[A-CG36] Extratropical oceans and atmosphere

[ACG36-P14] Regional characteristic of diabatic heating using upper positive heat content during the Northern Hemisphere winter

*Kent Kumeta¹, Yoshiaki Miyamoto¹ (1.Keio University)

Keywords:mass-weighted isentropic zonal means, upper warm airmass flux, extratropical direct circulation, upper positive heat content

In the mass-weighted isentropic zonal means (MIM) framework, at the extratropical direct circulation (ETD circulation) appears opposite to the Ferrell circulation in winter. In MIM, vertical velocity is associated with diabatic heating, indicating the formation and dissipation of cold and warm airmass. The upper-level warm airmass flux defined between 290 and 320 K isentropic surfaces indicates the three-dimensional ETD circulation. Diabatic heating is considered only at 290K and 320K. The 290K isentropic surface shows interaction with the lower cold airmass, and the 320K isentropic surface shows interaction with the stratosphere. Thus, it is not suitable for dealing with warm airmass diabatic process.
The purpose of this study is to suggest the upper positive heat content (UPHC) to clear the regional diabatic process of upper-level warm air mass transformation. Warm airmass is generated in the Pacific and Atlantic Oceans and transported poleward. Warm airmass lost over the Americas flows equatorward, but Siberia flows less north-south wind. This is thought to be due to the flow being blocked by the mountains.