upwelling: one construct, many systems

In geodynamics, upwelling is the slow rise of hotter, less dense rock through the solid-but-creeping mantle, the ascending limb of mantle convection that feeds mid-ocean ridges and, in concentrated columns, surface hotspots. Morgan's 1971 Convection plumes in the lower mantle proposed that narrow upwelling plumes rising from deep in the mantle supply the volcanism at places like Hawaii. The referent is the buoyancy-driven ascent of deep material toward the surface of a stratified system, the same upward-transport construct that physical oceanography calls upwelling, here realised in rock rather than seawater.[1]

Unit

The vertical velocity of rising mantle material, in centimetres per year

Recovery means

Not applicable

Measured by

Inferred from seismic tomography of low-velocity columns, surface heat flow and uplift, and the geochemistry of hotspot volcanism

In physical oceanography, upwelling is the rise of cold, nutrient-rich deep water to the surface, classically where winds along a coast drive the surface layer offshore and deeper water flows up to replace it, fuelling some of the ocean's most productive fisheries. Bakun's 1990 Global climate change and intensification of coastal ocean upwelling argued that stronger land–sea temperature contrasts could intensify these upwelling-favourable winds. It is the same ascending-limb construct as mantle upwelling (deeper material transported up into a stratified system), though here the driver is wind-forced surface divergence rather than thermal buoyancy, a mechanism difference worth holding separate from the shared pattern.[2]

Unit

The vertical velocity of rising water and the resulting surface nutrient supply

Recovery means

Not applicable

Measured by

Indexed by wind-driven offshore transport, satellite sea-surface temperature and chlorophyll, and vertical-velocity estimates at the coast