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_KT19_PROCESSED_20121012_120453.txt

IAKST1B_KT19_PROCESSED_YYYYMMDD_hhmmss.txt

Where:

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

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

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.

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.

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.

• IceBridge CAMBOT L1B Geolocated Images
• IceBridge DMS L1B Geolocated and Orthorectified Images
• IceBridge NSERC L1B Geolocated Meteorologic and Surface Temperature Data

• Heitronics KT19.85 Infrared Pyrometer, Wintronics Web site:(http://www.wintron.com/infrared/kt19iip/kt19iip.html).
• IceBridge Data Web site at NSIDC (http://nsidc.org/data/icebridge/index.html).
• IceBridge Web site at NASA (http://www.nasa.gov/mission_pages/icebridge/index.html).
• ICESat/GLAS Web site at NASA Wallops Flight Facility (http://glas.wff.nasa.gov/).
• ICESat/GLAS Web site at NSIDC (http://nsidc.org/daac/projects/lidar/glas.html).