In the present study, using in-situ and satellite observations, we investigate the influence of physical processes on the enhancement of phytoplankton biomass in the eastern Arabian Sea (EAS). Water column measurements were carried out from 9⁰N to 21⁰N (stations II-2 to II-14) along 68⁰E transect in the EAS during the beginning of fall intermonsoon (FIM) of 2014. Both in-situ and satellite-derived chlorophyll a (Chl a) showed higher biomass at 15⁰N (station II-8) compared to northern and southern stations. We explored the possible physical processes which can lead to high biological productivity at this station. Our study shows that nearly two times enhancement in Chl a at station II-8 was contributed by an open-ocean front, which occurred two days before the measurement. Based on phytoplankton marker pigments, it was evident that haptophytes were abundant at II-8 with a minor contribution from diatoms and dinoflagellates. This condition also led to a high concentration (4.9 nM) of dimethylsulphide (DMS), an anti-green house gas with a net flux of 3.76 μmol m⁻²d⁻¹ at this site. Among the picophytoplankton, Synechococcus were abundant at this station, however Prochlorococcus were absent as confirmed by both marker pigment and flow cytometric counts. The case study presented here demonstrates the dynamic nature of open ocean fronts and their overall contribution to the productivity of the eastern Arabian Sea during the oligotrophic inter-monsoon period.

在本研究中，我们使用原位和卫星观测，研究了物理过程对东部阿拉伯海（EAS）浮游植物生物量增强的影响。在2014年秋季季风开始（FIM）期间，在EAS沿68⁰E断面从9⁰N到21⁰N（站II-2至II-14）进行了水柱测量。原位和卫星衍生的叶绿素a（Chl a）与北部和南部站相比，在15⁰N（站II-8）处显示出更高的生物量。我们探索了可能导致该站高生物生产率的物理过程。我们的研究表明，Chl a的提高了近两倍II-8站的一次观测是在测量前两天发生的一个开放海面。基于浮游植物标记色素，很明显，II-8位的触附植物丰富，硅藻和鞭毛鞭毛藻的贡献较小。该条件还导致高浓度（4.9 nM）的二甲基硫化物（DMS），这是一种防温室气体， 在该位置的净通量为3.76μmolm ^-2 d ^-1。在浮游浮游植物中，该部位的浮游球菌丰富，而原球菌如标记色素和流式细胞仪计数所证实的，它们均不存在。这里介绍的案例研究表明，在贫营养化季风间，开放海域的动态性质及其对阿拉伯东部东部生产力的总体贡献。