Winter Patterns of the Hadley Circulation's Response to Increased CO2 are Distinct between the Upper and Lower Troposphere (submitted)
Dec 2, 2024·,·
0 min read
Molly E Menzel
Clara Orbe
Abstract
It is well documented that in response to a quadrupling of CO2, the Hadley Circulation (HC) weakens and widens. In practice, however, the HC response to increased CO2 is more nuanced, consisting of vertically dependent and regional patterns of change that deviate from the zonal-mean response. Here, we present a more comprehensive view than previously shown of the HC’s response to increased CO2 by a) assessing the extent to which the response reflects a vertical shift in the circulation, b) examining zonal variations in the three-dimensional streamfunction, and c) considering its dependence on a braod forcing range spanning 2-to-8xCO2. Consideration of this more nuanced response reveals that the upper and mid-to-lower troposphere feature distinct respones to increased CO2 forcing. While the upper tropospheric response largely reflects a zonally uniform upward extension of the troposphere, the mid-to-lower tropospheric response features strong regional variations. In addition, the lower troposphere responds more non-linearly to CO2 forcing, compared to the upper troposphere. Our results suggest that assessments of the HC response to climate change should clearly distinguish between upper versus lower tropospheric circulations.
Type
Publication
Journal of Climate