Blended sea level anomaly fields with enhanced coastal coverage along the U.S. West Coast.

We form a new data set of fields of sea level anomalies by combining gridded daily fields derived from altimeter data with coastal tide gauge data. Within approximately 50-80 km of the coast, the altimeter data are discarded and replaced by a linear interpolation between the tide gauge and remaining offshore altimeter data. A 20-year mean is subtracted from each time series (tide gauge or altimeter) before combining the data sets to form the merged sea level anomaly data set. Geostrophic velocity anomaly fields are formed from the surface heights. Daily mean fields are produced for the period 1 January 1993 - 31 December 2014. The primary validation compares geostrophic velocities calculated from the height fields and velocities measured at four moorings covering the north-south range of the new data set. The merged data set improves the alongshore (meridional) component of the currents, indicating an improvement in the data set

Zonal and Meridional Discontinuities and Other Issues with the HadISST1.1 Dataset

3) The standard deviations of the SST anomalies in the HadISST1.1 dataset are 0.2–0.4°C smaller prior to 1949 than after 1949. This nonstationarity could complicate interpretations of the long HadISST1.1 data record for some studies of climate variability. It is likely attributable mostly to the improved sampling of SST observations in the later time period.4) There is a large zonal discontinuity of SST in the HadISST1.1 dataset along 179.5°W that results in SST variations that are typically smaller in magnitude by about 0.2°C compared with the adjacent 1° grid cells to the west and east. It appears that this discontinuity becomes noticeable abruptly in 1949.1) The HadISST1.1 maps are much smoother than maps of SST from the Reynolds et al. (2007) Daily Optimal Interpolation SST (OISST) dataset. This is attributable at least partly to the coarser grid resolution of 1°×1° for HadISST1.1 compared with 0.25°×0.25° for OISST. The lower resolution of the HadISST1.1 dataset is not a major issue for many studies of large-scale climate variability.5) There are additional zonal discontinuities of SST at very regular intervals of 4° and 2° of longitude in, respectively, the pre-1949 and post-1949 portions of the HadISST1.1 data record. These discontinuities in zonal first differences of SST are manifest as step-like structures in SST itself, with typical jumps of 0.1°C prior to 1949 and 0.05°C after 1949.While all of the above issues are significant concerns, we show that the HadISST1.1 dataset is useful for studies of the large-scale signals associated with short-term climate variability (interannual to decadal time scales). The dataset is inadequate, however, for studies that require information about spatial derivatives of the SST field. An example is investigation of ocean-atmosphere interaction on oceanic mesoscales of 100–1000 km.A detailed analysis of the Version 1.1 Hadley Centre Sea Ice and Sea Surface Temperature (HadISST1.1) dataset has identified numerous problems, some of which limit the utility of the dataset for certain scientific applications. The issues identified from our analysis are:2) The standard deviations of the SST anomalies are 0.2–0.4°C smaller in the HadISST1.1 dataset than in the OISST dataset. This is likely also attributable at least partly to the coarser grid resolution of the HadISST1.1 dataset. However, the magnitudes of these differences seem larger than could be accounted for solely by the coarser resolution of the HadISST1.1 dataset.6) There are also meridional discontinuities at intervals of 4° and 2° of latitude in, respectively, the pre-1949 and post-1949 portions of the HadISST1.1 data record. The amplitudes of the meridionally oscillating striations in the standard deviations of meridional first differences are as large or larger than the amplitudes of the zonally oscillating striations in the standard deviations of zonal first differences

Variability in satellite winds over the Benguela upwelling system during 1999–2000

