Life cycles of persistent anomalies. Part II: the development of persistent negative height anomalies over the north Pacific Ocean

Abstract

These cases are generally manifested at the surface by an anomalously intense and eastward-displaced Aleutian low and, at upper levels, by an abnormally strong zonal jet that extends across most of the western and central Pacific at midlatitudes. The associated flow anomalies usually resemble particularly strong realizations of the Pacific-North American (PNA) teleconnection pattern. The overall impression that emerges is of initial baroclinic development at long synoptic scales, followed by increasing barotropic contributions and decreasing baroclinic contributions to the growth of the anomalies after the disturbance reaches the jet exit region over the central Pacific. Additional baroclinic contributions to the developments may also occur at later stages. -from Authors