@article {RN75,
	title = {Why Gliders Appreciate Good Company: Glider Assimilation in the Oregon-Washington Coastal Ocean 4DVAR System With and Without Surface Observations},
	journal = {Journal of Geophysical Research: Oceans},
	volume = {124},
	number = {1},
	year = {2019},
	pages = {750-772},
	type = {Journal Article},
	abstract = {Gliders are low-power autonomous underwater vehicles used to obtain oceanic measurements in vertical sections. Assimilation of glider temperature and salinity into coastal ocean circulation models holds the potential to improve the ocean subsurface structure estimate. In this study, the impact of assimilation of glider observations is studied using a four-dimensional variational (4DVAR) data assimilation and forecast system set offshore of Oregon and Washington on the U.S. West Coast. Four test cases are compared: (1) no assimilation, (2) assimilation of glider temperature and salinity data alone, (3) assimilation of the glider data in combination with the surface observations including satellite sea surface temperature, sea surface height, and high-frequency radar surface velocities, and (4) assimilation of the surface data alone. It is found that the assimilation of glider observations alone creates unphysical eddies in the vicinity of the glider transect. As a consequence, the forecast errors in the surface velocity and temperature increase compared to the case without data assimilation. Assimilation of surface and subsurface observations in combination prevents these features from forming and reduces the errors in the forecasts for the subsurface fields compared to the other three experiments. These improvements persisted in 21-day forecasts run after the last data assimilation cycle.

},
	issn = {2169-9275},
	doi = {10.1029/2018JC014230},
	url = {https://doi.org/10.1029/2018JC014230},
	author = {Pasmans, I. and Kurapov, A. L. and Barth, J. A. and Ignatov, A. and Kosro, P. M. and Shearman, R. K.}
}
@article {RN33,
	title = {Temporal and Spatial Dynamics of Physical and Biological Properties along the Endurance Array of the California Current Ecosystem},
	journal = {Oceanography},
	volume = {31},
	number = {1},
	year = {2018},
	pages = {80-89},
	type = {Journal Article},
	abstract = {The coastal margin of the Pacific Northwest of the United States is a highly dynamic and productive region. Here, we use satellite, high-frequency mooring, and glider estimates of biologically relevant physical and optical variables to characterize seasonal patterns and latitudinal and cross-shore gradients in particle concentrations between the Washington and Oregon shelves. Consistent with prior research, we find that the Columbia River exerts a strong seasonal influence on the Washington shelf, but smaller coastal rivers and resuspension processes also appear important in determining particle distributions nearshore during winter across the full study region. We find fluorescence-based measurements of chlorophyll to be similar in magnitude across the two shelves over the time period examined, although the much weaker wind stresses off Washington indicate that processes other than upwelling are important determinants of chlorophyll changes in those areas, as previously suggested. These in situ observations contrast with the overall differences observed from satellite data, which consistently show higher chlorophyll concentrations off the Washington coast. This research suggests that latitudinal differences in chromophoric dissolved organic matter may be a partial explanation for perceived trends in satellite-derived chlorophyll. The observations presented are nascent; maturation of temporal and spatial coverage of OOI data sets will be necessary to more conclusively link physical forcing and biogeochemical responses.},
	issn = {1042-8275},
	doi = {10.5670/oceanog.2018.113},
	url = {<Go to ISI>://WOS:000427367300013},
	author = {Freitas, F. H. and Saldias, G. S. and Goni, M. and Shearman, R. K. and White, A. E.}
}
@article {RN35,
	title = {Intraseasonal Cross-Shelf Variability of Hypoxia along the Newport, Oregon, Hydrographic Line},
	journal = {Journal of Physical Oceanography},
	volume = {46},
	number = {7},
	year = {2016},
	pages = {2219-2238},
	type = {Journal Article},
	abstract = {Observations of hypoxia, dissolved oxygen (DO) concentrations < 1.4 ml L-1, off the central Oregon coast vary in duration and spatial extent throughout each upwelling season. Underwater glider measurements along the Newport hydrographic line (NH-Line) reveal cross-shelf DO gradients at a horizontal resolution nearly 30 times greater than previous ship-based station sampling. Two prevalent hypoxic locations are identified along the NH-Line, as is a midshelf region with less severe hypoxia north of Stonewall Bank. Intraseasonal cross-shelf variability is investigated with 10 sequential glider lines and a midshelf mooring time series during the 2011 upwelling season. The cross-sectional area of hypoxia observed in the glider lines ranges from 0 to 1.41 km2. The vertical extent of hypoxia in the water column agrees well with the bottom mixed layer height. Midshelf mooring water velocities show that cross-shelf advection cannot account for the increase in outer-shelf hypoxia observed in the glider sequence. This change is attributed to an along-shelf DO gradient of -0.72 ml L-1 over 2.58 km or 0.28 ml L-1 km-1. In early July of the 2011 upwelling season, near-bottom cross-shelf currents reverse direction as an onshore flow at 30-m depth is observed. This shoaling of the return flow depth throughout the season, as the equatorward coastal jet moves offshore, results in a more retentive near-bottom environment more vulnerable to hypoxia. Slope Burger numbers calculated across the season do not reconcile this return flow depth change, providing evidence that simplified two-dimensional upwelling model assumptions do not hold in this location.},
	keywords = {Circulation/Dynamics, Coastal flows, Upwelling/downwelling},
	issn = {0022-3670},
	doi = {10.1175/Jpo-D-15-0119.1},
	author = {Adams, K. A. and Barth, J. A. and Shearman, R. K.}
}
@article {RN52,
	title = {Anomalous Near-Surface Low-Salinity Pulses off the Central Oregon Coast},
	journal = {Sci Rep},
	volume = {5},
	year = {2015},
	pages = {17145},
	type = {Journal Article},
	abstract = {From mid-May to August 2011, extreme runoff in the Columbia River ranged from 14,000 to over 17,000 m(3)/s, more than two standard deviations above the mean for this period. The extreme runoff was the direct result of both melting of anomalously high snowpack and rainfall associated with the 2010-2011 La Ni{\~n}a. The effects of this increased freshwater discharge were observed off Newport, Oregon, 180 km south of the Columbia River mouth. Salinity values as low as 22, nine standard deviations below the climatological value for this period, were registered at the mid-shelf. Using a network of ocean observing sensors and platforms, it was possible to capture the onshore advection of the Columbia River plume from the mid-shelf, 20 km offshore, to the coast and eventually into Yaquina Bay (Newport) during a sustained wind reversal event. Increased freshwater delivery can influence coastal ocean ecosystems and delivery of offshore, river-influenced water may influence estuarine biogeochemistry.},
	issn = {2045-2322 (Electronic) 2045-2322 (Linking)},
	doi = {10.1038/srep17145},
	url = {https://www.ncbi.nlm.nih.gov/pubmed/26607750},
	author = {Mazzini, P. L. and Risien, C. M. and Barth, J. A. and Pierce, S. D. and Erofeev, A. and Dever, E. P. and Kosro, P. M. and Levine, M. D. and Shearman, R. K. and Vardaro, M. F.}
}
