Digital Bathymetry for the Fram Strait Region

Thomas O. Manley
Marine Research Corporation
8 Nedde Lane - Battell Hill
Middlebury, VT 05753 USA

1.1. Data Description

The digital bathymetry data base described below is on this CD-ROM in the file \BATHY\MANLEY.BTH.

As many people have come to realize, there is at this time no acceptable digital data base of bottom bathymetry in the region of Fram Strait although there are many useful maps. DBDB5 omits or poorly represents the Molloy Deep, for example. The digital data base presented here is an attempt to address this problem until such time as sufficient observations in the Arctic are obtained to provide a complete, high-resolution digital bathymetry. The data base was created for my own research purposes, early in 1990.

The digital data base consists of both bottom bathymetry and continental topography in the region of Fram Strait and for a portion of the Arctic Ocean. Specifically, this data base covers a region between 74N and 88N over the centrally deep regions of Fram Strait and the Arctic Ocean as well as the East Greenland continental shelf. It covers a region 1650 km by 1650 km, with data values every 10 km in both the horizontal and vertical directions. Within the Arctic Ocean the zonal extent is 60W to 60E. This data base includes only the fringes of the Barents Sea that border the deeper regions. Surface topography is also included for some realism but should not be relied on too heavily.

The digital bathymetry was created by melding three different data sets, incorporating data for a given region based on the priority order listed below:

1) a higher spatial-resolving hand-digitized map of 1983 bathymetry that extended from 76N to 83N and from 17.5W to 15.0E (taken from a contour map provided by K. Aagaard, then at University of Washington);

2) digital coastline data; and

3) the lower resolution DBDB5 data, used only in areas outside the hand-digitized region.

The scattered data were converted from latitude/longitude to an X-Y cartesian system using a Lambert's Conic Conformal transformation, gridded using a minimum tension algorithm, and then contoured to check for accuracy. If specific regions were not modeled accurately enough, additional data were employed and the process was repeated.

Since the 1983 bathymetry did not show the Belgica Bank and its associated troughs located on the northeast Greenland Shelf (Bourke et al., 1987), the resulting bathymetry was GRAPHICALLY EDITED to include this feature for completeness. The graphical editing of the bathymetry within the region of the Belgica Bank is by its very nature not exact, but provides a fair degree of realism. Separate files do exist for the continental coastlines of Greenland, Svalbard, and many of the smaller islands.

The bathymetry here includes Fram Strait topography on a 10km by 10km grid that covers from roughly 73N to 90N and from 60W to 60E. Latitude and longitude are given in decimal degrees.

1.2. Data Format

Data are presented in 54-character ASCII records containing five columns:

Latitude, longitude, Z, X and Y, where:

Z is elevation in meters, 0 being sea level
if Z<0 → bottom bathymetry,
if Z>0 → continental topography (crude);

X (km) is the resulting transform of the latitude and longitude pair using Lambert Conic Conformal (LCC) mapping;

Y (km) is the resulting transform of the latitude and longitude pair using LCC mapping.

The Lambert transformation used a latitude-longitude origin of 74N - 25W, a a central meridian of 0, a central parallel of 79N, minimum and maximum parallels of 76N and 82N, and a scale factor of 1:10000. A conversion factor of 0.25423619 was used to convert LCC output to true distance in km, determined from great circle distance.

Data sample: The first twelve records in the file are shown below. Records 1 and 2 are informative headers.

  Latitude  Longitude      Z         Y      X
   73.0026  -25.1198      14      -100    -50
   73.0396  -24.8420     -21      -100    -40
   73.0763  -24.5631     -20      -100    -30
   73.1125  -24.2829     -11      -100    -20
   73.1484  -24.0016      -5      -100    -10
   73.1839  -23.7191       0      -100      0
   73.2190  -23.4354      11      -100     10
   73.2537  -23.1505     -49      -100     20
   73.2880  -22.8644     -68      -100     30
   73.3218  -22.5772     -29      -100     40               

3. Contact Information

Dr.Thomas O. Manley
Marine Research Corporation
8 Nedde Lane - Battell Hill
Middlebury, VT 05753
Phone: 802-338-6884

December 1990