Robert O. Reid

A Meta-Analysis of the Academic Status of Students with Emotional/Behavioral Disturbance

Emotional/behavioral disturbance (EBD) is characterized by a range of behaviors that adversely affect a childs academic performance and cannot be explained by other sensory or health impairments. Although research has clearly demonstrated that children and youth with EBD tend to exhibit high rates of problem behavior, research on the characteristics of their academic performance has been less clear. This article reports the results of a meta-analysis of the academic status of students with EBD. The overall effect size was −.64, which indicated that students with EBD had significant deficits in academic achievement. An examination of moderators (subject area, setting, and age) indicated that students with EBD performed at a significantly lower level than did students without disabilities across academic subjects and settings; greater deficits were not observed in older students with EBD (i.e., those more than 12 years old), as compared to younger students. Implications and areas for future research are discussed.

Near‐inertial oscillations over the Texas‐Louisiana shelf

Wind-induced, near-inertial oscillations over the Texas-Louisiana shelf in spring and summer 1992 are described using the current and wind observations taken during the first year of the Texas-Louisiana Shelf Circulation and Transport Processes Study (LATEX A). Rotary spectral analysis shows clockwise-rotating energy peaks at near-inertial frequencies for records from all current meter moorings after the suppression of principal tidal signals. The vertical structure of near-inertial oscillations is characterized by a first baroclinic mode with a near 180° phase difference between the upper mixed layer and the lower stratified layer. The oscillations are intermittent with a modulation timescale of about 5–10 days. They are surface-intensified and have maximum values near the shelf break, decaying gradually toward the coast but rapidly offshore. Near-inertial oscillations appear to accompany a sudden change of the wind stress during frontal passages. Diagnostic analysis suggests that the large near-inertial oscillations over the LATEX shelf are mainly generated by high-frequency (near-inertial) variation of the wind stress accompanying the passage of atmospheric fronts. When the downward transfer of the near-inertial energy to the deep stratified layer is small, a simple mixed layer model forced by the observed wind stress provides a reasonable prediction of the near-inertial currents in the mixed layer.

Characterization of the principal tidal current constituents on the Texas‐Louisiana shelf

We analyzed 81 current meter records of varying lengths (3 to 30 months) to describe the principal diurnal (O1, K1, P1, and Q1) and semidiurnal (S2, M2, K2, and N2) tidal current constituents on the Texas-Louisiana continental shelf. The Louisiana-Texas Shelf Physical Oceanography Program (LATEX) had 81 current meters at 31 sites and varying depths from April 1992 to December 1994. The local inertial period range across the shelf (24.4 hours to 26.2 hours) and thermal diurnal cycling during the summer season make it difficult to estimate the diurnal tidal constituents. Dominant tidal modes on the shelf are K1, O1, and M2. Absolute and relative energy contained in each tidal constituent varies with shelf location. The northeast corner of the shelf, near Atchafalaya Bay, has the largest tidal currents with maximum surface current amplitudes (at 3 m depth) of about 9 cm s−1, while typical maximum tidal surface currents near the shelf break are between 1 and 2 cm s−1 for each of the K1, O1, and M2 components. In general, the surface tidal currents decrease in magnitude as water depth increases toward the shelf break, although the semidiurnal components are amplified more at midshelf locations than the diurnal components. Examination of tidal ellipses at different depths suggests that the M2 tide has less vertical structure, while the diurnal tides exhibit more shear, particularly at the more shallow locations. Sea surface height constituents estimated at five locations along the Texas-Louisiana coast are in agreement with historical values.

Low‐Frequency Circulation Over the Texas‐Louisiana Continental Shelf

Low-frequency circulation over the Texas-Louisiana continental shelf is examined. Currents over the inner shelf are upcoast (Rio Grande to Mississippi River) in summer and downcoast in nonsummer and are driven by an annual cycle of winds. This results in an annual signal for salinity, with lowest salinity waters occurring (a) in late spring along the inner portion of the western shelf when downcoast flows carry the high discharges from the Mississippi-Atchafalya and other rivers to the Mexican border, and (b) in summer over the inner and outer eastern shelf when the upcoast flow causes a pooling of the discharges from the Mississippi-Atchafalya rivers over that shelf. Upcoast winds during summer also result in high salinities over the western shelf due to advection from off Mexico and upwelling. Currents over the outer shelf are variable, but predominantly upcoast throughout the year, probably a result of the integrated effects of anticy-clonic eddies impinging on the shelf edge. Comparison of currents in the weather band (2-10 d) with the mesoscale band (10-100 d) suggests the shelf is divided at approximately the 50-m isobath. The weather band predominates over the inner shelf, reflecting frequent passage of fronts over the region. The mesoscale band predominates over the outer shelf, indicating the presence of offshelf eddies that frequent this region.