Wind stress variability over the Benguela upwelling system is considered using 16 months (01 August 1999 to 29 November 2000) of satellite-derived QuikSCAT wind data. Variability is investigated using a type of artificial neural network, the self-organizing map (SOM), and a wavelet analysis. The SOM and wavelet analysis are applied to an extracted data set to find that the system may be divided into six discrete wind regimes. The wavelet power spectra for these wind regions span a range of frequencies from 4 to 64 days, with each region appearing to contain distinct periodicities. To the north, 10°–23.5°S, the majority of the power occurs during austral winter, with a 4–16 day periodicity. Further investigation of National Centers for Environmental Prediction reanalysis outgoing longwave radiation data indicates that the winter intensification of wind stress off the Angolan coast is linked with convective activity over equatorial West Africa. The summer activity appears to be linked with the intensification of the Angolan heat low. Convective activity over the Congo basin appears to impact upon wind stress variability, off the Angolan coast, throughout the year. Farther south, 24°– 35°S, the majority of the power occurs in the summer. Here a bimodal distribution occurs, with peaks of 4–12 and 25–50 days. The southernmost regions appear to be forced at higher frequencies by both midlatitude cyclones (austral winter) and mesoscale coastal lows (austral summer). At lower frequencies, eastward propagating periodic wind events that originate over eastern South America appear to be important to the forcing of wind stress over the southern Benguela

At Sea Test 2 recovery cruise : Cruise 206 on board R/V Knorr April 10 - 15, 2012 Woods Hole - Woods Hole, MA

The R/V Knorr, on Cruise 206, carried out the recovery of three moorings for the Coastal and Global Scale Nodes (CGSN) Implementing Organization of the NSF Ocean Observatories Initiative. These three moorings are prototypes of the moorings to be used by CGSN at the Pioneer, Endurance, and Global Arrays. Knorr departed from Woods Hole, Massachusetts on April 10, 2012 and steamed south to the location of the mooring deployments on the shelf break. Over five days, April 10-15, Knorr surveyed the bottom at the planned mooring sites, recovered the moorings, and carried out preliminary investigations of mechanical and electrical functionality on the recovered moorings and mooring hardware, including observations of biofouling and corrosion. Knorr returned to Woods Hole on April 15, 2012.Funding was provided by the National Science Foundation contract #SA9-10 through the Consortium for Ocean Leadershi

Planktonic foraminiferal assemblages reflect warming during two recent mid-latitude marine heatwaves

Under future climate scenarios, ocean temperatures that are presently extreme and qualify as marine heatwaves (MHW) are forecasted to increase in frequency and intensity, but little is known about the impact of these events on one of the most common paleoproxies, planktonic foraminifera. Planktonic foraminifera are globally ubiquitous, shelled marine protists. Their abundances and geochemistry vary with ocean conditions and fossil specimens are commonly used to reconstruct ancient ocean conditions. Planktonic foraminiferal assemblages are known to vary globally with sea surface temperature, primary productivity, and other hydrographic conditions, but have not been studied in the context of mid-latitude MHWs. For this study, the community composition and abundance of planktonic foraminifera were quantified for 2010-2019 along the Newport Hydrographic Line, a long-term monitoring transect at 44.6°N in the Northern California Current (NCC). Samples were obtained from archived plankton tows spanning 46 to 370 km offshore during annual autumn (August – October) cruises. Two MHWs impacted the region during this timeframe: the first during 2014-2016 and a second, shorter duration MHW in 2019. During the 2014-2016 MHW, warm water subtropical and tropical foraminifera species were more prevalent than the typical polar, subpolar, and transitional species common to this region. Cold water species were abundant again after the first MHW dissipated in late 2016. During the second, shorter-duration MHW in 2019, the assemblage consisted of a warm water assemblage but did not include tropical species. The foraminiferal assemblage variability correlated with changes in temperature and salinity in the upper 100 meters and was not correlated with distance offshore or upwelling. These results suggest that fossil foraminiferal assemblages from deep sea sediment cores may provide insight into the magnitude and frequency of past MHWs

Anomalous Near-Surface Low-Salinity Pulses off the Central Oregon Coast

From mid-May to August 2011, extreme runoff in the Columbia River ranged from 14,000 to over 17,000 m³/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 Niña. 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.This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by Nature Publishing Group. The published article can be found at: www.nature.com/articles/srep1714

