Fred M. Vukovich

Cyclonic Eddies in the Eastern Gulf of Mexico

Abstract Cold-domed cyclonic eddies juxtaposed to the cyclonic shear side of the Gulf Loop Current are observed in simultaneously obtained hydrographic, current meter mooring, and satellite infrared data. The cyclones are initially observed in the satellite data as cold perturbations on the northern extreme of the current and grow either into a cold tongue or a quasi-stable meander off the Dry Tortugas Florida. Areal shipboard surveys show closed isopleths of temperature and salinity, and surface geostrophic current speeds relative to 1000 db are in excess of 100 cm s−1. The diameter of the cold domes varied from 80 to 120 km. Separation of large anticyclonic rings is always observed to be preceded by cyclonic eddies in the transition zone between Campeche Bank and the West Florida Shelf, but only on the eastern side. Not every cyclonic eddy off Dry Tortups is associated with the separation of an anticyclonic ring; some are eroded away by the Florida Current, but they have never been observed in 10 years ...

An updated evaluation of the Loop Current's eddy‐shedding frequency

The Loop Currents eddy-shedding frequency was reevaluated using two existing data sets which were updated with 5 years of additional data. The data sets are a 22-year data set (1972–1993) on the eddy-shedding period and a 17-year data set (1977–1993) of the monthly averaged distance between the northern boundary of the Loop Current and the 30°N latitude line. Only Loop Current eddies having diameters larger than 250 km were considered in this study. The histogram of the eddy-shedding periods indicated that there is a primary mode (9 months) and a secondary mode (14 months). The range in the data is from 6.0 to 17 months, and the average period is 11 months, with a standard deviation of ±3 months. In the histogram of the eddy-shedding periods the frequency of occurrence for the 11-month period is smaller than those for the primary and secondary modes. However, the 11-month period will have a frequency of occurrence identical to the secondary mode, with only one more occurrence of the 11-month period and identical to the primary mode, with two more occurrences. The spectrum of the Loop Currents northern boundary displacements indicated that the predominant period was 11.1 months, which conformed to the average separation period.

Climatology of Ocean Features in the Gulf of Mexico Using Satellite Remote Sensing Data

Summary report on a project that used twelve different statistics to develop a climatology of currents in the Gulf of Mexico. The results are advantageous for planning future programs, providing information for environmental impact statements, furthering additional studies, and guiding oil and gas exploration.

Regional-scale boundary layer ozone variations in the eastern United States and their association with meteorological variations

Abstract Four regions (north, northeast, south, and southeast regions) were established in the eastern United States to study the variation of the diurnal maximum ozone concentration (DMOC) at the surface with the variation of certain surface meteorological parameters over two 31 day periods, 15 June to 15 July 1990 and 1–31 July 1988. The DMOC variations in the south region were different from those in the north, northeast, and southeast regions. In the north, northeast, and southeast regions, ozone increases and decreases occurred almost simultaneously, whereas in the south region, ozone variations were often out of phase with the other regions. The north, northeast, and southeast regions were directly affected by the same migratory high-pressure systems, if not simultaneously at least consecutively; but these high-pressure systems seldom moved directly into the south region. The south region was affected either by the peripheral regions of these high-pressure systems or by the weak and not well-organized migratory systems that had very little influence in the north, northeast, and southeast regions.

An Analysis of the Ground Temperature and Reflectivity Pattern about St. Louis, Missouri, Using HCMM Satellite Data

Abstract Ground temperatures and reflectivity patterns have been examined for the area in and surrounding St. Louis, Missouri, using HCMM satellite data. Analyses demonstrate marked seasonal and day/night differences. In the warm season and during the day, the ground temperature distribution is influenced by small-scale land use features. The temperature contrast between the urban and rural region averages about 4.3°C. In the cold season and during the daytime, the pattern is similar to that found in the warm season, but the temperature contrasts are not as large (the temperature contrast between the urban and rum region is 2.4°C). At night, the ground temperature pattern does not show a strong dependence on small-scale land-use features. The temperature contrast between the urban and rural regions is about 2.5°C, which is similar to that found in the cold season during the day. The reflectivity is low in the central portion of St. Louis and in other smaller urban areas surrounding St. Louis. Difference i...

