A drifter for observing small spatial and temporal scales of motion in the coastal zone is presented. The drifter uses GPS to determine its position, and the Mobitex terrestrial cellular communications system to transmit the position data in near–real time. This configuration allows position data with order meter accuracy to be sampled every few minutes and transmitted inexpensively. Near-real-time transmission of highly accurate position data enables the drifters to be retrieved and redeployed, further increasing economy. Drifter slip measurements indicate that the drifter follows water to within ∼1–2 cm s−1 during light wind periods. Slip values >1 cm s−1 are aligned with the direction of surface wave propagation and are 180° out of phase, so that the drifter “walks” down waves. Nearly 200 drifter tracks collected off the Santa Barbara, California, coast show comparisons with high-frequency (HF) radar observations of near-surface currents that improve by roughly 50% when the average drifter values are computed from more than 25 observations within a 2-km square HF radar bin. The improvement is the result of drifter resolution of subgrid-scale eddies that are included in time–space-averaged HF radar fields. The average eddy kinetic energy on 2-km space and hour time scales is 25 cm2 s−2, when computed for bins with more than 25 drifter observations. Comparisons with trajectories that are computed from HF radar data show mean separation velocities of 5 and 9 cm s−1 in the along- and across-shore directions, respectively. The drifters resolve scales of motion that are not present in HF radar fields, and are thus complementary to HF radar in coastal ocean observing systems.

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There have been well-documented changes in the composition of the Arctic ice pack over the last few decades. Summertime changes are dramatic, with declines of 12.9% per decade (Kwok, 2018;Perovich et al., 2019;Stroeve & Notz, 2018). Delays in autumn freezing produce an ice pack that is dominated by thinner and more fragile first-year ice (Richter-Menge & Druckenmiller, 2020), which has also been documented to accumulate less snow, although this is variable across Arctic regions (Johnson & Eicken, 2016;Webster et al., 2018). The combination of thinner, less deformed first-year ice and a reduction in snow cover leads to earlier and increased surface ponding (Perovich & Polashenski, 2012;Polashenski et al., 2012). In addition, a trend toward earlier first spring rainfall observed since the 1990s also hastens the onset of snow melt and surface ponding (Dou et al., 2019). This overall trend of thinner ice and less snow combined with earlier snow and surface melting has a considerable impact on the timing and magnitude of the springtime increase in light transmission to the bottom of the ice and the underlying water column (

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