Evaluation of Front Detection Methods for Satellite-Derived SST Data Using In Situ Observations

Sea surface temperature (SST) fronts detected in Advanced Very High Resolution Radiometer (AVHRR) data using automated edge-detection algorithms were compared to fronts found in continuous measurements of SST made aboard a ship of opportunity. Two histograms (a single-image and a multi-image method) and one gradient algorithm were tested for the occurrence of two types of errors: (a) the detection of false fronts and (b) the failure to detect fronts observed in the in situ data. False front error rates were lower for the histogram methods (27%–28%) than for the gradient method (45%). Considering only AVHRR fronts for which the SST gradient along the ship track was greater than 0.1°C km−1, error rates drop to 14% for the histogram methods and 29% for the gradient method. Missed front error rates were lower using the gradient method (16%) than the histogram methods (30%). This error rate drops significantly for the histogram methods (5%–10%) if fronts associated with small-scale SST features (km) are omitted from the comparison. These results suggest that frontal climatologies developed from the application of automated edge-detection methods to long time series of AVHRR images provide acceptably accurate statistics on front occurrence

Cross-shelf mixing and mid-shelf front dynamics in the Mid-Atlantic Bight evaluated using the radium quartet

Mid-shelf fronts (MSFs) are thought to be ubiquitous in shelf areas. However, their dynamical role in cross-shelf mixing has yet to be fully characterized. In January, February, and April of 2007, radium isotopes (223Ra, t1/2 = 11 d; 224Ra, t1/2 = 3.7 d; 226Ra, t1/2 = 1600 yr; 228Ra, t1/2 = 5.7 yr) were measured along a transect in the Mid-Atlantic Bight to constrain mixing rates at and around a MSF. Cross-shelf eddy diffusivities (Kx) were determined from 223Ra and 224Ra distributions using a variable-depth model. Two key assumptions – minimal advection and negligible benthic radium input – involving the use of 223Ra and 224Ra as tracers of mixing were quantitatively evaluated in order to assess the accuracy of the Kx estimates. Eddy diffusivities over the three-month sampling period range from 0.1 ± 0.05 – 1.6 ± 0.5 × 102 m2 s–1 for 223Ra and from 1.7 ± 0.4 – 2.2 ± 0.6 × 102 m2 s–1 for 224Ra. The temporal variability in Kx is low in comparison to the uncertainty of the derived values, indicating that eddy diffusivity in this area is relatively constant throughout the sampling period. Observations in the Mid-Atlantic Bight differ from theoretical data corresponding to the tidal dispersion frontogenesis model, suggesting that a different mechanism is responsible for MSF formation. Variability in supported 223Ra and 228Ra observed near the front indicates that cross-shelf mixing may be inhibited by MSFs. Conversely, along-shelf transport is enhanced by the front\u27s presence. These results indicate that the equatorward jet associated with the front is capable of effectively transporting dissolved chemicals over hundreds of kilometers

Ten-month-old infants infer the value of goals from the costs of actions

Infants understand that people pursue goals, but how do they learn which goals people prefer? We tested whether infants solve this problem by inverting a mental model of action planning, trading off the costs of acting against the rewards actions bring. After seeing an agent attain two goals equally often at varying costs, infants expected the agent to prefer the goal it attained through costlier actions. These expectations held across three experiments that conveyed cost through different physical path features (height, width, and incline angle), suggesting that an abstract variable—such as “force,” “work,” or “effort”—supported infants’ inferences. We modeled infants’ expectations as Bayesian inferences over utility-theoretic calculations, providing a bridge to recent quantitative accounts of action understanding in older children and adults

Enzymatic formation of hydroxy ceramides and comparison with enzymes forming nonhydroxy ceramides

Radioactive 2-hydroxystearic and cerebronic acids were converted to the coenzyme A thio esters, then tested for reactivity with -sphingosine. Microsomes from mouse brain were found to catalyze the formation of ceramides containing both hydroxy acids. Both the - and -forms of the hydroxy acids reacted. Comparisons of reactivity were made with stearoyl and lignoceroyl CoA, the analogous nonhydroxy acids, which also form ceramides. The ratios of activities of the substrates were found to vary with animal age, with various subcellular fractions, with different rat brain cell preparations, and with different mouse organs. Competition experiments with mixtures of thio ester substrates showed that stearate and lignocerate did not interfere with each other in the formation of ceramide, but hydroxystearoyl CoA inhibited the utilization of the two nonhydroxy substrates and cerebronoyl CoA inhibited the utilization of lignoceroyl CoA. The kinetics of the inhibitions indicated that the effects were noncompetitive. A similar type of inhibition was seen with stearoyl CoA against hydroxystearate incorporation. On the basis of these findings, we suggest that four different enzymes are involved in the acyl transfer reaction: for stearate, hydroxystearate, lignocerate, and cerebronate. Neuronal cell preparations were found to be relatively rich in stearate transferase, while glial cells were relatively rich in hydroxystearate and lignocerate transferases.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34029/1/0000306.pd

Assessing the Multiple Impacts of Extreme Hurricanes in Southern New England, USA

