Editorial Type:
Article
Article Type:
Research Article

Extratropical Transition of Southwest Pacific Tropical Cyclones. Part I: Climatology and Mean Structure Changes

Mark R. Sinclair Embry-Riddle Aeronautical University, Prescott, Arizona

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Print Publication:
01 Mar 2002
DOI:
https://doi.org/10.1175/1520-0493(2002)130<0590:ETOSPT>2.0.CO;2
Page(s):
590–609
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Abstract

A database of tropical cyclone best track and intensity information for the southwest Pacific Ocean basin is used to construct a 28-year climatology for tropical cyclones that move into middle latitudes. Of the nine or so tropical cyclones that form each year, an average of about three can be expected to migrate south of 35°S, with the greatest fraction in March. Storms entering the Tasman Sea west of New Zealand (NZ) move almost due south on average and retain greater intensity than those to the east of NZ, where storms decay quickly while moving rapidly away to the southeast. Storms east of NZ are embedded in a stronger, more zonal flow than those to the west, which move poleward ahead of a larger-amplitude trough. During El Niño years, tropical cyclones that move into middle latitudes exhibit stronger zonal motion and occur over a wider range of longitudes than during La Niña years. Storm intensity is only weakly correlated with concurrent SST anomalies, suggesting that atmospheric circulation is the dominant influence on storm properties.

Average structure changes during extratropical transition (ET) are identified using the NCEP–NCAR reanalysis dataset, for a subset of 33 transitioning storms during 1980–97. Composites are used to construct a three-dimensional conceptual model of the transformation from a mature hurricane to an asymmetric baroclinic midlatitude cyclone. Southwest Pacific tropical cyclones encounter the baroclinic westerlies early in their lives, accounting for their average eastward (and poleward) motion. At maximum average intensity near 20°S, baroclinic effects are already important, with warm frontogenesis appearing in the southeast quadrant and outflow aloft into a downstream subtropical wind maximum that moves poleward with the storm. By 25°S, the average TC has lost the characteristic symmetric anticyclonic outflow aloft and acquired the characteristics of a baroclinic midlatitude storm, including regions of warm and cold frontogenesis, a vertical motion dipole and a westward tilt with height. From about 30°S poleward, a second upper-tropospheric wind maximum appears west of the storm, with strengthening cyclonic vorticity advection aloft. Below about 400 hPa, the storm retains the vertical, warm cyclonic core as it migrates poleward.

Corresponding author address: Dr. Mark R. Sinclair, Embry-Riddle Aeronautical University, 3800 Willow Creek Road, Prescott, AZ 86301. Email: sinclam@pr.erau.edu

Abstract

A database of tropical cyclone best track and intensity information for the southwest Pacific Ocean basin is used to construct a 28-year climatology for tropical cyclones that move into middle latitudes. Of the nine or so tropical cyclones that form each year, an average of about three can be expected to migrate south of 35°S, with the greatest fraction in March. Storms entering the Tasman Sea west of New Zealand (NZ) move almost due south on average and retain greater intensity than those to the east of NZ, where storms decay quickly while moving rapidly away to the southeast. Storms east of NZ are embedded in a stronger, more zonal flow than those to the west, which move poleward ahead of a larger-amplitude trough. During El Niño years, tropical cyclones that move into middle latitudes exhibit stronger zonal motion and occur over a wider range of longitudes than during La Niña years. Storm intensity is only weakly correlated with concurrent SST anomalies, suggesting that atmospheric circulation is the dominant influence on storm properties.

Average structure changes during extratropical transition (ET) are identified using the NCEP–NCAR reanalysis dataset, for a subset of 33 transitioning storms during 1980–97. Composites are used to construct a three-dimensional conceptual model of the transformation from a mature hurricane to an asymmetric baroclinic midlatitude cyclone. Southwest Pacific tropical cyclones encounter the baroclinic westerlies early in their lives, accounting for their average eastward (and poleward) motion. At maximum average intensity near 20°S, baroclinic effects are already important, with warm frontogenesis appearing in the southeast quadrant and outflow aloft into a downstream subtropical wind maximum that moves poleward with the storm. By 25°S, the average TC has lost the characteristic symmetric anticyclonic outflow aloft and acquired the characteristics of a baroclinic midlatitude storm, including regions of warm and cold frontogenesis, a vertical motion dipole and a westward tilt with height. From about 30°S poleward, a second upper-tropospheric wind maximum appears west of the storm, with strengthening cyclonic vorticity advection aloft. Below about 400 hPa, the storm retains the vertical, warm cyclonic core as it migrates poleward.

