Documentation for US International Trans-Antarctic Scientific Expedition 400 MHz Subsurface Radar Profiles, Version 1

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Detailed Data Description


Society of Exploration Geophysicists Y (SEGY)-format files contain 400 MHz radar data.

The Excel files in the "ITASEI_Arcone_400MHZTransects_ElevationVsDistanceFTP directory give elevations (m) along the profiles. The Microsoft Access database (MDB) files in this directory contain elevations (m), distance (km), position, and scan numbers along the profiles.

The Excel files in the "ITASEI_Arcone_Depth-density-TimeDelayFTP directory give density (g/cm3), dielectric constant, refractive index, middle depth (m) bottom depth (m), time delay in layer (ns), total delay to layer bottom (ns), effective dielectric constant, and meters of equivalent water depth along the profiles.

Following are summaries of each profile:

BYRD_99-2.SGY: This profile was recorded from core site 99-2 (location of Swithinbank All Weather Station) back to the Byrd Surface Camp (BSC), and is now reversed. The distance is 177 km, the profile crosses Ice Stream D (now called Bindschadler Ice Stream), and elevation drops from about 1,498 m at BSC to 935 m at 99-2. The average wind directions recorded at Byrd and 99-2 are about 30° to the southwest from the profile direction. The ice speed varies from about 11 m/yr at BSC to 40–50 m/year at Ice Stream D, all the way to 99-2. The profile contains dramatic examples of folded firn and is discussed in papers in the References below.

The original profile was recorded at 600 ns time range and 2048 samples/trace. The processed profile starts at 0 ns and extends to 580 ns, or about 56 m depth.

00-1_EW.SGY and 00_1_ELEW.SGY: These profiles are the same data; the second one is with elevation corrections. The profile is 45 km long and was recorded from east to west with the West Antarctica Ice Sheet (WAIS) site at 21 km. This is called the WAIS site because of its potential consideration for a deep core. It was recorded in early December 2000, at a time range of 1000 ns, 4096 samples/trace, and 16 bits. At the lesser sampling rate, the system recorded at 13 traces/sec using a 32 stack.

A profile from BSC to 00-1 was recorded at 700 ns, but the first 50 km are missing. The profile BSC_01-1 described below virtually covers this transect and was recorded at 1500 ns.

00-1_00-2.SGY: This profile is 72 km long and was recorded at 1000 ns and 4096 samples/trace. All subsequent files were recorded at 1500 ns.

00-2MINUS30_00-2.SGY: This profile is 30 km long and was recorded east of core site 00-2, which is nearly on an ice divide. The accumulation rate measured from the radar profiles, after following horizons from site 00-4, is about 45 cm water equivalent per year. There are no elevation corrections for this segment, because Global Positioning System (GPS) data were recorded but could not be retrieved for processing. These profiles and those from 00-2 to 00-5 constitute a near-linear profile 333 km long. Continuing in a straight line, another 47 km was recorded toward an original site 00-6 near Mt. Sidley that was abandoned.

00-2_00-3.SGY: This profile is 101 km long and contains some of the deepest reflectors seen in all of ITASE. This and the following profile are discussed in Arcone, Spikes, and Hamilton (in review). Elevation data are missing between about 47 and 57 km.

00-3_00-4.SGY: This profile is 101 km long.

00-4_00-5.SGY: This profile is 101 km long. Horizons were tracked between the core sites (cores were processed for dates) to prove they are isochrones (Spikes et al. 2002). Site 002 through 00-5 generally parallels and is very close to an ice divide, as mapped by Liu et al. (1999) from a Digital Elevation Model (DEM).

00-5_00-6.SGY: This profile is 72 km long and heads in a southerly direction.

00-6_00-7.SGY: This profile is 100 km long and heads in an even more southerly direction.

00-7_BYRD.SGY: This profile is 111 km long and ends up back at BSC. The 1995 Karl Kreuz core site is just beyond 110 km.

BYRD_01_1PARTA.SGY, etc: This profile comes in five parts (A–E) and is 300 km long. It goes from approximately west to east. Part A is 0 to 59 km. Part B is 59 to 118 km. Part C is 118 to 78 km. Part D is 178 to 243 km. Part E is 243 to 300 km.

