Collapse of the General Circulation in Shortwave-absorbing Atmospheres: An Idealized Model Study
Collapse of the General Circulation in Shortwave-absorbing Atmospheres: An Idealized Model Study
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DOI：
10.3847/2041-8213/ab4c43
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发表时间：
2019-10
期刊：
影响因子：
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通讯作者：
W. Kang;R. Wordsworth
中科院分区：
文献类型：
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作者：
W. Kang;R. Wordsworth
在灰色辐射三维大气环流模型中研究了干燥大气中大气环流对各种大气短波吸收率的响应。大气中的短波吸收减少了到达表面的入射辐射，但使高层大气变暖，使宜居带显着向恒星移动。高短波吸收率下的强分层以与之前的哈德利环流缩放相匹配的方式抑制哈德利环流。通过云层覆盖和超级旋转可以观察到总体环流的变化。正如根据辐射对流平衡剖面的梯度风预测的那样，高层大气中的赤道超自转随着短波不透明度的增强而增强。在非常低的短波不透明度下，赤道超自转突然下降。这是因为在这种情况下，哈德来环流圈的强度足以使整个对流层充满来自地表的零动量空气。昼夜循环（星下点相对于行星的向西运动）通过增强赤道涡流动量传输，总体上导致赤道西风带加速，但响应并不完全单调，可能是由于热带波和昼夜强迫的共振。
The response of the general circulation in a dry atmosphere to various atmospheric shortwave absorptivities is investigated in a three-dimensional general circulation model with gray radiation. Shortwave absorption in the atmosphere reduces the incoming radiation reaching the surface but warms the upper atmosphere, significantly shifting the habitable zone toward the star. The strong stratification under high shortwave absorptivity suppresses the Hadley cell in a manner that matches previous Hadley cell scalings. General circulation changes may be observable through cloud coverage and superrotation. The equatorial superrotation in the upper atmosphere strengthens with the shortwave opacity, as predicted based on the gradient wind of the radiative–convective equilibrium profile. There is a sudden drop of equatorial superrotation at very low shortwave opacity. This is because the Hadley cell in those cases are strong enough to fill the entire troposphere with zero momentum air from the surface. A diurnal cycle (westward motion of substellar point relative to the planet) leads to acceleration of the equatorial westerlies in general, through the enhancement of the equatorward eddy momentum transport, but the response is not completely monotonic, perhaps due to the resonance of tropical waves and the diurnal forcing.