A significant component  of the summer mass balance is the temperature distribution 
in leads versus the ponded ice. An important question is how much of the solar and 
longwave radiation absorbed by the water remains in the surface layers and is 
available for lateral melting. In order to relate detailed surface-based observations 
in a few leads near the ship to the local and intermediate spatial scales, periodic 
helicopter based observations were carried out in conjunction with the photographic 
surveys from mid-June through late August including spatial transects of up to 100 km. 
A Heimann Kt-19 infrared radiometer recording in a wavelength band of 8-14microns was 
mounted looking directly downward below the helicopter. Its field of view was 
approximately 2 degrees providing a spatial resolution at the surface of 1/30th of the 
altitude or about 75 meters at 6000’. Data were sampling at 1 Hz providing an overlap 
of about 20% of the field of view at this elevation. This was sufficient to resolve the 
major leads and polynyas.Representative results seen in the accompanying figures show the 
contrast between the ice and the cold water that was exposed upon lead opening near 
-1.8oC (Figure A) followed by the transition to the opposite situation (Figure B) where 
the lead surface was nearly 2oC warmer than the ice due to radiation absorption in the 
water in conjunction with weak vertical mixing. The relative radiometric accuracy of the 
measurements is approximately ± 1oC.The data files are designated as KT19mmdd.csv, where 
mm denotes the month and dd the day. Each file contains observed infrared brightness 
temperature in degrees Celsius versus the local time in decimal hours


Aerial: KT-19 
Instrument: A Heimann Kt-19 infrared radiometer recording in a wavelength band of 8-14microns.
Uncertainty: The relative radiometric accuracy of the measurements is approximately ± 1oC.
File format: The data files are designated as KT19mmdd.csv, where mm denotes the month and dd the day. 
Each file contains observed infrared brightness temperature in degrees Celsius versus the local time 
in decimal hours.
Contacts: tcg@atmos.washington.edu