Storm track activity over the North Pacific associated with the Madden-Julian Oscillation under ENSO conditions during boreal winter

2014 ◽  
Vol 119 (18) ◽  
pp. 10,663-10,683 ◽  
Author(s):  
Chiharu Takahashi ◽  
Ryuichi Shirooka
Keyword(s):  
North Pacific ◽  
Storm Track ◽  
Boreal Winter ◽  
Madden Julian Oscillation ◽  
The North ◽  
Storm Track Activity ◽  
The North Pacific

Influence of Atmospheric Blocking on Storm Track Activity Over the North Pacific During Boreal Winter

2021 ◽  
Vol 48 (17) ◽  
Author(s):  
Minghao Yang ◽  
Dehai Luo ◽  
Chongyin Li ◽  
Yao Yao ◽  
Xin Li ◽  
...  
Keyword(s):  
North Pacific ◽  
Storm Track ◽  
Boreal Winter ◽  
Atmospheric Blocking ◽  
The North ◽  
Storm Track Activity ◽  
The North Pacific

Interdecadal changes in the storm track activity over the North Pacific and North Atlantic

2011 ◽  
Vol 39 (1-2) ◽  
pp. 313-327 ◽  
Author(s):  
Sun-Seon Lee ◽  
June-Yi Lee ◽  
Bin Wang ◽  
Kyung-Ja Ha ◽  
Ki-Young Heo ◽  
...  
Keyword(s):  
North Atlantic ◽  
North Pacific ◽  
Storm Track ◽  
The North ◽  
Storm Track Activity ◽  
The North Pacific ◽  
Interdecadal Changes

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

2015 ◽  
Vol 28 (12) ◽  
pp. 4950-4970 ◽  
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).

scholarly journals Energetics of transient eddies related to the midwinter minimum of the North Pacific storm-track activity

2021 ◽  
pp. 1-55
Keyword(s):  
Energy Conversion ◽  
North Pacific ◽  
Storm Track ◽  
Generation Rate ◽  
Net Energy ◽  
The North ◽  
Eddy Heat Flux ◽  
Storm Track Activity ◽  
Baroclinic Energy Conversion ◽  
The North Pacific

Abstract Storm-track activity over the North Pacific climatologically exhibits a clear minimum in midwinter, when the westerly jet speed sharply maximizes. This counterintuitive phenomenon, referred to as the “midwinter minimum (MWM)”, has been investigated from various perspectives, but the mechanisms are still to be unrevealed. Toward better understanding of this phenomenon, the present study delineates the detailed seasonal evolution of climatological-mean Eulerian statistics and energetics of migratory eddies along the NP storm-track over 60 years. As a comprehensive investigation of the mechanisms for the MWM, this study has revealed that the net eddy conversion/generation rate normalized by the eddy total energy, which is independent of eddy amplitude, is indeed reduced in midwinter. The reduction from early winter occurs mainly due to the decreased effectiveness of the baroclinic energy conversion through seasonally weakened temperature fluctuations and the resultant poleward eddy heat flux. The reduced net normalized conversion/generation rate in midwinter is also found to arise in part from the seasonally enhanced kinetic energy conversion from eddies into the strongly diffluent Pacific jet around its exit. The seasonality of the net energy influx also contributes especially to the spring recovery of the net normalized conversion/generation rate. The midwinter reduction in the normalized rates of both the net energy conversion/generation and baroclinic energy conversion was more pronounced in the period before the late 1980s, during which the MWM of the storm-track activity was climatologically more prominent.

scholarly journals Comments on “The Source of the Midwinter Suppression in Storminess over the North Pacific”

2011 ◽  
Vol 24 (19) ◽  
pp. 5187-5191 ◽  
Author(s):  
Edmund K. M. Chang ◽  
Yanjuan Guo
Keyword(s):  
North Pacific ◽  
Feature Tracking ◽  
Storm Track ◽  
Northern Asia ◽  
The North ◽  
Relative Minimum ◽  
The Pacific ◽  
Storm Track Activity ◽  
The North Pacific ◽  
Midwinter Suppression

In a recent paper, Penny et al. employed feature tracking to investigate why there is a relative minimum in storminess during winter within the Pacific storm track. They concluded that reduced upstream seeding, especially seeding from northern Asia, is the main “source” of the midwinter suppression of the Pacific storm track. Results presented here show that during midwinter months when upstream seeding is as strong as that in spring/fall, the Pacific storm track is not significantly stronger than average and is still much weaker than that in spring/fall, suggesting that the strength of upstream seeding cannot be the primary cause of the midwinter suppression of Pacific storm-track activity.

Intraseasonal Modulation of the North Pacific Storm Track by Tropical Convection in Boreal Winter

2011 ◽  
Vol 24 (4) ◽  
pp. 1122-1137 ◽  
Author(s):  
Yi Deng ◽  
Tianyu Jiang
Keyword(s):  
North Pacific ◽  
Storm Track ◽  
Tropical Convection ◽  
Boreal Winter ◽  
Mean Flow ◽  
Central Pacific ◽  
Synoptic Eddy ◽  
The North ◽  
The North Pacific ◽  
North Pacific Storm Track

