Rates of scattering occurrence in routine HF radar observations during solar cycle maximum
Rates of scattering occurrence in routine HF radar observations during solar cycle maximum
复制标题
太阳周期最大值期间常规高频雷达观测中的散射发生率
DOI：
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
R. Greenwald
中科院分区：
文献类型：
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作者：
J. Ruohoniemi;R. Greenwald
超级双极光雷达网络（SuperDARN）的高频雷达对北半球和南半球大片区域的高纬度电离层进行连续监测。当存在合适的小规模（∼10 m）不规则性并在有利的磁方面条件（雷达 k 向量 ⊥ 到 B）下观察时，HF 技术会生成电离层等离子体 E×B 对流漂移的估计。在本文中，我们报告了高频散射发生的统计数据。研究周期涵盖 5.5 年（1988 年至 1993 年中），使用位于加拿大拉布拉多古斯湾的高频雷达进行常规观测，对应于最近的太阳活动周期最大值。当在 1°×3° 磁纬度/经度区域和 12 分钟 UT 间隔内获得高置信度 F 区域速度测量值时，对数据进行了仔细过滤。对于平均条件，MLT 在特定纬度值下发生散射的比率范围为 <10% 到 >40%。在雷达视场某处进行速度测量的概率从夜间的 80% 到正午子午线的 45% 不等。当检测到散射时，平均纬度覆盖范围从白天的最小 4°Λ 到夜间的超过 6°Λ 不等。对 Kp 和季节有很大的依赖性。安静条件下的夜间和受干扰条件下的下午，发生率最高 (>60%)。冬季是最活跃的季节。高频散射受到费尔德斯坦椭圆形赤道方向边界的限制，但向椭圆形极地方向延伸至极冠。正午区域的散射与尖点/地幔/低纬度边界层区域的聚集有关。在受干扰条件下的上午区域以及夏季的中午和下午区域，散射活动受到显着抑制。我们讨论影响产生高频散射可能性的地球物理因素。这些结果对于涉及 SuperDARN HF 雷达的实验设计具有价值。
The HF radars of the Super Dual Auroral Radar Network (SuperDARN) provide continuous monitoring of the high‐latitude ionosphere over large areas in both the northern and southern hemispheres. The HF technique generates estimates of the E×B convective drift of ionospheric plasma when suitable small‐scale (∼10 m) irregularities are present and viewed under favorable magnetic aspect conditions (radar k vector ⊥ to B). In this paper we report on the statistics of HF scattering occurrence. The study period encompasses 5.5 years (1988 to mid‐1993) of routine observations with the HF radar located at Goose Bay, Labrador, Canada, and corresponds to the most recent period of solar cycle maximum. The data were carefully filtered for those instances when high‐confidence F region velocity measurements were obtained within 1°×3° magnetic latitude/longitude regions and 12‐min UT intervals. For average conditions the rates at which scatter occurred at particular values of invariant latitude ranged from <10% to >40% with MLT. The probability of making velocity measurements somewhere in the radar field of view varied from ∼80% on the nightside to ∼45% on the noon meridian. When scatter was detected, the average latitudinal coverage varied from a minimum of 4° Λ on the dayside to over 6° Λ on the nightside. There were significant dependencies on Kp and season. The highest occurrence rates (>60%) were obtained on the nightside for quiet conditions and in the afternoon for disturbed conditions. Winter was the most active season. HF scattering was limited by the equatorward boundary of the Feldstein oval but extended poleward of the oval into the polar cap. Scattering in the noon sector was associated with the aggregate cusp/mantle/low‐latitude boundary layer region. The scattering activity was notably suppressed in the morning sector under disturbed conditions and in the noon and afternoon sectors in summer. We discuss the geophysical factors that influence the likelihood of generating HF scatter. These results have value for the design of experiments involving the SuperDARN HF radars.