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Abstract
A small broadband UV radiometer, SKU 430 was manufactured by Skye Instrument Ltd. in UK. To evaluate the performance of the radiometer, some tests were carried out using NIST lamps, optical filters and the calibration system, as well as outdoor comparison with Brewer MKIII spectrophotometer. The results are summarized as follows: 1) NIST lamp tests by eight lamps showed that the error of calibrated responsivity was less than 4%, bearing in mind that irradiance error of lamp is about 2%. The responsivity changed by +3.5% during three months under solar radiation, and +0.4% in a month in the dark room. 2) NIST lamp tests were repeated by changing the distance between the lamp and the detector surface to find the optimum distance for calibration. The result was that the calibration of the instrument could be properly performed at the distance from 30 to 70 cm with errors of -1.4 to +0.8%. 3) Cosine response deviation from the ideal value of 1/cosZ was under -5% at the zenith angle (Z) from 0 to 35 degrees, under -10% from 35 to 60 degrees, and about -20% at Z = 70 degrees, respectively. The azimuth response test indicated that the best azimuth position (AZ) to minimize the effect of directional response was AZ = 180 degrees (south side). 4) Tests using sixteen kinds of optical filters suggested that about 85% of total output was attributed to the wavelength range of UVB from 280 to 315nm. 5) Water pool on the flat detector surface produced the output decrease of 22% at a maximum. 6) Outdoor comparison between SKU 430 calibrated by NIST lamp and Brewer MKIII showed that the irradiance ratio of SKU 430 to Brewer MKIII scattered around 1.8 at noon for clear sky.
Compact and low-priced, the SKU 430 demonstrated good performance comparable
to other UV radiometers such as UV-S-AB-T and MS212WF. Water holding tendency
of the flat detector surface is recommended to be improved for all-weather
meteorological use.
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