Abstract The modulation of the North Pacific storm track by tropical convection on intraseasonal time scales (30–90 days) in boreal winter (December–March) is investigated using the NCEP–NCAR reanalysis and NOAA satellite outgoing longwave radiation (OLR) data. Multivariate empirical orthogonal function (MEOF) analysis and case compositing based upon the principal components (PCs) of the EOFs reveal substantial changes in the structure and intensity of the Pacific storm track quantified by vertically (925–200 mb) averaged synoptic eddy kinetic energy (SEKE) during the course of a typical Madden–Julian oscillation (MJO) event. The storm-track response is characterized by an amplitude-varying dipole propagating northeastward as the center of the anomalous tropical convection moves eastward across the eastern Indian Ocean and the western-central Pacific. A diagnosis of the SEKE budget indicates that the storm-track anomaly is induced primarily by changes in the convergence of energy flux, baroclinic conversion, and energy generation due to the interaction between synoptic eddies and intraseasonal flow anomalies. This demonstrates the important roles played by eddy–mean flow interaction and eddy–eddy interaction in the development of the extratropical response to MJO variability. The feedback of synoptic eddy to intraseasonal flow anomalies is pronounced: when the center of the enhanced tropical convection is located over the Maritime Continent (western Pacific), the anomalous synoptic eddy forcing partly drives an upper-tropospheric anticyclonic (cyclonic) and, to its south, a cyclonic (anticyclonic) circulation anomaly over the North Pacific. Associated with the storm-track anomaly, a three-band (dry–wet–dry) anomaly in both precipitable water and surface precipitation propagates poleward over the eastern North Pacific and induces intraseasonal variations in the winter hydroclimate over western North America.

scholarly journals Change In The Variability In The Western Pacific Pattern During Boreal Winter: Roles of Tropical Pacific Sea Surface Temperature Anomalies And North Pacific Storm Track Activity

2021 ◽  
Author(s):  
Hasi Aru ◽  
Shangfeng Chen ◽  
Wen Chen
Keyword(s):  
Surface Temperature ◽  
North Pacific ◽  
Storm Track ◽  
High Variability ◽  
Sea Surface ◽  
Boreal Winter ◽  
The North ◽  
The Western Pacific ◽  
The North Pacific ◽  
North Pacific Storm Track

Abstract Using multiple reanalysis datasets, this study reveals that the variability in the Western Pacific pattern (WP) in boreal winter has shown notable changes during recent decades. The variability in the winter WP exhibited a marked weakening trend before the early 2000s and increased slightly thereafter. Two epochs with the highest and lowest WP variabilities are selected for a comparative analysis. Winter WP-related meridional dipole atmospheric anomalies over the North Pacific were stronger and had a broader range during the high-variability epoch than during the low-variability epoch. Correspondingly, the winter WP had larger impacts on surface temperature variations over Eurasia and North America during the high-variability epoch than during the low-variability epoch. We find that the shift in the winter WP variability is closely related to changes in the connection between the winter WP and the El Niño-Southern Oscillation (ENSO) and to changes in the amplitude of the North Pacific storm track. Specifically, ENSO had a closer connection with the WP during the high-variability epoch, at which time the amplitude of the North Pacific storm track was also stronger. During the high-variability epoch, the extratropical atmospheric anomalies generated by the tropical ENSO shifted westward and projected more on the WP-related atmospheric anomalies, thus contributing to an increase in WP variability. In addition, the larger amplitude of the North Pacific storm track that occurred during the high-variability epoch led to the stronger feedback of synoptic-scale eddies to the mean flow and contributed to stronger WP variability. Further analysis indicates that the change in the connection of ENSO with the WP may be partly related to the zonal shift of the sea surface temperature anomaly in the tropical Pacific associated with ENSO.

scholarly journals Drivers of uncertainty in future projections of Madden–Julian Oscillation teleconnections

2021 ◽  
Vol 2 (3) ◽  
pp. 653-673
Author(s):  
Andrea M. Jenney ◽  
David A. Randall ◽  
Elizabeth A. Barnes
Keyword(s):  
North America ◽  
North Pacific ◽  
Static Stability ◽  
Boreal Winter ◽  
Madden Julian Oscillation ◽  
Future Projections ◽  
The North ◽  
The Mean ◽  
The North Pacific ◽  
Mean State

Abstract. Teleconnections from the Madden–Julian Oscillation (MJO) are a key source of predictability of weather on the extended timescale of about 10–40 d. The MJO teleconnection is sensitive to a number of factors, including the mean dry static stability, the mean flow, and the propagation and intensity characteristics of the MJO, which are traditionally difficult to separate across models. Each of these factors may evolve in response to increasing greenhouse gas emissions, which will impact MJO teleconnections and potentially impact predictability on extended timescales. Current state-of-the-art climate models do not agree on how MJO teleconnections over central and eastern North America will change in a future climate. Here, we use results from the Coupled Model Intercomparison Project Phase 6 (CMIP6) historical and SSP585 experiments in concert with a linear baroclinic model (LBM) to separate and investigate alternate mechanisms explaining why and how boreal winter (January) MJO teleconnections over the North Pacific and North America may change in a future climate and to identify key sources of inter-model uncertainty. LBM simulations suggest that a weakening teleconnection due to increases in tropical dry static stability alone is robust across CMIP6 models and that uncertainty in mean state winds is a key driver of uncertainty in future MJO teleconnections. Uncertainty in future changes to the MJO's intensity, eastward propagation speed, zonal wavenumber, and eastward propagation extent are other important sources of uncertainty in future MJO teleconnections. We find no systematic relationship between future changes in the Rossby wave source and the MJO teleconnection or between changes to the zonal wind or stationary Rossby wave number and the MJO teleconnection over the North Pacific and North America. LBM simulations suggest a reduction of the boreal winter MJO teleconnection over the North Pacific and an uncertain change over North America, with large spread over both regions that lends to weak confidence in the overall outlook. While quantitatively determining the relative importance of MJO versus mean state uncertainties in determining future teleconnections remains a challenge, the LBM simulations suggest that uncertainty in the mean state winds is a larger contributor to the uncertainty in future projections of the MJO teleconnection than the MJO.

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