Small-scale variability of the cross-shelf flow over the outer shelf of the Ross Sea

The importance of cross-shelf transport across the Ross Sea on local and remote processes has been well documented. In the Ross Sea, mid-water intrusions of Circumpolar Deep Water (CDW) are modified by shelf water near the shelf break to form Modified Circumpolar Deep Water (MCDW). In 2010–2011, we deployed multi-platform technologies focused on this MCDW intrusion in the vicinity of Mawson and Pennell Banks to better understand its role in ecosystem processes across the shelf. The high-resolution time and space sampling provided by an underwater glider, a short-term mooring, and a ship-based survey highlight the scales over which these critical cross-shelf transport processes occur. MCDW cores were observed as small-scale well-defined features over the western slopes of Pennell and Mawson Banks. The mean transport along Pennell Bank was estimated to be about 0.24 Sv but was highly variable in time (hours to days). The observations suggest that the core of MCDW is transported by a predominately barotropic flow that follows topography around the banks toward the south until the slope of the bank flattens and the warmer water moves up and over the bank. This pathway is shown to link the source MCDW with an area of high productivity over the shallows of Pennell Bank

Wave Heights during Hurricane Katrina: An Evaluation of PPP and PPK Measurements of the Vertical Displacement of the GPS Antenna

In August 2005 the eye of Hurricane Katrina passed 49 n mi to the west of a 3-m discus buoy operated by the Central Gulf of Mexico Ocean Observing System (CenGOOS). Buoy motions were measured with a strapped-down 6 degrees of freedom accelerometer, a three-axis magnetometer, and a survey-grade GPS receiver. The significant wave heights were computed from the buoy\u27s accelerometer record and from the dual-frequency GPS measurements that were processed in two different ways. The first method was postprocessed kinematic (PPK) GPS, which requires another GPS receiver at a fixed known location, and the other was precise point positioning (PPP) GPS, which is another postprocessed positioning technique that yields absolute rather than differential positions. Unlike inertial measurement units, either GPS technique can be used to obtain both waves and water levels. The purpose of this note is to demonstrate the excellent reliability and accuracy of both methods for determining wave heights and periods from a GPS record. When the motion of the GPS antenna is properly understood as the motion of the buoy deck and not the true vertical motion of the sea surface, the GPS wave heights are as reliable as a strapped-down 1D accelerometer

Defining the ecologically relevant mixed-layer depth for Antarctica's coastal seas

Mixed‐layer depth (MLD) has been widely linked to phytoplankton dynamics in Antarctica's coastal regions; however, inconsistent definitions have made intercomparisons among region‐specific studies difficult. Using a data set with over 20,000 water column profiles corresponding to 32 Slocum glider deployments in three coastal Antarctic regions (Ross Sea, Amundsen Sea, and West Antarctic Peninsula), we evaluated the relationship between MLD and phytoplankton vertical distribution. Comparisons of these MLD estimates to an applied definition of phytoplankton bloom depth, as defined by the deepest inflection point in the chlorophyll profile, show that the maximum of buoyancy frequency is a good proxy for an ecologically relevant MLD. A quality index is used to filter profiles where MLD is not determined. Despite the different regional physical settings, we found that the MLD definition based on the maximum of buoyancy frequency best describes the depth to which phytoplankton can be mixed in Antarctica's coastal seas

Antarctic Peninsula ROMS model Palmer Deep area drifter data

Dataset: WAP model float dataAntarctic Peninsula ROMS model Palmer Deep area drifter data For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/867442NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-1745009, NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-1744884, NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-174501

Mixing and phytoplankton dynamics in a submarine canyon in the West Antarctic Peninsula

