Relating Zonal Variability in Sea Surface Temperature to the Structure of North Pacific Anticyclones

Traditional Hadley Cell theory explains the presence of subsidence in the subtropical troposphere (20˚ - 40˚ N/S) but does little to elucidate the zonally asymmetric distribution of the resultant high-pressure centers over the oceans. Persistent regions of high pressures over the subtropical oceans are focused into distinct anticyclonic cells that strongly lean eastward against the coastlines, especially in the summer months. Identifying various dynamical processes behind the eastward-leaning anticyclones will offer insight into what shapes the subtropics and inform studies of North American climate impacts and variability. We use a global atmospheric general circulation model (AGCM) to investigate geographic variability in the North Pacific subtropical anticyclone through experiments with three different prescribed sea surface temperature (SST) fields: increasing, constant, and decreasing SSTs from west to east in the subtropical latitudes. Preliminary results highlight the relationship between SST and the position of the subtropical high and indicate that this relationship is significant during the spring and fall months when land-sea temperature contrasts are minimal.