Radiation:
Spectral incident

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The spectral incident solar irradiance was measured on 42 occassions using an Analytical Spectral Devices FieldSpecPro spectroradiometer. The instrument provided spectral coverage from 375 to 2500 nm. Measurements were typically made near solar noon from the flying bridge of the ship. As the data table below indicates, sky conditions were typically cloudy, with the solar disk not visible. A shadowing correction of a few percent was made to the results to account for the ships superstructure.

The first step was to measure the spectrum of a calibration lamp in the laboratory. Keeping the same instrument sensitivity settings, the spectroradiometer was taken up to the flying bridge and the incident spectra was measured. Multiple scans were taken and averaged. The calibration spectrum was then used to normalize the incident values. A cosine collector, consisting of a spectralon plate, was used to measure irradiance.

The cruise track (black line) and location of spectral incident measurements (magenta squares) are mapped on the left and spectral incident irradiances measured in August are plotted to the right. Scans from individual days can be accessed using the links in the table below.

 


Calibrating the instrument in lab using a calibrated lamp.
 


Measurements of spectral incident from the flying bridge.
 
Date Time (UT) Latitude Longitude Solar Sky conditions
7-Aug-05 2220 64.472 -166.418 40.9 CO-SDNV
9-Aug-05 2150 73.931 -161.690 31 CO-SDNV, clear sky off on the horizon, no fog
10-Aug-05 2110 74.752 -159.319 30.3 CO-SDNV, low clouds, fog, mist, visibility less than 500 m
11-Aug-05 2315 76.232 -157.480 28.6 CO-SDNV, low clouds, fog, mist, visibility about 1 km
12-Aug-05 2230 77.218 -157.075 27.5 CO-SDNV, light fog, visibility about 1 km
13-Aug-05 2120 77.461 -152.575 26.6 CO-SDV, light fog, visibility about 1 km
14-Aug-05 2330 78.230 -154.104 25.3 CO-SDV, fog is gone, cloud ceiling about 3000 feet, variable clouds.
15-Aug-05 2250 78.183 -160.175 25.6 CO-SDV, fog is gone, cloud ceiling about 800 feet, intermittent light snow
16-Aug-05 2310 78.295 -172.554 25.4 SDCV, scattered fog, shadows,
17-Aug-05 2253 78.294 -172.276 24.7 SDCV, low fog,  bits of blue sky 
18-Aug-05 2230 78.186 -176.961 23.9 SDNV, low fog, total clouds
19-Aug-05 2241 78.566 -177.831 23.3 SDCV, foggy visibility a couple of km
21-Aug-05 2216 79.999 -170.990 21.3 SDCV, foggy visibility a couple of km
22-Aug-05 2308 81.086 -176.915 20.3 CO-SDNV, great visibility to the horizon, no fog at all
23-Aug-05 2308 82.047 -178.277 18.9 CO-SDNV, snowing hard
24-Aug-05 2247 83.198 -179.270 17.3 PO-SDCV, sun bright enough to cast shadows, some blue sky.
25-Aug-05 2340 83.155 -174.514 17.3 CO-SDV, no fog
27-Aug-05 1823 84.108 -167.932 11.6 CO-SDNV, totally overcast with intermittent light precipitation
27-Aug-05 2234 84.108 -167.932 15.6 CO-SDCV, no fog
28-Aug-05 2320 84.209 -156.848 15.1 PC-SDCV, no fog, good visibility, 
29-Aug-05 2340 84.310 -149.072 14.2 CO-SDCV, can see sun, but no shadows
30-Aug-05 2345 83.955 -143.190 13.7 CO-SDCV, can see sun, but no shadows
31-Aug-05 1920 84.169 -150.974 12.8 CO-SDV, light snowfall
1-Sep-05 2242 84.602 -153.620 13.3 CO-SDV sun in and out
2-Sep-05 2100 85.580 -157.280 12 PC
4-Sep-05 2130 86.603 176.215 9.5 CO-SDNV, no fog, very windy 25 knots with 30 kt gusts
5-Sep-05 2153 86.656 155.205 8.4 CO-SDNV, no fog, low ceiling, still fairly windy
7-Sep-05 2235 87.692 153.140 7.3 CO-SDNV, no fog, low ceiling, blowing like crazy
10-Sep-05 2243 88.827 164.547 5.6 CO-SDNV, dark skies while traversing open water and nilas
11-Sep-05 2253 89.399 -176.033 4.8 CO-SDNV
14-Sep-05 1200

89.088
74.109 3.6 CO-SDNV
15-Sep-05 1230 88.193 60.662 3.6 PC-SDCV, sun breaking through
16-Sep-05 0745 87.610 59.084 4.9 BC, some thin clouds on horizon
16-Sep-05 1210 87.689 58.638 3.6 BC 
19-Sep-05 1120 86.341 50.364 4.4 BC, some low clouds near the sun
20-Sep-05 1155 85.788 48.687 3.9 CO-SDNV, low stratus present
21-Sep-05 1205 85.242 45.094 4.0 PC-SDBV, there is a definite bright glow to the south.
22-Sep-05 1200 84.356 42.925 4.9 CO-SDNV
23-Sep-05 0800 82.555 42.890 7.3 CO-SDNV, dull glow to the south
24-Sep-05 1120 81.464 20.917 7.6 Sunny skies with some haze, diamond dust and low clouds
25-Sep-05 1120 81.152 15.538 8.3 CO-SDNV
26-Sep-05 1140 80.472 7.428 8.5 CO-SDNV

CO - complete overcast     PC - partly cloudy     BC - brillantly clear
SDNV - solar disk not visible     SDBV - solar disk barely visible     SDV - solar disk visible     SDCV - solar disk clearly visible