Abstract
Abstract. The intertropical convergence zone (ITCZ) is an important component of the tropical rain belt. Climate models continue to struggle to adequately represent the ITCZ and differ substantially in its simulated response to climate change. Here we employ complex network approaches, which extract spatiotemporal variability patterns from climate data, to better understand differences in the dynamics of the ITCZ in state-of-the-art global circulation models (GCMs). For this purpose, we study simulations with 14 GCMs in an idealized slab-ocean aquaplanet setup from TRACMIP – the Tropical Rain belts with an Annual cycle and a Continent Model Intercomparison Project. We construct network representations based on the spatial correlation patterns of monthly surface temperature anomalies and study the zonal-mean patterns of different topological and spatial network characteristics. Specifically, we cluster the GCMs by means of the distributions of their zonal network measures utilizing hierarchical clustering. We find that in the control simulation, the distributions of the zonal network measures are able to pick up model differences in the tropical sea surface temperature (SST) contrast, the ITCZ position, and the strength of the Southern Hemisphere Hadley cell. Although we do not find evidence for consistent modifications in the network structure tracing the response of the ITCZ to global warming in the considered model ensemble, our analysis demonstrates that coherent variations of the global SST field are linked to ITCZ dynamics. This suggests that climate networks can provide a new perspective on ITCZ dynamics and model differences therein.
Highlights
One-third of Earth’s precipitation falls within the narrow band of the deep tropics within 10◦ N–S (Kang et al, 2018)
To better understand the effect of spatiotemporal sea surface temperature (SST) patterns on intertropical convergence zone (ITCZ) dynamics, we present the first application of functional climate network analysis to idealized aquaplanet simulations from the TRACMIP (Tropical Rain belts with an Annual cycle and a Continent Model Intercomparison Project) model ensemble (Voigt et al, 2016) that is freely available via the Earth System Grid Federation and the Pangeo project
We have proposed a new perspective on the ITCZ by means of complex network theory
Summary
One-third of Earth’s precipitation falls within the narrow band of the deep tropics within 10◦ N–S (Kang et al, 2018). Wolf et al.: A climate network perspective on the intertropical convergence zone cesses and their coupling with the large-scale circulation, e.g., via cloud radiative effects (Voigt et al, 2014) and convective mixing (Moebis and Stevens, 2012), and have motivated a large amount of theoretical and idealized work (Kang et al, 2009; Donohoe et al, 2013; Schneider et al, 2014; Biasutti et al, 2018) This has led to important insights into how the position of the ITCZ is controlled by atmospheric energy transport and sea surface temperatures (SSTs)
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