Principal Modes of Southern Hemisphere Low-Frequency Variability Obtained from NCEP–NCAR Reanalyses

John W. Kidson National Institute of Water and Atmospheric Research Ltd., Wellington, New Zealand

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Abstract

Analysis of the 300-hPa streamfunction from the 40-year NCEP–NCAR dataset has identified the principal modes of Southern Hemisphere variability on intraseasonal (IS), interannual (IA), and intradecadal (ID) timescales. The variance of streamfunction departures from the annual cycle is zonally symmetric in the IS and IA range with the largest values at midlatitudes. The ID variance is concentrated in the Pacific sector, where it extends to lower latitudes.

For the IS band, obtained by applying a 10–50-day bandpass filter to the twice-daily streamfunction fields, three pairs of EOF patterns were obtained. These show eastward-propagating wavenumber-4 and -5 patterns largely confined to middle and higher latitudes, and two interleaved wavenumber-4 patterns expressing intensification of the zonal wind near 30°S. The wavenumber-5 patterns are more prominent in summer (December–February).

On the interannual timescale, including all periods beyond 50 days, the leading EOF with 26% of the variance expresses fluctuations in the strength of the subtropical jet. EOFs 2 and 3 contain mixed representations of the high-latitude mode and an ENSO (El Niño–Southern Oscillation) related pattern largely confined to the Pacific. EOFs 4 and 5 depict a wave train extending from Australia across the South Pacific to the east of South America. These appear to be stable throughout the period of analysis and contribute around 52% of the >50-day variance.

Variations on ID timescales were isolated by forming 11-month running means of the streamfunction anomalies, and five leading EOFs were found to be significant. The first of these, with 37% of the variance, captured variations forced by ENSO that extend from the equator to higher latitudes in the South Pacific. The second EOF with 18% of the variance accounted for changes in the circulation occurring in the early part of the record, and its amplitude since 1970 has been small. The third was identifiable as the high-latitude mode.

Corresponding author address: Dr. John W. Kidson, NIWA, P.O. Box 14901, Wellington, New Zealand.

Email: j.kidson@niwa.cri.nz

Abstract

Analysis of the 300-hPa streamfunction from the 40-year NCEP–NCAR dataset has identified the principal modes of Southern Hemisphere variability on intraseasonal (IS), interannual (IA), and intradecadal (ID) timescales. The variance of streamfunction departures from the annual cycle is zonally symmetric in the IS and IA range with the largest values at midlatitudes. The ID variance is concentrated in the Pacific sector, where it extends to lower latitudes.

For the IS band, obtained by applying a 10–50-day bandpass filter to the twice-daily streamfunction fields, three pairs of EOF patterns were obtained. These show eastward-propagating wavenumber-4 and -5 patterns largely confined to middle and higher latitudes, and two interleaved wavenumber-4 patterns expressing intensification of the zonal wind near 30°S. The wavenumber-5 patterns are more prominent in summer (December–February).

On the interannual timescale, including all periods beyond 50 days, the leading EOF with 26% of the variance expresses fluctuations in the strength of the subtropical jet. EOFs 2 and 3 contain mixed representations of the high-latitude mode and an ENSO (El Niño–Southern Oscillation) related pattern largely confined to the Pacific. EOFs 4 and 5 depict a wave train extending from Australia across the South Pacific to the east of South America. These appear to be stable throughout the period of analysis and contribute around 52% of the >50-day variance.

Variations on ID timescales were isolated by forming 11-month running means of the streamfunction anomalies, and five leading EOFs were found to be significant. The first of these, with 37% of the variance, captured variations forced by ENSO that extend from the equator to higher latitudes in the South Pacific. The second EOF with 18% of the variance accounted for changes in the circulation occurring in the early part of the record, and its amplitude since 1970 has been small. The third was identifiable as the high-latitude mode.

Corresponding author address: Dr. John W. Kidson, NIWA, P.O. Box 14901, Wellington, New Zealand.

Email: j.kidson@niwa.cri.nz

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  • Ambrizzi, T., B. J. Hoskins, and H.-H. Hsu, 1995: Rossby wave propagation and teleconnection patterns in the austral winter. J. Atmos. Sci.,52, 3661–3672.

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

  • Berbery, E. H., and J. Nogues-Paegle, 1993: Intraseasonal fluctuations between the Tropics and extratropics in the Southern Hemisphere. J. Atmos. Sci.,50, 1950–1965.

