Structures in sporadic‐E observed with an impedance probe during the SEEK Campaign: Comparisons with neutral‐wind and radar‐echo observations
Structures in sporadic‐E observed with an impedance probe during the SEEK Campaign: Comparisons with neutral‐wind and radar‐echo observations
复制标题
SEEK 活动期间用阻抗探头观察到的零星-E 结构：与中性风和雷达回波观测的比较
DOI：
--
复制
发表时间：
1998
期刊：
影响因子：
--
通讯作者：
M. Yamamoto
中科院分区：
文献类型：
--
作者：
Masayuki K. Yamamoto;T. Ono;H. Oya;R. Tsunoda;M. Larsen;S. Fukao;M. Yamamoto
为了澄清在夜间中纬度电离层中存在零星E（Es）层的情况下经常被雷达观测检测到的所谓准周期回波（QPE）的起源，在SEEK（九州上空零星E实验）活动期间发射了两枚探空火箭。每枚火箭都携带一个扫频阻抗探针来测量E区的电子密度（Ne）分布。使用在两次火箭飞行期间获得的四个Ne廓线，以及从其中一个火箭上的三甲基铝（TMA）化学释放实验获得的中性风廓线和用地面雷达获得的QPE，我们考虑风切变在观察到的Es层形成中的作用，以及QPE是否与高度调制的Es层相关的问题。在QPE存在下获得的Es结构的Ne分布的特征在于高度集中的薄层。通过与TMA测量结果的比较，证实了中性风切变过程形成了这样一个薄层。在100 km高度附近，Es层的Ne峰值介于2.2至9.3 × 104 el/cm³之间。这些主要的Es层伴随着重要的二级结构，位于主Es层上方约12至20公里处，峰值Ne范围为5.2 × 10³至1.3×104 el/cm³。QPE的平均高度分布大致覆盖了Es层峰值出现的范围。我们的主要发现是，所观察到的Es结构倾向于类似于水平分层层，而不是像以前的QPE模型那样具有深高度调制的结构，尽管火箭测量与雷达测量相隔90至145公里。
In order to clarify the origin of the so‐called quasi periodic echoes (QPE) that have been often detected by radar observations in the presence of sporadic‐E (Es) layers in the nighttime midlatitude ionosphere, two sounding rockets were launched during the SEEK (Sporadic‐E Experiment over Kyushu) campaign. Each rocket carried a swept‐frequency impedance probe to measure the E‐region electron‐density (Ne) profile. Using the four Ne profiles obtained during the two rocket flights together with a neutral‐wind profile obtained from a trimethyl aluminum (TMA) chemical release experiment on one of the rockets and QPE obtained with a ground‐based radar, we consider the role of wind shear in the formation of the observed Es layers, and the question of whether QPE are associated with Es layers that are modulated in altitude. The Ne profiles of Es structures that were obtained in the presence of QPE were characterized by the highly concentrated thin layers. The formation of such a thin layer by a neutral‐wind shear process was confirmed in comparison with the TMA measurements. The peak Ne values of the Es layers ranged from 2.2 to 9.3 × 104 el/cm³ near 100‐km altitude. These primary Es layers were accompanied by significant secondary structures that were located about 12 to 20 km above the main Es layers and had peak Ne that ranged from 5.2 × 10³ to 1.3×104 el/cm³. The average altitude profiles of QPE approximately covered the range where the Es‐layer peaks appeared. Our principal finding is that the observed Es structures tended to resemble horizontally stratified layers rather than structures with deep altitude modulation like previous QPE model, although the rocket measurements were separated from those by radar by 90 to 145 km.