Distant Influence of Kuroshio Eddies on North Pacific Weather Patterns?

Xiaohui Ma,R Saravanan,Raffaele Montuoro,Jen-Shan Hsieh,Xiaopei Lin,Dexing Wu,Lixin Wu,Zhao Jing,Ping Chang

doi:10.1038/srep17785

Xiaohui Ma, R Saravanan + Show 7 more

Open Access

https://doi.org/10.1038/srep17785

Copy DOI

Abstract

High-resolution satellite measurements of surface winds and sea-surface temperature (SST) reveal strong coupling between meso-scale ocean eddies and near-surface atmospheric flow over eddy-rich oceanic regions, such as the Kuroshio and Gulf Stream, highlighting the importance of meso-scale oceanic features in forcing the atmospheric planetary boundary layer (PBL). Here, we present high-resolution regional climate modeling results, supported by observational analyses, demonstrating that meso-scale SST variability, largely confined in the Kuroshio-Oyashio confluence region (KOCR), can further exert a significant distant influence on winter rainfall variability along the U.S. Northern Pacific coast. The presence of meso-scale SST anomalies enhances the diabatic conversion of latent heat energy to transient eddy energy, intensifying winter cyclogenesis via moist baroclinic instability, which in turn leads to an equivalent barotropic downstream anticyclone anomaly with reduced rainfall. The finding points to the potential of improving forecasts of extratropical winter cyclones and storm systems and projections of their response to future climate change, which are known to have major social and economic impacts, by improving the representation of ocean eddy–atmosphere interaction in forecast and climate models.

Highlights

Midlatitude oceanic fronts, such as the Kuroshio and Gulf Stream extension, play an anchoring role for atmospheric storm tracks through their effect on low-level baroclinicity in the troposphere[1,2]
The rainfall and ocean eddy statistics were derived from the high-resolution rainfall data from the Tropical Rainfall Measuring Mission (TRMM3B42)[17] and sea-surface height (SSH) data from the TOPEX/Poseidon and other ocean surface topography measurement missions[18], respectively
Along with the change in the winter mean precipitation, there is a marked difference in the daily rainfall probability density function (PDF) distribution with increased occurrence of heavy rain events along the Kuroshio when eddies are active, but the opposite over the eastern North Pacific (Fig. 1B)

Summary

Introduction

Midlatitude oceanic fronts, such as the Kuroshio and Gulf Stream extension, play an anchoring role for atmospheric storm tracks through their effect on low-level baroclinicity in the troposphere[1,2]. The extent to which the variability of these oceanic fronts can have an impact on atmospheric storm tracks and weather patterns has been a topic of vigorous debate. Few of the existing studies[14,15], explicitly address the potential role of meso-scale SST variability associated with ocean eddies in remotely influencing atmospheric storm track and winter rainfall variability, even though it has been well established that energetic eddies along the oceanic fronts can generate strong meso-scale SST anomalies, varying on seasonal-to-decadal time scales[16]

Methods

Results

Conclusion