This recipe allows to quantify the relationships between Arctic sea-ice drift speed, concentration and thickness (Docquier et al., 2017). A decrease in concentration or thickness, as observed in recent decades in the Arctic Ocean (Kwok, 2018; Stroeve and Notz, 2018), leads to reduced sea-ice strength and internal stress, and thus larger sea-ice drift speed (Rampal et al., 2011). This in turn could provide higher export of sea ice out of the Arctic Basin, resulting in lower sea-ice concentration and further thinning. Olason and Notz (2014) investigate the relationships between Arctic sea-ice drift speed, concentration and thickness using satellite and buoy observations. They show that both seasonal and recent long-term changes in sea ice drift are primarily correlated to changes in sea ice concentration and thickness. This recipe allows to quantify these relationships in climate models.
In this recipe, four process-based metrics are computed based on the multi-year monthly mean sea-ice drift speed, concentration and thickness, averaged over the Central Arctic.
The first metric is the ratio between the modelled drift-concentration slope and the observed drift-concentration slope. The second metric is similar to the first one, except that sea-ice thickness is involved instead of sea-ice concentration. The third metric is the normalised distance between the model and observations in the drift-concentration space. The fourth metric is similar to the third one, except that sea-ice thickness is involved instead of sea-ice concentration.
Available recipes and diagnostics#
Recipes are stored in recipes/
Diagnostics are stored in diag_scripts/seaice_drift/
seaice_drift.py: Compute metrics and plot results
User settings in recipe#
Required settings (scripts)
One of the following two combinations is required:
latitude_threshold: metric will be computed north of this latitude value
polygon: metric will be computed inside the give polygon. Polygon is defined as a list of (lon, lat) tuple
polygon_name: name of the region defined by the polygon
sispeed, sithick, siconc (daily)
Scatter plots of modelled (red) and observed (blue) monthly mean sea-ice drift speed against sea-ice concentration (left panel) and sea-ice thickness (right panel) temporally averaged over the period 1979–2005 and spatially averaged over the SCICEX box.