Data from the National Oceanic and Atmospheric Administration (NOAA) Optimum Interpolation (1/4)° Daily Sea Surface Temperature Analysis, the National Oceanographic Data Center (NODC) Upper Ocean heat con-tent, and the Joint Typhoon Warning Center (JTWC) best-track tropical cyclone (TC) for the period 1982 to 2014 was utilized in order to analyze the spatial and temporal characteristics of the Northwest Pacific (0°-30°N, 105°-155°E) tropical cyclone activities. Our research on the relation between the tropical cyclone and the thermal structure of the Upper Ocean which indicates the following: The interannual variation in the frequency of tropical cyclone is evident. The low-frequency years were from 1982 to 1992 and 2003 to 2014, whereas the high-frequency years were from 1993 to 2002. For the period from 1982 to 2014, the frequency characteristics of cyclones were slow increase, rapid increase, decrease in that order. The number of tropical cyclones has shown a clear downward trend in the last 15 years (2000-2014). Tropical cyclone originates from three distinct birthplaces: birthplace 1 (10°-22°N, 110°-120°E), birthplace 2 (8°-20°N, 125°-145°E), and birthplace 3 (5°-20°N, 145°-155°E). The fre-quency of TC in birthplace 1 and birthplace 2 increases slowly, whereas the frequency of TC in birthplace 3 de-creases significantly. The influence of changes in the thermal state of the upper ocean to the TC is multifaceted TC frequency response to the upper heat content more obvious. The sea surface temperature is not the key factor af-fecting the frequency of the TC.With the warming of the Upper Ocean, the duration of the TC shows a decreasing trend, whereas the TC intensity shows an increasing trend. Global warming will intensify the potential threat posed by TC activities to the Pacific Northwest countries.%使用1982—2014年美国国家海洋和大气管理局(National Oceanic and Atmospheric Administration,NOAA)最优插值(1/4)°逐日海温分析资料、美国国家海洋数据中心(National Oceanographic Data Center,NODC)提供的海洋上层700 m热含量数据和美国联合台风警报中心(Joint Typhoon Warning Center,JTWC)的热带气旋(tropical cyclone,TC)最佳路径资料,分析西北太平洋地区(0°～30°N,105°～155°E)TC活动的时空分布特征,探讨TC与海洋上层热状态之间的关系.结果表明:TC频数具有显著的年代际变化特征:1982—1992年和2003—2014年皆为低频期,而1993—2002年则为高频期,33年来TC发生频数表现为缓慢增加—快速增加—减少的特征.最近15年(2000—2014年),TC数量呈现明显下降的趋势.在西北太平洋,TC有3个明显的源地,分别为源地1(10°～22°N、110°～120°E);源地2(8°～20°N、125°～145°E);和源地3(5°～20°N、145°～155°E).源地1、源地2的频数呈上升趋势,而源地3呈下降趋势.海洋上层热状态的变化给TC带来的影响是多方面的,TC频数对上层热含量(heat content)的响应较明显,而海表面温度(sea surface temperature,SST)不是影响TC数量变化的主要因素.伴随着海洋上层的增暖,TC的年持续时间有减少趋势,TC强度正在增强.在全球变暖背景下,TC活动给西北太平洋沿岸国家带来的潜在威胁极有可能加剧.
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