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Data Set ID:
IAPRS1B

IceBridge Paroscientific L1B Pressure Altimeter Time-Tagged Air Pressure, Version 1

This data set contains static pressure values for Antarctica using the Paroscientific Digiquartz Transmitter. The data were collected by scientists working on the Investigating the Cryospheric Evolution of the Central Antarctic Plate (ICECAP) project, which is funded by the National Science Foundation (NSF) and the Natural Environment Research Council (NERC) with additional support from NASA Operation IceBridge.

Geographic Coverage

Parameter(s):
  • Atmospheric Pressure > Atmospheric Pressure Measurements
Spatial Coverage:
  • N: -53, S: -90, E: 180, W: -180

Spatial Resolution:
  • Varies x Varies
Temporal Coverage:
  • 29 December 2008
(updated 2014)
Temporal Resolution: Varies
Data Format(s):
  • XML
  • ASCII Text
Platform(s) BT-67
Sensor(s): PRS Altimeter
Version: V1
Data Contributor(s): Donald Blankenship, Scott Kempf, Duncan Young
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.

Blankenship, D. D., S. D. Kempf, and D. A. Young. 2012, updated 2014. IceBridge Paroscientific L1B Pressure Altimeter Time-Tagged Air Pressure, Version 1. [Indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: http://dx.doi.org/10.5067/N1F4NBFMIREJ. [Date Accessed].

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Detailed Data Description

Format

The data files are in space-delimited ASCII text format, with a header offset by # leading characters, corresponding to the NASA Aerogeophysical ASCII data standard. Each data file is paired with an associated XML file. The XML files contain location, platform, and instrument metadata.

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File and Directory Structure

Data are available on the FTP site in the https://n5eil01u.ecs.nsidc.org/ICEBRIDGE/IAPRS1B.001/ directory. Within this directory are folders organized by date, for example /2013.01.26/.

Data stored in the /2008.12.29/ and /2008.12.31/ folders were collected as part of the 2009 campaign.

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File Naming Convention

Files are named according to the following convention and as described in Table 1:

IAPRS1B_2013025_ICP5_JKB2h_RIGGS1c_pressure.txt 
IAPRS1B_2013025_ICP5_JKB2h_RIGGS1c_pressure.txt.xml

IAPRS1B_YYYYDOY_AAAA_JKBnx_XXXX_pressure.xxx

Where:

Table 1. Naming Convention
Variable Description
IAPRS1B Short name for IceBridge Paroscientific L1B Pressure Altimeter Time-Tagged Air Pressure
YYYY Four-digit year of survey
DOY Day of year of survey
AAAA Geographic area
JKBnx Host platform
XXXX Geographic track line
pressure Static pressure
.xxx Indicates ASCII text file (.txt), or XML file (.xml)
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File Size

The data files range from approximately 10 KB to 5 MB.

XML files range from approximately 10 KB to 63 KB.

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Volume

The entire data set is approximately 933 MB.

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Spatial Coverage

Spatial coverage for this data set is Antarctica, represented by this extent:

Southernmost Latitude: 90° S
Northernmost Latitude: 53° S
Westernmost Longitude: 180° W
Easternmost Longitude: 180° E

Spatial Resolution

20 meters along track. 150 meters along track for late 2011 field season.

Projection and Grid Description

WGS-84 ellipsoid; ITRF 2008

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Temporal Coverage

These data were collected from 29 December 2008 to the present as part of ICECAP, NSF, NERC, and Operation IceBridge funded campaigns. Data collected in late December 2008 are part of the 2009 campaign.

Temporal Resolution

ICECAP campaigns were conducted on an annual basis. East Antarctic campaigns for this data set typically extend from November to early January.

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Parameter or Variable

Parameter Description

The L1B Pressure Altimeter Time-Tagged Air Pressure data files contain fields as described in Table 2.

