Goose Bay radar observations of Earth‐reflected, atmospheric gravity waves in the high‐latitude ionosphere
Goose Bay radar observations of Earth‐reflected, atmospheric gravity waves in the high‐latitude ionosphere
复制标题
古斯湾雷达观测高纬度电离层中地球反射的大气重力波
DOI：
--
复制
发表时间：
1990
期刊：
影响因子：
--
通讯作者：
K. Baker
中科院分区：
文献类型：
--
作者：
J. Samson;R. Greenwald;J. Ruohoniemi;A. Frey;K. Baker
在秋末冬初，位于拉布拉多古斯湾的约翰·霍普金斯大学高频雷达观察大气重力波对从电离层倾斜反射并随后从地球表面反向散射的雷达传输的影响。这些波存在于各种地磁条件下；然而，它们在安静条件下特别明显（O {le} Kp {le} 1 +）。波的最清晰特征是反向散射功率的空间局部增强以及反向散射功率、多普勒速度和反射高度的准周期波动。这些波通常在白天观测到，并从位于电离层对流反转边界附近的高纬度电离层反向散射区域向赤道传播。重力波似乎是在高度为 115 至 135 公里的极光电射流附近的日面流动反转边界的赤道方向产生的，并沿 156{度} 至 180{度} 的方位角大致垂直于边界传播。这些波通过低层大气倾斜向下传播，直到被地球表面反射回高层大气。与这些重力波相关的频率范围为 0.3 至 0.6 mHz，波长为 300more » 至 500 km，平均相速度为 110 至 180 m/s。最大相速为270至300 m/s，略小于低层大气中的声速。当极冠和对流反转边界向赤道扩展时，有时会在受干扰的条件下观察到向极地传播的重力波。« less
In the late fall and early winter, The Johns Hopkins University HF radar at Goose Bay, Labrador, observes the effects of atmospheric gravity waves on radar transmissions that are obliquely reflected from the ionosphere and subsequently backscattered from the Earth's surface. The waves exist under a wide variety of geomagnetic conditions; however, they are particularly noticeable under quiet conditions (O {le} Kp {le} 1 +). The clearest signatures of the waves are spatially localized enhancements in the backscattered power and quasi-periodic fluctuations in the backscatter powers, Doppler velocities, and reflection heights. The waves are generally observed during daylight hours and propagate equatorward from regions of high-latitude ionospheric backscatter that are located near the ionospheric convection reversal boundary. The gravity waves appear to be generated just equatorward of the dayside flow-reversal boundary in the vicinity of the auroral electrojet at altitudes of 115 to 135 km and propagate approximately perpendicular to the boundary along azimuths ranging from 156{degree} to 180{degree}. The waves propagate obliquely downward through the lower atmosphere until they are reflected by the Earth's surface back into the upper atmosphere. The frequencies associated with these gravity waves cover the range of 0.3 to 0.6 mHz, with wavelengths of 300more » to 500 km, and with average phase velocities of 110 to 180 m/s. The maximum phase speeds are 270 to 300 m/s, which is slightly less than the speed of sound in the lower atmosphere. Poleward-propagating gravity waves are sometimes observed under disturbed conditions when the polar cap and convection reversal boundary have expanded equatorward.« less