3.2.9. Arctic UV Monitoring
In September 1997, the STAR group and the University of Alaska, Fairbanks, began an investigation of the UV-B radiation environment in the U.S. arctic by deploying two portable, inexpensive UV-measuring instruments at BRW. Rare and fragile life forms and the potential for excessive stratospheric ozone loss in the arctic make the monitoring of actual variations in the biologically sensitive regions of the UV spectrum particularly important in the Alaskan arctic and the Bering Sea region [DeFabo, 1995, 1997; Nilsson, 1997; Madronich et al., 1996]. Because ozone in the stratosphere strongly absorbs energy in the UV-B portion of the solar spectrum (280 to 320 nm), any changes in the total amount of ozone affect the levels of UV-B radiation reaching the ground.
Support for this effort was received under a NOAA Arctic Research Initiative managed for NOAA by the Cooperative Institute for Arctic Research. One instrument in use is a Yankee broadband UV pyranometer that measures global solar UV-B irradiance. The other instrument is a Biospherical Instruments, Inc. (BSI) narrowband UV radiometer that measures irradiance in five optical channels (305, 313, 320, 340, and 380 nm). Figure 3.28 and Figure 3.29 show the daily average total irradiance for both instruments for September 17-November 17, 1997. Another multi-channel radiometer purchased from the Norwegian Institute for Air Research (NILU) will be installed at BRW sometime in early 1998. The BSI radiometer has compared favorably with the BSI scanning spectroradiometers linked to the U.S. National Science Foundation's polar UV monitoring network. However, the spectroradiometers are expensive and not always feasible for conducting studies in remote regions in the arctic.
Fig. 3.28. Daily average total irradiance for the BSI radiometer at wavelengths 305, 313, 320, 340, and 380 nm for the period September 17-November 17, 1997. The data for November 4 were eliminated because the instrument may have malfunctioned that day.
Fig. 3.29. Daily average total irradiance for the YES UV pyranometer for the period September 18-November 17, 1997.
Within NOAA there have been significant efforts to evaluate and calibrate UV instrumentation [Bodhaine et al., 1996, 1997, 1998; Weatherhead and Webb, 1997; Webb and Weatherhead, 1996]. These efforts were well received internationally and formed the basis for continued efforts in collaboration with the Universities of Alaska (Fairbanks) and Colorado (Boulder), for 1998 and 1999 to assess the UV variability in and near the Bering Sea. The Bering Sea is an important region for biological primary production. The area has shown strong variability in biological production that, so far, is not well understood [DeFabo, 1995; Nilsson, 1997; Jin et al., 1994]. The use of UV monitoring over the next 2 years, in conjunction with other current and planned studies, should help discern if UV and photosynthetically active radiation (PAR) have a strong role in current primary production variability. In other biological studies of UV effects, the magnitude and even the sign of these effects can be linked to other stressors in the environment. The unique nature of the effects of UV with other stressors make it important for many biological studies to have access to accurate UV measurements.
In May 1998 two additional BSI radiometers will be deployed in Alaska: one on St. Paul in the Pribilof Islands (57.09°N; 170.13°W), and the other at Nome, Alaska (64.30°N; 165.26°W), in collaboration with the National Weather Service. These instruments will operate in conjunction with the BSI instruments currently at BRW and the University of Alaska, Fairbanks. The combination of Bering Sea, coastal Arctic Ocean, and internal Alaska sites will allow for a wide range of atmospheric conditions to be monitored in a fairly uniform manner.
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