Bathymetric depressions (canyons) exist along the West Antarctic Peninsula shelf and have been linked with increased phytoplankton biomass and sustained penguin colonies. However, the physical mechanisms driving this enhanced biomass are not well understood. Using a Slocum glider data set with over 25,000 water column profiles, we evaluate the relationship between mixed layer depth (MLD, estimated using the depth of maximum buoyancy frequency) and phytoplankton vertical distribution. We use the glider deployments in the Palmer Deep region to examine seasonal and across canyon variability. Throughout the season, the ML becomes warmer and saltier, as a result of vertical mixing and advection. Shallow ML and increased stratification due to sea ice melt are linked to higher chlorophyll concentrations. Deeper mixed layers, resulting from increased wind forcing, show decreased chlorophyll, suggesting the importance of light in regulating phytoplankton productivity. Spatial variations were found in the canyon head region where local physical water column properties were associated with different biological responses, reinforcing the importance of local canyon circulation in regulating phytoplankton distribution in the region. While the mechanism initially hypothesized to produce the observed increases in phytoplankton over the canyons was the intrusion of warm, nutrient enriched modified Upper Circumpolar Deep Water (mUCDW), our analysis suggests that ML dynamics are key to increased primary production over submarine canyons in the WAP

Concepções de saúde e doença mental na perspectiva de jovens brasileiros

O estudo investiga a perspectiva de adolescentes e jovens acerca de suas concepções de saúde e doença mental. Compreende-se que o processo de construção da saúde-doença é influenciado pela perspectiva individual, familiar e sociocultural. Participaram do estudo 1163 jovens de ambos os sexos, com idade média de 15,84 anos. Utilizou-se como instrumento um questionário autoaplicável, formulado em estudo anterior com jovens suíços de língua portuguesa. Investigaram-se as concepções de saúde e doença mental, dentre outros aspectos do tema. Nos resultados, observaram-se aspectos da visão holística e do modelo tradicional de saúde mental. A doença mental foi caracterizada como uma desordem emocional, revelando a influência das experiências internas e relacionais na concepção de adoecimento mental. Diferenças de nível socioeconômico foram observadas nas concepções de saúde e doença mental.Brazilian young people perceptions of mental health and illness. The study investigates young people conceptions of health and mental illness. The theoretical approach understands that the process of construction of health and disease is influenced by individual, family and sociocultural factors. Participants were 1163 young people of both sexes with a mean age of 15.84 years. A Self-administered questionnaire was formulated in a previous study with young Portuguese-speaking Switzerland. Mental health and illness concepts were investigated and also others issues about it. In the results, we found aspects of holist and traditional concepts of mental health. Mental illness was characterized as an emotional disorder, revealing the influence of internal and relational experiences in the design of mental illness. Socioeconomic differences were observed in this concept

A Recirculating Eddy Promotes Subsurface Particle Retention in an Antarctic Biological Hotspot

Palmer Deep Canyon is one of the biological hotspots associated with deep bathymetric features along the Western Antarctic Peninsula. The upwelling of nutrient-rich Upper Circumpolar Deep Water to the surface mixed layer in the submarine canyon has been hypothesized to drive increased phytoplankton biomass productivity, attracting krill, penguins and other top predators to the region. However, observations in Palmer Deep Canyon lack a clear in-situ upwelling signal, lack a physiological response by phytoplankton to Upper Circumpolar Deep Water in laboratory experiments, and surface residence times that are too short for phytoplankton populations to reasonably respond to any locally upwelled nutrients. This suggests that enhanced local upwelling may not be the mechanism that links canyons to increased biological activity. Previous observations of isopycnal doming within the canyon suggested that a subsurface recirculating feature may be present. Here, using in-situ measurements and a circulation model, we demonstrate that the presence of a recirculating eddy may contribute to maintaining the biological hotspot by increasing the residence time at depth and retaining a distinct layer of biological particles. Neutrally buoyant particle simulations showed that residence times increase to upwards of 175 days with depth within the canyon during the austral summer. In-situ particle scattering, flow cytometry, and water samples from within the subsurface eddy suggest that retained particles are detrital in nature. Our results suggest that these seasonal, retentive features of Palmer Deep Canyon are important to the establishment of the biological hotspot

Operation and Application of a Regional High-Frequency Radar Network in the Mid-Atlantic Bight

