Co-variation Between Global Sea Surface Temperature and MODIS Ocean Chlorophyll-a (2002–2025): A Time-Series Regression Analysis

Abstract

The statistical association between global sea surface temperature (SST) and ocean color remains poorly quantified. This study analyzes monthly globally averaged SST and chlorophyll-a from August 2002 to December 2025 using ordinary least squares regression with three specifications: (1) baseline bivariate, (2) seasonal adjustment via month fixed effects, and (3) additional linear time trend. Analysis of 264 observations reveals a robust positive relationship: coefficients range from 0.97 to 1.38 (p < 0.001), with R² increasing from 0.105 to 0.481. The association persists after controlling for seasonality and trends, indicating systematic covariation between surface temperature and ocean color. These findings provide an empirical benchmark for coupled thermal-optical ocean dynamics and inform policy on climate monitoring, Earth system model validation, and marine resource management.