Particulate Organic Carbon (POC) is a key component of the oceanic carbon pool and plays an important role in marine biogeochemical processes and the biological carbon pump. Long-term satellite observations provide an effective means for establishing Climate Data Records (CDRs) of ocean biogeochemical variables, enabling assessment of seasonal to interannual variability and long-term changes in marine carbon cycling. The continuity of ocean-colour satellite missions offers an unprecedented opportunity to develop consistent POC records; however, evaluating inter-sensor consistency and uncertainty remains essential for reliable climate applications.

In this study, satellite-derived POC products from MODIS-Aqua, SNPP-VIIRS, and PACE were intercompared over the Arabian Sea for the period May 2024 to April 2025. The analysis employed spatial comparisons, pairwise statistical metrics, diversity indices, k-means clustering, and ternary diagrams to evaluate consistency and variability among the three sensors. All products successfully captured the dominant seasonal cycle of POC across the basin. Inter-sensor agreement was generally high in the central and southern Arabian Sea, whereas larger differences were observed in the western and southeastern Arabian Sea during the southwest monsoon and in the northern Arabian Sea during the winter monsoon. These discrepancies were associated with enhanced biogeochemical variability driven by coastal upwelling, vertical mixing, and monsoon-related physical processes.

Cluster analysis identified four distinct regions characterized by varying levels of inter-sensor agreement, ranging from strong consistency to pronounced differences among products. The results demonstrate the complementary strengths of MODIS, VIIRS, and PACE observations and provide valuable insight into uncertainties associated with multi-sensor ocean-colour products. This study contributes to ongoing efforts toward developing robust long-term POC Climate Data Records and improving the use of multi-sensor observations for monitoring carbon dynamics in monsoon-influenced oceanic regions.