Fifteen years of satellite observations of sea surface temperature (SST) are used to identify frontal activities in the eastern Pacific Ocean. The frontogenesis and variability of frontal activities are mainly determined by wind forces. Strong frontal activities are distributed mainly near the coast and decrease with increasing offshore distance. The seasonal cycle dominates the variability in the SST frontal probability (FP) in coastal regions, and large interannual variability is identified in the tropics. Coastal frontal activities are driven by the local wind such that the equatorward wind stress forces coastal upwelling, which brings subsurface cold water to the surface and induces fronts. Frontal activities are generally enhanced during local summer, when an upwelling‐favorable wind prevails. A prominent offshore migration pattern is identified for mid‐latitude regions, and the associated propagation speed is consistent with the wind‐induced offshore Ekman transport and mesoscale eddies. The coastal tropical Pacific is also characterized by a strong FP with large seasonal variability. The corresponding fronts result from the confluence between the boundary current and wind‐driven cold water as the wind jet passes through mountain gaps. The frontal activities near the equator are driven by wind‐induced tropical upwelling associated with a westward propagation at speeds close to the speed of Rossby waves. In the tropics, strong interannual variability in FP is identified that is, modulated by the El Niño‐Southern Oscillation. Frontal activities are suppressed during El Niño years because trade winds are characterized by strong convergence, which induces downwelling and subsequently reduces FP.

中文翻译：

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东太平洋海表温度锋面的季节和年际变化

使用卫星对海面温度（SST）进行的15年观测来确定东太平洋的额叶活动。额叶活动的锋生和变异主要由风力决定。强烈的锋线活动主要分布在海岸附近，并随着离岸距离的增加而减少。季节性周期主导着沿海地区SST锋面概率（FP）的变化，而热带地区的年际变化也很大。沿海的锋面活动是由局部风驱动的，因此赤道风向迫使沿海上升流，这将地下冷水带到地表并诱发锋面。在当地夏季，当上升气流有利的风盛行时，额叶活动通常会增强。在中纬度地区确定了一个突出的近海迁移模式，并且相关的传播速度与风致近海埃克曼运输和中尺度涡旋一致。沿海热带太平洋的特征还在于其强FP具有季节性大变化性。相应的前沿是当风流穿过山间的间隙时，边界流和风驱动的冷水之间的汇合产生的。赤道附近的额叶活动是由风诱发的热带上升运动推动的，该上升运动以接近罗斯比波的速度向西传播。在热带地区，FP的年际变化很大，这是由厄尔尼诺-南方涛动调节的。