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UV spectral irradiance measurements in New Zealand: Effects of Pinatubo volcanic aerosolSince late 1989, regular UV spectral irradiance measurements have been made at Lauder, New Zealand (45 deg S, 170 deg E), whenever weather permits. Here, the instrumentation and measurement strategy are outlined, and early results are discussed. Following the eruption of Mt Pinatubo in June 1991, large amounts of volcanic aerosol were injected into the stratosphere and were subsequently transported to New Zealand's latitudes in the latter half of 1991. This provides an opportunity to investigate the effects of volcanic aerosols on UV irradiances measured at this clean-air site. Although changes in global (sum of diffuse plus direct) irradiances were below the detection threshold, there were significant changes in the partitioning of radiation between the direct beam and diffuse skylight. Decreases by nearly a factor of two in the direct/diffuse ratio were observed at longer wavelengths, and at smaller solar zenith angles (sza's). The aerosol optical depth due to volcanic aerosol over Lauder in December 1991 was 0.15 plus or minus 0.02 at 450 nm, with lower values at shorter wavelengths. Although effects were relatively small in the UVB region, an implication of the changes is that the contrast between shade and direct sun is reduced, so that shaded areas received relatively more radiation in the summer of 1991/92 in New Zealand.
Document ID
19950004639
Document Type
Conference Paper
Authors
Mckenzie, Richard L. (National Inst. of Water and Atmospheric Research Lauder, New Zealand)
Date Acquired
September 6, 2013
Publication Date
April 1, 1994
Publication Information
Publication: NASA. Goddard Space Flight Center, Ozone in the Troposphere and Stratosphere, Part 2
Subject Category
ENVIRONMENT POLLUTION
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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