A Theoretical Study of the St. Louis Heat Island: The Wind and Temperature Distribution

Abstract A three-dimensional primitive equation model was used to study the St. Louis heat island. In this paper, the influence of synoptic wind speed and wind direction on the heat island is presented. With respect to the synoptic wind speed, it was found that the temperature and wind distribution associated with the St. Louis heat island changed markedly as the wind speed increased. When the synoptic wind speed was small, the intensity of the heat island was independent of the wind direction. However, for large synoptic wind speeds, the intensity of the heat island changed, and the change was dependent on the wind direction. These changes were due to the influence of the local topography.

The photochemistry of synoptic-scale ozone synthesis Implications for the global tropospheric ozone budget

The oxidation of nonmethane hydrocarbons represents a source of tropospheric ozone that is primarily confined to the boundary layers of several highly industrialized regions. (Each region has an area greater than one million km2). Using a photochemical model, the global tropospheric ozone budget is reexamined by including the in-situ production from these localized regimes. The results from these calculations suggest that the net source due to this photochemistry, which takes place on the synoptic scale, is approximately as large as the amount calculated for global scale photochemical processes which consider only the oxidation of methane and carbon monoxide. Such a finding may have a considerable impact on our understanding of the tropospheric ozone budget. The model results for ozone show reasonable agreement with the climatological summer distribution of ozone and the oxides of nitrogen at the surface and with the vertical distribution of ozone and nonmethane hydrocarbons obtained during a 1980 field program.

A Theoretical Study of the St. Louis Heat Island: Some Parameter Variations

Abstract A sensitivity analysis was performed to determine the more important parameters affecting the urban heat island circulation in St. Louis. The effects of heat island intensity, surface roughness, horizontal diffusion and boundary layer stability on the heat island circulation were studied using a three-dimensional primitive equation model. The results indicated that the heat island intensity and boundary layer stability play the dominant roles in the heat island circulation.

Interaction of a Warm Ring with the Western Slope in the Gulf of Mexico

Abstract Between November 1985 and May 1986, a warm ring encountered the western slope in the Gulf of Mexico, moved away from the slope, and began to dissipate. Before encountering the slope, the ring was quasi-circular. After encountering the slope, it became elliptically shaped with a center of circulation that changed position rapidly and erratically. The major axis of the ring rotated rapidly in a clockwise sense as the ring increased in size, most probably through interaction with two other rings in the western Gulf. During this period, neither satellite nor in situ data indicated large-scale exchange of shelf and ring water. When the ring moved eastward, then southward, away from the slope, it was observed to decrease in size by a factor of 3 to 5; the upper layer manifestation of the ring had weakened considerably. To the north of the center of the ring was a cyclonic feature which was apparently coupled to the ring and remained so throughout the period examined. The cyclone was quasi-circular and ...

Total ozone mapping by integrating databases from remote sensing instruments and empirical models

Atmospheric studies often require the generation of high-resolution maps of ozone distribution across space and time. The high natural variability of ozone concentrations and the different levels of accuracy of the algorithms used to generate data from remote sensing instruments introduce major sources of uncertainty in ozone modeling and mapping. These aspects of atmospheric ozone distribution cannot be confronted satisfactorily by means of conventional interpolation and statistical data analysis. We suggest that the techniques of Modern Spatiotemporal Geostatistics (MSG) can be used efficiently to integrate salient (although of varying uncertainty) physical knowledge bases about atmospheric ozone in order to generate and update realistic pictures of ozone distribution across space and time. The MSG techniques rely on a powerful scientific methodology that does not make the restrictive modeling assumptions of previous techniques. A numerical study is discussed involving datasets generated by measuring instruments onboard the Nimbus 7 satellite. In addition to exact (hard) ozone data, the MSG techniques process uncertain measurements and secondary (soft) information in terms of total ozone-tropopause pressure empirical relationships. Nonlinear estimators are used, in general, and non-Gaussian probability laws are automatically incorporated. The proposed total ozone analysis can take into consideration major sources of error in the Total Ozone Mapping Spectrometer solar backscatter ultraviolet tropospheric ozone residual (related to data sampling, etc.) and produce high spatial resolution maps that are more accurate and informative than those obtained by conventional interpolation techniques.