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Title: A Nonlinear Theory of Atmospheric Blocking: A Potential Vorticity Gradient View

Journal Article · · Journal of the Atmospheric Sciences
 [1];  [1];  [1];  [2]
  1. Key Laboratory of Regional Climate-Environment for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Science, and University of Chinese Academy of Sciences, Beijing, China
  2. Department of Atmospheric and Environmental Sciences, University at Albany, State University of New York, Albany, New York
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In this paper, an extended nonlinear multiscale interaction model of blocking events in the equivalent barotropic atmosphere is used to investigate the effect of a slowly varying zonal wind in the meridional direction on dipole blocking that is regarded as a nonlinear Rossby wave packet. It is shown that the meridional gradient of potential vorticity [Formula: see text] prior to the blocking onset, which is related to the background zonal wind and its nonuniform meridional shear, can significantly affect the lifetime, intensity, and north–south asymmetry of dipole blocking, while the blocking dipole itself is driven by preexisting incident synoptic-scale eddies. The magnitude of the background PV y determines the energy dispersion and nonlinearity of blocking. It is revealed that a small background PV y is a prerequisite for strong and long-lived eddy-driven blocking that behaves as a persistent meandering westerly jet stream, while the blocking establishment further reduces the PV y within the blocking region, resulting in a positive feedback between blocking and PV y . When the core of the background westerly jet shifts from higher to lower latitudes, the blocking shows a northwest–southeast-oriented dipole with a strong anticyclonic anomaly to the northwest and a weak cyclonic anomaly to the southeast as its northern pole moves westward more rapidly and has weaker energy dispersion and stronger nonlinearity than its southern pole because of the smaller PV y in higher latitudes. The opposite is true when the background jet shifts toward higher latitudes. The asymmetry of dipole blocking vanishes when the background jet shows a symmetric double-peak structure. Thus, a small prior PV y is a favorable precursor for the occurrence of long-lived and large-amplitude blocking.

Research Organization:
State Univ. of New York (SUNY), Albany, NY (United States)
Sponsoring Organization:
USDOE Office of Science (SC); National Natural Science Foundation of China (NSFC); National Key Research and Development Program of China; National Science Foundation (NSF); US National Oceanic and Atmospheric Administration (NOAA)
Grant/Contract Number:
SC0012602; 41430533; 2016YFA0601802; AGS-1353740; OISE-1743738; NA15OAR4310086
OSTI ID:
1543030
Alternate ID(s):
OSTI ID: 1611900
Journal Information:
Journal of the Atmospheric Sciences, Journal Name: Journal of the Atmospheric Sciences Vol. 76 Journal Issue: 8; ISSN 0022-4928
Publisher:
American Meteorological SocietyCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 33 works
Citation information provided by
Web of Science

Cited By (1)

Trends in northern midlatitude atmospheric wave power from 1950 to 2099 journal February 2020

Figures / Tables (20)

FIG. 1(p. 2)figure FIG. 1
Fig. 2(p. 4)figure Fig. 2
Fig. 2 (Continued)(p. 4)figure Fig. 2 (Continued)
TABLE 1(p. 9)table TABLE 1
FIG. 3(p. 10)figure FIG. 3
FIG. 4(p. 11)figure FIG. 4
FIG. 5(p. 12)figure FIG. 5
FIG. 6(p. 14)figure FIG. 6
FIG. 7(p. 15)figure FIG. 7
FIG. 8(p. 16)figure FIG. 8
FIG. 9(p. 17)figure FIG. 9
FIG. 10(p. 18)figure FIG. 10
FIG. 11(p. 19)figure FIG. 11
FIG. 12(p. 20)figure FIG. 12
FIG. 13(p. 21)figure FIG. 13
FIG. 14(p. 22)figure FIG. 14
FIG. 15(p. 23)figure FIG. 15
FIG. 16(p. 24)figure FIG. 16
FIG. 17(p. 25)figure FIG. 17
FIG. 18(p. 26)figure FIG. 18

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Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
meteorology & atmospheric sciences
blocking
eddies
nonlinear dynamics
potential vorticity