The North Atlantic phytoplankton bloom depends on a confluence of environmental factors that drive transient periods of exponential phytoplankton growth and interannual variability in bloom magnitude. I analyze interannual bloom variability in the North Atlantic via extreme value theory where the generalized extreme value distribution (GEVD) is fitted spatially to annual maxima of satellite-measured surface chlorophyll. I find excellent agreement between the observed distribution of interannual bloom maxima and those predicted from the GEVD. The spatial distribution of fitted GEVD parameters closely follows basin bathymetry where the largest extremes and heaviest distribution tails are found on the continental shelves and slopes. Trend analyses suggest weak evidence for changes in GEVD parameters, despite regional trends in mean chlorophyll levels and sea surface temperature. These results provide a framework to quantify interannual bloom variability and call for further work examining how extreme blooms propagate through food webs and contribute to carbon export.

中文翻译：

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极值分布描述季节性北大西洋浮游植物水华的年际变化

北大西洋浮游植物水华取决于环境因素的汇合，这些环境因素推动了浮游植物指数生长的短暂时期和水华程度的年际变化。我通过极值理论分析了北大西洋的年际水华变化，其中广义极值分布 (GEVD) 在空间上与卫星测量的地表叶绿素的年度最大值拟合。我发现观测到的年际水华最大值分布与 GEVD 预测的分布非常一致。拟合的 GEVD 参数的空间分布与盆地测深密切相关，在大陆架和斜坡上发现了最大的极值和最重的分布尾部。趋势分析表明 GEVD 参数变化的证据不足，尽管平均叶绿素水平和海面温度存在区域趋势。这些结果为量化年际水华变化提供了一个框架，并呼吁进一步研究极端水华如何通过食物网传播并有助于碳输出。