ORCID

0000-0003-2695-9001 (Ishaque), 0000-0001-7473-4873 (Clayton), 0000-0003-4312-5201 (Klinck)

Document Type

Article

Publication Date

2026

DOI

10.1029/2025JC023417

Publication Title

Journal of Geophysical Research: Oceans

Volume

131

Issue

5

Pages

e2025JC023417

Abstract

Recent studies have shown that the Indian Ocean is warming significantly, but how this warming impacts primary production is largely unresolved due to a relative lack of depth-resolved biological observations. In this study, we have used Biogeochemical-Argo data from 2013 to 2022, comprising over 9,000 individual profiles, to examine regional patterns and trends in depth-integrated chlorophyll, depth-integrated net primary production and stratification in the northern and Equatorial Indian Ocean. Our analysis shows that water column stratification is increasing in the majority of the study area, with the highest rate of increase observed in the western Bay of Bengal. At the same time, we find that depth-integrated chlorophyll and depth-integrated net primary production show an increasing trend in most parts of the Bay of Bengal, the western Arabian Sea, and some parts of the Equatorial Indian Ocean. However, the eastern Arabian Sea, the northern Bay of Bengal, and other parts of the Equatorial Indian Ocean have experienced a decrease in depth-integrated chlorophyll and net primary production. The Indian Ocean Dipole and El Niño Southern Oscillation were found mostly to be weakly negatively correlated with the depth-integrated chlorophyll and depth-integrated net primary production in the northern Indian Ocean. Our results show that depth-integrated chlorophyll and depth-integrated net primary production are not strongly or consistently correlated with stratification within our study region, suggesting that the projected increases in stratification with ocean warming in this region may not drive concurrent reductions in primary production.

Rights

© 2026. Jet Propulsion Laboratory, California Institute of Technology and The Authors.

This is an open access article under the terms of the Creative Commons Attribution-NonCommercial  4.0 International (CC BY-NC 4.0) License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Data Availability

Article states: "Publicly available BGC-Argo data were analyzed in this study (https://argo.ucsd.edu/data/). These data were collected and made freely available by the international Argo project and the national programs that contribute to it (Argo, 2026). DMI (IOD Index) data was obtained from https://psl.noaa.gov/data/timeseries/month/DMI/ (N. Saji & Yamagata, 2003). Multivariate ENSO Index Version 2 (MEI.v2) was downloaded from https://psl.noaa.gov/enso/mei/ (Wolter & Timlin, 2011; Zhang et al., 2019). Gibbs-SeaWater (GSW) Oceanographic Toolbox was used in this study and the codes were downloaded from https://www.teos-10.org/ (Li et al., 2020). Surface PAR used from Moderate Resolution Imaging Spectroradiometer (MODIS) products and the monthly data for each year were collected from https://oceancolor.gsfc.nasa.gov (Yang et al., 2022). MATLAB codes of Mann-Kendall Tau-b with Sen's Method (enhanced) by Jeff Burkey (2024) https://www.mathworks.com/matlabcentral/fileexchange/11190-mann-kendall-tau-b-with-sen-s-method-enhanced was used to calculate the trends. The quality-controlled data generated in this study are publicly available through the Zenodo repository: https://doi.org/10.5281/zenodo.18308385 (Ishaque, 2026)."

Original Publication Citation

Ishaque, M., Clayton, S., & Klinck, J. (2026). Autonomous float data reveal decoupled trends in chlorophyll and stratification in the Indian Ocean. Journal of Geophysical Research: Oceans, 131(5), Article e2025JC023417. https://doi.org/10.1029/2025JC023417

Additional Files
2025jc023417-sup-0001-supporting information si-s01.pdf (1437 kB)
Supporting Information
Download

Share

Article Location

 
COinS