Low‐frequency attenuation in the North Pacific subarctic‐subtropical transition zone

1982 ◽  
Vol 72 (S1) ◽  
pp. S57-S58
Author(s):  
D. G. Browning ◽  
R. K. Chow
2015 ◽  
Vol 28 (12) ◽  
pp. 4941-4949 ◽  
Author(s):  
Tae-Won Park ◽  
Yi Deng ◽  
Wenhong Li ◽  
Song Yang ◽  
Ming Cai

Abstract The mass footprints associated with atmospheric blocks over the North Pacific are evaluated by constructing daily tendencies of total mass over the blocking domain from three-dimensional mass fluxes throughout the life cycle of a composite blocking event. The results highlight the major role of mass convergence driven by low-frequency (with periods >1 week) atmospheric disturbances during both the development and decay stage of a block. Specifically, low-frequency eddies are responsible for the accelerated mass buildup 4 days prior to the peak intensity of a block, and they also account for the rapid mass loss afterward. High-frequency, subweekly scale disturbances have statistically significant positive contributions to the mass loss during the decay stage, and also show weak negative contributions to the development of the blocking high prior to the peak of the high. The majority of the mass convergence (divergence) responsible for the intensification (decay) of the blocking high occurs in the middle-to-lower troposphere and is largely attributed to mass flux driven by low-frequency meridional (zonal) winds. Also discussed are the implications of this new mass perspective of atmospheric blocks for understanding dynamics of blocking highs and for model bias detection and attribution.


2005 ◽  
Vol 117 (3) ◽  
pp. 1643-1665 ◽  
Author(s):  
Arthur B. Baggeroer ◽  
Edward K. Scheer ◽  
(J. A. Colosi ◽  
B. D. Cornuelle ◽  
B. D. Dushaw ◽  
...  

2015 ◽  
Vol 72 (12) ◽  
pp. 4569-4590 ◽  
Author(s):  
Gwendal Rivière ◽  
Marie Drouard

Abstract Rapid onsets of positive and negative tropospheric northern annular mode (NAM) events during boreal winters are studied using ERA-Interim datasets. The NAM anomalies first appear in the North Pacific from low-frequency Rossby wave propagation initiated by anomalous convection in the western tropical Pacific around 2 weeks before the peak of the events. For negative NAM, the enhanced convection leads to a zonal acceleration of the Pacific jet, while for positive NAM, the reduced convection leads to a poleward-deviated jet in its exit region. The North Atlantic anomalies, which correspond to North Atlantic Oscillation (NAO) anomalies, are formed in close connection with the North Pacific anomalies via downstream propagation of low-frequency planetary-scale and high-frequency synoptic waves, the latter playing a major role during the last onset week. Prior to positive NAM, the generation of synoptic waves in the North Pacific and their downstream propagation is strong. The poleward-deviated Pacific jet favors a southeastward propagation of the waves across North America and anticyclonic breaking in the North Atlantic. The associated strong poleward eddy momentum fluxes push the Atlantic jet poleward and form the positive NAO phase. Conversely, prior to negative NAM, synoptic wave propagation across North America is significantly reduced and more zonal because of the more zonally oriented Pacific jet. This, together with a strong eddy generation in the North Atlantic, leads to equatorward eddy momentum fluxes, cyclonic wave breaking, and the formation of the negative NAO phase. Even though the stratosphere may play a role in some individual cases, it is not the main driver of the composited tropospheric NAM events.


2014 ◽  
Vol 119 (8) ◽  
pp. 5190-5202 ◽  
Author(s):  
C. Petrick ◽  
H. Dobslaw ◽  
I. Bergmann-Wolf ◽  
N. Schön ◽  
K. Matthes ◽  
...  

1996 ◽  
Vol 100 (4) ◽  
pp. 2733-2733
Author(s):  
Keith R. Curtis ◽  
Bruce M. Howe ◽  
James A. Mercer

2000 ◽  
Vol 107 (5) ◽  
pp. 2922-2922
Author(s):  
Rex K. Andrew ◽  
Bruce M. Howe ◽  
James A. Mercer

1999 ◽  
Vol 106 (6) ◽  
pp. 3189-3200 ◽  
Author(s):  
Keith R. Curtis ◽  
Bruce M. Howe ◽  
James A. Mercer

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