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Data Set ID:
IAKST1B

IceBridge KT19 IR Surface Temperature, Version 1

The NASA IceBridge KT19 IR Surface Temperature data set contains surface temperature measurements of Arctic and Antarctic sea ice and land ice acquired using the Heitronics KT19.85 Series II Infrared Radiation Pyrometer alongside the NASA Airborne Topographic Mapper (ATM) instrument onboard the NASA P-3 and NASA DC-8 aircrafts. The data were collected as part of the Operation IceBridge funded survey campaigns.

Geographic Coverage

Parameter(s):
  • Sea Ice > Ice Temperature
  • Snow/Ice > Snow/Ice Temperature
Spatial Coverage:
  • N: 90, S: 60, E: 180, W: -180

  • N: -53, S: -90, E: 180, W: -180

Spatial Resolution:
  • 15 m x 15 m
Temporal Coverage:
  • 12 October 2011
(updated 2014)
Temporal Resolution: Varies
Data Format(s):
  • XML
  • ASCII Text
Platform(s) DC-8, P-3B
Sensor(s): KT19 Pyrometer
Version: V1
Data Contributor(s): William Krabill, Eric Buzay

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.

Krabill, W. B. and E. Buzay. 2012, updated 2014. IceBridge KT19 IR Surface Temperature, 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/I883KXU7ZO8O. [Date Accessed].

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Detailed Data Description

The KT19 data are collected by the National Suborbital Education & Research Center (NSERC) and by the Airborne Topographic Mapper (ATM) team at the NASA/Wallops Flight Facility.

Format

The KT19 data files are in ASCII text format with each row of the file corresponding to a separate measurement record.

Each data file is paired with an associated XML file. The XML files contain location, platform, and instrument metadata. DC-8 platform data are from the NSERC team, while data from the P-3 and all other platforms are from the ATM team.

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File and Directory Structure

Data are available on the HTTPS site in the https://n5eil01u.ecs.nsidc.org/ICEBRIDGE/IAKST1B.001/ directory. This directory is organized by date, for example /2011.10.12/ to /2014.05.21/.

Folders contain ASCII text and XML files.

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File Naming Convention

KT19 data files are named according to the following convention and as described in Table 1.

File name example:

IAKST1B_KT19_PROCESSED_20121012_120453.txt
IAKST1B_KT19_PROCESSED_20121012_120453.txt.xml

IAKST1B_KT19_PROCESSED_YYYYMMDD_hhmmss.xxx

Where:

Table 1. File Naming Convention
Variable Description
IAKST1B Short name for IceBridge KT19 IR Surface Temperature
KT19_PROCESSED KT19 Level-1B processed data file
YYYY Four-digit year of survey
MM Two-digit month of survey
DD Two-digit day of survey
hh Two-digit hour for start of log file
mm Two-digit minute for start of log file
ss Two-digit second for start of log file
.xxx Indicates ASCII text file txt, or xml file .txt.xml

All dates and times included in the filenames are based on machine local-time.

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File Size

KT19 data files are approximately 2 MB in size for each hour of data collected, or 16 MB for a nominal 8-hour flight.

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Volume

The KT19 data set contains approximately 3 GB of data.

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Spatial Coverage

Spatial coverage includes Arctic sea ice and land ice, represented by the coverage noted below.

Arctic / Greenland:
Southernmost Latitude: 60° N
Northernmost Latitude: 90° N
Westernmost Longitude: 180° W
Easternmost Longitude: 180° E

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

Spatial Resolution

The KT19 sensor is fitted with a lens that has a two degree field of view. At 450 m above ground level, this produces an optical measurement footprint on the ground that is approximately 15 m in diameter. At a nominal aircraft speed of 125 m/sec and a sampling frequency of 10 Hz, the centers of two consecutive spots will be 12.5 m apart along the aircraft ground track.

Projection and Grid Description

The KT19 data incorporates a GPS location that is referenced to the WGS 84 datum.

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Temporal Coverage

Seasonal ongoing campaigns from 12 October 2011 to the present. Note: data files for 05 and 06 March 2012 are test flights.

Temporal Resolution

IceBridge campaigns are conducted on an annual repeating basis. Arctic and Greenland campaigns are conducted during March, April, and May, and Antarctic campaigns are conducted during October and November.

KT19 surface temperature measurements are collected for every science flight in the NASA IceBridge Arctic campaigns beginning in March 2012. The KT19 collects surface temperature measurements at 10 Hz for the duration of each flight.

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Parameter or Variable

The KT19.85 sensor provides a measurement of the surface temperature of an object in degrees Celsius. For compensation purposes, the sensor also provides a measurement of its internal temperature, in degrees Celsius, which may vary as much as 30°C throughout the course of a flight. The surface temperature measurement provided has not had any correction applied for changes in internal temperature.

Parameter Description

Each row of the KT19 ASCII data file corresponds to a separate measurement record. The data file contains eight columns of data, with each column corresponding to a different variable describing the measurement, as shown in Table 2.