Corresponding author address: Dr. Mark R. Sinclair, Embry-Riddle Aeronautical University, 3800 Willow Creek Road, Prescott, AZ 86301. Email: sinclam@pr.erau.edu

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  • Basher, R. E., and X. Zheng, 1995: Tropical cyclones in the southwest Pacific: Spatial patterns and relationships to Southern Oscillation and sea surface temperature. J. Climate, 8 , 1249–1260.

    • Search Google Scholar
    • Export Citation

  • Bosart, L. F., and D. B. Dean, 1991: The Agnes rainstorm of June 1972: Surface feature evolution culminating in inland storm redevelopment. Wea. Forecasting, 6 , 515–537.

    • Search Google Scholar
    • Export Citation

  • Brand, S., and C. P. Guard, 1978: Extratropical storm evolution from tropical cyclones in the western North Pacific Ocean. Tech. Rep. TR 78 02, Naval Environmental Prediction Research Facility, 20 pp.

    • Search Google Scholar
    • Export Citation

  • Brenstrum, E., 1997: The ghost of cyclones past: Drena, Fergus and the Cyclone of '36. N.Z. Geogr, 33 .

  • Browning, K. A., G. Vaughan, and P. Panagi, 1998: Analysis of an extratropical cyclone after its reintensification as a warm core extratropical cyclone. Quart. J. Roy. Meteor. Soc, 124 , 2329–2356.

    • Search Google Scholar
    • Export Citation

  • Carr, F. H., and L. F. Bosart, 1978: A diagnostic evaluation of rainfall predictability for Tropical Storm Agnes, June 1972. Mon. Wea. Rev, 106 , 363–374.

    • Search Google Scholar
    • Export Citation

  • DiMego, G. J., and L. F. Bosart, 1982a: The transformation of Tropical Storm Agnes into an extratropical cyclone. Part I: The observed fields and vertical motion computations. Mon. Wea. Rev, 110 , 385–411.

    • Search Google Scholar
    • Export Citation

  • DiMego, G. J., and L. F. Bosart, 1982b: The transformation of Tropical Storm Agnes into an extratropical cyclone. Part II: Moisture, vorticity and kinetic energy budgets. Mon. Wea. Rev, 110 , 412–433.

    • Search Google Scholar
    • Export Citation

  • Dvorak, V. F., 1975: Tropical cyclone intensity analysis and forecasting from satellite imagery. Mon. Wea. Rev, 103 , 420–430.

  • Dvorak, V. F., 1984: Tropical cyclone intensity analysis using satellite data. NOAA Tech. Rep. NESDIS 11, U.S. Dept. of Commerce, Washington, DC, 47 pp.

    • Search Google Scholar
    • Export Citation

  • Elsberry, R. L., W. M. Frank, G. J. Holland, J. D. Jarrell, and R. L. Southern, 1987: A global view of tropical cyclones. Dept. of Meteorology, Naval Postgraduate School, Monterey, CA, 185 pp.

    • Search Google Scholar
    • Export Citation

  • Foley, G. R., and B. N. Hanstrum, 1994: The capture of tropical cyclones by cold fronts off the west coast of Australia. Wea. Forecasting, 9 , 577–592.

    • Search Google Scholar
    • Export Citation

  • Frank, W. M., and E. A. Ritchie, 1999: Effects of environmental flow upon tropical cyclone structure. Mon. Wea. Rev, 127 , 2044–2061.

  • Harr, P. A., and R. L. Elsberry, 2000: Extratropical transition of tropical cyclones over the western North Pacific. Part I: Evolution of structural characteristics during the transition process. Mon. Wea. Rev, 128 , 2613–2633.