Better Regional Ocean Observing Through Cross-National Cooperation: A Case Study From the Northeast Pacific

The ocean knows no political borders. Ocean processes, like summertime wind-driven upwelling, stretch thousands of kilometers along the Northeast Pacific (NEP) coast. This upwelling drives marine ecosystem productivity and is modulated by weather systems and seasonal to interdecadal ocean-atmosphere variability. Major ocean currents in the NEP transport water properties such as heat, fresh water, nutrients, dissolved oxygen, pCO2, and pH close to the shore. The eastward North Pacific Current bifurcates offshore in the NEP, delivering open-ocean signals south into the California Current and north into the Gulf of Alaska. There is a large and growing number of NEP ocean observing elements operated by government agencies, Native American Tribes, First Nations groups, not-for-profit organizations, and private entities. Observing elements include moored and mobile platforms, shipboard repeat cruises, as well as land-based and estuarine stations. A wide range of multidisciplinary ocean sensors are deployed to track, for example, upwelling, downwelling, ocean productivity, harmful algal blooms, ocean acidification and hypoxia, seismic activity and tsunami wave propagation. Data delivery to shore and observatory controls are done through satellite and cell phone communication, and via seafloor cables. Remote sensing from satellites and land-based coastal radar provide broader spatial coverage, while numerical circulation and biogeochemical modeling complement ocean observing efforts. Models span from the deep ocean into the inland Salish Sea and estuaries. NEP ocean observing systems are used to understand regional processes and, together with numerical models, provide ocean forecasts. By sharing data, experiences and lessons learned, the regional ocean observatory is better than the sum of its parts

Blended sea level anomaly fields with enhanced coastal coverage along the U.S. West Coast. Version 3

We form a new data set of fields of sea level anomalies by combining gridded daily fields derived from altimeter data with coastal tide gauge data. Within approximately 50-80 km of the coast, the altimeter data are discarded and replaced by a linear interpolation between the tide gauge and remaining offshore altimeter data. A 20-year mean is subtracted from each time series (tide gauge or altimeter) before combining the data sets to form the merged sea level anomaly data set. Geostrophic velocity anomaly fields are formed from the surface heights. Daily mean fields are produced for the period 1 January 1993 - 31 December 2016. The primary validation compares geostrophic velocities calculated from the height fields and velocities measured at four moorings covering the north-south range of the new data set. The merged data set improves the alongshore (meridional) component of the currents, indicating an improvement in the data set

mean_aviso_field_1993_2012_v2.nc

We form a new data set of fields of sea level anomalies by combining gridded daily fields derived from altimeter data with coastal tide gauge data. Within approximately 50-80 km of the coast, the altimeter data are discarded and replaced by a linear interpolation between the tide gauge and remaining offshore altimeter data. A 20-year mean is subtracted from each time series (tide gauge or altimeter) before combining the data sets to form the merged sea level anomaly data set. Geostrophic velocity anomaly fields are formed from the surface heights. Daily mean fields are produced for the period 1 January 1993 - 31 December 2016. The primary validation compares geostrophic velocities calculated from the height fields and velocities measured at four moorings covering the north-south range of the new data set. The merged data set improves the alongshore (meridional) component of the currents, indicating an improvement in the data set

osu_daily_sla_geovel_v3.tar

We form a new data set of fields of sea level anomalies by combining gridded daily fields derived from altimeter data with coastal tide gauge data. Within approximately 50-80 km of the coast, the altimeter data are discarded and replaced by a linear interpolation between the tide gauge and remaining offshore altimeter data. A 20-year mean is subtracted from each time series (tide gauge or altimeter) before combining the data sets to form the merged sea level anomaly data set. Geostrophic velocity anomaly fields are formed from the surface heights. Daily mean fields are produced for the period 1 January 1993 - 31 December 2016. The primary validation compares geostrophic velocities calculated from the height fields and velocities measured at four moorings covering the north-south range of the new data set. The merged data set improves the alongshore (meridional) component of the currents, indicating an improvement in the data set