Two paradigms of baroclinic‐wave life‐cycle behaviour

摘要: Two idealized baroclinic wave-6 life cycles examined here suggest a framework of opposite extremes (a) in which to view the behaviour real synoptic-scale disturbances middle latitudes, and (b) interrelate synoptic wave-theoretic viewpoints, using ‘saturation-propagation-saturation’ (SPS) picture life-cycle behaviour. The two cycles. dented by LC1 LC2, are higher-resolution versions Simmons-Hoskins ‘basic’ ‘anomalous’ cases (showing strong weak late decay eddy kinetic energy, EKE). They illustrate, varying degrees. extreme types disignated ‘anticyclonic’ ‘cyclonic’, epitomized strongly contrasting upper-air trough ‘Anticyclonic’ dominates stages is characterized backward-tilted, thinning troughs being advected anticyclonically equatorward, as commoner planetary-scale mid-stratospheric ‘Rossby-wave breaking’. ‘Cyclonic’ LC2 forward-tilted, broadening wrapping themselves up cyclonically poleward. producing major cut-off cyclones high latitudes. These morphologies visualized maps potential temperature on nominal tropopause, defined constant-potential-vorticity surface. Some atmospheric mid-latitude here, same visualization applied operational analyses, show together with intermediate cases. The SPS re-examined, Eliassen-palm refractive-index cross-sections. It shown, particular, reference wave-activity theorem Haynes, that can be looked upon remarkably clear, morphologically novel, large-amplitude counterpart nonlinear reflection scenario Rossby-wave critical-layer theory. LC1, constrast, look more akin an absorption scenario. exhibits region largely undular PV contours adjacent irreversiby deformen contous. In latter rearrangement, hence activity, has ceased. This accounts for persistent EKEE case.