Solar ultraviolet spectroradiometry in New Zealand: instrumentation and sample results from 1990.

In 1988 the New Zealand Department of Scientific and Industrial Research initiated a program to characterize the spectrum of solar ultraviolet radiation reaching the ground in New Zealand and to identify the extent and causes of its variability. Routine measurements began at Lauder (45 degrees S 170 degrees E) in December 1989. The instrumentation, measurement strategy, and calibration procedures are discussed and uncertainties in the measurements are analyzed. With the present system useful measurements at 1-nm resolution are limited to irradiances greater than 10(-3) microW cm(-2) nm(-1), which corresponds to a lower limit in wavelength in the region 290-295 nm (depending on the Sun angle and ozone amount). This is a useful lower limit for many applications of relevance to the biosphere. Results from the first year of operation are presented and discussed.