No abstract

No abstract

No abstract

Most data visualization systems only show static data or produce "canned" movies of time-varying data. Others incorporate visualization in real-time monitoring but these are generally customized to the particular application. The ability to interactively navigate through geospatial data is common but interactive navigation along the time dimension is not. And yet, visualization of data from interacting dynamic systems is increasingly necessary to interpret biological process, physical oceanographic processes, the motion of instrument platforms (such as ships, ROVs and AUVs), and the interactions between all of these. To address this need, we have enhanced our GeoZui3D system so that it seamlessly handles multiple time varying data sets: anything can be handled that can be represented through time varying surfaces, curved colored lines, curved colored tubes, arrow arrays, or color-, shape-, and size-coded points. The system can be used in both real-time and replay modes and data sets that have different sampling rates can still be visualized together. GeoZui3D can visualize events over a wide range of time scales from sensor readings at the millisecond scale to glacial movements evolving over tens of thousands of years. The system is illustrated with examples from collaborative research projects including modeled ocean and estuarine currents, tides, ship movements, changes in surface topography, AUV and ROV movements and the movements of marine mammals.

No abstract

No abstract

In this study of ship tracks, Moderate Resolution Imaging Spectroradiometer (MODIS) measurements from late-morning (Terra) and early-afternoon (Aqua) Earth Observing System platforms are analyzed in five separate geographically distributed cases to compare estimates of the sizes (and their changes in time) of droplets associated with ship exhaust. Ship tracks are readily detected in near-infrared imagery as bright features, especially in 2.13-mm observations. The Terra ''MOD06'' and Aqua ''MYD06'' cloud products are used to determine the effective radius of the ship-track droplets; droplet age (time in the atmosphere) is estimated as a function of the distance from the ship. Terra and Aqua MODIS estimates of droplet sizes in ship-track plumes are found to be in agreement, with a correlation greater than 0.90; for the cases studied, droplet sizes in the ship plumes are between 6 and 18 mm. Moreover, the droplets' size growth rates inferred from the length of the ship track were found to average between 0.5 and 1.0 mm h 21 .

Hog Island Bay, Virginia, is a shallow back barrier lagoon that is subject to seasonal inputs of inorganic nitrogen and related episodes of hypoxia. Numerical simulations were carried out to estimate the importance of physical flushing times relative to biochemical turnover times known to be a few days or less within the system. A 2D vertically averaged finite element hydrodynamic model, which was designed to accommodate regular flooding and dewatering of shallow flats and marshes, was coupled with a particle tracking model to estimate median lagoon residence time and the spatial distribution of local residence time in the lagoon. The model was forced with observed tidal elevations and winds from the end of the growing season when hypoxia tends to occur. The median residence time estimated by numerical modeling is on the order of weeks (358 hours), and variations in tidal stage, tidal range and wind produced deviations in median residence time on the order of days. Residence times near the inlets were very short, while those near the mainland were long, showing that (i) horizontal mixing in the Bay is insufficient to successfully apply integral methods to obtain residence times, and (ii) residence times near the mainland are long compared to timescales of biologically driven chemical transformations.