The year‐to‐year seasonal variability of the vertical distribution of concentration of chlorophyll‐a (Chla) in the Black Sea, its relation to light (photosynthetically available irradiance [PAR]), and mixing conditions were studied based on the 6‐year (2014–2019) measurements of Bio‐Argo floats. Variations in PAR caused by changes in incoming solar radiation and light attenuation determine the position of the deep chlorophyll maximum (DCM). During all seasons, the DCM was located between isolume of daily integrated PAR of 0.080 and 10.0 mole photons m⁻² d⁻¹. Analysis of Bio‐Argo data allowed to distinguish seven different stages of Chla seasonal variability. In February, the minimum of Chla in the entire water column was often observed in areas with a deep mixed layer (Stage 1), followed by the March early spring peak, occupying both the mixed layer and the seasonal thermocline (Stage 2). In April–May, Chla decreased throughout the 0–40 m layer, which was accompanied by the maximum in light penetration and an increase in Chla in the deepest layers (Stage 3). In summer, two deep peaks of Chla were distinguished: the first, a thin and shallow peak in June, and the second, a large and deeper peak in August (Stage 4 and 5). The August peak was followed by the deepest seasonal minimum of Chla in September–October, coincided with the autumn rise of the zooplankton biomass (Stage 6). Autumn–winter convection in November–January led to the third seasonal peak of Chla (Stage 7). The study discusses the role of various abiotic and biotic factors in the formation of each of these stages.

中文翻译：

---

叶绿素a垂直分布的季节阶段及其与黑藻光照条件的关系（根据生物程序测量）

在6年的基础上，研究了黑海中叶绿素a（Chla）浓度的垂直分布，与光的关系（光合有效辐照度[PAR]）和混合条件的逐年季节性变化。 （2014-2019）Bio-Argo浮标的测量。由入射太阳辐射的变化和光衰减引起的PAR的变化决定了深层叶绿素最大值（DCM）的位置。在所有季节中，DCM都位于每日积分PAR为0.080的等量线与10.0摩尔光子m ^-2  d ^-1之间。通过对Bio-Argo数据的分析，可以区分出Chla季节变化的七个不同阶段。在2月，经常在混合层较深的地区（阶段1）观察到整个水柱中的Chla最小值，随后是3月初春高峰，同时占据混合层和季节性温跃层（阶段2）。在4月至5月，整个0-40 m层的Chla下降，同时伴随着最大的透光率和最深层的Chla增大（阶段3）。夏季，Chla有两个深峰：第一个是6月的浅而浅的峰，第二个是8月的较大而较深的​​峰（第四和第五阶段）。8月达到峰值，随后是9月至10月最深的Chla季节性最低值，正好是浮游动物生物量的秋季上升（第6阶段）。11月至1月的秋冬季对流导致Chla的第三个季节高峰（第7阶段）。该研究讨论了各种非生物和生物因素在每个阶段形成中的作用。