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Lake Mohave Geophysical Survey 2002: GIS Data Release
OF 2004-1247


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Introduction

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Navigation:

Navigation is available in two formats: ASCII field navigation and Environmental Systems Research Institute (ESRI) formatted shapefiles. All of these files are contained in the data/nav directory.

Field Navigation:

These files represent the raw navigation files that were collected during the survey using a USGS plugger GPS navigation system. These data were recorded using Coastal Oceanographics Hypack software. WARNING: These files have not been checked for errors. In particular be aware of zero depths from the fathometer when that system was not in operation. Use with caution.

Format:

The navigation is stored in an ASCII file using four fields separated by commas.

Field 1: Date and time (GMT): julian day(xxx):hour(xx):minute(xx): second(xx)
(note that time fields are colon delimited)
Field 2: Longitude (decimal degrees)
Field 3: Latitude (decimal degrees)
Field 4: Depth from fathometer (in meters - add 1 to 1.5 meters to account for draft)

Download ZIP file: hypackall.zip


ESRI Shapefiles:

The data/nav directory also contains trackline and shotpoint navigation shapefiles. The trackline shapefiles are polylines indicating where seismic-reflection and sidescan-sonar data were acquired during the survey. The data are in geographic coordinates, NAD83. The shotpoint navigation enables the seismic-reflection profiles to be spatially correlated based on shotpoint fixes. These shapefiles are 100 shotpoint intervals or 500 shotpoint intervals. In each case, the first and last navigated shotpoint is retained. All of these shapefiles can either be read directly from the CD, or by transferring the "zipped" files to a preferred location and uncompressing them.

These shapefiles are intended to be opened and viewed with the ESRI ArcView or ArcGIS software. For those individuals who do not have the ESRI software or a compatible GIS data browser on their computer, a free viewer, ArcExplorer, is available from ESRI (www.esri.com/software/arcexplorer/). Please note that the ArcExplorer software is limited to the Microsoft Windows operating systems and some UNIX operating systems.

These compressed files were created using the Windows program WINZIP v8.0. For those users who do not have software capable of uncompressing the files, software may be obtained from www.winzip.com or www.pkzip.com.

Download ZIP Files: sidescan tracklines, seismic tracklines, shotpoint nav (100 shots, 500 shots).


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