A primary study of the correlation between the net air-sea heat flux and the interannual variation of western North Paci
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A primary study of the correlation between the net air-sea heat flux and the interannual variation of western North Pacific tropical cyclone track and intensity WU Liang1,2 , WEN Zhiping1∗ , HUANG Ronghui2 1
Center for Monsoon and Environment Research/Department of Atmospheric Sciences, Sun Yat-sen University, Guangzhou 510275, China
2
Center for Monsoon System Research, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
Received 2 June 2009; accepted 14 May 2010 ©The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg 2011
Abstract A singular value decomposition (SVD) analysis is carried out to reveal the relationship between the interannual variation of track and intensity of the western North Pacific tropical cyclones (WNPTCs) in the tropical cyclone (TC) active season (July–November) and the global net airsea heat flux (Qnet ) in the preceding season (April–June). For this purpose, a tropical cyclone track and intensity function (TIF) is defined by a combination of accumulated cyclone energy (ACE) index and a cyclone track density function. The SVD analysis reveals that the first mode is responsible for the positive correlation between the upward heat flux in the tropical central Pacific and the increased activity of western North Pacific (WNP) TIF, the second mode for the positive correlation between the upward heat flux in the North Indian Ocean and the northeastward track shift of WNPTCs and the third mode for the negative correlation between the upward heat flux in mid-latitude central Pacific and the northwest displacement of the WNP TC-active center. This suggests that Qnet anomalies in some key regions have a substantial remote impact on the WNP TC activity. Key words: tropical cyclone, western North Pacific, the net air-sea heat flux (Qnet ), interannual variation
be that in the statistical study the simultaneous correlation between the TC activity and the underlying SSTA in the TC season also includes the decrease of the SSTA in response to the negative feedback of typhoons (Price, 1981), whereas those numerical models do not include the upper ocean response to typhoons. The other reason can be that the energy supply from the sea to WNPTCs depends not only on the SST but also on other factors such as the differences between the SST and the air temperature right above the sea, as well as the corresponding surface wind velocity and moisture. In other words, The WNPTCs gain energy from the oceans in terms of heat fluxes rather than the SST alone. The previous studies (e.g., Tuleya, 1994) have pointed out that the energy supplied through surface fluxes is necessary for tropical cyclone development and maintenance. Several modeling and
1 Introduction One of the six large-scale environment parameters responsible for the tropical cyclone (TC) genesis and development is the warm sea surface temperature (SST) (Gray, 1979). With higher underlying SST, TCs would be more active as shown in some climate models (Krisbnamurti et al., 1998; Broccoli and Manabe, 1990). Howeve
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