A Model Investigation of Aerosol - induced Changes in Boreal 1 Winter Extratropical Circulation
نویسندگان
چکیده
5 We examine the key characteristics of the boreal winter extratropical circulation changes in 6 response to anthropogenic aerosols, simulated with a coupled atmosphere-slab ocean general 7 circulation model. The zonal-mean response features a pronounced equatorward shift of 8 the Northern Hemisphere subtropical jet owing to the mid-latitude aerosol cooling. The 9 circulation changes also show strong zonal asymmetry. In particular, the cooling is more 10 concentrated over the North Pacific than over the North Atlantic despite similar regional 11 forcings. With the help of an idealized model, we demonstrate that the zonally asymmetrical 12 response is linked tightly to the stationary Rossby waves excited by the anomalous diabatic 13 heating over the tropical East Pacific. The altered wave pattern leads to a southeastward 14 shift of the Aleutian low (and associated changes in winds and precipitation), while leaving 15 the North Atlantic circulation relatively unchanged. 16 Despite the rich circulation changes, the variations in the extratropical meridional latent 17 heat transport are controlled strongly by the dependence of atmospheric moisture content on 18 temperature. This suggests that one can project reliably the changes in extratropical zonal19 mean precipitation solely from the global-mean temperature change, even without a good 20 knowledge of the detailed circulation changes caused by aerosols. On the other hand, such 21 knowledge is indispensable for understanding zonally asymmetrical (regional) precipitation 22 changes. 23
منابع مشابه
A Model Investigation of Aerosol-Induced Changes in Boreal Winter Extratropical Circulation
The authors examine the key characteristics of the boreal winter extratropical circulation changes in response to anthropogenic aerosols, simulated with a coupled atmosphere–slab ocean general circulation model. The zonal-mean response features a pronounced equatorward shift of the Northern Hemisphere subtropical jet owing to the midlatitude aerosol cooling. The circulation changes also show st...
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