The files also contain a number of header lines, each one beginning with a # to identify it as part of the header. The header contains the settings used for acquisition (emissivity, response time, temperature units, etc.) and the last header line describes the information found in each column of the data.

Table 2. Parameter Description
Parameter Description Units
Year Year of measurement Years
Day_Of_Year Day of year of measurement Days
Seconds_Of_Day Seconds of day of measurement (UTC) Seconds
Latitude Latitude of GPS antenna Decimal degrees
Longitude Longitude of GPS antenna Decimal degrees
Aircraft_Altitude_Above_Ellipsoid Height of GPS antenna above WGS84 ellipsoid Meters
KT19_Temperature Surface temperature measured by the KT19 Degrees Celsius
KT19_Internal_Temperature KT19 instrument internal temperature Degrees Celsius

Sample Data Record

Below is a list of the header and the first ten records from data file IAKST1B_KT19_PROCESSED_20120323_195720.txt. The eight comma-separated fields in each record correspond to the parameters described in Table 2.

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Software and Tools

The data files may be opened using any software capable of reading ASCII text data.

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Data Acquisition and Processing

Data collection for the KT19 data takes place on a CappuccinoPC mini-PC running Ubuntu 10.4. The computer communicates with the KT19 sensor over the RS-232 interface, and communicates with a GPS-logging computer over Ethernet. The combination of these two data streams provides geo-located surface temperature measurements.

Data Acquisition Methods

The collection and logging of the KT19 data is managed by a python script called KTlogger.py. After the KT19 sensor is powered on, the script is initiated and issues initialization commands to the sensor that set the temperature units, response time, reference temperature method, and emissivity constant. After that, the script begins the data collection loop, which queries the KT19 sensor at 10 Hz for the surface temperature, and at 0.5 Hz for internal temperature. This script also communicates with a separate GPS logging machine onboard the ATM GPS rack, which is running a program called linlogger. The linlogger program broadcasts a real-time GPS message over Ethernet at 2 Hz. All of the messages returned from the KT19, as well as the real-time GPS messages, are time-stamped with machine local-time and written to a log file as they arrive.

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Derivation Techniques and Algorithms

No special algorithms or techniques are used in the processing of the KT19 data set.

Processing Steps

A processing script, called KTproc.py, loads in all of the collected data from a flight and linearly interpolates the measurements to the frequency at which the KT19 surface measurements were collected. The interpolation uses the machine local-time stamp as the independent variable.

Error Sources

On a few flights, the KT19.85 sensor would return an empty string when queried for a temperature measurement. As soon as the operator identified this error, the data file would be closed, power would be cycled to the sensor, and a new data file started. Therefore, some flights have more than one data file.

The Heitronics KT19 Infrared Radiation Pyrometer is a nadir-viewing optical instrument, so it will measure the temperature of the first surface that appears below the aircraft. As long as no clouds are between the aircraft and the ice below, the surface measurement will correspond to the ice surface. However, if any clouds appear between the aircraft and the ice surface, then the KT19 temperature measurement will correspond to the clouds. The KT19 data set does not contain any information about the presence of clouds. A secondary data set, such as IceBridge DMS L1B Geolocated and Orthorectified Images or IceBridge CAMBOT L1B Geolocated Images, can be used to identify the objects that were measured by the KT19.

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Sensor or Instrument Description

The Heitronics KT19 Infrared Radiation Pyrometer measures infrared radiation wavelengths between 9.6 and 11.5 microns. By assuming an emissivity of 0.97, a reasonable estimate for most sea and land ice, the radiation measurement can be directly converted to a measurement of the target's surface temperature. The KT19.85 model is designed for long-distance measurement of water, ice, and clouds, and has an effective measurement range from -50°C to 200°C, with a resolution of 0.01°C. The lens has a two degree field of view, which yields a 15-meter viewing footprint on the ground at 450 m above ground level. The response time of the KT19 detector is nominally set to 0.3 second to provide a good balance between measurement sensitivity and noise reduction for a measurement frequency of 10 Hz. For instrument accuracy and other instrument specifications, see http://www.wintron.com/infrared/kt19iip/kt19iip.html.

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References and Related Publications

Contacts and Acknowledgments

William Krabill 
NASA/Wallops Flight Facility (WFF)
Code 615
Cryospheric Sciences Laboratory
Wallops Island, VA 23337

Eric Buzay 
University of North Dakota
National Suborbital Education and Research Center
4149 University Avenue Stop 9011
Grand Forks, ND
58202-9011 USA

Acknowledgments: 

The ATM project team would like to acknowledge the dedicated NASA P-3 flight crew, whose efforts allowed the safe and efficient collection of this data over some of the most isolated and extreme regions on this planet.

Document Information

Document Creation Date

01 August 2012

Document Revision Date

25 February 2013

09 April 2013

21 April 2014

09 June 2014

05 January 2015

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