This data set contains surface temperature measurements of Arctic sea ice and land ice acquired using the KT19 pyrometer alongside the NASA Airborne Topographic Mapper (ATM) Instrument onboard the NASA P-3 aircraft. The data were collected as part of the Operation IceBridge funded survey campaigns.
Operation IceBridge products may include test flight data that are not useful for research and scientific analysis. Test flights usually occur at the beginning of campaigns. Users should read flight reports for the flights that collected any of the data they intend to use. Check IceBridge campaign Flight Reports for dates and information about test flights.
The following example shows how to cite the use of this data set in a publication. For more information, see our Use and Copyright Web page.
Krabill, William, and Eric Buzay. 2012, updated current year. IceBridge KT19 IR Surface Temperature, [indicate subset used]. Boulder, Colorado USA: NASA DAAC at the National Snow and Ice Data Center. http://nsidc.org/data/iakst1b.html.
NASA P-3 aircraft
Heitronics KT19.85 Series II Infrared Radiation Pyrometer
Arctic and Antarctic sea ice and land ice
15 m diameter spot below the aircraft
12 October 2011 to the present
Comma delimited ASCII text
NASA/Wallops Flight Facility (WFF)
Cryospheric Sciences Laboratory
Wallops Island, VA 23337
University of North Dakota
National Suborbital Education and Research Center
4149 University Avenue Stop 9011
Grand Forks, ND
NSIDC User Services
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449 USA
phone: +1 303.492.6199
fax: +1 303.492.2468
form: Contact NSIDC User Services
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.
This data set is a result of a request from the IceBridge Sea Ice Science Team to provide infrared radiation surface temperature measurements over sea ice for flights onboard the NASA P-3 aircraft. For surface temperature measurements and other parameters from IceBridge missions onboard the NASA DC-8, see the IceBridge NSERC L1B Geolocated Meteorologic and Surface Temperature Data data set.
The KT19 data files are in ASCII text format with each row of the file corresponding to a separate measurement record.
Each IceBridge flight has a single KT19 data file. Therefore, all the KT19 data files from a campaign will be supplied in a single campaign folder. Files describing instrument or software errors may be included separately.
Data files are organized on the FTP site, ftp://n4ftl01u.ecs.nasa.gov/SAN2/ICEBRIDGE_FTP/, as described in Figure 1.
Figure 1. Directory Structure
KT19 data files are named according to the following convention and as described in Table 1.
File name example:
|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|
|.txt||Indicates ASCII text file|
All dates and times included in the filenames are based on machine local-time.
KT19 data files are approximately 2 MB in size for each hour of data collected, or 16 MB for a nominal 8-hour flight.
The KT19 data set contains 1.5 GB of data.
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
Southernmost Latitude: 90° S
Northernmost Latitude: 53° S
Westernmost Longitude: 180° W
Easternmost Longitude: 180° E
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.
The KT19 data incorporates a GPS location that is referenced to the WGS 84 datum.
Seasonal ongoing campaigns from 12 October 2011 to the present. Note: data files for 05 and 06 March 2012 are test flights.
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. Currently, this comprises 43 flights from 14 March 2012 through 17 May 2012. The KT19 collects surface temperature measurements at 10 Hz for the duration of each flight.
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.
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.
|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|
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.
Data are available via FTP.
The data files may be opened using any software capable of reading ASCII text data.
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.
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.
No special algorithms or techniques are used in the processing of the KT19 data set.
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.
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 KT19 sensor 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.
The Heitronics KT19.85 Series II 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.
The acronyms used in this document are listed in Table 3.
|ASCII||American Standard Code for Information Interchange|
|ATM||Airborne Topographic Mapper|
|CIRES||Cooperative Institute for Research in Environmental Science|
|FTP||File Transfer Protocol|
|GPS||Global Positioning System|
|KT19||Heitronics KT19.85 Series II pyrometer|
|NASA||National Aeronautics and Space Administration|
|NSIDC||National Snow and Ice Data Center|
|WGS 84||World Geodetic System 1984|
01 August 2012
25 February 2013
09 April 2013