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首页> 外文期刊>Journal of Geophysical Research, A. Space Physics: JGR >Is thermospheric global cooling caused by gravity waves?
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Is thermospheric global cooling caused by gravity waves?

机译：thermospheric全球变冷引起的重力吗波?

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摘要

We analyze ion temperature data near 350 km altitude over the years 1966-2012 to seek explanations for three outstanding questions concerning the long-term cooling observed in the upper thermosphere: (1) Why is the cooling so much larger than expected, (2) why has the cooling lasted so long, and (3) why is the thermospheric density response to the cooling so small? We speculate that gravity waves may cause this cooling and provide answers to these questions. Recent simulations have shown that gravity waves are expected to cool the upper thermosphere by an amount comparable to that observed over our data timeline. A gravity wave proxy formed from the nontidal fluctuations in temperature shows a positive long-term trend throughout its timeline, consistent with the increasing cooling observed. The time scales of the long-term trend and its decadal fluctuations are characteristic of the ocean, not the atmosphere. We suggest that the following scenario may explain these behaviors: (a) the climate regime shift of 1976-1977 launched slow Rossby waves across the oceans which continue to propagate to this day, (b) winds over this increasingly corrugated ocean have launched increasing fluxes of gravity waves into the atmosphere, and (c) these increasing fluxes of gravity waves have propagated to the thermosphere to produce increasing amounts of cooling. The strong thermospheric cooling seen would be expected to produce thermospheric density declines much larger than those observed via satellite drag. These temperature and density results would be compatible if the turbopause were lowered 4 km over the time span of observations.
机译：我们分析离子温度数据接近350公里高度1966 - 2012多年来寻求解释三个突出的问题关于长期冷却中观察到上热电离层:(1)为什么冷却比预期更大,(2)为什么冷却持续了这么长时间,和(3)为什么thermospheric密度反应冷却小呢?这种冷却并提供回答这些的问题。重力波预计上降温由一个与量热大气层观察到在我们的数据的时间表。代理nontidal波动形成的温度显示了积极的长期趋势在整个时间轴,符合增加冷却。长期趋势及其年代际波动是海洋的特征,不是吗的气氛。场景可以解释这些行为:(a)1976 - 1977年的气候制度转变启动慢罗斯比波在继续的海洋传播到这一天,(b)风越来越多的海洋已经启动了波纹增加通量的重力波气氛,和(c)这些通量的增加重力波传播到热大气层产生越来越多的冷却。强thermospheric冷却看到预计生产thermospheric密度比通过观察下降更大卫星的阻力。结果将是如果turbopause兼容降低4公里的时间吗观察。

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