Evidence of long term global decline in the Earth's thermospheric densities apparently related to anthropogenic effects
Evidence of long term global decline in the Earth's thermospheric densities apparently related to anthropogenic effects
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DOI：
10.1029/2000gl003771
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发表时间：
2000-05-15
影响因子：
5.2
通讯作者：
Bradford, MS
中科院分区：
文献类型：
--
作者：
Keating, GM;Tolson, RH;Bradford, MS
对近地点高度平均接近 350 公里的五颗地球卫星的长期轨道衰变进行了研究。为了将长期趋势测量与太阳变率的影响分开，在太阳极小期（1976 年、1986 年和 1996 年）期间对测量进行了评估。从这些基本上是全球性的测量中得出的大气密度显示出大量证据表明，20 年来热层密度平均下降了 9.8 +/- 2.5%，这表明高层大气将长期变冷。据推测，人类活动引起的温室气体增加会使地球表面和低层大气变暖，但会使高层大气强烈变冷。假设这 20 年来二氧化碳增加 10%，导致冷却导致密度下降 10%，那么二氧化碳增加一倍可能会导致 350 公里附近测得的热层密度减少 3 倍。这种下降可能会使恒定密度表面的高度在 21 世纪末缩小 40 公里。
A study was performed of the long-term orbital decay of five Earth satellites with perigee altitudes averaging near 350km. To decouple long-term trend measurements from the effects of solar variability, measurements were evaluated during the years of solar minimum (1976, 1986 and 1996). Atmospheric densities derived from these essentially global measurements showed substantial evidence of a decline averaging 9.8 +/- 2.5% in thermospheric density over 20 years pointing toward a long-term cooling of the upper atmosphere. Increases in greenhouse gases induced by human activity are hypothesized to warm the Earth's surface and lower atmosphere, but strongly cool the upper atmosphere. Assuming that the 10% increase in CO2 over these 20 years caused cooling resulting in the 10% decline in density, a doubling of CO2 could cause the thermospheric densities measured near 350km to decrease by a factor of 3. This decrease may shrink the altitude of a constant density surface by 40km before the end of the 21(st) century.