Mechanisms for Zonal Mean Wind Responses in the Thermosphere to Doubled CO2 Concentration
Mechanisms for Zonal Mean Wind Responses in the Thermosphere to Doubled CO2 Concentration
复制标题
热层中纬向平均风对二氧化碳浓度加倍的响应机制
DOI：
10.1029/2022ja030643
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发表时间：
2022
期刊：
影响因子：
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通讯作者：
Tao Chihiro
中科院分区：
文献类型：
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作者：
Kogure Masaru;Liu Huixin;Tao Chihiro
通过6月GAIA模式对热层纬向平均动量平衡的模拟，探讨了CO2浓度倍增对热层纬向平均风场的影响机制。分析表明，由于CO2浓度加倍，离子阻力、分子粘度和径向压力梯度力的变化比其他力大3 - 20倍。这三种力彼此强烈减弱;因此，纬向平均纬向离子阻力的增加主要加强了北方（夏季）半球和35 S以北纬度的南风（最大值为15 ms − 1）。这种增强的离子阻力归因于北方/南半球中离子和中性粒子之间的离子密度/相对速度的增加。35 °以南，纬向气压梯度力和纬向风的纬向平流使南风增强4 - 12 ms − 1。另一方面，纬向风主要是由纬向气压梯度力（最大值为15 ms − 1）的增加所改变，这是由热层密度对CO2浓度增加的纬向不对称响应所引起的。我们的研究结果表明，在北方的离子密度增加是潜在的触发风响应增加CO2浓度。此外，我们还发现，纬向平流的主要（约70%）是由于DW1分潮。
We explored mechanisms for the thermospheric zonal mean wind responses to doubled CO2concentration through investigating the zonal mean momentum balance in the thermosphere using GAIA model simulations in June. The analysis shows that ion drag, molecular viscosity, and meridional pressure gradient force vary 3–20 times more than the other forces due to the doubled CO2concentration. The three forces strongly attenuate each other; consequently, the increase in zonal mean zonal ion drag dominantly strengthens the southward wind (∼15 ms−1at maximum) in the northern (summer) hemisphere and latitudes north of 35S. This strengthened ion drag was attributed to increased ion density/relative velocity between ions and neutral particles in the northern/southern hemisphere. Southward of 35, the zonal pressure gradient force and the meridional advection of zonal wind strengthen the southward wind by 4–12 ms−1in total. On the other hand, the zonal wind is mainly altered by increased meridional pressure gradient force (∼15 ms−1at maximum) caused by a latitudinally asymmetric response of the thermosphere density to increasing CO2concentration. Our results suggest that the increased ion density in the northern hemisphere is the underlying trigger for the wind responses to increasing CO2concentration. Furthermore, we show that the meridional advection was mainly (∼70%) due to that of the DW1 tidal component.