The southern New England coast of the United States is particularly vulnerable to land-falling hurricanes because of its east-west orientation. The impact of two major hurricanes on the city of Providence (Rhode Island, USA) during the middle decades of the 20th century spurred the construction of the Fox Point Hurricane Barrier (FPHB) to protect the city from storm surge flooding. Although the Rhode Island/Narragansett Bay area has not experienced a major hurricane for several decades, increased coastal development along with potentially increased hurricane activity associated with climate change motivates an assessment of the impacts of a major hurricane on the region. The ocean/estuary response to an extreme hurricane is simulated using a high-resolution implementation of the ADvanced CIRCulation (ADCIRC) model coupled to the Precipitation-Runoff Modeling System (PRMS). The storm surge response in ADCIRC is first verified with a simulation of a historical hurricane that made landfall in southern New England. The storm surge and the hydrological models are then forced with winds and rainfall from a hypothetical hurricane dubbed “Rhody”, which has many of the characteristics of historical storms that have impacted the region. Rhody makes landfall just west of Narragansett Bay, and after passing north of the Bay, executes a loop to the east and the south before making a second landfall. Results are presented for three versions of Rhody, varying in the maximum wind speed at landfall. The storm surge resulting from the strongest Rhody version (weak Saffir–Simpson category five) during the first landfall exceeds 7 m in height in Providence at the north end of the Bay. This exceeds the height of the FPHB, resulting in flooding in Providence. A simulation including river inflow computed from the runoff model indicates that if the Barrier remains closed and its pumps fail (for example, because of a power outage or equipment failure), severe flooding occurs north of the FPHB due to impoundment of the river inflow. These results show that northern Narragansett Bay could be particularly vulnerable to both storm surge and rainfall-driven flooding, especially if the FPHB suffers a power outage. They also demonstrate that, for wind-driven storm surge alone under present sea level conditions, the FPHB will protect Providence for hurricanes less intense than category five

Observation of diurnal variations in mesoscale eddy sea-surface currents using GOCI data

The surface current field of a mesoscale eddy in the East Sea (Sea of Japan) was derived from consecutive Geostationary Ocean Color Imager chlorophyll-a (chl-a) concentration images using the normalized maximum cross-correlation method. The estimated current field of the eddy exhibited anticyclonic structure demonstrated by the objective dynamic thresholds of correlation coefficients. The eddy periphery was defined by fitting an ellipse to subjectively selected points from the frontal map of chl-a concentration data. Radial distribution and hourly variation of the current speed around the eddy were presented. In terms of the magnitude and direction, the estimated current field was in good agreement with altimeter-based current field and current vectors from surface drifters. Diurnal variations in the current speeds of the mesoscale eddies showed a quadratic relation to the wind speed

Розвиток творчої активності студентів-гітаристів через імпровізацію під час роботи над музичним твором

(uk) У статті розглядається питання розвитку творчої активності студентів-гітарістів. Надається обґрунтування того, що одним з ефективних засобів розвитку творчої активності студентів-гітарістів є високий рівень засвоєння прийомів імпровізації на заняттях з основного музичного інструменту. Наголошується, що розвиток творчого потенціалу в процесі музично-творчої діяльності студентів буде ефективним за умов здійснення педагогічного керівництва.(ru) В статье рассматривается вопрос развития творческой активности студентов-гитаристов. Предоставляется обоснование того, что одним из эффективных средств развития творческой активности студентов-гитаристов является высокий уровень усвоения приемов импровизации на занятиях основного музыкального инструмента. Отмечается, что развитие творческого потенциала в процессе музыкально-творческой деятельности студентов будет эффективным в условиях осуществления педагогического руководства.(en) This article deals with the development of the creative activity of students guitarists. The ground of being one of the most effective means of creative activity of students guitarists is a high level of mastering techniques of improvisation in the classroom with the main musical instrument. It is noted that the development of creativity in the process of musical and creative activities students will be effective on condition that educational leadership. ndependent work on a musical composition is a productive form of developing students creative musical thinking. In the work plan of the students must be enabled as works of high complexity and fragments or themes from the works that are very difficult to implement fully. The basic weight school repertoire is designed for self-study students

The front on the Northern Flank of Georges Bank in spring : 2. Cross-frontal fluxes and mixing

Hydrographic observations made with an undulating vehicle carrying a CTD and concurrent shipboard ADCP velocity observations over a 12‐day period are combined to investigate vertical mixing and cross‐frontal fluxes on the Northern Flank of Georges Bank. The CTD density time series is analyzed to detect the presence of vertical overturns, the statistics of which are used to infer vertical mixing parameters. Vertical turbulent buoyancy fluxes are downward and most intense, reaching values of 5 × 10−7 W/kg, near the bottom at the edge of the bank and decrease both on‐ and off‐bank. Horizontal, cross‐bank buoyancy fluxes are partitioned into mean, tidal pumping, and nontidal eddy components and are computed as a function of cross‐isobath/vertical position by averaging in the along‐isobath direction. The tidal pumping component is dominant over most of the cross‐bank section with a peak value of ∼1 × 10−4 W/kg, directed off‐bank near the bank edge. A diagnosed tidal vertical velocity field is used with mean buoyancy gradients to compute the along‐isopycnal skew flux. The horizontal component of this skew flux has similar spatial structure and magnitude to that of the observed tidal pumping flux. The divergent component of the skew flux, at depths above the bottom boundary layer, appears to be convergent north of the bank edge and divergent at the bank edge, suggesting that tidally driven advective processes drive buoyant bank water downward and off‐bank at mid‐depth and force the upwelling of deep, dense water near the bottom at the bank edge