Table 2. File Parameter Description
Parameter Description Units
YEAR Year of survey UTC
DOY Day of Year of survey UTC
SOD Second of day UTC
SEC Packet Sequence Number n/a
LON Longitude Decimal degrees WGS-84
LAT Latitude Decimal degrees WGS-84
AC_ELEVATION Aircraft elevation Meters WGS-84
ROLL Roll, right wing down positive Degrees
PITCH Pitch, nose up positive Degrees
HEADING Heading w.r.t north Degrees
PRESSURE Static pressure kiloPascals

Note: Positions are interpolated from the real time GPS feed and have an accuracy of several meters.

Sample Data Record

Figure 1 shows the first ten records from the data file IAPRS1B_2013025_ICP5_JKB2h_RIGGS1c_pressure.txt.

sample data record
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Software and Tools

No special tools are required for the ASCII text files.

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Data Acquisition and Processing

Theory of Measurements

Outside air pressure is directed into a commercial off the shelf pressure transducer (Paroscientific). The pressure transducer internally digitizes the pressure measurements and outputs a serial data packet at regular intervals. This data set is acquired to assist with atmospheric corrections for laser altimetry, and to validate vertical acceleration data.

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Data Acquisition Methods

Static air was piped from a port on the exterior right side of the cockpit, via a sealed rubber hose to the pressure transducer. RS-232 packets are output at a rate of 4 Hz with the calibrated pressure value in millibars to the ELSA acquisition system.

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Derivation Techniques and Algorithms

The only processing was to time register the samples and to convert the units to International System (SI) units (kiloPascals).

Trajectory and Attitude Data

Trajectory and attitude data were interpolated to this product from the IceBridge GPS L1B Time-Tagged Real-Time Position and Attitude Solution (IPUTN1B) product.

Processing Steps

Missing values have been replaced by "nan".

Version History

On 02 May 2012, V01 2011 Antarctica data were replaced by V01.1. In V01.1, additional fields were added containing low-precision real-time position and orientation data resampled to match the times of the existing geophysical samples.

On 26 April 2013, the 2009, 2010, and 2011 Antarctica data were replaced. The format of 2009 and 2010 Antarctica data was revised to that of the 2011 Antarctica data, ensuring the time stamps are UTC year, day, and time, and adding georeferencing fields including real time position, roll, pitch and heading. For some campaigns V01.2 includes more flights than V01.1.

Error Sources

Resolution on the instrument data is 1 Pa (Pascal); observed jitter between consecutive samples is on the order of 1.3 Pa. Total range of the instrument is 0 to 103.4 kPa; the vendors quoted uncertainty is 10 Pa.

During the late 2011 field season, the raw output unit of the sensor was set to pounds per square inch, and the sample rate was set to 0.67 Hz.

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Sensor or Instrument Description

Paroscientific Pressure Altimeters consist of a Digiquartz pressure transducer and a digital interface board in an integral package. Commands and data requests are sent via two-way RS-232 serial interfaces. Digital outputs are provided directly in engineering units with typical accuracy of 0.01 per cent over a wide temperature range. Output pressure is fully thermally compensated using a quartz crystal temperature signal. All intelligent transmitters are pre-programmed with calibration coefficients for full plug-in interchangeability

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Contacts and Acknowledgments

Donald D. Blankenship, Scott D. Kempf, Thomas G. Richter, and Duncan A. Young
University of Texas at Austin
Institute for Geophysics
Austin, TX, 78759-8500

Acknowledgments: 

Funding: NASA's Operation Ice Bridge (grant NNX09AR52G, contract NNG10HP06C (American Recovery and Reinvestment Act), and grant NNX11AD33G) to the University of Texas at Austin. NSF's International Polar Year activities (grant ANT-0733025) to the University of Texas at Austin, the Antarctic Ecosystems and Climate Collaborative Research Center at the University of Tasmania, and the UK's NERC grant NE/D003733/1 to University of Edinburgh. See data file header for funding information for each transect.

Document Information

Document Creation Date

10 December 2014

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