Atmosphere Ocean Science Friday Seminar

---

Dependence of Regional Sea Level on the Depth of Meltwater Input

Speaker: Aurora Basinski

Location: Warren Weaver Hall 1314

Date: Friday, March 1, 2024, 4 p.m.

Synopsis:

State-of-the-art global climate models, including the current generation of CMIP models, do not have ice sheets coupled to the atmosphere-ocean system. Thus, current projections of sea level change due to ice sheet mass loss are investigated by inputting meltwater into the ocean in runs often called “hosing experiments”; this meltwater is generally inputted at the sea surface. However, observational evidence suggests that a significant proportion of meltwater, from basal melt of ice shelves, enters the ocean at depth. Here, we investigate the sensitivity of the ocean response to meltwater input at different depths. We utilize the MITgcm run at ¼ degree resolution with an idealized geometry and find that the regional sea level response has a timescale dependence on the depth of forcing at the southern edge of the domain – deeper forcings result in a slower response of the Northern Hemisphere sea level. We also use a simple reduced gravity model to develop a theory for the timescales of adjustment that helps explain the MITgcm results. The results suggest that current hosing experiments for regional sea level projections, which generally use surface meltwater forcing, may have timescale errors due to the depth of forcing.

1