The Mid-Atlantic Regional Coastal Ocean Observing System (MARCOOS) High- Frequency Radar Network, which comprises 13 long-range sites, 2 medium-range sites, and 12 standard-range sites, is operated as part of the Integrated Ocean Observing System. This regional implementation of the network has been operational for 2 years and has matured to the point where the radars provide consistent coverage from Cape Cod to Cape Hatteras. A concerted effort was made in the MARCOOS project to increase the resiliency of the radar stations from the elements, power issues, and other issues that can disable the hardware of the system. The quality control and assurance activities in the Mid-Atlantic Bight have been guided by the needs of the Coast Guard Search and Rescue Office. As of May,, 2009, these quality-controlled MARCOOS High-Frequency Radar totals are being served through the Coast Guard\u27s Environmental Data Server to the Coast Guard Search and Rescue Optimal Planning System. In addition to the service to U.S. Coast Guard Search and Rescue Operations, these data support water quality, physical oceanographic, and fisheries research throughout the Mid-Atlantic Bight

Annual and Seasonal Surface Circulation Over the Mid Atlantic Bight Continental Shelf Derived From a Decade of High Frequency Radar Observations

A decade (2007–2016) of hourly 6‐km‐resolution maps of the surface currents across the Mid‐Atlantic Bight (MAB) generated by a regional‐scale High Frequency Radar network are used to reveal new insights into the spatial patterns of the annual and seasonal mean surface flows. Across the 10‐year time series, temporal means and interannual and intra‐annual variability are used to quantify the variability of spatial surface current patterns. The 10‐year annual mean surface flows are weaker and mostly cross‐shelf near the coast, increasing in speed and rotating to more alongshore directions near the shelfbreak, and increasing in speed and rotating to flow off‐shelf in the southern MAB. The annual mean surface current pattern is relatively stable year to year compared to the hourly variations within a year. The 10‐year seasonal means exhibit similar current patterns, with winter and summer more cross‐shore while spring and fall transitions are more alongshore. Fall and winter mean speeds are larger and correspond to when mean winds are stronger and cross‐shore. Summer mean currents are weakest and correspond to a time when the mean wind opposes the alongshore flow. Again, intra‐annual variability is much greater than interannual, with the fall season exhibiting the most interseasonal variability in the surface current patterns. The extreme fall seasons of 2009 and 2011 are related to extremes in the wind and river discharge events caused by different persistent synoptic meteorological conditions, resulting in more or less rapid fall transitions from stratified summer to well‐mixed winter conditions

Testing the Canyon Hypothesis: Evaluating light and nutrient controls of phytoplankton growth in penguin foraging hotspots along the West Antarctic Peninsula

Biological hotspots along the West Antarctic Peninsula (WAP) are characterized by high phytoplankton productivity and biomass as well as spatially focused penguin foraging activity. While unique physical concentrating processes were identified in one of these hotspots, understanding the mechanisms driving the blooms at these locations is of high importance. Factors posited to explain the blooms include the upwelling of macronutrient‐ and micronutrient‐enriched modified Upper Circumpolar Deep Water (mUCDW) and the depth of the mixed layer influencing overall light availability for phytoplankton. Using shipboard trace‐metal clean incubation experiments in three different coastal biological hotspots spanning a north‐south gradient along the WAP, we tested the Canyon Hypothesis (upwelling) for enhanced phytoplankton growth. Diatoms dominated the Southern region, while the Northern region was characterized by a combination of diatoms and cryptophytes. There was ample concentration of macronutrients at the surface and no phytoplankton growth response was detected with the addition of nutrient‐enriched mUCDW water or iron solution to surface waters. For all treatments, addition of mUCDW showed no enhancement in phytoplankton growth, suggesting that local upwelling of nutrient‐enriched deep water in these hotspots was not the main driver of high phytoplankton biomass. Furthermore, the dynamics in the photoprotective pigments were consistent with the light levels used during these incubations showing that phytoplankton are able to photoacclimate rapidly to higher irradiances and that in situ cells are low light adapted. Light availability appears to be the critical variable for the development of hotspot phytoplankton blooms, which in turn supports the highly productive regional food web