Introduction | Geomorphology | VectorsLake Ontario Gridded Data
This CD-ROM contains 3-arc-second 1 degree in latitude by 1 degree in longitude elevation grids with corresponding shaded relief images (which will print on 8.5"x11" paper). Gridded data for the lake are referenced to meters above sea level in the Grddasg2/griddata directory and below lake level in the Grddasg2/grid_ds directory. The gridded data for land are referenced to meters above sea level. Easy access is provided to the images and to the Grid Translator (for MS Windows® 95/98/NT, UNIX, and Linux users), which enables downloading custom grids into one of several common grid formats at a variety of resolutions by clicking on the button above (or below). There is an extensive help system available for this section of the CD-ROM that was originally designed for NGDC's Coastal Relief Model. The Coastal Relief Model combines survey data from the National Ocean Service Hydrographic Data Base (NOSHDB) and multibeam data from various academic institutions with US Geological Survey DEM grids to create a gridded database of coastal zone elevations.
This Lake Ontario bathymetric gridded dataset, part of the Great Lakes gridded data, was generated using digital contours compiled from US and Canadian digital and analog survey data, while the Coastal Relief Model bathymetric dataset was generated with digital soundings exclusively. All of the gridded data in the lake bounded by -80W, 44N and -76W, 43N (-78W, 45N and -76W, 44N) are from the bathymetric vectors. Topographic data in the grids bounded by boxes -80W, 45N and -77W, 44.5N (-77.5W, 44.5N and -77W, 44N) are from the GLOBE dataset (30 arc seconds). Topographic gridded data bounded by -80W, 44.5N and -77.5W, 44N are from the Geological Survey of Canada (30 meters). All other land data are from the USGS 3 arc second gridded dataset. The white areas on these maps are areas of the CD-ROM grids that contain no gridded data (NaN). It should be noted that the land gridded data does have artificial boundaries that show up between the different datasets used for land. This is to be expected when using different resolution datasets. The land grids used may not even be the best available at this point in time. Our primary purpose has been to provide Lake Ontario's bathymetry. The land data is provided only as a reference to the new Lake Ontario Bathymetry.
Portions of the Coastal Relief Model software used for this section of the CD-ROM and corresponding help text are not applicable to the Lake Ontario gridded data because of the differences in source data. Specifically, Grid Radius, part of the software that allows the user to choose the distances to the nearest original data point for computing the value of each grid cell, will not function since it requires access to point source distribution files as opposed to vector files for Lake Ontario presented on this CD-ROM.
To access the grids click on the button below or above.
Introduction | Geomorphology | Vectors