Internal tsunamigenesis and ocean mixing driven by glacier calving in Antarctica

Abstract

Ocean mixing around Antarctica exerts key influences on glacier dynamics and ice shelf retreats, sea ice, and marine productivity, thus affecting global sea level and climate. The conventional paradigm is that this is dominated by winds, tides, and buoyancy forcing. Direct observations from the Antarctic Peninsula demonstrate that glacier calving triggers internal tsunamis, the breaking of which drives vigorous mixing. Being widespread and frequent, these internal tsunamis are at least comparable to winds, and much more important than tides, in driving regional shelf mixing. They are likely relevant everywhere that marine-terminating glaciers calve, including Greenland and across the Arctic. Calving frequency may change with higher ocean temperatures, suggesting possible shifts to internal tsunamigenesis and mixing in a warming climate.

Multi‐Decadal Record of Sensible‐Heat Polynya Variability From Satellite Optical and Thermal Imagery at Pine Island Glacier, West Antarctica

“…Building long-term records of coevolving ocean and ice-shelf dynamics is therefore crucial to better constrain the drivers of mass loss. Finally, we also observed a sharp drop in polynya area (Figure 4a) shortly after the 2007 calving event (Figure 4c), which may suggest that calving dynamics can disrupt basal channel outflow by shifting or blocking the channel path and/or upper ocean stratification by mixing the water column (e.g., Meredith et al, 2022). To ensure this area change was not substantially influenced by the sensor change following the 2007 event, we compared areas from thermal and visible images and found they were comparable (Figure S10 in Supporting Information S1).…”

Internal gravity waves generated by subglacial discharge: implications for tidewater glacier melt

“…A mechanism for wave generation must explain the properties of the waves found above, in particular, their near-N frequency, persistence and correlations with discharge forcing. Possible mechanisms for generating internal waves include iceberg calving (Meredith et al, 2022), flow-topography interactions (Farmer & Armi, 1999), and turbulent emission (Dohan & Sutherland, 2005). The latter mechanism may occur when turbulent eddies in the discharge plume and its surface expression excite internal waves.…”

“…Very recent observations from the Antarctic Peninsula suggest that iceberg calving events are also a source of internal waves and significant mixing (Meredith et al, 2022).…”

Spatiotemporal variability of dissolved inorganic macronutrients along the northern Antarctic Peninsula (1996–2019)

“…1). At the southernmost part of the northern Antarctic Peninsula, the Gerlache Strait is a relatively shallow region (depth ~ 800 m), with high concentrations of sea ice (Parra et al 2020; Monteiro et al 2020 a ) and strongly impacted by meltwater from continental glaciers (Meredith et al 2022). Despite covering a small area, Gerlache Strait acts as a stronger summer CO 2 sink than larger regions such as Bransfield Strait (Monteiro et al 2020 b ).…”

“…For example, intense diatom blooms enhance CO 2 uptake (Anadón and Estrada 2002; Costa et al 2020) and can lead to nutrient depletion in the upper ocean and subsequently increase the local remineralization of carbon and macronutrients below the mixed layer (Henley et al 2017, 2018). In addition, melting sea ice and glacial ice regulates summer water column stability (Wang et al 2020; Meredith et al 2022), driving phytoplankton blooms (Kim et al 2016; Costa et al 2020), CO 2 uptake (Costa et al 2020; Monteiro et al 2020 b ), and nutrient depletion and replenishment in the upper ocean (Henley et al 2017, 2018).…”