摘要:利用1979~2015年JTWC（Joint Typhoon Warning Center）最佳路径资料（2001~2015年资料用于台风风圈结构分析）及ERA-interim（0.5°×0.5°）再分析数据，统计分析我国海南岛附近区域（15.5°N~23.5°N，106°E~116°E）热带气旋（Tropical Cyclone，简称TC）低层风场的变化特征。结果表明：（1）年均5.5个TC于4~12月主要以西偏北路径进入该区域，其中海南岛东南侧海域TC出现频率最高且强TC比例最多，而岛西北区域出现频率最低，强TC比例最少。（2）TC中心位于海南岛不同方位时，其外围低层风场分布具有不同的非对称特征，且大风出现比率也各有差异；TC中心位于海南岛上时出现大风比率最高，位于岛南侧时次之，位于岛北侧时最小。（3）该区域TC平均最大风速半径（RMW）为58.3 km；TC位于岛上时RMW最大，而位于岛西南侧最小。（4）TC近中心最大风速由海上向陆地急剧减小，其高值中心主要位于雷州半岛东侧及西侧海域。（5）研究区域内TC的34节风圈半径在TC环流的东侧大而西侧小，强TC大而弱TC小。（6）不同区域TC变形程度有所差异。平均而言，位于岛西南侧TC变形最大而位于岛东南侧时变形最小。
关键词:热带气旋/
低层风场/
风圈半径/
海南岛
Abstract:Using the tropical cyclone best track dataset from the Joint Typhoon Warning Center (JTWC) and the ERA-Interim reanalysis data on global 0.5°×0.5° grids from 1979 to 2015, characteristics of low-level winds around tropical cyclones (TC) over Hainan (15.5°N-23.5°N, 106°E-116°E) are statistically analyzed. Results are as follows. (1) On average, annually there are 5.5 TCs entering the study region during April to December. Most of the TCs occur over the ocean to the southeast of Hainan and their intensities are stronger than those occurred to the northwest of Hainan. (2) When the TC centers are located at different quadrants of the island, the low-level wind fields in the TC periphery have different asymmetric features and high wind occurrence frequencies. The strong wind occurrence frequency is the highest when TC centers are located at the island, followed by that when the TC centers are located to the south of the island, and the occurrence frequency is the lowest when the TC centers are located to the north of the island. (3) Radiuses of the maximum wind (RMW) for TCs around Hainan are within the range of 9-185 km and the averaged value is 58.3 km. On the average, the RMWs of TCs located at the island (to the southwest of the island) are the biggest (smallest). (4) The maximum wind speeds near the TC centers sharply decrease from the ocean to the land for all TCs. And high wind speed regions are located at oceanic areas to the west and east of Leizhou Peninsula. (5) The 34-kts wind radiuses on the eastern side of the TCs are larger than that on the western side. And the stronger the TC is, the larger and more symmetry its specific wind radius will be. (6) Different regions have different degrees of wind circle deformation. On average, when the TC is located to the southwest (southeast) of the island, its wind circle experiences the largest (least) deformation.
Key words:Tropical cyclone/
Low-level wind field/
Radius of specific wind circle/
Hainan
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