Lifecycle of the ‘FrozeLifecycle Frozen-in Anticyclone’ in the 2005 Arctic Summer

摘要

Immediately following the breakup of the 2005 Arctic spring stratospheric vortex, a tropical air mass,characterized by low potential vorticity (PV) and high nitrous oxide (N2O), was advected poleward andbecame trapped in the easterly summer polar vortex. This feature, known as a “Frozen-In Anticyclone(FrIAC)”, was observed in Earth Observing System (EOS) Aura Microwave Limb Sounder (MLS) data to spanthe potential temperature range from ~580 to 1100 K (~25 to 40 km altitude) and to persist from late Marchto late August 2005. This study compares MLS N2O observations with simulations from the Global ModelingInitiative (GMI) chemistry and transport model, the GEOS-5/MERRA Replay model, and the Van LeerIcosahedral Triangular Advection (VITA) isentropic transport model to elucidate the processes involved inthe lifecycle of the FrIAC, which is here divided into three distinct phases, as described below.