Year: 2025
Type: preprint
Abstract: Global ocean heat and water mass distributions are shaped by both internal and external forces, including natural processes and anthropogenic-induced change.Among the internal processes, climate modes such as the El Niño Southern Oscillation (ENSO) over the Pacific Ocean, and the Atlantic Multidecadal Oscillation (AMO) over the Atlantic Ocean affect the movement of water and heat and generate important regional variations in sea level.Here, we examine the role and structure of climate modes and other variations on the hemispheric redistribution of ocean volume and sea level variability.By analysing a large sample of Coupled Model Intercomparison Project (CMIP) models and observations of SSH, we find that the combination of the commonly examined climate modes fails to explain a large fraction of the interhemispheric climate asymmetric variation.We define a new pattern of internal variability known as asymmetric internal variation (ASYM), that is associated with most of the hemispheric asymmetric volume change between the hemispheres.ASYM is characterised by variations in sea level, with sea level higher (lower) in the Southern (Northern) Hemisphere during the positive phase of this statistical mode.ASYM is unique relative to other climate modes, as it is defined over the global ocean and expressed in terms of sea level or ocean heat content.In characterizing ASYM variability, we find power across interannual to multi-decadal timescales.Our preliminary analysis suggests that ASYM is closely linked to the coupled response of ocean-atmosphere interactions, wind-driven circulation, the heat exchange between the ocean and the atmosphere, and meridional ocean heat and volume transport.
Authors: Sandeep Mohapatra, Nathaniel Lee Bindoff, Alex Sen Gupta, Saurabh Rathore
Language: English
Subfield: Global and Planetary Change
Field: Environmental Science
Domain: Physical Sciences
SDG: Climate action
Open Access status: green
OpenAlex ID: W4412373340