BATHYMETRIC VALUES FROM CONTOUR MAP DIGITIZING


Acceptance and utilization of LTER data requires that:


BATHYMETRIC VALUES FROM CONTOUR MAP DIGITIZING

FILE NAME: bthdigit.docDocument File (Ascii Format)
bthdigit.datData File (Comma Delimited Ascii Format)
bthdigit.txtData File (MS-DOS Text File - Table Layout).

PRINCIPAL INVESTIGATOR: John Priscu
Address:Department of Biology, Montana State University, Bozeman MT, 59717
Phone:(406)994-3250
E-Mail:ubijp@gemini.oscs.montana.edu or JPriscu@LTERnet.edu

OTHERS: Peter Doran
Address:University of Illinois at Chicago
Department of Earth and Environmental Sciences
845 W. Taylor Street
Chicago IL, 60607-7059
Phone:(312)413-7275
E-Mail:pdoran@uic.edu

KEYWORDS: lake, bathymetry, area, depth, polygon, Antarctica, LTER

ABSTRACT: As part of the Long Term Ecological Research in the McMurdo Dry Valleys of Antarctica, bathymetric data was collected for Lakes Hoare, Fryxell and Bonney. This table contains the values for depth, perimeter length, polygon area and total area per contour used for contour map digitizing.

VARIABLES: location, label, depth (m), perimeter length, polygon area (m2), total area per contour (m2), comments

RESEARCH LOCATION:

METHODS: Data was collected by Jeffrey Schmok in November 1995 in order to prepare the Golder report on the bathymetry of Lakes Hoare, Fryxell, and Bonney. A 0.0 m contour is based on a shoreline survey of the frozen moat, and therefore is closer to piezometric water level than to top surface of floating permanent ice. Deeper contours are based on piezometric water level. Thus volume calculations within the ice cover represent volumes of liquid water as if the ice was melted.

Third order polynomial equations were fit to the area vs. depth data both from Schmok's report and from the digitized map data, using SigmaPlot's curve fitting routine. However, since the contour data are already a "best-fit" of measured depth data, and contour intervals are relatively small, it was decided to linearly interpolate the depth:area relationships for depths between the measured depth contours, at 0.5m intervals. Volume was calculated for each 0.5m increment as a truncated cone (V=(h/3)*(A1+A2+sqrt(A1*A2)).

TIMING:

CITATIONS:

COMMENTS:

STATUS: Public Access (Type 1).

VARIABLE DESCRIPTION:

 
VARIABLE	TYPE	UNITS		MISSING VALUE INDICATOR   MINIMUM	MAXIMUM	    PRECISION

Location	String	None		  Required entry	   n/a		  n/a	       n/a
Latitude	String	DD-MM-SS South	  Required entry	   n/a		  n/a	       n/a
Longitude	String	DDD-MM-SS East	  Required entry	   n/a		  n/a	       n/a
Description	String	None			Null		   n/a		  n/a	       n/a

LOG:

NOTE: Data contained in these files has been subjected to quality control standards imposed by the investigator. The user of this data should be aware that, while efforts have been taken to ensure that these data are of the highest quality, there is no guarantee of perfection for the data contained herein and the possibility of errors exists. If you encounter questionable data, please contact the MCM LTER data manager (; (303)492-4639) so that the data can be corrected or qualified. Thus, these data may be modified and future data will be appended.