Intensity Evolutions of the Western North Pacific Super Typhoons in 2016 Using the Deviation Angle Variance Technique with FY Data (#1065)
The genesis and development of tropical cyclones (TCs) have an adverse impact on maritime activities. Therefore, it is imperative to strengthen research on the evolution of TC intensity and structure in the whole lifecycle to improve the prediction ability of TCs. This paper analyzes the complete lifecycle of super typhoons in 2016 in the WNP using the deviation angle variance technique (DAV-T), which is based on the infrared images from Fengyun (FY) satellites. This objective technique not only quantifies the axisymmetry of TCs, and also helps improve the capability of TC intensity estimation. Case analysis of the super typhoons are performed to explore the distribution characteristics of the DAV values at different TC stages. The results show that the minimum DAV values (or map minimum values: MMVs) gradually decrease and their locations constantly approach the circulation center with an enhancement of TC organization; when the ring or disk structure is formed, significant changes in MMV locations are no longer observed. However, when large-scale non-closed deep convective cloud clusters exist at the early stage or in the dissipation stage of the TC, the axisymmetry of the TC is poor and the MMV locations tend to lie in the strongest convective region rather than in the TC circulation center. Combined with the Best Track Dataset for statistical analysis of all research samples, the data reveal that the correlation coefficient between the MMVs and the maximum surface wind speeds is -0.80; the relative distance root-mean square (RMS) error between the MMV locations and the TC centers is 140.3 km. Especially, when the samples below tropical depression intensity are removed, the RMS error of the relative distance decreases dramatically to 95.0 km. The value and location of the MMVs are important indicators for estimation of TC intensity and center.