Simulation of monthly mean circulation anomalies using a linear anomay model

Abstract To highlight the details of stratosphere–troposphere dynamical coupling during the onset of strong polar vortex variability, this study identifies stratospheric vortex weakening (SVW) events by rapid deceleration of the polar vortex and performs composite budget analyses in the transformed Eulerian-mean (TEM) framework on daily time scales. Consistent with previous work, a rapid deceleration of the polar vortex, followed by a rather slow recovery, is largely explained by conservative dynamics with nonnegligible contribution by nonconservative sinks of wave activity. During the onset of such events, stratospheric zonal wind anomalies show a near-instantaneous vertical coupling to the troposphere, which results from an anomalous upward and poleward propagation of planetary-scale waves. In the troposphere, zonal wind anomalies are also influenced by synoptic-scale waves, confirming previous studies. The SVW events driven by wavenumber-1 disturbances show comparable circulation anomalies to those driven by wavenumber-2 disturbances both in the stratosphere and troposphere. The former, however, exhibits more persistent anomalies after the onset than the latter. During both events, tropospheric wavenumber-1 and 2 disturbances project strongly onto the climatological waves, indicating that vertical propagation of planetary-scale waves into the stratosphere is largely caused by constructive linear interference. It is also found that the SVW-related vertical coupling is somewhat sensitive to the stratospheric mean state. Although overall evolution of zonal-mean circulation anomalies are reasonably similar under an initially weak or strong polar vortex, the time-lagged downward coupling is evident only when the polar vortex is decelerated under a weak vortex state. These results are compared with other definitions of weak polar vortex events, such as stratospheric sudden warming events.

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Evolution of monthly mean circulation and weather patterns

Transactions American Geophysical Union ◽

10.1029/tr029i006p00777 ◽

1948 ◽

Vol 29 (6) ◽

pp. 777 ◽

Cited By ~ 20

Author(s):

Jerome Namias

Keyword(s):

Weather Patterns ◽

Monthly Mean Circulation ◽

Mean Circulation

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Observations on Cardiac Output and ”Pulmonary Blood Volume” in Normal Man by External Recording of the Intracardiac Flow of 131I Labelled Albumin

Nuklearmedizin ◽

10.1055/s-0037-1621159 ◽

1961 ◽

Vol 1 (04) ◽

pp. 353-379

Author(s):

Jacques Lammerant ◽

Norman Veall ◽

Michel De Visscher

Keyword(s):

Cardiac Output ◽

Blood Volume ◽

Normal Subjects ◽

Published Data ◽

Total Blood Volume ◽

Total Blood ◽

Pulmonary Blood Volume ◽

Intracardiac Flow ◽

Normal Man ◽

Mean Circulation

Summary1. The technique for the measurement of cardiac output by external recording of the intracardiac flow of 131I labelled human serum albumin has been extended to provide a measure of the mean circulation time from right to left heart and hence a new approach to the estimation of the pulmonary blood volume.2. Values for the basal cardiac output in normal subjects and its variations with age are in good agreement with the previously published data of other workers.3. The pulmonary blood volume in normal man in the basal state was found to be 28.2 ± 0.6% of the total blood volume.4. There was no correlation between cardiac output and pulmonary blood volume in a series of normal subjects in the basal state.5. The increase in cardiac output during digestion was associated with a decrease in pulmonary blood volume equal to 6.3 ± 1.2% of the total blood volume, that is, about 280 ml.6. The increase in cardiac output during exercise was associated with a decrease in pulmonary blood volume equal to 4.5 ± 1.0% of the total blood volume, that is, about 200 ml.7. The increase in cardiac output attributed to alarm is not associated with a decrease in pulmonary blood volume, the latter may in fact be increased.8. The total blood volume is advocated as a standard of reference for studies of this type in normal subjects in preference to body weight or surface area.9. The significance of these results and the validity of the method are discussed.

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Origins of Biases in CMIP5 Models Simulating Northwest Pacific Summertime Atmospheric Circulation Anomalies during the Decaying Phase of ENSO

Journal of Climate ◽

10.1175/jcli-d-17-0289.1 ◽

2018 ◽

Vol 31 (14) ◽

pp. 5707-5729 ◽

Cited By ~ 3

Author(s):

Weichen Tao ◽

Gang Huang ◽

Renguang Wu ◽

Kaiming Hu ◽

Pengfei Wang ◽

...

Keyword(s):

Atmospheric Circulation ◽

Southern Oscillation ◽

Coupled Model ◽

Tropical Indian Ocean ◽

Shortwave Radiation ◽

Cmip5 Models ◽

Northwest Pacific ◽

Circulation Anomalies ◽

Atmospheric Circulation Anomalies ◽

Sst Anomalies

Abstract The present study documents the biases of summertime northwest Pacific (NWP) atmospheric circulation anomalies during the decaying phase of ENSO and investigates their plausible reasons in 32 models from phase 5 of the Coupled Model Intercomparison Project. Based on an intermodel empirical orthogonal function (EOF) analysis of El Niño–Southern Oscillation (ENSO)-related 850-hPa wind anomalies, the dominant modes of biases are extracted. The first EOF mode, explaining 21.3% of total intermodel variance, is characterized by a cyclone over the NWP, indicating a weaker NWP anticyclone. The cyclone appears to be a Rossby wave response to unrealistic equatorial western Pacific (WP) sea surface temperature (SST) anomalies related to excessive equatorial Pacific cold tongue in the models. On one hand, the cold SST biases increase the mean zonal SST gradient, which further intensifies warm zonal advection, favoring the development and persistence of equatorial WP SST anomalies. On the other hand, they reduce the anomalous convection caused by ENSO-related warming, and the resultant increase in downward shortwave radiation contributes to the SST anomalies there. The second EOF mode, explaining 18.6% of total intermodel variance, features an anticyclone over the NWP with location shifted northward. The related SST anomalies in the Indo-Pacific sector show a tripole structure, with warming in the tropical Indian Ocean and equatorial central and eastern Pacific and cooling in the NWP. The Indo-Pacific SST anomalies are highly controlled by ENSO amplitude, which is determined by the intensity of subtropical cells via the adjustment of meridional and vertical advection in the models.

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