Data Set ID:
NSIDC-0540

WAIS Divide Laser Dust Logger Data, Version 1

This data set consists of data from optical logs made at the WAIS Divide with a laser dust logger in clear ice at depths between 1403.58 meters and 3329.8 meters.

NSIDC does not archive these data.

Version Summary:

initial release

Parameter(s):
  • AEROSOLS > AEROSOL OPTICAL DEPTH/THICKNESS
  • ICE CORE RECORDS > PARTICULATE MATTER > ICE CORE RECORDS
  • SEA ICE > ICE DEPTH/THICKNESS
  • PALEOCLIMATE INDICATORS > ICE CORE RECORDS > PARTICULATE MATTER > MICROPARTICLE CONCENTRATION
Data Format(s):
  • ASCII Text
Spatial Coverage:
N: -79.482778, 
S: -79.482778, 
E: -112.135833, 
W: -112.135833
Platform(s):LABORATORY
Spatial Resolution:Not SpecifiedSensor(s):OPTICAL DUST LOGGERS
Temporal Coverage:
  • 6 December 2011
Version(s):V1
Temporal ResolutionNot specifiedMetadata XML:View Metadata Record
Data Contributor(s):Ryan Bay

Geographic Coverage

Please contact the data provider for the correct Data Citation for this data set.

Literature Citation

As a condition of using these data, we request that you acknowledge the author(s) of this data set by referencing the following peer-reviewed publication.

  • Aartsen, M.. 203. South Pole Glacial Climate Reconstruction from Multi-Borehole Laser Particulate Stratigraphy, Journal of Glaciology. 52. 1117-1129. https://doi.org/10.3189/2013JoG13J068

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Detailed Data Description

This data set consists of data from optical logs made at the WAIS Divide with a laser dust logger in clear ice at depths between 1403.58 meters and 3329.8 meters. The dust logger (Bay et.al. 2001) grew out of years of AMANDA (Antarctic Muon and Neutrino Detector Array) collaboration experience in using emitters and receivers embedded in ice to measure optical properties (Aartsen 2013).

Optical and photonic logging instruments deployed in glacial boreholes can provide a wealth of information without retrieval or destruction of core samples. The borehole laser dust logger can often produce a more stratigraphically coherent environmental particulate record than ice core measurements and can be used to immediately determine chronology. The logger signal responds markedly to thin volcanic ash layers and in deep clear ice is a nearly direct tracer of ash and continental mineral dust. The logger reveals meaningful, repeatable structures at the sub-centimeter depth scale for synchronizing records (Aartsen 2013).

Together with hot-water or mechanical fast access drilling, optical logging can be used to determine age, stratigraphic integrity, and scientific potential of a site before devoting the resources of a coring mission. A detailed particulate depth profile can be used to immediately date any site on the continent precisely and confidently (Aartsen 2013). With this method the ice is sampled at ambient pressure in a much larger volume than is the case in a core study, and the entire length can be logged in one day. In ice in which scattering is dominated by bubbles, the absorption from dust impurities is perceived as a drop in signal, whereas in bubble-free ice the scattering from dust increases the light collected (Bay et.al. 2001).

Format

Data are provided in ASCII text (.dat) file format.

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File and Directory Structure

Data are available on the FTP site in the ftp://sidads.colorado.edu/pub/DATASETS/AGDC/nsidc0540_bay_V01/ directory. Within this directory, there is one ASCII text file: optical_log.up1.dat

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File Size

22 MB

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Spatial Coverage

79° 28.058' S, 112° 05.189' W

Spatial Resolution

Depths between 1403.58 meters and 3329.8 meters.

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Temporal Coverage

Data were collected on 06 December 2011.

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Parameter or Variable

Depth (meters, corrected)
Optical Intensity (normalized (arbitrary) units)

Sample Data Record

This sample data record lists the depth measurements in Column 1 and Column 2 lists the measured light (optical) intensity. The depths were corrected to match the core to an accuracy of < 5 cm typical and ~20 cm maximum using tie points known from visual core assays. The Dust Logger measures the amount of light beamed into the horizon which exits the borehole and returns.

sample data record

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Software and Tools

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Data Acquisition and Processing

Data Acquisition Methods

Processing Steps

The data was obtained with a temperature-controlled 404 nm diode laser that can detect bubbles, dust, volcanic ash, and microbes in the ice out to several meters from the borehole, and measure optical properties of those particles. The laser emits light in a horizontal fan as it enters the ice and interacts with bubbles and particles. A fraction of this emitted light reenters the borehole and is detected in the downward pointing photon counter (Aartsen 2013).

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Sensor or Instrument Description

Optical and photonic logging instruments deployed in glacial boreholes can provide a wealth of information without retrieval or destruction of core samples. The dust logger (Bay et.al. 2001) grew out of years of AMANDA collaboration (Antarctic Muon and Neutrino Detector Array) experience in using emitters and receivers embedded in ice to measure optical properties. The ~1 m-long logger shines light into the ice surrounding a borehole; photons scatter off bubbles and impurities to be eventually absorbed; a small fraction (10–10 to 10–6) of photons return to be detected. Annular black nylon brush baffles sweep ice crystals and debris from the source beam and intercept stray light to ensure that all detected photons have exited and reentered the borehole after interacting with the target layer (Aartsen 2013). Refer to Figure 1.

borehole logger
Figure 1. Ruggedized Laser Dust Logger

The 404nm diode laser is focused into a fan beam to probe 608 of the horizon in one pass. Brush baffles block photons which circumvented the ice through the borehole, and clear away detritus in the hole that could obstruct the image.

The intrinsic depth resolution of the logger is determined by the thickness of the laser line and not the distance of the receiver from the source, which we have confirmed using Monte Carlo simulations (Bay et.al. 2001) and other logger geometries we have tested (Bay et.al. 2006). The signal is dominated by first encounters of the laser with particulates in the coherence plane of the beam, which probes approximately one effective scattering length into the ice. The further the source beam penetrates horizontally the greater the coherence with the target dust layer, up to the scale of stratigraphic undulations or tilt. At depths where scattering is bubble-dominated, the ice is diffusively illuminated by scattered light and the logger signal tracks impurity levels through absorption, responding markedly to thin volcanic ash layers. In deep clear ice, the backscattering signal is a nearly direct tracer of ash and continental mineral dust (Aartsen 2013).

However, in 2004 a new dust logger was designed and built for use during IceCube commissioning (Bramall et. al. 2005). It improved upon previous designs by using a temperatureregulated diode laser at 404 nm wavelength near the absorption minimum for glacial ice (Askebjer et. al.1997a), a photon-counting detector (Hamamatsu HC135), onboard computer control (Rabbit RCM3720) and DSL (Digital Subscriber Line, Patton Electronics Co., Gaithersburg, MD, USA) telemetry to the surface (Aartsen 2013).

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References and Related Publications

Contacts and Acknowledgments

Ryan Bay
University of California, Berkeley
Physics Department
Berkeley, CA 94720

Acknowledgments: 

This research was supported by NSF OPP Grant Number 0738658.

Document Information

Document Creation Date

April 2014

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