Mean hydrographic fields and their interannual variability over the Texas-Louisiana continental shelf in spring, summer, and fall

New hydrographic data from the Texas-Louisiana continental shelf were combined with data from older cruises covering significant portions of this shelf to produce spatial distributions of surface and bottom temperature and salinity as well as of surface geopotential anomaly relative to 70 dbar. These were used to calculate mean fields with their standard deviations for spring (May), summer (July–August), and fall (November). For each season, histograms were prepared of differences between properties in the individual fields and our seasonal mean values at each grid point in the individual fields. These histograms have highly tuned Gaussian distributions centered on zero differences, proving that a distribution selected randomly will likely be quite similar to the mean for the season in which the sample was made. The individual fields of salinity for summer and geopotential anomaly for spring are included for comparison with the mean fields. The mean fields, produced by adding a large data set to that used by Cochrane and Kelly [1986], substantiate the bimodal annual patterns of circulation and property distributions over the inner shelf region described by them. Essentially, there is downcoast (directed from the Mississippi toward Brownsville) nearshore flow except during the summer months. That flow is driven by downcoast along-shelf wind and enhanced by Mississippi-Atchafalaya River discharge. In July and August the average wind has an upcoast component and the nearshore flow is reversed. Patterns and values of the standard deviations are used to infer causes and magnitudes of interannual variability, respectively. Three examples of anomalous property distributions are presented to illustrate the effects of the principal external forcing mechanisms affecting interannual variability on the Texas-Louisiana shelf. These mechanisms are wind stress, Mississippi-Atchafalaya River discharge, and mesoscale eddies in the offshore circulation near the shelf-slope break. For each cruise examined, residuals of geopotential anomaly and surface salinity relative to the seasonal mean are examined in relation to departures of river discharge from the long-term (64 year) average and an index of along-shelf wind component appropriate to the times of the cruises. The residuals of geopotential anomaly were found to be significantly negatively correlated with those of surface salinity, with an intercept of approximately zero indicating that salinity plays the dominant role relative to temperature in year-to-year variability of the geopotential anomaly. Positive river discharge residuals were correlated with negative surface salinity residuals; enhanced downcoast wind resulted in negative surface salinity residuals; and enhanced upcoast wind resulted in positive surface salinity residuals. Most correlations were significant (different from zero) at the 95% confidence level.

Seasonal variation of wind-driven diurnal current cycling on the Texas-Louisiana Continental Shelf

We describe observations of large amplitude wind-driven current oscillations of 24-hr period occurring in the near-surface layer of waters of the Texas-Louisiana continental shelf. The near-surface anti-cyclonic current amplitudes can reach 60 cm s−1 and represent the largest non-storm induced high-frequency currents on the shelf. These currents can persist for a week or more, as long as driving diurnal winds persist with uninterrupted phase. The latitude of the shelf and the diurnal period of the wind-forcing combine to produce conditions for a near-resonant response of the surface currents to the wind stress, such that, the resulting currents are almost an order of magnitude greater than those found from steady Ekman drift. The oscillations are phase-locked to time of day suggesting a connection to the daily cycle of heating and cooling. The oscillations generally occur during the summer months when there is a shallow mixed layer, strong vertical stratification, maximum insolation, and infrequent frontal passages.

Analyzed Surface Meteorological Fields over the Northwestern Gulf of Mexico for 1992–94: Mean, Seasonal, and Monthly Patterns

Abstract The primary objective of this work is to formulate surface meteorological fields over the northwestern Gulf of Mexico for the period from April 1992 through November 1994 useful for the study of mesoscale processes and for model forcing of the near-coastal circulation. Observations were adjusted to standard heights, and a method of statistical interpolation was applied to time series of in situ observations to produce the required surface fields. Resulting monthly and seasonal mean fields show two principal patterns over the Texas-Louisiana shelf region—for summer and nonsummer. From June through August, surface winds are relatively constant, with alongshore wind components generally directed upcoast (from Mexico toward the Mississippi Delta). In other (nonsummer) months, surface winds are much more variable with alongshore wind components generally directed downcoast. The relatively large interannual variability is illustrated. Using these meteorological fields together with rather complete ocea...