    • Search Google Scholar
    • Export Citation

  • Harr, P. A., R. L. Elsberry, and T. F. Hogan, 2000: Extratropical transition of tropical cyclones over the western North Pacific. Part II: The impact of midlatitude circulation characteristics. Mon. Wea. Rev, 128 , 2634–2653.

    • Search Google Scholar
    • Export Citation

  • Hart, R. E., and J. L. Evans, 2001: A climatology of the extratropical transition of Atlantic tropical cyclones. J. Climate, 14 , 546–564.

    • Search Google Scholar
    • Export Citation

  • Hastings, P. A., 1990: Southern Oscillation influences on tropical cyclone activity in the Australian/South-west Pacific region. Int. J. Climatol, 10 , 291–298.

    • Search Google Scholar
    • Export Citation

  • Hill, H. W., 1970: The precipitation in New Zealand associated with the cyclone of early April 1968. N.Z. J. Sci, 13 , 641–662.

  • Holland, G. J., 1983: Tropical cyclones in the Australian/southwest Pacific region. Dept. of Atmospheric Science, Paper 363, Colorado State University, Fort Collins, CO, 264 pp.

    • Search Google Scholar
    • Export Citation

  • Holland, G. J., and R. T. Merrill, 1984: On the dynamics of tropical cyclone structural changes. Quart. J. Roy. Meteor. Soc, 110 , 723–745.

    • Search Google Scholar
    • Export Citation

  • Jones, S. C., 1995: The evolution of vortices in vertical shear. I: Initially barotropic vortices. Quart. J. Roy. Meteor. Soc, 121 , 821–851.

    • Search Google Scholar
    • Export Citation

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

  • Kerr, I. S., 1976: Tropical storms and hurricanes in the southwest Pacific. New Zealand Meteorological Service Misc. Pub. 148, 114 pp.

  • Kistler, R., and and Coauthors, 2001: The NCEP–NCAR 50-Year Reanalysis: Monthly means CD-ROM and documentation. Bull. Amer. Meteor. Soc, 82 , 247–267.

    • Search Google Scholar
    • Export Citation

  • Klein, P. M., P. A. Harr, and R. L. Elsberry, 2000: Extratropical transition of western North Pacific tropical cyclones: An overview and conceptual model of the transformation stage. Wea. Forecasting, 15 , 373–395.

    • Search Google Scholar
    • Export Citation

  • Littlejohn, R. N., 1984: Extreme winds and forest devastation resulting from cyclone “Bernie.”. Wea. Climate, 4 , 47–52.

  • Malmquist, D., 1999: Meteorologists and insurers explore extratropical transition of tropical cyclones. Eos, Trans. Amer. Geophys. Union, 80 , 79–80.

    • Search Google Scholar
    • Export Citation

  • Muramatsu, T., 1985: A study on the changes of the three-dimensional structure and movement speed of the typhoon through its life time. Tech. Rep. 14, Meteorological Research Institute (Japan), 117 pp.

    • Search Google Scholar
    • Export Citation

  • Nichols, N., 1984: The Southern Oscillation, sea-surface temperature, and interannual fluctuations in Australian tropical cyclone activity. J. Climatol, 4 , 661–670.

    • Search Google Scholar
    • Export Citation

  • Palmén, E., 1958: Vertical circulation and release of kinetic energy during the development of Hurricane Hazel into an extratropical storm. Tellus, 10 , 1–21.

    • Search Google Scholar
    • Export Citation

  • Petterssen, S., 1936: Contribution to the theory of frontogenesis. Geofys. Publ, 11 (6,) 1–27.

  • Radford, D., R. Blong, A. M. d'Aubert, I. Kuhnel, and P. Nunn, 1996: Occurrence of tropical cyclones in the southwest Pacific region. Greenpeace Report, 35 pp. [Available from Greenpeace International, Keizersgracht 176, 1016 DW Amsterdam, Netherlands.].

    • Search Google Scholar
    • Export Citation

  • Revell, C. G., 1981: Tropical cyclones in the southwest Pacific, Nov. 1969 to April 1979. New Zealand Meteorological Service Misc. Pub. 170, 53 pp.