  • ——, ——, and J. D. Horel, 1992: Wavelike Southern Hemisphere extratropical teleconnections.. J. Atmos. Sci.,49, 155–177.

  • Chen, T.-C., and M.-C. Yen, 1997: Interdecadal variation of the Southern Hemisphere circulation. J. Climate,10, 805–812.

  • Cheng, X., G. Nitsche, and J. M. Wallace, 1995: Robustness of low-frequency circulation patterns derived from EOF and rotated EOF analyses. J. Climate,8, 1709–1713.

  • Craddock, J. M., and C. R. Flood, 1969: Eigenvectors for representing the 500 mb geopotential surface over the Northern Hemisphere. Quart. J. Roy. Meteor. Soc.,95, 576–593.

  • Farrara, J. D., M. Ghil, C. R. Mechoso, and K. C. Mo, 1989: Empirical orthogonal functions and multiple flow regimes in the Southern Hemisphere winter. J. Atmos. Sci.,46, 3219–3223.

  • Ghil, M., and K. Mo, 1991: Instraseasonal oscillations in the global atmosphere. Part II: Southern Hemisphere. J. Atmos. Sci.,48, 780–790.

  • Hamilton, K., 1983: Aspects of wave behavior in the mid- and upper-troposphere of the Southern Hemisphere. Atmos.–Ocean,21, 40–54.

  • Horel, J. D., 1981: A rotated principal component analysis of the interannual variability of the Northern Hemisphere 500 mb height field. Mon. Wea. Rev.,109, 2080–2092.

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

  • ——, H. H. Hsu, I. N. James, M. Masutani, P. D. Sardeshmuk, and G. H. White, 1989: Diagnostics of the global atmospheric circulation based on ECMWF analyses 1979–1989. WCRP 27, WMO/TD No. 326, WMO, Geneva, Switzerland, 217 pp.

  • Hsu, H., and J. M. Wallace, 1985: Vertical structure of wintertime teleconnection patterns. J. Atmos. Sci.,42, 1693–1710.

  • Hurrell, J., H. van Loon, and D. J. Shea, 1998: The mean state of the troposphere. Meteorology of the Southern Hemisphere, Meteor. Monogr., No. 49, Amer. Meteor. Soc., 1–46.

  • Kalnay, E., and Coauthors, 1996: The NCEP/NCAR 40-year Reanalysis Project. Bull. Amer. Meteor. Soc.,77, 437–471.

  • Karoly, D. J., 1989: Southern Hemisphere circulation features associated with El Niño–Southern Oscillation events. J. Climate,2, 1239–1252.

  • ——, 1990: The role of transient eddies in low-frequency zonal variations of the Southern Hemisphere circulation. Tellus,42A, 41–50.

  • Kidson, J. W., 1988a: Indices of the Southern Hemisphere zonal wind. J. Climate,1, 183–194.

  • ——, 1988b: Interannual variations in the Southern Hemisphere circulation. J. Climate,1, 1177–1198.

  • ——, 1991: Intraseasonal variations in the Southern Hemisphere circulation. J. Climate,4, 939–953.

  • ——, and M. R. Sinclair, 1995: The influence of persistent anomalies on Southern Hemisphere storm tracks. J. Climate,8, 1938–1950.

  • Kiladis, G. N., and K. M. Weickmann, 1992a: Circulation anomalies associated with tropical convection during northern winter. Mon. Wea. Rev.,120, 1900–1923.

  • ——, and ——, 1992b: Extratropical forcing of tropical Pacific convection during northern winter. Mon. Wea. Rev.,120, 1924–1938.

  • ——, and ——, 1997: Horizontal structure and seasonality of large-scale circulations associated with submonthly tropical convection. Mon. Wea. Rev.,125, 1997–2013.

  • ——, and K. C. Mo, 1998: Interannual and intraseasonal variability in the Southern Hemisphere. Meteorology of the Southern Hemisphere, Meteor. Monogr., No. 49, Amer. Meteor. Soc., 307–336.

  • Kousky, V. E., and G. D. Bell, 1992: Atlas of Southern Hemisphere 500 mb Teleconnection Patterns Derived from National Meteorological Center Analyses. NOAA, NOAA Atlas No. 9, Dept. of Commerce, Camp Springs, MD, 90 pp.

