Small changes in the ways that the ocean transports heat to the overlying ice cover could have a substantial effect on future changes in Arctic ice cover.

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In the past two decades, the Argo Program has collected, processed, and distributed over two million vertical profiles of temperature and salinity from the upper two kilometers of the global ocean. A similar number of subsurface velocity observations near 1,000 dbar have also been collected. This paper recounts the history of the global Argo Program, from its aspiration arising out of the World Ocean Circulation Experiment, to the development and implementation of its instrumentation and telecommunication systems, and the various technical problems encountered. We describe the Argo data system and its quality control procedures, and the gradual changes in the vertical resolution and spatial coverage of Argo data from 1999 to 2019. The accuracies of the float data have been assessed by comparison with high-quality shipboard measurements, and are concluded to be 0.002 • C for temperature, 2.4 dbar for pressure, and 0.01 PSS-78 for salinity, after delayed-mode adjustments. Finally, the challenges faced by the vision of an expanding Argo Program beyond 2020 are discussed.

While satellite data indicate that the surface expression of the North Pacific marine heatwave, nicknamed "The Blob," disappeared in late 2016, Argo float and ship-based conductivity-temperature-depth data show that warm conditions persisted below the surface mixed layer through at least March 2018. We trace this anomalously warm subsurface water from the open ocean through Queen Charlotte Sound to Rivers Inlet, on British Columbia's central coast. In Rivers Inlet, deep water below the sill depth continues to be 0.3°t o 0.6°C warmer than the monthly average, suggesting that impacts of this marine heatwave have persisted in coastal waters at least 4 years after its onset, with potentially substantial effects on coastal ecosystems.Plain Language Summary The Northeast Pacific Ocean was affected by two warm water events, the first was the 2013 to 2015 marine heatwave, nicknamed The Blob, and the second was the 2015 to 2016 El Niño. Surface satellite data have shown that the warm water was gone by 2016. Using temperature data collected by ship and by autonomous robots, we find that abnormally warm water continues to exist in the open ocean below the surface, at about 140-m depth. In the coastal ocean, we find that deep waters in Rivers Inlet are still 0.3°to 0.6°C warmer than normal, at least 4 years after The Blob was first observed. This warm water could have a big impact on the Rivers Inlet ecosystem.North of Oregon, the Pacific coast features hundreds of fjords that support rich cold-water ecosystems. Fjords are the life-support system of early life stages of salmon (Healey, 1982;Simenstad et al., 1982). Rivers Inlet, located within Wuikinuxv Nation traditional territory, is a typical glacial-fed fjord on British Columbia's central coast (Figure 1) that is about 45 km long, 3 km wide, and 340 m deep. A 140-m (Pickard, 1961) sill at the JACKSON ET AL. 9757

The OceanGliders program started in 2016 to support active coordination and enhancement of global glider activity. OceanGliders contributes to the international efforts of the Global Ocean Observation System (GOOS) for Climate, Ocean Health, and Operational Services. It brings together marine scientists and engineers operating gliders around the world: (1) to observe the long-term physical, biogeochemical, and biological ocean processes and phenomena that are relevant for societal applications; and, (2) to contribute to the GOOS through real-time and delayed mode data dissemination. The OceanGliders program is distributed across national and regional observing systems and significantly contributes to integrated, multi-scale and multi-platform sampling strategies. OceanGliders shares best practices, requirements, and scientific knowledge needed for glider operations, data collection and analysis. It also monitors global glider activity and supports the dissemination of glider data through regional and global databases, in realtime and delayed modes, facilitating data access to the wider community. OceanGliders currently supports national, regional and global initiatives to maintain and expand the capabilities and application of gliders to meet key global challenges such as improved measurement of ocean boundary currents, water transformation and storm forecast.