    • Search Google Scholar
    • Export Citation

  • Revell, C. G., 1985: Tropical Cyclone Saba. Wea. Climate, 5 , 42–51.

  • Revell, C. G., 1986: Tropical Cyclone Namu. Wea. Climate, 6 , 67–69.

  • Revell, C. G., 1987: The 1986/87 hurricane season in the South Pacific. Wea. Climate, 7 , 38–54.

  • Revell, C. G., and S. W. Goulter, 1986a: South Pacific tropical cyclones and the Southern Oscillation. Mon. Wea. Rev, 114 , 1138–1145.

  • Revell, C. G., and S. W. Goulter, 1986b: Lagged relations between the Southern Oscillation and numbers of tropical cyclones in the South Pacific region. Mon. Wea. Rev, 114 , 2669–2670.

    • Search Google Scholar
    • Export Citation

  • Reynolds, R. W., 1988: A real-time global sea surface temperature analysis. J. Climate, 1 , 75–86.

  • Ritchie, E. A., and R. L. Elsberry, 2001: Simulations of the transformation stage of the extratropical transition of tropical cyclones. Mon. Wea. Rev, 129 , 1462–1480.

    • Search Google Scholar
    • Export Citation

  • Sawyer, J. S., 1950: Formation of secondary depressions in relation to the thickness pattern. Meteor. Mag, 79 , 1–5.

  • Schultz, D. M., D. Keyser, and L. F. Bosart, 1998: The effect of large-scale flow on low-level frontal structure and evolution in midlatitude cyclones. Mon. Wea. Rev, 126 , 1767–1791.

    • Search Google Scholar
    • Export Citation

  • Shapiro, M. A., and D. Keyser, 1990: Fronts, jets streams and the tropopause. Extratropical Cyclones—The Erik Palmén Memorial Volume, C. W. Newton and E. O. Holopainen, Eds., Amer. Meteor. Soc., 167–191.

    • Search Google Scholar
    • Export Citation

  • Sinclair, M. R., 1993a: Synoptic-scale diagnosis of the extratropical transition of a southwest Pacific extratropical cyclone. Mon. Wea. Rev, 121 , 941–960.

    • Search Google Scholar
    • Export Citation

  • Sinclair, M. R., 1993b: A diagnostic study of the extratropical precipitation resulting from tropical cyclone Bola. Mon. Wea. Rev, 121 , 2690–2707.

    • Search Google Scholar
    • Export Citation

  • Sinclair, M. R., 1997: Objective identification of cyclones and their circulation intensity, and climatology. Wea. Forecasting, 12 , 591–608.

    • Search Google Scholar
    • Export Citation

  • Sinclair, M. R., and X. Cong, 1992: Polar airstream cyclogenesis in the Australasian region: A composite study using ECMWF analysis. Mon. Wea. Rev, 120 , 1950–1972.

    • Search Google Scholar
    • Export Citation

  • Sinclair, M. R., and M. Revell, 2000: Classification and composite diagnosis of extratropical cyclogenesis events in the southwest Pacific. Mon. Wea. Rev, 128 , 1089–1105.

    • Search Google Scholar
    • Export Citation

  • Thompson, C. S., S. Ready, and X. Zheng, 1992: Tropical cyclones in the southwest Pacific: November 1979 to May 1989. New Zealand Meteorological Service, 35 pp.

    • Search Google Scholar
    • Export Citation

  • Thorncroft, C., and S. C. Jones, 2000: The extratropical transitions of Hurricanes Felix and Iris in 1995. Mon. Wea. Rev, 128 , 947–972.

    • Search Google Scholar
    • Export Citation

  • Tomlinson, A. I., 1975: Cyclone Alison. New Zealand Meteorological Service Tech. Information Circular 148, 26 pp.

  • Trenberth, K. E., 1977: A diagnostic investigation of the behaviour of tropical cyclone Norman. New Zealand Meteorological Service Tech. Note 231, 26 pp.

    • Search Google Scholar
    • Export Citation

  • Uccellini, L. W., and P. C. Kocin, 1987: The interaction of jet streak circulations during heavy snow events along the east coast of the United States. Wea. Forecasting, 2 , 289–308.

    • Search Google Scholar
    • Export Citation
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