01-1_01-2PARTA.SGY, etc.: This profile comes in three parts (A-C) and is 150 km long. It is the first of two legs (the next profile is the second leg) that obtained some coverage for the Thwaites drainage basin. The profile turned north from the previous one. Part A is 0 to 51 km. Part B is 51 to 103 km. Part C is 103 to 150 km.

01-2_01-3PARTA.SGY, etc.: This profile comes in three parts (A-C) and is 169 km long. It is the second of two legs (the previous profile is the first leg) that attempted to get some coverage for the Thwaites drainage basin. The profile turned south from the previous leg. Part A is 0 to 57 km. Part B is 57 to 113 km. Part C is 113 to 169 km.

01-3_01-4PARTA.SGY, etc.: This profile is 96 km long, comes in parts A and B, and is back on track heading east. It also contains very deep stratigraphy, as do profiles near site 00-2. Part A is 0 to 48 km. Part B is 48 to 96 km.

01-4_01-5PARTA.SGY, etc.: This profile is 106.3 km long and goes to the original, planned (old) core site 5; however, the stratigraphy was unacceptable here, so the investigators moved back along the line 10 km. Part A is 0 to 28 km. About 0.8 km of data are missing between parts A and B, resulting in a slight loss of continuity between the two parts. Part B is 37 km long and covers 28.8 to 65.8 km. Part C is 41 km long, but the segment from 96 to 97 km (31 to 32 km in this segment) is only 0.5 km long; therefore, Part C goes from 65.8 km to 106.3 km. In part C, the drilled core site 01-5 is at 30.1 km (from the start of Part C). The actual distance from site 01-5 to 01-4 is 95.9 km when all parts are concatenated.

OLD01-5_01-6PARTA.SGY, etc.: This profile comes in two parts (A, B) and is 99 km long. It goes from the original (old) site 01-5 (the end of the previous profile) to core site 01-6. Part A is 0 to 56 km. Part B is 56 to 99 km. The investigators encountered a four-day storm at the site, so they only retrieved about 18 m of core. The transect headed in a more northerly direction from 01-5 and is generally in the Pine Island Drainage.

BYRD_02-1.SGYPARTA, etc.: This profile comes in five parts (A-E) and is the first leg of the second (and successful) attempt to reach South Pole Station. Part A is down ice from buried Mt. Resnick, where the investigators encountered highly variable stratigraphy, despite the lack of topographic expression. Part A is from 0 to 58 km. Part B is 58 to 112 km. Part C is 112 to 162 km. Parts D and E were combined from 162 to 272 km, with excellent continuity throughout. The elevation in the file "Byrdto02-1DandE.xls" is 1 km short. The missing elevation should be taken from the next file for site 02-2.

02-1_02-2PARTA, etc.: This profile comes in three parts (A-C) and is 178 km long. Part A is 0 to 60 km, or 272 to 332 km as measured from Byrd. Part B is 332 to 393 km from Byrd with highly variable stratigraphy. Part C is 393 to 450 km from Byrd. This profile has excellent continuity.

02-2_02-3PARTA, etc.: This profile comes in three parts (A-C) and is 164 km long. Part A is 0 to 59 km. Part B is 59 to 121 km with loss of continuity. Part C is 121 to 164 km.

02-3_02-4PARTA, etc.: This profile comes in three parts (A-C) and is 166 km long. Part A is 0 to 41 km. Part B is 41 to 117 km. Part C is 117 to 166 km. This profile has excellent continuity throughout. Hercules Dome is somewhere around 97 km, but the crew never saw anything to indicate a dome.

02-4_02-5PARTA, etc.: This profile comes in three parts (A-C) and is about 163 km long. Part A is from 0 to 59 km and has excellent continuity. Part B is from 59 to 119 km with two sections (centered near 40 and 55 km). Part C is from 119 to 163 km and contains the section (125 to 137 km) where the expedition moved erratically while climbing on the plateau and where continuity is hopeless.

02-5_POLEPARTA, etc.: This profile comes in four parts (A-D) and is about 167 km long. Part A is 0 to 60 km with no continuity from 9 to 14 km. Part B is 60 to 116 km with good continuity. Part C is 116 to 175 km with good continuity. Part D is 175 to 220 km. There are two outstanding reflection horizons at about 50 to 60 m depth that can be traced for about the last 200 km to the South Pole.

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File Naming Convention

Elevation (Excel) and radar (SEGY) files: names include two-digit year (00) and site number. For example, "01-4to01-5.xls" includes data from 2001 at site 4 to site 5. Some files are from Byrd or South Pole stations and include the station name.

