Observed Zonal Variations of the Relationship between ITCZ Position and Meridional Temperature Contrast

Abstract

While the zonal-mean position of the intertropical convergence zone (ITCZ) is well explained using the zonal-mean energetic framework, the regional variations of the ITCZ have been more difficult to characterize. We show a simple metric, the interhemispheric tropical sea surface temperature (SST) contrast, is useful for estimating the local ITCZ position over seasonal and interannual timescales in modern observations. We demonstrate a linear correspondence between the SST contrast and ITCZ position across oceanic sectors. Though consistently linear, the sensitivity of the ITCZ position to the SST contrast varies from ~1°/K to ~7°/K depending on location. We also find that the location of the Western Pacific interannual ITCZ is negatively correlated with the temperature of the North Atlantic Ocean. This result may help put constraints on past and future regional migrations of the ITCZ.

Response of the global ITCZ to different ENSO phases and how the ITCZ determined from the maximum precipitation compares with the surface tropical winds convergence

“…The sea surface temperatures (SSTs) influence the spatio-temporal dynamics of the ITCZ (Mischell & Lee, 2022;Wolf et al, 2020). Therefore, the seasonal position of the ITCZ which is an area of intense precipitation (Philander et al, 1996;Roldán-Gómez et al, 2022) and maximum surface wind convergence (Faulk et al, 2017), is plotted with an overlay of the seasonal SSTs and seasonal surface tropical winds for visual analysis of seasonal ITCZ and phases of ENSO (with their corresponding seasonal SSTs).…”

“…The understanding of the role of internal variability and external radiative forcing on the spatial position of the ITCZ is one of the open research questions. Studies demonstrate that the estimate of the location of the ITCZ does not only vary according to the data used (Liu et al, 2020) but there are also minor to major differences based on the data and methods used (Burns et al, 2022;Lashkari et al, 2017;Mischell & Lee, 2022;Roldán-Gómez et al, 2022;Vindel et al, 2020;Wei & Bordoni, 2020). It is, however, important to study the variations and possible drivers of the ITCZ position evolution over different regions.…”

“…Roldán-Gómez et al (2022) explored, in depth, the spatial ITCZ over the Pacific, Atlantic and Indian ocean basins leaving out the continents in between. Mischell & Lee (2022), on the other hand, explored the spatial ITCZ over the Indian, Pacific, Atlantic, Western Pacific, Central Pacific, and Eastern Pacific. The centroid method or the maximum precipitation method are used among all the studies for the quantification of the position of the ITCZ.…”

High‐Latitude, Indian Ocean, and Orbital Influences on Eastern African Hydroclimate Across the Plio‐Pleistocene Boundary

“…Similarly, high‐northern latitude cooling can influence tropical rainfall through several processes, including latitudinal migration of the ITCZ (Broccoli et al., 2006; Chiang & Bitz, 2005; Chiang et al., 2003; Lechleitner et al., 2017; Mischell & Lee, 2022). With few exceptions (Sarnthein et al., 2009), North Atlantic SSTs exhibit little secular change in the late Pliocene (Clotten et al., 2018; Lawrence et al., 2009; Naafs et al., 2020).…”

Dynamics of the Atlantic Marine Intertropical Convergence Zone

“…The AMI lies at the nexus of the trade wind systems of the Northern and Southern Hemispheres, which provide the moisture for the convection, respond to the associated convective heating, and interact with the underlying ocean to shape the climate of the larger tropical domain (Okumura & Xie, 2004; Peyrillé et al., 2016; Sultan & Janicot, 2003). Seasonal and interannual variability of the AMI and its extensions over the neighboring continents are closely associated with seasonal and interannual anomalies in the trade winds, sea surface temperature (SST), and the upper ocean circulation (Doi et al., 2012; Lamb et al., 1986; Mischell & Lee, 2022).…”