• Barnston, A. G., and R. E. Livezey, 1987: Classification, seasonality, and persistence of low-frequency atmospheric circulation patterns. Mon. Wea. Rev.,115, 1083–1126.

  • Black, R. X., and R. M. Dole, 1993: The dynamics of large-scale cyclogenesis over the North Pacific Ocean. J. Atmos. Sci.,50, 421–442.

  • Borges, M. D., and D. L. Hartmann, 1992: Barotropic instability andoptimal perturbations of observed nonzonal flows. J. Atmos. Sci.,49, 335–354.

  • Branstator, G., 1984: The relationship between the zonal mean flow and quasi-stationary waves in the midtroposphere. J. Atmos. Sci.,41, 2163–2178.

  • ——, 1990: Low-frequency patterns induced by stationary waves. J. Atmos. Sci.,47, 629–648.

  • ——, 1992: The maintenance of low-frequency atmospheric anomalies. J. Atmos. Sci.,49, 1924–1945.

  • Cai, M., and H. M. van den Dool, 1994: Dynamical decomposition of low-frequency tendencies. J. Atmos. Sci.,51, 2086–2100.

  • Dole, R. M., 1986: The life cycles of persistent anomalies and blocking over the North Pacific. Advances in Geophysics, Vol. 29, Academic Press, 31–69.

  • ——, and R. X. Black, 1990: Life cycles of persistent anomalies. Part II: The development of persistent negative height anomalies over the North Pacific Ocean. Mon. Wea. Rev.,118, 824–846.

  • Egger, J., and H.-D. Schilling, 1983: On the theory of the long-term variability of the atmosphere. J. Atmos. Sci.,40, 1073–1085.

  • Farrell, B. F., 1989: Optimal excitation of baroclinic waves. J. Atmos. Sci.,46, 1193–1206.

  • Feldstein, S. B., and S. Lee, 1996: Mechanisms of zonal index variability in an aquaplanet GCM. J. Atmos. Sci.,53, 3541–3555.

  • Frederiksen, J. S., 1983: A unified three-dimensional instability theory of the onset of blocking and cyclogenesis. II: Teleconnection patterns. J. Atmos. Sci.,40, 2593–2609.

  • Gordon, C. T., and W. T. Stern, 1982: A description of the GFDL global spectral model. Mon. Wea. Rev.,110, 625–644.

  • Haltiner, G. J., and R. T. Williams, 1980: Numerical Prediction and Dynamic Meteorology. Wiley and Sons, 477 pp.

  • Hansen, A. T., and A. Sutera, 1995: Large amplitude flow anomalies in the Northern Hemisphere midlatitudes. J. Atmos. Sci.,52, 2133–2151.

  • Higgins, R. W., and S. D. Schubert, 1994: Simulated life cycles of persistent anticyclonic anomalies over the North Pacific: Role of synoptic-scale eddies. J. Atmos. Sci.,51, 3238–3260.

  • ——, and ——, 1996: Simulations of persistent North Pacific circulation anomalies and interhemispheric teleconnections. J. Atmos. Sci.,53, 188–207.

  • Horel, J. D., 1985: Persistence of the 500-mb height field during Northern Hemisphere winter. Mon. Wea. Rev.,113, 2030–2042.

  • Hoskins, B. J., and D. Karoly, 1981: The steady linear response of a spherical atmosphere to thermal and orographic forcing. J. Atmos. Sci.,38, 1179–1196.

  • ——, I. N. James, and G. H. White, 1983: The shape, propagation and mean-flow interaction of large-scale weather systems. J. Atmos. Sci., 40, 1595–1612.

  • Kang, I.-S., 1990: Influence of zonal mean flow change on stationary wave fluctuations. J. Atmos. Sci.,47, 141–147.

  • ——, and K.-M. Lau, 1994: Principal modes of atmospheric circulation anomalies associated with global angular momentum fluctuations. J. Atmos. Sci.,51, 1194–1205.

  • Lau, N.-C., 1988: Variability of the observed midlatitude storm tracks in relation to low-frequency changes in the circulation pattern. J. Atmos. Sci.,45, 2718–2743.

  • Lee, S., 1995: Localized storm tracks in the absence of local instability. J. Atmos. Sci.,52, 977–989.

  • ——, and S. B. Feldstein, 1996: Mechanisms of zonal index evolution in a two layer model. J. Atmos. Sci.,53, 2232–2246.

  • Mo, K. C., 1986: Quasi-stationary states in the Southern Hemisphere. Mon. Wea. Rev.,114, 808–823.

  • Nakamura, H., and J. M. Wallace, 1990: Observed changes in baroclinic wave activity during the life cycles of low-frequency circulation anomalies. J. Atmos. Sci.,47, 1100–1116.

  • Navarra, A., and K. Miyakoda, 1988: Anomaly general circulation models. J. Atmos. Sci.,45, 1509–1530.

