the density of 3-5×10 14 (m −2 ).…”

Phase and group velocity tracing analysis of projected wave packet motion along oblique radar beams – qualitative analysis of QP echoes

“…This campaign, along with SEEK-1, confirmed that the QP echoes are associated with Es-layers mainly around 105 km. Accumulation of the E-region plasma into the layers is well explained by the shear of the neutral wind (Bernhardt et al, 2005;Larsen et al, 2005;Pfaff et al, 2005;Wakabayashi and Ono, 2005;Yokoyama et al, 2005). The Es-layers are spatially modulated by the motion of the neutral atmosphere (Maruyama et al, 2006), and then FAI echoes start to appear.…”