Double North Pacific High in Summer

Kern E Kenyon

doi:10.4236/ns.2016.85026

Abstract

An example of sea level pressure (SLP) and sea surface temperature (SST) is displayed for a summer month based on historical monthly mean data for the North Pacific. A double North Pacific High (NPH) co-occurred with a double large-scale SST maximum along 40 N. Centers of the two NPHs had very nearly the same longitudes as did the SST maxima. Seven similar coincidences happened within the 30-year records. These particular associations between extrema of SLPs and SSTs enhance a previously published conjecture that single and double NPHs are caused by heat transfer from the sea surface to the atmosphere. The eastern SST maximum is the signature of a permanent wide warm surface current flowing northeast off California. To the west of it in the summer is a transient wide warm surge of surface water flowing north as it crosses mid-latitudes. These are the heat sources that generate the single and double NPHs.

Highlights

A particular example in the climatological records of monthly mean temperature and pressure sparks a new investigation into the relationship between relatively high sea surface temperatures and the generation of high sea level pressure
How fast can a North Pacific High (NPH) develop from scratch? When a double NPH occurs, there is some chance of answering the question because the western NPH is not a permanent feature like the eastern one is, but rather a transient phenomenon, in summer
There is an aspect of the time-scale for the growth of the high sea level pressure that is especially relevant to the western cell of a double NPH in summer: the speed of the northward flow of warm surface water, which provides the heat source for the cause of the high pressure

Summary

Introduction

A particular example in the climatological records of monthly mean temperature and pressure sparks a new investigation into the relationship between relatively high sea surface temperatures and the generation of high sea level pressure. A double NPH (North Pacific High) coincided in time and place with a double longitudinal maximum in SST (sea surface temperature). Except for the summer months the warm current is considerably longer than it is wide, connecting the western tropical Pacific to the Gulf of Alaska With such a shape for the heat source one could readily conceive of two separate high pressure cells that each have the same width as the current (about 4000 km). More recent interpretations of the SST data show that there are two wide warm currents every summer: one is the permanent year around northeastward flow and the other is a northward surge of warm surface water taking place only in summer and located west of the main flow [3].

Observations

Discussion

Conclusion