A Statistical Description of the Velocity Fields from Upper Ocean Drifters in the Gulf of Mexico

We analyzed 1397 drifter records collected in the Gulf of Mexico and northwestern Cayman Basin between the years 1989 and 1999 to describe the general features of the upper ocean circulation. These drifters were generally drogued at 50 m below the surface and exclude those of the Surface CUrrent Lagrangian Program (SCULP). In addition to the dominant flows through the Yucatan Channel and Straits of Florida, robust circulation features clearly seen include: a weak cyclone south of 21°N in the Bay of Campeche, westward zonal flow across the Gulf between 21°N and 24°N, a northward western boundary current between 95°W and 97°W and 24°N and 26°N, mean downcoast (westward) flow on the Texas-Louisiana shelf, highly variable mean flow on the shelves and slope of the northeastern Gulf, mean upcoast (southward) flow on the lower West Florida Shelf, and a large region of high variability in the deep regions of the central Gulf of Mexico. Although much of the driving of the Gulf of Mexico is attributed to currents associated with the Loop Current and its associated Loop Current Eddies (particularly in the deep waters), other features can be directly correlated with seasonal wind driving, particularly on the shelves of the northern Gulf, near the western boundary, and in the Bay of Campeche.

Spatial‐scale analysis of hydrographic data over the Texas‐Louisiana continental shelf

On the basis of hydrographic data collected by the Texas-Louisiana Shelf Circulation and Transport Processes Study (LATEX A) and on earlier cruises, we examined the energetic scales of spatial variability over the Texas-Louisiana continental shelf. Shelf-scale spatial reference fields were sought to represent the general distributions of circulation and water properties over the shelf at the time of the observations. Various methods were explored for determining such reference fields of potential temperature, salinity, and geopotential anomaly at the sea surface relative to 70 dB. Spatial reference fields obtained from mean May fields and from polynomials fitted to individual May cruise data were compared. On the basis of those comparisons, quadratics were selected to fit property distributions from individual cruises and so to yield reference fields. Smaller-scale anomaly fields were obtained by removing the reference fields from the observed distributions. Calculation of correlation versus separation distance based on these anomaly fields then allowed estimation of spatial scales of anomaly fields for cross-shelf and along-shelf transects. The zero-crossing scale and the Gaussian decay scale are shown to be essentially the same, and the zero-crossing scale is used. The principal results for the anomaly scales are (1) cross-shelf scales over the western shelf are shorter (order 15 km) than those in the eastern and central regions (order 20 km), (2) along-shelf spatial scales are of the order of 35 km, (3) there is no significant difference in cross-shelf scales at the surface, middepth, and bottom, and (4) along-shelf scales are essentially the same over the western and eastern regions of the shelf, over the midshelf (50-m isobath) and along the shelf break (200-m isobath), and at different depths along the 200-m isobath. The same spatial scales are found when using data with spatial resolution of 1–10 km cross shelf and 10–20 along shelf to obtain the anomaly fields, so the data resolution used is adequate to represent the scales. The variances of the observed (shelf-wide) salinity, temperature, and geopotential anomaly are greater cross shelf than along shelf. The variance of the cross-shelf anomaly fields is around 10% of the shelf-wide fields; that of the along-shelf anomaly fields is about 35% of that in the shelf-wide fields. The analysis of scales when grouped by season did not show persuasive evidence of seasonal variation.

Bay of campeche circulation : An update

We address four independent sources of observational evidence pertaining to circulation in the Bay of Campeche (BOC), located south of 23°N in the western Gulf of Mexico, with the objective of characterizing its mean circulation, its variability, and the probable forcing thereof. The observational information includes historic hydrographic and dissolved oxygen data, Lagrangian current data, satellite-derived sea surface height anomaly (SSHA), and special observations of marine winds in the BOC. The hydrographic data reveals that the mean surface circulation relative to 425 db and to 800 db includes a weak cyclone with cyclic transport of about 4x10 6 m 3 .s -1 . Ten years of near-surface drifter observations shows a statistically meaningful mean cyclonic pattern of current with westward intensification that is consistent with the mean surface dynamic topography relative to 800 db. Observations of mean currents in the BOC at 900 m based on deep floats by G. L. Weatherly and others allows estimation of the current shear from the Lagrangian data and this is geostrophically consistent with that from the dynamic topography relative to 800 m. The mean cyclonic wind stress curl field deduced from two sources of marine wind data indicate a forced Sverdrup transport consistent with that observed. Moreover a seasonal cycle is suggested in the near surface drifter data that is coherent with the seasonal signal in the wind stress curl. Finally, the historic SSHA for a period of over 8 years in the 1990s allows a characterization of the dominant empirical spatial patterns and their temporal variability.