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首页> 外文期刊>Annales Geophysicae >Comparative investigations of equatorial electrodynamics and low-to-mid latitude coupling of the thermosphere-ionosphere system
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Comparative investigations of equatorial electrodynamics and low-to-mid latitude coupling of the thermosphere-ionosphere system

机译：赤道电动力学与热圈-电离层系统中低纬度耦合的比较研究

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The thermospheric midnight temperature maximum (MTM) is a highly variable,but persistent, large scale neutral temperature enhancement which occurs atlow latitudes. Its occurrence can impact many fundamental upper atmosphericparameters such as pressure, density, neutral winds, neutral density, andF-region plasma. Although the MTM has been the focus of severalinvestigations employing various instrumentation including photometers,satellites, and Fabry-Perot interferometers, limited knowledge existsregarding the latitude extent of its influence on the upper atmosphere. Thisis largely due to observational limitations which confined the collectivegeographic range to latitudes within ±23°. This paper investigatesthe MTM's latitudinal extent through all-sky imaging observations of its6300Å airglow signature referred to by Colerico et al. (1996) as themidnight brightness wave (MBW). The combined field of view of threeSouthern Hemisphere imaging systems located at Arequipa, Peru, and Tucuman and ElLeoncito, Argentina, for the first time extends the contiguous latitudinalrange of imager observations to 8° S-39° S in the American sector.Our results highlight the propagation of MBW events through the combinedfields of view past 39° S latitude, providing the first evidence that theMTM's effect on the upper atmosphere extends into mid-latitudes. Theobservations presented here are compared with modeled 6300Å emissionscalculated using the NCAR thermosphere-ionosphere-electrodynamic generalcirculation model (TIEGCM) in conjunction with an airglow code. We reportthat at this time TIEGCM is unable to simulate an MBW event due to themodel's inability to reproduce an MTM of the same magnitude and occurrencetime as those observed via FPI measurements made from Arequipa. This workalso investigates the origins of an additional low latitude airglow featurereferred to by Colerico et al. (1996) as the pre-midnight brightness wave(PMBW) and described as an enhancement in 6300Å emission which occurstypically between 20:00-22:00 LT and exhibits equatorward propagation. We presentthe first successful simulation of a PMBW event using the TIEGCM and theairglow code. We find that the PMBW's origin is electro-dynamical in nature,resulting from the expected evening decay of the inter-tropical arcs.
机译：热圈午夜最高温度（MTM）是高度可变的，但是在低纬度地区会持续出现大规模的中性温度升高。它的发生会影响许多基本的高层大气参数，例如压力，密度，中性风，中性密度和F区等离子体。尽管MTM一直是使用各种仪器（包括光度计，卫星和Fabry-Perot干涉仪）进行的多项研究的重点，但是关于其对高空大气影响的纬度范围，知之甚少。这主要是由于观测限制，将集体地理范围限制在±23°以内的纬度。本文通过对全天候图像的纬度范围进行全天候成像观察，以观察到Colerico等人提到的其6300Å气辉特征。 （1996）作为午夜亮度波（MBW）。位于秘鲁阿雷基帕，阿根廷图库曼和埃莱昂奇托的三个南半球成像系统的合并视野首次将成像仪观测的连续纬度范围扩大到美国范围内的南北8°至39°S。 MBW事件在超过北纬39°的联合视场中的传播，提供了第一个证据表明MTM对高层大气的影响扩展到了中纬度。将此处介绍的观测结果与使用NCAR热层-电离层-电动力总循环模型（TIEGCM）结合气辉代码计算出的6300Å排放模型进行了比较。我们报告说，由于模型无法重现与通过Arequipa进行的FPI测量所观察到的幅度和发生时间相同的MTM，因此TIEGCM目前无法模拟MBW事件。这项工作还研究了Colerico等人提到的另一种低纬度气辉特征的起源。 （1996年）作为午夜前的亮度波（PMBW），并描述为6300Å发射的增强，通常在LT 20：00-22：00之间出现，并表现出赤道传播。我们展示了首次使用TIEGCM和气辉代码成功模拟PMBW事件。我们发现，PMBW的起源本质上是电动力学的，这是由热带弧的预期晚间衰落导致的。

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