Oceanic Routing of Wind-Sourced Energy Along the Arctic Continental Shelves

Abstract

Data from coastal tide gauges, oceanographic moorings, and a numerical model show that Arctic storm surges force continental shelf waves (CSWs) that dynamically link the circumpolar Arctic continental shelf system. These trains of barotropic disturbances result from coastal convergences driven by cross-shelf Ekman transport. Observed propagation speeds of 600−3000 km day −1 , periods of 2−6 days, wavelengths of 2000−7000 km, and elevation maxima near the coast but velocity maxima near the upper slope are all consistent with theoretical CSW characteristics. Other, more isolated events are tied to local responses to propagating storm systems. Energy and phase propagation is from west to east: ocean elevation anomalies in the Laptev Sea follow Kara Sea anomalies by one day and precede Chukchi and Beaufort Sea anomalies by 4−6 days. Some leakage and dissipation occurs. About half of the eastward-propagating energy in the Kara Sea passes Severnaya Zemlya into the Laptev Sea. About half of the eastward-propagating energy from the East Siberian Sea passes southward through Bering Strait, while one quarter is dissipated locally in the Chukchi Sea and another quarter passes eastward into the Beaufort Sea. Likewise, CSW generation in the Bering Sea can trigger elevation and current speed anomalies downstream in the Northeast Chukchi Sea of 25 cm and 20 cm s −1 , respectively. Although each event is ephemeral, the large number of CSWs generated annually suggest that they represent a non-negligible source of time-averaged energy transport and bottom stress-induced dissipative mixing, particularly near the outer shelf and upper slope. Coastal water level and landfast ice breakout event forecasts should include CSW effects and associated lag times from distant upstream winds.

Turbulent Mixing and the Formation of an Intermediate Nepheloid Layer Above the Siberian Continental Shelf Break

“…The passage of a continental shelf wave and the associated cross‐slope barotropic pressure gradient would hence explain the observed enhanced current velocities in both east‐ and northward direction, but more observational data are needed to confirm this hypothesis. Continental shelf waves were found to be episodic, but re‐occurring in the Arctic (Danielson et al., 2020). Based on a 9‐year model hindcast, on average 12 surface anomalies linked to CSW were identified per year, with over 60% of these anomalies occurring between August and January (Danielson et al., 2020).…”

“…Continental shelf waves were found to be episodic, but re‐occurring in the Arctic (Danielson et al., 2020). Based on a 9‐year model hindcast, on average 12 surface anomalies linked to CSW were identified per year, with over 60% of these anomalies occurring between August and January (Danielson et al., 2020). This temporal distribution of CSWs roughly resembles the seasonal distribution of the downslope flow events reported here (Figure 3f), which occur exclusively between July and January.…”

Arctic sea surface height maps from multi-altimeter combination

“…The variance distribution is consistent with previous datasets (Armitage et al, 2016;Rose et al, 2019) with high variance levels along the Russian Arctic coasts. Such variance levels could result from continental shelf waves propagation (Danielson et al, 2020). Another prominent feature is the SL variance slight drop above 81.5°N.…”

Sea surface height anomaly and geostrophic velocity from altimetry measurements over the Arctic Ocean (2011–2018)

“…For instance, Quinn and Ponte (2012) found that the coherence between ocean mass variability (from GRACE satellite) and altimetric sea surface height variability after applying only IB correction, increases with latitude. In the Arctic, the effect of pressure and wind forcing is not only local but also travels eastwards over the shelves in the form of mass waves (Fukumori et al, 1998;Danielson et al, 2020;Fukumori et al, 2015;Peralta-Ferriz et al, 2011). However, to date there is no study showing the effect of this waves on sea surface height measured from altimetry.…”