  • Lau, K.-M., P.-J. Sheu, and I.-S. Kang, 1994: Multiscale low-frequency circulation modes in the global atmosphere. J. Atmos. Sci.,51, 1169–1193.

  • Madden, R., and P. Julian, 1994: Observations of the 40–50 day tropical oscillation—A review. Mon. Wea. Rev.,122, 814–837.

  • Mechoso, C. R., J. D. Farrara, and M. Ghil, 1991: Intraseasonal variability of the winter circulation in the Southern Hemisphere atmosphere. J. Atmos. Sci.,48, 1387–1404.

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

  • ——, and H. van Loon, 1984: Some aspects of the interannual variation of mean monthly sea level pressure on the Southern Hemisphere. J. Geophys. Res.,89 (D6), 9541–9546.

  • ——, and G. H. White, 1985: Teleconnections in the Southern Hemisphere. Mon. Wea. Rev.,113, 22–37.

  • ——, and M. Ghil, 1987: Statistics and dynamics of persistent anomalies. J. Atmos. Sci.,44, 877–901.

  • ——, and R. W. Higgins, 1997: Planetary waves in the Southern Hemisphere and linkages to the tropics. Harry van Loon Symposium, Studies in Climate, Part II. NCAR Tech. Note TN-433+Proc., 290 pp.

  • ——, and ——, 1998: The Pacific–South American modes and tropical convection during the Southern Hemisphere winter. Mon. Wea. Rev.,126, 1581–1596.

  • Newell, R. E., J. W. Kidson, D. G. Vincent, and G. J. Boer, 1972: The General Circulation of the Tropical Atmosphere and Interactions with Extratropical Latitudes. Vol. 1. The MIT Press, 258 pp.

  • 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.

  • O’Lenic, E. A., and R. E. Livezey, 1988: Practical considerations in the use of rotated principal component analysis (RPCA) in diagnostic studies of upper air heights. Mon. Wea. Rev.,116, 1682–1689.

  • Rasmusson, E. M., and K. Mo, 1993: Linkages between 200-mb tropical and extratropical circulation anomalies during the 1986–1989 ENSO cycle. J. Climate,6, 595–616.

  • Renwick, J. A., R. J. Hurst, and J. W. Kidson, 1998: Climatic influences on the recruitment of Southern Gemfish (Rexea Solandri, Gempylidae) in New Zealand waters. Int. J. Climatol.,18, 1655–1667.

  • Richman, M. B., 1986: Rotation of principal components. Int. J. Climatol.,6, 293–335.

  • Rogers, J. C., and H. van Loon, 1982: Spatial variability of sea level pressure and 500 mb height anomalies over the Southern Hemisphere. Mon. Wea. Rev.,110, 1375–1392.

  • Salby, M. L., 1982: A ubiquitous wavenumber 5 anomaly in the Southern Hemisphere during FGGE. Mon. Wea. Rev.,110, 1712–1720.

  • Swanson, G. S., and K. E. Trenberth, 1981: Interannual variability in the Southern Hemisphere troposphere. Mon. Wea. Rev.,109, 1890–1897.

  • Trenberth, K. E., 1981: Observed Southern Hemisphere eddy statistics at 500 mb: Frequency and spatial dependence. J. Atmos. Sci.,38, 2585–2605.

  • ——, 1991: Storm tracks in the Southern Hemisphere. J. Atmos. Sci.,48, 2159–2178.

  • ——, and J. W. Hurrell, 1994: Decadal atmosphere–ocean variations in the Pacific. Climate Dyn.,9, 303–319.

  • ——, G. W. Branstator, D. Karoly, A. Kumar, N.-C. Lau, and C. Ropelewski, 1998: Progress during TOGA in understanding and modeling global teleconnections associated with tropical sea surface temperatures. J. Geophys. Res.,103 (C7), 14 291–14 324.

  • van Loon, H., J. W. Kidson, and A. B. Mullan, 1993: Decadal variation of the annual cycle in the Australian dataset. J. Climate,6, 1227–1231.

  • 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.

  • White, W. B., and R. G. Peterson, 1996: An Antarctic circumpolar wave in surface pressure, wind, temperature and sea-ice extent. Nature,380, 699–702.

  • Yanai, M., and T. Tomita, 1998: Seasonal and interannual variability of atmospheric heat sources and moisture sinks as determined from NCEP–NCAR Reanalysis. J. Climate,11, 463–482.

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