Abstract
Antarctic Bottom Water (AABW) formation and transport constitute a key
component of the global ocean circulation. Direct observations suggest
that AABW volumes and transport rates may be decreasing, but these
observations are too temporally or spatially sparse to determine the
cause. To address this problem, we develop a new method to reconstruct
AABW transport variability using data from the GRACE (Gravity Recovery
and Climate Experiment) satellite mission. We use an ocean general
circulation model to investigate the relationship between ocean bottom
pressure and AABW: we calculate both of these quantities in the model,
and link them using a regularised linear regression. Our reconstruction
from modelled ocean bottom pressure can capture 65-90% of modelled AABW
transport variability, depending on the ocean basin. When realistic
observational uncertainty values are added to the modelled ocean bottom
pressure, the reconstruction can still capture 30-80% of AABW transport
variability. Using the same regression values, the reconstruction skill
is within the same range in a second, independent, general circulation
model. We conclude that our reconstruction method is not unique to the
model in which it was developed and can be applied to GRACE satellite
observations of ocean bottom pressure. These advances allow us to create
the first global reconstruction of AABW transport variability over the
satellite era. Our reconstruction provides information on the
interannual variability of AABW transport, but more accurate
observations are needed to discern AABW transport trends.