S64 The Correlation between Sea Surface Temperature and the Structure of North Pacific Subtropical Anticyclones

Sunday, 12 January 2020
Alyssa Walker, Univ. of Colorado, Boulder, CO; and J. K. Rader, K. B. Karnauskas, and L. Zhang

The Hadley Cell is the underlying force responsible for the formation of the majority of Earth’s deserts and semi-arid regions. These regions, geographically located in the subtropics (20˚– 40˚ N/S), are the direct result of permanent high-pressure zones created by the subsiding branch of the Hadley Cell. While it is understood that these high-pressure zones play a key role in determining local climates, the fact that Earth’s subtropical anticyclones tilt eastward remains a critical unknown in our understanding of Earth’s atmosphere. Specifically, anticyclonic cells residing in Earth’s subtropical oceans possess a notable eastward lean during the summer months. Distinguishing the origin of this lean will facilitate further understanding of the subtropic’s structure, as well as the global climatic conditions it imposes. Through the use of a global atmospheric general circulation model (AGCM), we investigate the relationship between sea surface temperatures (SSTs) and the geographic position of the North Pacific subtropical anticyclone. We run three scenarios, each corresponding with different fixed sea surface temperatures (SSTs): zonal mean, increasing, and decreasing SSTs from west to east in the subtropical latitudes. Results indicate that the correlation between SST and the position of the subtropical anticyclone is mainly noteworthy upon examining seasons when land-sea temperature contrasts are minute: spring and fall months.
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