A crucial element of SHEBA is to extend process-oriented observations and models 
to larger-scales. Local measurements provide data on mass changes, optical 
properties and structural properties of individual ice categories, while ground 
surveys allowed us to define spatial variability within each category. We then 
use larger-scale aerial surveys to generate regional estimates of the fractional 
area covered by these categories Combining these observations with process-oriented 
modeling results makes it possible to generate areally-averaged estimates of such 
quantities as albedo, solar heat input to the ice and ocean, ice concentration, pond 
fraction, and lateral melt rates. 

Between May and October 1998 more than a dozen helicopter survey flights were made. 
An instrument package consisting of a Nikon 35 mm camera, a videocamera, and a KT-19 
thermal radiometer was mounted, in a downward looking orientation, on the back of the 
helicopter's storage compartment. On a few occassions we also mounted the ASD 
spectroradiometer to make aerial measurements of reflected irradiance. Whenever 
possible surveys were flown at an altitude of 6000 feet under either clear skies or 
high clouds. The flight pattern was a box centered on the Des Groseilliers. The first 
leg was 25 km east followed by 25 km due north, 50 km due west, 50 km south, then 
25 km east, and finally 25 km north back to the ship. 

Photos: During each survey flight approximately 200-250 photographs were taken using 
a Nikon 35 mm camera. On most days a 35 mm lens and an F-stop of 4.0 and a shutter 
speed of 1/1000 were used. On 17 May, 1998 and 25 July 1998 photomosaics were made 
of a 10 km square centered on the ship. The aerial photographs were digitized and 
placed on CD-ROM's in Kodak PSD format generating a library of over 30 CD-ROM's. These
CD's are part of the JOSS archive.

KT-19: 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. 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.

HeloAlb: On a few of the helo flights the ASD Ice-1 spectroradiometer was used to measure 
incident and reflected irradiance. One detector was mounted on a metal plate with an unobstructed 
view looking downward. The other detector was mounted high on the fuselage looking upward. 
Unfortunately the field of view of this detector was somewhat blocked by the cowling of the 
helicopter. To minimize the effects of this we: 1) only measured on cloudy days with a 
dense uniform cloud cover and 2) tried to calibrate the two sensors in the working 
configuration by measuring a lead, where the surface was uniform and the albedo known. 
Our precautions were only partially successful. Discrete jumps occurred when the helicopter 
turned to do a different leg of the flight pattern. These jumps are artifacts of sensor shadowing. 
Information can be obtained from the legs where the incident detector was not shadowed.

Flight Information:
Date Latitude (N) Longitude (W) Altitude Type Instruments Photo CD 
17-May 76 21.2 165 39.9 6000 Mosaic C,V Yes 
20-May 76 21.0 166 40.0 6000 Survey C,V Yes 
10-Jun 76 52.00 166 10.0 6000 Survey C,V,KT Yes 
15-Jun 77 08.80 166 15.3 6000 Survey C,V,KT Yes 
22-Jun 77 41.9 167 16.0 6000 Survey C,V,KT Yes 
27-Jun 77 47.3 167 59.5 Various Albedo, temperature A,V,KT No 
30-Jun 78 00.0 167 33.2 6000 Survey C,V,KT Yes 
7-Jul 78 5.2 166 48.1 100 Albedo, temperature A,V,KT No 
8-Jul 78 05.0 166 18.0 6000 Survey C,V,KT Yes 
15-Jul 78 06.1 166 07.0 6000 Survey C,V,KT Yes 
16-Jul 78 09.8 166 05.3 100 Albedo, temperature A,V,KT No 
20-Jul 78 15.9 165 56.3 6000 Survey C,V,KT Yes 
25-Jul 78 31.0 165 30.0 6000 Mosaic C,V,KT Yes 
28-Jul 78 34.2 166 48.1 Various Albedo, temperature A,V,KT No 
7-Aug 78 29.0 158 49.5 6000, 4000 Survey C,V,KT Yes 
9-Aug 78 37.8 158 23.6 Various Albedo, temperature A,V,KT No 
19-Aug 78 59.5 158 10.1 Various Albedo, temperature A,V,KT No 
22-Aug 78 15.9 165 56.3 6000 Survey C,V,KT Yes 
27-Aug 79 45.0 160 37.0 100 Freeboard L No 
29-Aug 79 33.2 160 3.2 Various Albedo, temperature A,V,KT No 
2-Sep 79 51.2 159 33.50 100 Freeboard L No 
7-Sep 79 43.2 161 36.8 Various Albedo, temperature A,V,KT No 
11-Sep 79 34.0 161 58.0 6000 Survey C,V,KT Yes 
4-Oct 80 8.0 166 16.0 5000 Survey C,V,KT Yes 
Legend: C: camera, V: video, KT: KT-19 infrared radiometer, A: spectroradiometer (400 -850 nm), and L: laser rangefinder. 



 

 


KT-19: