Abstract
This study reveals the barotropic dynamics associated with the formation and growth of tropical cyclone Nargis in 2008, during its formation stage. Strong equatorial westerlies occurred over the southern Bay of Bengal in association with the arrival of an intraseasonal westerly event during the period 22–24 April 2008. The westerlies, together with strong tropical-subtropical easterlies, constituted a large-scale horizontal shear flow, creating cyclonic vorticity and thereby promoting the incipient disturbance that eventually evolved into Nargis. This basic zonal flow in the lower troposphere was barotropically unstable, with the amplified disturbance gaining more kinetic energy from the easterly jet than from the westerly jet during 25–26 April. This finding suggests that more attention should be paid to the unstable easterly jet when monitoring and predicting the development of tropical cyclones. Energetics analyses reveal that barotropic energy conversion by the meridional gradient of the basic zonal flow was indeed an important energy source for the growth of Nargis.
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Chen, G., and R. Huang, 2008: Influence of monsoon over the warm pool on interannual variation on tropical cyclone activity over the western North Pacific. Adv. Atmos. Sci., 25, 319–328, doi: 10.1007/s00376-008-0319-7.
Eliassen, A., 1983: The Charney-Stern theorem on barotropic-baroclinic instability. Pure Appl. Geophys., 121, 261–285.
Ferreira, R. N., and W. H. Schubert, 1996: Dynamical aspects of twin tropical cyclones associated with the Madden-Julian oscillation. J. Atmos. Sci., 53, 929–945.
Ferreira, R. N., and W. H. Schubert, 1997: Barotropic aspects of ITCZ breakdown. J. Atmos. Sci., 54, 261–285.
George, L., and S. K. Mishra, 1993: An observational study on the energetics of the onset monsoon vortex, 1979. Quart. J. Roy. Meteor. Soc., 119, 755–778.
Gill, A. E., 1980: Some simple solutions for heat-induced tropical circulation. Quart. J. Roy. Meteor. Soc., 106, 447–462.
Gray, W. M., 1968: Global view of the origin of tropical disturbances and storms. Mon. Wea. Rev., 96, 669–700.
Gray, W. M., 1975: Tropical cyclone genesis. Department of Atmospheric Science Paper No. 234, Colorado State University, Fort Collins, CO, 121pp.
Guinn, T. A., and W. H. Schubert, 1993: Hurricane spiral bands. J. Atmos. Sci., 50, 3380–3403.
Harr, P. A., and R. L. Elsberry, 1995: Large-scale circulation variability over the tropical western North Pacific Part I: Spatial patterns and tropical cyclone characteristics. Mon. Wea. Rev., 123, 1225–1246.
Holland, G. J., 1993: The Global Guide to Tropical Cyclone Forecasting. WMO/TD-560, World Meteorological Organization, Geneva, 342pp.
Kikuchi, K., B. Wang, and H. Fudeyasu, 2009: Genesis of tropical cyclone Nargis revealed by multiple satellite observations. Geophys. Res. Lett., 36, L06811, doi: 10.1029/2009GL037296.
Krishnamurti, T. N., P. Ardanuy, and Y. Ramanathan, R. Pasch, 1981: On the onset vortex of the summer monsoons. Mon. Wea. Rev., 109, 344–363.
Kuo, H. L., 1949: Dynamical instability of two-dimensional non-divergent flow in a barotropic atmosphere. J. Meteor., 6, 105–122.
Liebmann, B., H. H. Hendon, and J. D. Glick, 1994: The relationship between tropical cyclones of the western Pacific and Indian Oceans and the Madden-Julian oscillation. J. Meteor. Soc. Japan, 72, 401–411.
Lindzen, R. S., and S. Nigam, 1987: On the role of the sea surface temperature gradients in forcing low level winds and convergence in the tropics. J. Atmos. Sci., 44, 2418–2436.
Lorenz, E. N., 1955: Available potential energy and the maintenance of the general circulation. Tellus, 7, 157–167.
Madden, R. A., and P. R. Julian, 1994: Observations of the 40–50 day tropical oscillation—A review. Mon. Wea. Rev., 122, 814–837.
Maloney, E. D., and D. L. Hartmann, 2001: The Madden-Julian oscillation, barotropic dynamics, and North Pacific tropical cyclone formation, Part I: Observations. J. Atmos. Sci., 58, 2545–2558.
Mao, J., and G. Wu, 2010: Intraseasonal modulation of tropical cyclogenesis in the western North Pacific: A case study. Theor. Appl. Climatol., 100, 397–411.
McPhaden, M. J., and Coauthors, 2009: Oceanatmosphere interactions during cyclone Nargis. EOS, Transactions, American Geophysical Union, 90, 53–60.
Mishra, S. K., M. D. Patwardhan, and L. George, 1985: A primitive equation barotropic instability study of the monsoon onset vortex, 1979. Quart. J. Roy. Meteor. Soc., 111, 427–444.
Nitta, T., and K. Masuda, 1981: Observational study of a monsoon depression developed over the Bay of Bengal during summer MONEX. J. Meteor. Soc. Japan, 59, 672–682.
Nitta, T., and M. Yanai, 1969: A note on the barotropic instability of the tropical easterly current. J. Meteor. Soc. Japan., 47, 127–130.
Norquist, D. C., E. E. Recker, and R. J. Reed, 1977: The energetics of African wave disturbances as observed during phase III of GATE. Mon. Wea. Rev., 105, 334–343.
Ross, R. S., 1991: Energetics of African wave disturbances derived from the FSU global spectral model. Meteor. Atmos. Phys., 45, 139–158.
Ross, R. S., and T. N. Krishnamurti, 2008: barotropic energy conversion as a predictor of development for NAMMA African easterly waves. Proc. 28th Conf. on Hurricanes and Tropical Meteorology, Orlando, FL, Amer. Meteor. Soc., 7–10.
Shenoi, S. S. C., D. Shankar, and S. R. Shetye, 1999: On the sea surface temperature high in the Lakshad-weep Sea before the onset of the southwest monsoon. J. Geophys. Res., 104, 15703–15712.
Subrahmanyam, D., M. K. Tandon, L. George, and S. K. Mishra, 1981: Role of barotropic mechanism in the development of a monsoon depression: A MONEX study. Pure Appl. Geophys., 119, 901–912.
Tomas, R., R. Holton, and P. J. Webster, 1999: The influence of cross-equatorial pressure gradients on the location of near-equator convection. Quar. J. Roy. Meteor. Soc., 125, 1107–127.
Wheeler, M. C., and H. H. Hendon, 2004: An all-season real-time multivariate MJO index: Development of an index for monitoring and prediction, Mon. Wea. Rev., 132, 1917–1932.
Zehr, R. M., 1992: Tropical cyclogenesis in the western North Pacific. NOAA Tech. Rep. NESDIS 61, Department of Commerce, Washington DC.
Zhou, W., and J. C. L. Chan, 2005: Intraseasonal oscillations and the South China Sea summer monsoon onset. Int. J. C1imatol., 25, 1585–1609.
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Mao, J., Wu, G. Barotropic process contributing to the formation and growth of tropical cyclone Nargis. Adv. Atmos. Sci. 28, 483–491 (2011). https://doi.org/10.1007/s00376-010-9190-4
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DOI: https://doi.org/10.1007/s00376-010-9190-4