Effects of Moisture in a Two-Layer Model of the Midlatitude Jet Stream
Effects of Moisture in a Two-Layer Model of the Midlatitude Jet Stream
复制标题
中纬度急流两层模型中水分的影响
DOI：
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发表时间：
2019
影响因子：
3.1
通讯作者：
T. Merlis
中科院分区：
文献类型：
--
作者：
Eric Bembenek;D. Straub;T. Merlis
本文用一个两层β平面浅水模式研究了水汽对代表中纬度大气的统计定常斜压不稳定急流能量的影响。流动是由两层之间的界面松弛到斜压不稳定的轮廓驱动的。水分通过蒸发输入到下层。当过饱和发生时，沉淀被触发，相关的潜热释放驱动两层之间的传质。干燥和潮湿的参考大气之间的比较表明，降水减少涡动动能。这与降水的纬向分布有关，它发生在急流的极向一侧（界面场升高的地方）。这种降水的纬向结构与向极流和上升之间的相关性有关，这是用浅水模拟ω方程进行分析的。降水对能量收支的影响主要是由于纬向和时间平均项。正因为如此，干模拟中的热力强迫进行修改，以模仿纬向平均降水的影响，并与他们的降水同行进行比较。这些模拟结果表明，斜压涡动动能的减少是相似的，但正压涡动动能的响应显示出较大的差异。
The effects of moisture on the energetics of a statistically stationary, baroclinically unstable jet representing the midlatitude atmosphere are examined using a two-layer, β-plane shallow-water model. Flow is driven by a relaxation of the interface between the two layers to a baroclinically unstable profile. Moisture is input to the lower layer by evaporation. When supersaturation occurs, precipitation is triggered and the related latent heat release drives a mass transfer between the two layers. A comparison between dry and moist reference atmospheres shows that precipitation reduces eddy kinetic energy. This is related to the meridional distribution of precipitation, which occurs on the poleward side of the jet (where the interface field is raised). This latitudinal structure of precipitation is related to a correlation between poleward flow and ascent, which is analyzed using a shallow-water analog to the ω equation. The precipitation effect on the energy budget is predominately due to zonal- and time-averaged terms. Because of this, dry simulations in which the thermal forcing is modified to mimic the effect of zonally averaged precipitation are carried out and compared with their precipitating counterparts. These simulations show a similar reduction of baroclinic eddy kinetic energy; however, the barotropic eddy kinetic energy response shows a larger difference.
影响因子：
6.7
作者：
Lehmann, Jascha;Coumou, Dim;Levermann, Anders
通讯作者：
Levermann, Anders