Climate Changes in the Upper Atmosphere: Contributions by the Changing Greenhouse Gas Concentrations and Earth's Magnetic Field From the 1960s to 2010s
Climate Changes in the Upper Atmosphere: Contributions by the Changing Greenhouse Gas Concentrations and Earth's Magnetic Field From the 1960s to 2010s
复制标题
高层大气的气候变化：2010 年代温室气体浓度变化和地球磁场的贡献
DOI：
10.1029/2020ja029067
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
A. Burns
中科院分区：
文献类型：
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作者：
L. Qian;J. McInerney;S. Solomon;Han L. Liu;A. Burns
以前的研究已经确定了温室气体（GHG）浓度增加对引起热层和电离层（T‐I）趋势的重要性。最近的研究表明，不断变化的地球磁场也很重要。我们进行了全大气模式模拟，以检验由这两个驱动因素驱动的T - I趋势及其相对重要性。我们发现：(1)在这两个驱动因素的驱动下，T - I的趋势表现出显著的纬度和纵向变化；(2)在热层中，除磁场对中性温度趋势的影响较小（约25%）外，温室气体对中性温度趋势的影响主要集中在~ 120°W-20°E经度扇区。在~ 120°W-20°E经度扇区的电离层中，磁场驱动器的作用更为重要。在该经度扇区，两个驱动因素在驱动hmF2、NmF2和电子温度的趋势方面具有可比性；这两种驱动因素对离子温度趋势的相对重要性还取决于海拔高度，在较低海拔（~ 200-320 km），温室气体驱动因素是主要驱动因素，这两种驱动因素在海拔高度以上具有可比性；(3)虽然磁场驱动器在经度~ 120°W-20°E扇区很重要，但它对负趋势和正趋势的驱动量大致相等，因此，它对T‐I的全球平均趋势的贡献可以忽略不计。
Previous studies have established the importance of the increasing greenhouse gas (GHG) concentrations in causing trends in the thermosphere and ionosphere (T‐I). Recent work indicates that the changing Earth's magnetic field is also important. We conduct whole atmosphere model simulations to examine T‐I trends driven by these two drivers and their relative importance. We found that, (1) trends in the T‐I, driven by either of the two drivers, exhibited significant latitudinal and longitudinal variability; (2) in the thermosphere, trends were predominantly driven by the GHG driver except that the magnetic field driver played a small role in the neutral temperature trend (∼25%) in some regions mainly in the longitude sector ∼120°W–20°E. The magnetic field driver played a more important role in the ionosphere in the longitude sector ∼120°W–20°E. In this longitude sector, the two drivers were comparable in driving the trends of hmF2, NmF2, and electron temperature; the relative importance of the two drivers to the ion temperature trend additionally depends on altitude, with the GHG driver being the dominant driver at lower altitudes (∼200–320 km), and the two drivers becoming comparable above; (3) although the magnetic field driver is important in the longitude sector ∼120°W–20°E, it drove both negative and positive trends in roughly equal amounts, consequently, its contributions to the global average trends in the T‐I are negligible.