地磁暴恢复相中间层低热层高纬温度响应

利用TIMEGCM模拟了2005年9月10日至20日由日冕物质抛射引起的地磁暴事件，研究了此地磁暴恢复相高纬度中间层低热层（MLT）区域温度的变化，揭示了磁暴恢复相时温度、垂直风、总加热项和NO辐射冷却的内在联系.结果表明:地磁暴恢复相刚开始时，温度对磁暴的响应在晨侧为负扰动（降温），在其他地区都为正扰动（增温）；随着磁暴的恢复，整个北半球都变为正的温度扰动（增温）.这种高纬MLT区域的温度响应主要与垂直风密切相关.当垂直风为正时，总加热为负，增温减弱；当垂直风为负时，总加热为正，增温变强.辐射冷却特别是NO辐射冷却作用在热层被称为恒温器，降低了磁暴期间80%的热层增温.但是，在MLT区域NO辐射冷却作用不明显，一般比总加热项小一个量级，对温度响应造成的影响较小. 

Response of the Temperature in the Mesosphere and Lower Thermosphere during the Recovery Phase of the Storm

Using Thermosphere Ionosphere Mesosphere Electrodynamics General Circulation Model (TIMEGCM), the nature and causes of MLT temperature variations at high latitudes during the 10 September 2005 storm were elucidated, which were caused by Coronal Mass Ejection (CME). At the beginning of the recovery phase of the geomagnetic storm, the temperature decreased in the dusk region but increased in the other regions. As the recovery phase evolved, the temperature decreases at high latitudes disappeared and the temperature increases were distributed throughout the whole high-latitude north hemisphere. The storm-time temperature changes at high latitudes were closely correlated with vertical wind changes. When the vertical wind was upward, the total heating was negative, corresponding to the decreased temperature variations, vice versa. In the thermosphere, radiative cooling, especially NO cooling, was "natural thermostat", which is the most important cooling mechanism. The radiative cooling contributes about 80% temperature reduction due to Joule heating enhancement during the storm. However, the NO radiative cooling has little effect on the temperature changes during the recovery phase of the storm, which was only a tenth of total heating. Therefore, the NO radiative cooling was a minor cause of MLT high-latitude temperature changes during the recovery phase of the storm.