The annual episodes of high-biomass algal bloom are a known phenomenon in the northern Arabian Sea. In the present study, we demonstrate growth and decay of bloom using long-term satellite-retrieved parameters such as chlorophyll- a (chl- a ), sea surface temperature (SST), phytoplankton absorption ( a ph ), detritus–coloured dissolved organic matter absorption ( a dg ) and model-derived mixed layer depth (MLD). Chl- a , the index of phytoplankton biomass, showed an inverse relationship with SST with a lag of 2–8 days between lowest SST and highest chl- a . The deepening of MLD associated with high chl- a and low SST indicated a role of convective mixing in the formation of bloom. The average SST of ~ 25 °C was found to be a favourable condition for such open ocean bloom. The lag was more towards eastern boundary of the basin, indicating variable intensities of convective mixing influencing spatial extent of bloom. The positive correlation between a ph and a dg indicated simultaneous production and degradation showing delay of 3–10 days from peak production to degradation.

中文翻译：

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阿拉伯海北部高生物质藻华的生长和衰变

每年一度的高生物量藻华是阿拉伯海北部的一种已知现象。在本研究中，我们使用长期卫星获取的参数，如叶绿素 a (chl-a)、海面温度 (SST)、浮游植物吸收 (a ph )、碎屑色溶解有机物质吸收 (a dg) 和模型衍生的混合层深度 (MLD)。浮游植物生物量指数 Chl-a 与 SST 呈负相关，最低 SST 和最高 chl-a 之间存在 2-8 天的滞后。与高 chla 和低 SST 相关的 MLD 加深表明对流混合在水华形成中的作用。发现约 25 °C 的平均海温是这种公海水华的有利条件。滞后更多地朝向盆地的东部边界，表明对流混合的可变强度影响水华的空间范围。ph 值和 dg 之间的正相关表明同时生产和降解显示从峰值生产到降解延迟 3-10 天。