驗證影響熱帶氣旋(TC)強度產生變化的條件仍是大氣學門目前所面臨的巨大挑戰。前人的研究發現，當氣旋通過海洋暖渦 (warm eddy)時強度將會增強；而通過冷渦時則強度會減弱[Lin et al. 2005 & 2011]。在這為期三年的研究計畫中，第一年期的研究將著重於暖渦的實驗。我們已知海洋的暖渦因包含較厚的暖水而擁有較大的熱含量，即使在氣旋強風的作用之下也能有效的提升氣旋的最大潛在強度(MPI)。然而，海洋暖渦除了有較厚的上層暖海水之外，暖渦也會改變氣旋的結構，例如：垂直風切、水氣通量輻合、海表面熱通量分佈、導引氣流、氣旋內部的不對稱性…等，所有這些因素都會影響氣旋強度。但是，這些過程以及對氣旋強度變化的影響在前人的研究中並沒有被提及。基於上述的理由，我們將使用耦合大氣模式WRF與海洋模式mpiPOM [Oey et al. 2013]的耦合颱風與海洋預報模式(CTOP)，設計一個理想化的數值模式實驗，來研究與探討當氣旋通過暖渦時其強度增強的動力和熱力過程。我們建議在不同氣旋的強度和移動速度以及不同大小的暖渦下，有系統地透過數值實驗來檢驗和量化上述每個過程對氣旋強度的影響。本研究結果將會幫助我們更加瞭解TC強度的增強與變化過程，進而有助於改善颱風強度的預報結果。
Identifying the conditions under which a tropical cyclone (TC) undergoes intensity change remains to-date a tremendous challenge in atmospheric science. Previous studies have shown that a tropical cyclone passing over a warm ocean eddy can intensify (and conversely the storm may weaken when it passes over a cold eddy) [Lin et al. 2005 & 2011]. This 1th-year of 3-years proposal focuses on the warm case. The hypothesis is that the warm eddy with deep upper warm layer has large ocean heat content, which effectively increases the maximum potential intensity (MPI) even in the presence of strong mixing by the intense wind. On the other hand, in addition to warm upper-ocean layer, the warm eddy also can alter the structure of the tropical cyclone, such as the wind shear, pattern of moisture flux convergence, distribution of surface fluxes, steering flow, and the asymmetric flow component, all of which can affect the storm intensity. These processes and their effects on tropical cyclone intensity have not been previously addressed in the literature. We propose a set of idealized model experiments using the CTOP (Coupled Typhoon Ocean Prediction) model, which couples WRF [Chen and Dudhia 2000; Klemp et al. 2000; Michalakes et al. 2001] with mpiPOM [Oey et al. 2013], to study the dynamics and thermodynamics of intensification. We propose to systematically examine and quantify the effects of each of the above-mentioned processes on TC-intensification, under different TC translation speeds and with different sizes of the ocean eddy. The proposed study will significantly deepen our understanding of TC intensification process, which can help lead to improved prediction.
