Seasonal variation in the occurrence time of the equatorial midnight temperature bulge
Seasonal variation in the occurrence time of the equatorial midnight temperature bulge
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DOI：
10.1029/gl009i004p00457
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发表时间：
1982-04
影响因子：
5.2
通讯作者：
D. K. Bamgboye;J. P. McClure
中科院分区：
文献类型：
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作者：
D. K. Bamgboye;J. P. McClure
我们重新检查了Jicamarca雷达观测站（12°S, 77°W, 1°N） 1967-68年和1969年初的电子和离子温度的非相干散射雷达数据。我们发现了明显的证据，表明夜间温度的系统性升高可能与“午夜气压隆起”和中纬度F区域的崩塌有关。一项重要的新发现是，平均而言，气温上升往往发生在当地夏季午夜前两小时左右，而在当地冬季午夜后一小时左右。凸起以各种形状出现，增强幅度变化很大，从几乎无法检测到几十开尔文，但在冬季明显比夏季小，有时可观察到高达200k的增加。从“夏季”到“冬季”的转变发生在春分前后的两个月或更短的时间内。我们的结果与夜间赤道温度凸起随着反太阳子午线移动的假设是一致的，但是，在Jicamarca，系统地集中在12月至日附近的子午线以西~ 30°（午夜前~ 2小时）和6月至日附近的子午线以东~ 15°。我们的数据与潮汐模态的相位和振幅的季节变化有关，这些变化是造成午夜压力和温度膨胀的原因。
We have reexamined incoherent scatter radar data on electron and ion temperature from the Jicamarca Radar Observatory (12°S, 77°W; 1°N diplat) for the period 1967-68 and early 1969. We find clear evidence of systematic nighttime temperature increases presumably associated with the “midnight pressure bulge” and the collapse of the middle latitude F region. A significant new finding is that the temperature enhancements tend on the average to occur about two hours before midnight in the local summer and about one hour after midnight in the local winter. The bulges appear in various shapes and the enhancement magnitudes vary considerably from barely detectable to many tens of degrees Kelvin, but show a definite tendency to be smaller in winter than in summer, when increases of up to 200 K are sometimes observed. Changeover from “summer” to “winter” behavior occurs within two months or less around equinox. Our results are consistent with the hypothesis of a nighttime equatorial temperature bulge moving with the antisolar meridian, but, at Jicamarca, systematically centered ∼ 30° west of this meridian ( ∼ 2 hrs before midnight) near the December solstice and ∼ 15° east of it near the June solstice. Our data have relevance to the questions of seasonal changes in the phase and amplitude of the tidal modes responsible for the midnight pressure and temperature bulge.