ABSTRACT Observational analyses show that the equatorial trough in the western North Pacific (WNP) is a well-known origin for tropical cyclones (TC) which have tended to weaken in intensity and decrease in number during the last several decades under global warming. A scientific problem then arises as to why higher sea surface temperatures (SSTs), one of the necessary conditions for typhoon genesis, can cause a weakened equatorial trough and a decreased TC number. In this paper, the WNP is taken as an example to illustrate a possible mechanism for the above-mentioned seemingly counterintuitive phenomena and explain the causality between the unusually heterogeneous pattern of SSTs in a warming environment and TC number in the WNP. This mechanism is based substantially on the second law of thermodynamics.
Cite this paper
nullX. Zhou, C. Liu, Y. Liu, H. Xu and X. Wang, "Changes in Tropical Cyclone Number in the Western North Pacific in a Warming Environment as Implied by Classical Thermodynamics," International Journal of Geosciences, Vol. 2 No. 1, 2011, pp. 29-35. doi: 10.4236/ijg.2011.21003.
 D. R. Easterling, J. L. Evana, P. Y. Grosman, T. R. Karl, K. E. Kunkel and P. Ambenje, “Observed Variability and Trends in Extreme Climate Events: A Brief Review,” Bulletin of the American Meteorological Society, Vol. 81, No. 3, 2000, pp. 417-425.
 T. R. Karl, G. Kukla, V. N. Razuvayev, M. J. Changery, R. G. Quayle, R. T. Heim Jr, D. R. Easterling and C. B. Fu, “Global Warming: Evidence for Asymmetric Diurnal Temperature Change,” Geophysical Research Letters, Vol. 18, No. 12, 1991, pp. 2253-2256.
 M. Manton and J. Eral, “Trends in Extreme Daily Rainfall and Temperature in Southeast Asia and the South Pacific: 1961-1998,” International Journal of Climatology, Vol. 21, No. 3, 2001, pp. 269-284.
 S. W. Wang and D. Y. Gong, “Enhancement of the Warming Trend in China,” Geophysical Research Letters, Vol. 27, No. 16, 2000, pp. 2581-2584.
 R. S. Cerveny, J. Lawrimore, R. Edwards and C. Landsea, “Extreme Weather Records,” Bulletin of the American Meteorological Society, Vol. 88, No. 6, 2007, pp. 853-860.
 C. Wang, S. K. Li and D. B. Enfield, “Atlantic Warm Pool Acting as a Link between Atlantic Multidecadal Oscillation and Atlantic Tropical Cyclone Activity,” Geochemistry, Geophysics, Geosystems, Vol. 9, 2008, pp. 1-17.
 H. von Storch, “An Attempt to Homogeneously Describe 60 Years Statistics of TC Activity in East Asia: 1948- 2007,” Presented in 2008 Taiwan Climate Workshop, 18 November 2008, Taipei, Taiwan, China.
 J. L. McBride and H. Ramsay, “Relationship between Tropical Cyclone Activity and Sea Surface Temperature in the Southern Hemisphere,” Presented in 2nd International Summit on Hurricanes and Climate Change, May 31–June 5, 2009, Corfu, Greece (in “Aegean Conferences Series-Vol. 41”; p. 23).
 J. B. Elsner and J. T. Hagger, “Hurricanes and Climate Change,” Springer, 2009.
 L. Ma and L. Chen, “The Relationship between Global Warming and the Variation in Tropical Cyclone Fre- quency over the Western North Pacific,” Journal of Tropicalmeteorology, Vol. 15, No. 1, 2009, pp. 38-44.
 W. M. Gray, “Global View of the Origin of Tropical Disturbances and Storms,” Monthly Weather Review, Vol. 96, No. 4, 1967, pp. 669-700.
 J. R. Bates, “Dynamics of Disturbances on the Intertropical Convergence Zone,” Quarterly Journal of the Royal Meteorological Society, Vol. 96, No. 410, 1970, pp. 677- 701. doi:10.1002/qj.49709641010
 J. G. Charney, “Tropical Cyclonegenesis and the Formation of the Intertropical Convergence Zone, in Mathematical Problems of Geophysical Fluid Dynamics,” In: W. H. Reid, Eds., Lectures in Applied Mathematics, Ameri- can Mathematical Society, New York, Vol. 13, 1971, pp. 335-368.
