NOAA National Centers for Environmental Information, Center for Weather and Climate, 1225 W. Dayton Street, Madison, Wisconsin 53706, USA.
Nature. 2017 Jan 19;541(7637):390-393. doi: 10.1038/nature20783. Epub 2017 Jan 4.
The North Atlantic ocean/atmosphere environment exhibits pronounced interdecadal variability that is known to strongly modulate Atlantic hurricane activity. Variability in sea surface temperature (SST) is correlated with hurricane variability through its relationship with the genesis and thermodynamic potential intensity of hurricanes. Another key factor that governs the genesis and intensity of hurricanes is ambient environmental vertical wind shear (VWS). Warmer SSTs generally correlate with more frequent genesis and greater potential intensity, while VWS inhibits genesis and prevents any hurricanes that do form from reaching their potential intensity. When averaged over the main hurricane-development region in the Atlantic, SST and VWS co-vary inversely, so that the two factors act in concert to either enhance or inhibit basin-wide hurricane activity. Here I show, however, that conditions conducive to greater basin-wide Atlantic hurricane activity occur together with conditions for more probable weakening of hurricanes near the United States coast. Thus, the VWS and SST form a protective barrier along the United States coast during periods of heightened basin-wide hurricane activity. Conversely, during the most-recent period of basin-wide quiescence, hurricanes (and particularly major hurricanes) near the United States coast, although substantially less frequent, exhibited much greater variability in their rate of intensification, and were much more likely to intensify rapidly. Such heightened variability poses greater challenges to operational forecasting and, consequently, greater coastal risk during hurricane events.
北大西洋的海洋/大气环境表现出明显的年代际可变性，这种可变性被认为强烈调节着北大西洋飓风的活动。海表温度（SST）的变化通过与飓风的生成和热力学潜力强度的关系与飓风的变化相关联。另一个控制飓风生成和强度的关键因素是环境垂直风切变（VWS）。较暖的 SST 通常与更频繁的生成和更大的潜在强度相关，而 VWS 则抑制生成，并防止任何形成的飓风达到其潜在强度。当在大西洋主要飓风发展区域进行平均时，SST 和 VWS 呈反向变化，因此这两个因素协同作用，增强或抑制整个盆地的飓风活动。然而，我在这里表明，有利于更大范围大西洋飓风活动的条件与美国海岸附近飓风更可能减弱的条件同时出现。因此，在整个盆地飓风活动增强期间，VWS 和 SST 在沿着美国海岸形成一个保护屏障。相反，在最近的整个盆地相对平静的时期，美国海岸附近的飓风（特别是重大飓风）尽管频率显著降低，但在其强度增强的速度方面表现出更大的可变性，并且更有可能迅速增强。这种增强的可变性给业务预报带来了更大的挑战，因此在飓风事件期间增加了沿海地区的风险。
