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Data Set ID:
NSIDC-0468

Borehole Optical Stratigraphy Modeling, Antarctica, Version 1

This data set consists of scripts and code designed for modeling the properties of boreholes in polar ice sheets, under a range of variations in the borehole geometry, firn layering, and camera pointing and position. The data set contains two folders. One includes two perl scripts and a piece of C code, along with directions for setting up and running a Monte Carlo model of photons traveling to and from a borehole in the firn. The second includes scripts for generating ray-tracing input files to be used with the POV-Ray package (a standard, free raytracing package) to generate simulated borehole video frames based on the results of the Monte Carlo model. The project was conducted between February 2005 and April 2010.

The codes to run the models are available via FTP, in Perlscript (.pl) and C code.

Geographic Coverage

Parameter(s):
  • Land Records > Boreholes
Spatial Coverage:
  • N: -60, S: -90, E: 180, W: -180

Spatial Resolution: Not Specified
Temporal Coverage:
  • 1 February 2005 to 1 April 2010
Temporal Resolution: Not specified
Data Format(s): Not specified
Platform(s) LABORATORY
Sensor(s): OPTICAL DUST LOGGERS
Version: V1
Data Contributor(s): Ben Smith, Edwin Waddington, T. Fudge, Robert Hawley
Data Citation

As a condition of using these data, you must cite the use of this data set using the following citation. For more information, see our Use and Copyright Web page.

Smith, B., R. L. Hawley, T. J. Fudge, and E. D. Waddington. 2010. Borehole Optical Stratigraphy Modeling, Antarctica, Version 1. [Indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: http://dx.doi.org/10.7265/N5H70CR5. [Date Accessed].

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Detailed Data Description

Format

Two readme files, README_borehole_mc and README_Borehole_raytrace, provide detailed information required for running the two programs.

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File and Directory Structure

Data are available on the FTP site in the ftp://sidads.colorado.edu/pub/DATASETS/AGDC/nsidc0468_waddington_V01 directory. Within this directory, there are two subdirectories as described in Table 1.

Table 1. Directory Description
Directory Description
borehole_montecarlo_model The files in this folder allow Monte Carlo modeling of light transport in a borehole in firn. For more information, see the README_borehole_mc file.
borehole_raytrace_simulation The programs in this folder allow modeling of borehole optical stratigraphy measurements, undera range of variations in the borehole geometery, firn layering, and camera pointing and position. For more information see the README_Borehole_raytrace file.
 
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Program Descriptions

Borehole Raytrace Simulation

Programs in the borehole_raytrace_simulation folder are described in Table 2. These programs generate 16 bit Portable Network Graphics (PNG) files that may be read with standard image processing software. This folder also includes five POV-Ray (.pov) files: these serve as template files to generate valid inputs for the POV-Ray program.

Additional information for using the raytrace files is provided in the README_Borehole_raytrace file.

Table 2. Description of Programs for Running the Borehole Raytrace Simulation
Name Description
scan_3layer This program generates a set of images as the camera moves past a layer of contrasting reflectance in an otherwise uniform firn pack.
scan_scar This program generates a set of images as the camera moves past an annular scar in the borehole wall of specified radius.
scan_bump This program generates a set of images as the camera moves past an annular bump on the borehole wall of specified radius.
run_point_error This program generates a set of images as the camera and its light source rotate away from the down-borehole axis.
run_ctr_error This program generates a set of images as the camera and its light source move laterally away from the borehole center.

Monte Carlo Modeling

Programs for the borehole_montecarlo_model folder are described in Table 3. These programs allow Monte Carlo modeling of light transport in a borehole in firn. They simulate the path of packets of photons from the borehole wall, through the firn, and back to the borehole wall. This folder also contains example output files: grain_summary_1 and bubble_summary_1, which are based on example parameter files grain_params and bubble_params.

For detailed information on running the Monte Carlo model, see the README_borehole_mc file.

Table 3. Description of Programs for Running the Monte Carlo Model
Name Description
mc_borehole.c This C program tracks the photons and stores their output locations in a file
read_mc_results.pl This Perlscript program sums the contributiosn ot the total reflectance to give reflectance values.
generate_scattering_parameters.pl This Perlscript program generates the single-scattering parameters of firn, based on different density and grain or bubble size parameters.
 
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File Size

Files in this data set range in size from 4 KB to 106 KB.

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Volume

Total volume of the files is approximately 225 KB.

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Spatial Coverage

Antarctica:

Southernmost Latitude: 90°S 
Northernmost Latitude: 60°S
Westernmost Longitude: 180°W
Easternmost Longitude: 180°E

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Temporal Coverage

The project was conducted between February 2005 and April 2010.

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Parameter or Variable

This data set allows the modeling of optical properties of boreholes in polar ice sheets, under a range of variations in the borehole geometry, firn layering, and camera pointing and position.

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Software and Tools

Data can be viewed using the Persistence of Vision Raytracer (POV-Ray), a ray-tracing software, freely available at http://www.povray.org/.

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Data Acquisition and Processing

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References and Related Publications

Contacts and Acknowledgments

Dr. Ben Smith
University of Washington
Department of Earth and Space Sciences 
Seattle, Washington, USA

Dr. Bob Hawley
University of Washington
Department of Earth and Space Sciences 
Seattle, Washington, USA 

Dr. T. J. Fudge
University of Washington
Department of Earth and Space Sciences 
Johnson Hall 4000 15th Avenue NE
Seattle, Washington, USA

Dr. Edwin Waddington
University of Washington
Department of Earth and Space Sciences 
Box 351310 
Seattle, Washington, USA

Acknowledgments: 

This research was supported by NSF OPP Grant Number 0335330.

Document Information

DOCUMENT CREATION DATE

10 June 2010

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