Unclear impact of AMOC weakening on the Amazon seasonal precipitation cycle

Determine the net effect of an Atlantic Meridional Overturning Circulation (AMOC) weakening on the Amazon basin’s seasonal precipitation cycle—specifically a drier wet season and a wetter dry season—by quantifying how this shift modifies hydrological indicators such as Mean Annual Precipitation and Maximum Cumulative Water Deficit.

Background

The Atlantic Meridional Overturning Circulation (AMOC) can influence Amazon rainfall by shifting the InterTropical Convergence Zone (ITCZ), thereby altering precipitation patterns across the basin. Beyond mean changes, a weakening AMOC may modify the seasonal cycle, potentially producing opposing changes in wet vs. dry seasons.

The aggregate impact of these seasonal-cycle changes on Amazon hydrology remains unresolved, yet it is critical for understanding the potential for tipping cascades and for calibrating coupled process-based models that relate AMOC strength to Amazon precipitation metrics.