Impact of Kuroshio Extension dipole mode variability on the North Pacific storm track

Abstract Coherent, large-scale shifts in the paths of the Gulf Stream (GS) and the Kuroshio Extension (KE) occur on interannual to decadal time scales. Attention has usually been drawn to causes for these shifts in the overlying atmosphere, with some built-in delay of up to a few years resulting from propagation of wind-forced variability within the ocean. However, these shifts in the latitudes of separated western boundary currents can cause substantial changes in SST, which may influence the synoptic atmospheric variability with little or no time delay. Various measures of wintertime atmospheric variability in the synoptic band (2–8 days) are examined using a relatively new dataset for air–sea exchange [Objectively Analyzed Air–Sea Fluxes (OAFlux)] and subsurface temperature indices of the Gulf Stream and Kuroshio path that are insulated from direct air–sea exchange, and therefore are preferable to SST. Significant changes are found in the atmospheric variability following changes in the paths of these currents, sometimes in a local fashion such as meridional shifts in measures of local storm tracks, and sometimes in nonlocal, broad regions coincident with and downstream of the oceanic forcing. Differences between the North Pacific (KE) and North Atlantic (GS) may be partly related to the more zonal orientation of the KE and the stronger SST signals of the GS, but could also be due to differences in mean storm-track characteristics over the North Pacific and North Atlantic.

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Seasonal variations of the relationship between the North Pacific storm track and the meridional shifts of the subarctic frontal zone

Theoretical and Applied Climatology ◽

10.1007/s00704-018-2559-5 ◽

2018 ◽

Vol 136 (3-4) ◽

pp. 1249-1257 ◽

Cited By ~ 1

Author(s):

Yao Yao ◽

Zhong Zhong ◽

Xiu-Qun Yang ◽

Xiaogang Huang

Keyword(s):

Seasonal Variations ◽

North Pacific ◽

Frontal Zone ◽

Storm Track ◽

The North ◽

The Relationship ◽

Subarctic Frontal Zone ◽

The North Pacific ◽

North Pacific Storm Track

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The asymmetric eddy-background flow interaction in the North Pacific storm track

10.5194/egusphere-egu2020-12813 ◽

2020 ◽

Author(s):

Yuan-Bing Zhao

Keyword(s):

Energy Transfer ◽

North Pacific ◽

Storm Track ◽

Middle Level ◽

Background Flow ◽

The North ◽

Flow Interaction ◽

The North Pacific ◽

North Pacific Storm Track ◽

Canonical Transfer

<p>Using a recently developed methodology, namely, the multiscale window transform (MWT), and the MWT-based theory of canonical transfer and localized multiscale energetics analysis, we investigate in an eddy-following way the nonlinear eddy-background flow interaction in the North Pacific storm track, based on the ERA40 reanalysis data from ECWMF. It is found that more than 50% of the storms occur on the northern flank of the jet stream, about 40% are around the jet center, and very few (less than 5%) happen on the southern flank. For storms near or to the north of the jet center, their interaction with the background flow is asymmetric in latitude. In higher latitudes, strong downscale canonical available potential energy transfer happens, especially in the middle troposphere, which reduces the background baroclinicity and decelerates the jet; in lower latitudes, upscale canonical kinetic energy transfer intensifies at the jet center, accelerating the jet and enhancing the middle-level baroclinicity. The resultant effect is that the jet strengthens but narrows, leading to an anomalous dipolar pattern in the fields of background wind and baroclinicity. For the storms on the southern side of the jet, the baroclinic canonical transfer is rather weak. On average, the local interaction begins from about 3 days before a storm arrives at the site of observation, achieves its maximum as the storm arrives, and then weakens.</p>

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Winter Extreme Flux Events in the Kuroshio and Gulf Stream Extension Regions and Relationship with Modes of North Pacific and Atlantic Variability

Journal of Climate ◽

10.1175/jcli-d-14-00642.1 ◽

2015 ◽

Vol 28 (12) ◽

pp. 4950-4970 ◽

Cited By ~ 12

Author(s):

Xiaohui Ma ◽

Ping Chang ◽

R. Saravanan ◽

Dexing Wu ◽

Xiaopei Lin ◽

...

Keyword(s):

North Pacific ◽

Gulf Stream ◽

Kuroshio Extension ◽

Storm Track ◽

Propagation Path ◽

Northwestern Pacific ◽

Boreal Winter ◽

The North ◽

The Kuroshio ◽

The North Pacific

Abstract Boreal winter (November–March) extreme flux events in the Kuroshio Extension region (KER) of the northwestern Pacific and the Gulf Stream region (GSR) of the northwestern Atlantic are analyzed and compared, based on NCEP Climate Forecast System Reanalysis (CFSR), NCEP–NCAR reanalysis, and NOAA Twentieth Century Reanalysis data, as well as the observationally derived OAFlux dataset. These extreme flux events, most of which last less than 3 days, are characterized by cold air outbreaks (CAOs) with an anomalous northerly wind that brings cold and dry air from the Eurasian and North American continents to the KER and GSR, respectively. A close relationship between the extreme flux events over KER (GSR) and the Aleutian low pattern (ALP) [east Atlantic pattern (EAP)] is found with more frequent occurrence of the extreme flux events during a positive ALP (EAP) phase and vice versa. A further lag-composite analysis suggests that the ALP (EAP) is associated with accumulated effects of the synoptic winter storms accompanied by the extreme flux events and shows that the event-day storms tend to have a preferred southeastward propagation path over the North Pacific (Atlantic), potentially contributing to the southward shift of the storm track over the eastern North Pacific (Atlantic) basin during the ALP (EAP) positive phase. Finally, lag-regression analyses indicate a potential positive influence of sea surface temperature (SST) anomalies along the KER (GSR) on the development of the extreme flux events in the North Pacific (Atlantic).

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Importance of Resolving Kuroshio Front and Eddy Influence in Simulating the North Pacific Storm Track

Journal of Climate ◽

10.1175/jcli-d-16-0154.1 ◽

2017 ◽

Vol 30 (5) ◽

pp. 1861-1880 ◽

Cited By ~ 44

Author(s):

Xiaohui Ma ◽

Ping Chang ◽

R. Saravanan ◽

Raffaele Montuoro ◽

Hisashi Nakamura ◽

...

Keyword(s):

North Pacific ◽

Large Scale ◽

Climate Model ◽

Kuroshio Extension ◽

Storm Track ◽

Small Scale ◽

Low Resolution ◽

The North ◽

The North Pacific ◽

Sst Anomalies

Abstract Local and remote atmospheric responses to mesoscale SST anomalies associated with the oceanic front and eddies in the Kuroshio Extension region (KER) are studied using high- (27 km) and low-resolution (162 km) regional climate model simulations in the North Pacific. In the high-resolution simulations, removal of mesoscale SST anomalies in the KER leads to not only a local reduction in cyclogenesis but also a remote large-scale equivalent barotropic response with a southward shift of the downstream storm track and jet stream in the eastern North Pacific. In the low-resolution simulations, no such significant remote response is found when mesoscale SST anomalies are removed. The difference between the high- and low-resolution model simulated atmospheric responses is attributed to the effect of mesoscale SST variability on cyclogenesis through moist baroclinic instability. It is only when the model has sufficient resolution to resolve small-scale diabatic heating that the full effect of mesoscale SST forcing on the storm track can be correctly simulated.

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