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首页> 外文期刊>Earth, planets and space: EPS >Equatorial GPS ionospheric scintillations over Kototabang, Indonesia and their relation to atmospheric waves from below
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Equatorial GPS ionospheric scintillations over Kototabang, Indonesia and their relation to atmospheric waves from below

机译：印度尼西亚科托邦的赤道GPS电离层闪烁及其与来自下方的大气波的关系

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Using Global Positioning System (GPS) satellites, we have been conducting equatorial ionospheric scintillation observations at Kototabang, Indonesia since January 2003. Scintillations caused by equatorial plasma bubbles appear between 2000 and 0100 LT in equinoctial months with a seasonal asymmetry, and their activity decreases with decreasing solar activity. A comparison between scintillation index (S4) and Earth's brightness temperature (Tbb) variations suggests that the scintillation activity can be related to tropospheric disturbances over the Indian Ocean to the west of Kototabang. To understand better the reasons of day-to-day variability of S4, we analyze S4, Tbb and lower thermospheric neutral wind (u′2) data. The results show that S4 fluctuates with periods of about 2.5, 5, 8, 14 and 25 days, possibly due to atmospheric waves from below and that similar periods are also found in the Tbb and u′2 variations. Using a general circulation model, we made numerical simulations to determine the behavior of neutral wind in the equatorial thermosphere. The results indicate the following: (1) 2- to 20-day waves dissipate rapidly above about an altitude of 125 km, and 0.5- to 3-hour waves become predominant above 100 km, (2) zonal winds above 200 km altitude are, on the whole, eastward during sunset-sunrise, (3) zonal wind patterns due to short-period (1-4 h) atmospheric gravity waves (AGWs) above 120 km altitude change day by day, exhibit wavy structures with scale lengths of about 30-1000 km and, as a whole, move eastward at about 100-1 while changing patterns over time. These simulations suggest that the Rayleigh-Taylor instability responsible for plasma bubble generation can be seeded by AGWs with short periods of about 0.5-3 h, and that background conditions necessary for this instability are modulated by planetary-scale atmospheric waves propagating up to an altitude of about 120 km from below.
机译：自2003年1月以来，我们一直使用全球定位系统（GPS）卫星在印度尼西亚科托邦进行赤道电离层闪烁观测。在赤道等离子月份，赤道等离子体气泡引起的闪烁出现在2000至0100 LT之间，具有季节性不对称性，并且其活动性随着太阳活动减少。闪烁指数（S4）与地球亮度温度（Tbb）变化之间的比较表明，闪烁活动可能与科托邦邦西部印度洋上的对流层扰动有关。为了更好地了解S4日常变化的原因，我们分析了S4，Tbb和较低的热圈中性风（u'2）数据。结果表明，S4的周期大约为2.5、5、8、14和25天，这可能是由于来自下方的大气波引起的，并且在Tbb和u'2的变化中也发现了相似的周期。使用通用循环模型，我们进行了数值模拟，以确定赤道热圈中性风的行为。结果表明：（1）2至20天的海浪在125 km左右的高度以上迅速消散，而0.5至3小时的海浪在100 km以上的高度中占主导地位;（2）200 km以上的纬向风总体而言，在日落-日出期间向东，（3）海拔120 km以上的短时（1-4 h）大气重力波（AGW）引起的纬向风型逐日变化，呈现出波浪状结构，尺度长度为大约30-1000公里，并且总体上在大约100-1处向东移动，同时随时间变化模式。这些模拟表明，造成等离子气泡产生的瑞利-泰勒不稳定性可以由短时长约0.5-3 h的AGW植入，并且这种不稳定性所必需的背景条件由传播到一个高度的行星尺度大气波调制距离下方约120公里。

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