 L. M. Briegel and W. M. Frank, “Large-Scale Influences on Tropical Cyclogenesis in the Western North Pacific,” Monthly Weather Review, Vol. 125, No. 2, 1997, pp. 1397-1413.
 E. A. Ritchie and G. J. Holland, “Large-Scale Patterns A- ssociated with Tropical Cyclogenesis in the Western Pa- cific,” Monthly Weather Review, Vol. 127, No. 9, 1999, pp. 2027-2043.
 S. C. Cha and J. L. Evans, “Comparison of the Structure of the ITCZ in the West Pacific during the Boreal Sum- mers of 1989–93 Using AMIP Simulations and ECMWF Reanalysis,” Journal of Climate, Vol. 15, No. 24, 2002, pp. 3459-3568.
 E. Kalnay, et al., “The NCEP/NCAR 40-Year Reanalysis Project,” Bulletin of the American Meteorological Society, Vol. 77, No.3, 1996, pp. 437-471.
 J. Bjerknes, “Atmospheric Teleconnections from the Equatorial Pacific,” Monthly Weather Review, Vol. 97, No. 2, 1969, pp. 163-172.
 J. R. Holton, J. M. Wallace and J. A. Young, “On Boundary Layer Dynamics and the ITCZ,” Journal of the Atmospheric Sciences, Vol. 28, No. 2, 1971, pp. 275-280.
 C. -R. Ho, X. -H. Yan and Q. Zheng, “Satellite Observations of Upper-Layer Variabilities in the Western Pacific Warm Pool,” Bulletin of the American Meteorological Society, Vol. 76, No. 5, 1995, pp. 669-679.
 N. E. Graham and T. P. Barnett, “Sea Surface Tempera- ture, Surface Wind Divergence and Convection over Tropical Oceans,” Science, Vol. 238, No. 4827, 1987, pp. 657-659. doi:10.1126/science.238.4827.657
 K. -M. Lau, H. -T. Wu and S. Bony, “The Role of Large-Scale Atmospheric Circulation in the Relationship between Tropical Convection and Sea Surface Tempera- ture,” Journal of Climate, Vol. 10, No. 3, 1997, pp. 381- 392. doi:10.1175/1520-0442(1997)010<0381:TROLSA>2.0.CO;2
 R. S. Lindzen and S. Nigam, “On the Role of Sea Surface Temperature Gradients in Forcing Low Level Winds and Convergence in the Tropics,” Journal of the Atmospheric Sciences, Vol. 44, 1987, pp. 2440-2458.
 I. Prigogine, “Introduction to Thermodynamics of Irreversible Processes,” Charles C. Thomas, 1955.
 S. R. de Groot and P. Mazur, “Non-Equilibrium Thermodynamics,” North-Holland Publishing Company, 1962.
 C. Liu and Y. Liu, “An Attempt at Improving a Global Spectral Model by Incorporating the Second Law of Thermodynamics,” Geophysical Research Letters, Vol. 32, 2005, L03806.
 C. Liu, Y. Liu and H. Xu, “A Physics-Based Diffusion Scheme for Numerical Models,” Geophysical Research Letters, Vol. 33, 2006, L12805.
 Y. Liu and C. Liu, “Entropy Flow and the Evolution of a Storm,” Entropy, Vol. 10, No. 4, 2008, pp. 430-440.
 H. Xu and C. Liu, “Entropy Flow Properties of a Typhoon as Simulated by a Meso-Scale Model,” Europhys- ics Letters, Vol. 83, No. 1, 2008.
 M. Sugi, A. Noda and N. Sato, “Influence of Global Warming on Tropical Cyclone Climatology: An Experi- ment with the JMA Global Model,” Journal of the Meteorological Society of Japan, Vol. 80, No. 5, 2002, pp. 249-272. doi:10.2151/jmsj.80.249
 R. E. McDonald, D. G.Bleaken, D. R. Cresswell, V. D. Pope and C. A. Senior, “Tropical Storms: Representation and Diagnosis in Climate Models and the Impacts of Climate Change,” Climate Dynamics, 2005.
 F. J. Chauvin, F. Royer and M. De?que, “Response of Hurricane-Type Vortices to Global Warming as Simulated by ARPEGE-Climate at High Resolution,” Climate Dynamic, Vol. 27, No. 4, 2006, pp. 377-399.