The Sun's meridional flow is an axisymmetric flow that is generally directed from its equator toward its poles at the surface. The structure and strength of the meridional flow determine both the strength of the Sun's polar magnetic field and the intensity of sunspot cycles. We determine the meridional flow speed of magnetic features on the Sun using data from the Solar and Heliospheric Observatory. The average flow is poleward at all latitudes up to 75 degrees, which suggests that it extends to the poles. It was faster at sunspot cycle minimum than at maximum and substantially faster on the approach to the current minimum than it was at the last solar minimum. This result may help to explain why this solar activity minimum is so peculiar.
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Chaos
January 2025
CNRS-IRD-CONICET-UBA, Institut Franco-Argentin d'Études sur le Climat et ses Impacts (IRL 3351 IFAECI), C1428EGA CABA, Argentina.
Significant changes in a system's dynamics can be understood through modifications in the topological structure of its flow in phase space. In the Earth's climate system, such changes are often referred to as tipping points. One of the large-scale components that may pass a tipping point is the Atlantic Meridional Overturning Circulation.
View Article and Find Full Text PDFSci Rep
December 2024
Climate and Global Dynamics Laboratory, NSF National Center for Atmospheric Research, 1850 Table Mesa Drive, Boulder, CO, 80305, USA.
The warm Western Boundary Currents (WBCs) and their zonal extensions are persistent, deep, strong and narrow oceanic currents. They are known to anchor and energize the Extra-Tropical storm tracks by frontal thermal air-sea interactions. However, even in the latest generation of climate models, WBCs are characterized by large biases, and both the present storm-track activity and its recent intensification are poorly estimated.
View Article and Find Full Text PDFNat Commun
October 2024
Department of Marine Science and Convergence Engineering, Hanyang University, Ansan, South Korea.
Sci Adv
June 2024
Laboratory for Climate and Ocean-Atmosphere Studies, Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing, China.
The global meridional overturning circulation (GMOC) is important for redistributing heat and, thus, determining global climate, but what determines its strength over Earth's history remains unclear. On the basis of two sets of climate simulations for the Paleozoic characterized by a stable GMOC direction, our research reveals that GMOC strength primarily depends on continental configuration while climate variations have a minor impact. In the mid- to high latitudes, the volume of continents largely dictates the speed of westerly winds, which in turn controls upwelling and the strength of the GMOC.
View Article and Find Full Text PDFSpace Sci Rev
November 2023
Department of Astrophysical and Planetary Sciences, Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80309 USA.
The Sun's axisymmetric large-scale flows, differential rotation and meridional circulation, are thought to be maintained by the influence of rotation on the thermal-convective motions in the solar convection zone. These large-scale flows are crucial for maintaining the Sun's global magnetic field. Over the last several decades, our understanding of large-scale motions in the Sun has significantly improved, both through observational and theoretical efforts.
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