  • Nigam, S., and R. S. Lindzen, 1989: The sensitivity of stationary waves to variations in the basic state zonal flow. J. Atmos. Sci.,46, 1746–1768.

  • North, G. R., T. L. Bell, R. F. Cahalan, and F. J. Moeng, 1982. Sampling errors in the estimation of empirical orthogonal functions. Mon. Wea. Rev.,110, 699–706.

  • Robinson, W., 1991: The dynamics of the zonal index in a simple model of the atmosphere. Tellus,43A, 295–305.

  • Schubert, S. D., and C.-K. Park, 1991: Low-frequency intraseasonal tropical–extratropical interactions. J. Atmos. Sci.,48, 629–650.

  • ——, M. Suarez, C.-K. Park, and S. Moorthi, 1993: GCM simulations of intraseasonal variability in the Pacific/North American region. J. Atmos. Sci.,50, 1991–2007.

  • Simmons, A. J., J. M. Wallace, and G. Branstator, 1983: Barotropic wave propagation and instability and atmospheric teleconnection patterns. J. Atmos. Sci.,40, 1363–1392.

  • Ting, M., and N.-C. Lau, 1993: A diagnostic and modeling study of the monthly mean wintertime anomalies appearing in an 100- year GCM experiment. J. Atmos. Sci.,50, 2845–2867.

  • Wallace, J. M., and D. S. Gutzler, 1981: Teleconnections in the geopotential height field during the Northern Hemisphere winter. Mon. Wea. Rev.,109, 784–812.

  • Whitaker, J. S., and R. M. Dole, 1995: Organization of storm tracks in zonally varying flows. J. Atmos. Sci.,52, 1178–1191.

  • Yang, S., and B. Reinhold, 1991: How does the low-frequency variance vary? Mon. Wea. Rev.,119, 119–127.

  • Yu, J.-Y., and D. L. Hartmann, 1993: Zonal flow vacillation and eddy forcing in a simple GCM of the atmosphere. J. Atmos. Sci.,50, 3244–3259.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 141 141 93
PDF Downloads 54 54 9

The Growth and Decay of Low-Frequency Anomalies in a GCM

View More View Less
  • 1 Earth System Science Center, The Pennsylvania State University, University Park, Pennsylvania
© Get Permissions
Restricted access

Abstract

The temporal evolution of a regional-scale persistent low-frequency anomaly is examined with data from a 2100-day perpetual January general circulation model. The persistent episodes are determined with an objective analysis of the low-pass (>10 day) 350-mb streamfunction field that uses both pattern correlations and empirical orthogonal function (EOF) analysis.

The composite evolution of each term in the streamfunction tendency equation is calculated relative to the onset day (the first day of the persistent episode). By projecting each term in the streamfunction tendency equation onto an EOF (the EOF is associated with a particular low-frequency anomaly), the contribution of these terms toward the tendency of the corresponding principal component can be obtained. It is found that the sum of the linear terms dominates during most of the growth and the decay of the low-frequency anomaly. The linear term that accounts for the growth and maintenance of the low-frequency anomaly is the interaction between the anomaly and the time-mean zonally asymmetric flow. After the anomaly attains sufficient amplitude, its decay is accomplished through the divergence term. For one phase of the EOF, it is found that the high-frequency transients prolong the anomaly, whereas in the other phase they do not.

Implications of this study for examining monthly averaged anomalies are also discussed.

Corresponding author address: Dr. Steven Feldstein, Earth System Science Center, The Pennsylvania State University, 248 Deike Building, University Park, PA 16802.

Email: sbf@essc.psu.edu

Abstract

The temporal evolution of a regional-scale persistent low-frequency anomaly is examined with data from a 2100-day perpetual January general circulation model. The persistent episodes are determined with an objective analysis of the low-pass (>10 day) 350-mb streamfunction field that uses both pattern correlations and empirical orthogonal function (EOF) analysis.

The composite evolution of each term in the streamfunction tendency equation is calculated relative to the onset day (the first day of the persistent episode). By projecting each term in the streamfunction tendency equation onto an EOF (the EOF is associated with a particular low-frequency anomaly), the contribution of these terms toward the tendency of the corresponding principal component can be obtained. It is found that the sum of the linear terms dominates during most of the growth and the decay of the low-frequency anomaly. The linear term that accounts for the growth and maintenance of the low-frequency anomaly is the interaction between the anomaly and the time-mean zonally asymmetric flow. After the anomaly attains sufficient amplitude, its decay is accomplished through the divergence term. For one phase of the EOF, it is found that the high-frequency transients prolong the anomaly, whereas in the other phase they do not.

Implications of this study for examining monthly averaged anomalies are also discussed.

Corresponding author address: Dr. Steven Feldstein, Earth System Science Center, The Pennsylvania State University, 248 Deike Building, University Park, PA 16802.

Email: sbf@essc.psu.edu

Save