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File Size

Excel and MDB files range from 18 to 149 KB.
SEGY radar files range from 10 to 180 MB.

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All SEGY radar data total about 4.5 GB.
The Excel and MDB files in the "ITASEI_Arcone_400MHZTransects_ElevationVsDistance" and "ITASEI_Arcone_Depth-density-TimeDelayFTP directories total about 2.76 MB.

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Spatial Coverage

Data were obtained during ITASE traverses, shown in the spatial coverage map below.

Southernmost Latitude: 90° S
Northernmost Latitude: 75° S
Westernmost Longitude: 90° W
Easternmost Longitude: 135° W

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Parameter or Variable

Parameter Description

Data contain 400 MHz radar profiles with elevation data (in meters above sea level).

Sample Data Record

The following sample is from "01-1_ITASE01-3.xls."

Density(g/cm3) DielConst RefrIndex Mid depth (m) Bottom depth Time delay in layer TotDelaytoLayBot EffDielConst EqWatDepth
0.439167172 1.879904956 1.371096261 1.7085 2.2085 20.18710728 20.18710728 1.879904956 0.9699007
0.466735284 1.944327139 1.394391315 2.716 3.216 9.365661664 29.55276894 1.899970223 1.440136499
0.474550378 1.962787185 1.40099507 2.723 4.223 9.4053469 38.95811584 1.914856549 1.918008729

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Software and Tools

Data Access

Excel and MDB files are available via static FTP. Radar data in SEGY format are available by special request on DVD by contacting NSIDC User Services.

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Software and Tools

A SEGY viewer is required to view SEGY files. Viewers include Rockware productsRADAN software by GSSI, or IXSeg2Segy software available from Interpex. NSIDC does not support these SEGY viewers.

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Data Acquisition and Processing

Data Acquisition Methods

The following descriptions are for subsurface radar profiles recorded between core sites during the November-December seasons for 1999-2002.

  • The profiles were all recorded with a GSSI System 10B and Model 5103 400-MHz antenna unit, which contains transmitter and receiver antennas, separated about 15 cm. Peak radiated power is less than 1.4 W. The antenna was pushed in front of a Tucker Sno-Cat in 1999 and dragged in a banana sled alongside a van during the other years.

  • Antenna speed in 1999 was about 7 kmph, about 12 kmph in 2000-2001, and about 10 kmph in 2002.

  • All recordings were made at 16 bits/sample and a running 32 stack. In 1999, investigators recorded 24 traces/sec before stacking, and in other years, 7 to 13 traces/sec before stacking.

  • All profiles were processed with Radan software and converted to SEGY format for archival storage. These profiles were processed with 150 to 550 MHz bandpass filtering, 300 trace window background removal (horizontal filtering), range gain removal, and range gain addition to compensate for spherical geometric spreading losses.

  • The pulse center frequency, as checked with the Radan Fourier spectral analysis routine, were consistently near 400 MHz with only one exception; a profile recorded from core site 01-3 to 01-1 and then 01-Byrd Surface camp in 2001. These profiles had center frequencies near 270 MHz and horizontal bands of random noise.

  • The files are best displayed in the standard seismic Red (positive signals)-Blue (negative signals) and white (zero intensity color scheme, with color intensity linearly proportional to signal intensity.

  • The profiles are presented without elevation corrections. These corrections are supplied in separate Excel files and are given per kilometer. Applying these corrections to the profiles makes it difficult to analyze or see the folding dynamics, because the corrections (0 to 50 m range) are on the order of the depth of the profiles themselves (60 to 130 m).

  • The profiles are presented with a vertical range in nanoseconds. This range can be converted to depth with the aid of the density profiles recorded at each site, or to meters of equivalent water depth. Excel charts show the density profiles and conversion of nanoseconds to depth (m).

  • Transects for all years originated at Byrd surface camp (BSC) in central West Antarctica. Severe sastrugi was never encountered.

  • Prints of these plots on conventional printers usually show some computer noise even where the signal-to-noise ratio is high. This noise appears as short, vertical white streaks. Investigators printed some files on a professional-grade plotter and reported dramatic improvement.

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References and Related Publications

Contacts and Acknowledgments

Steven A. Arcone
U.S. Army ERDC-Cold Regions Research and Engineering Laboratory
Hanover, NH 03755

Document Information

Document Creation Date

May 2005