The potential loss of significant fractions of stratospheric ozone has prompted renewed efforts in assessing the potential damage to plant and animal life due to enhanced levels of solar Ultraviolet-B (UV-B, 280-320 nm) radiation. The objective of this study was to develop and evaluate analytical models to predict the UV-B radiation loading on potentially sensitive surfaces as influenced by vegetation. The UV-B irradiance measurements were made in a widely-spaced orchard and in a closely-spaced maize crop during cloud-free days in 1994 and 1995, at West Lafayette, Indiana (40.5{dollar}spcirc{dollar}N, latitude). Solar zenith angles ranged from 20{dollar}spcirc{dollar} to 80{dollar}spcirc.{dollar} The sky view was typically 0.59 for the orchard and 0.28 for the maize canopy. Two UV-B radiation transfer (UVRT) models (one dimensional UVRT and three dimensional UVRT) were developed and evaluated in conjunction with an additional one dimensional model for their ability to estimate the measured UV-B transmittance within vegetation canopies. The three dimensional UVRT model had an estimate error of 0.037 (MBE, mean bias error) and 0.076 (RMSE, root mean squared error) for both orchard and maize canopies combined. The one dimensional UVRT model had an estimate error of 0.014 (MBE) and 0.021 (RMSE) for the maize canopy only. The models can serve as a much-needed tool to examine UV-B loading of people and other life in and below tree and other vegetation canopies.
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