LAUSR

This study is to describe the degradation behavior of the optical constants (refractive index $$ \bar{n} $$n¯ and extinction coefficient $$ \bar{\sigma } $$σ¯) of PE-LD sheets during exposure to an arid climate. Values of $$ \bar{n} $$n¯ and $$ \bar{\sigma } $$σ¯ are used to determine the solar radiative properties of any PE-LD cover at any time without the need of measurements. Different greenhouse models were covered with PE-LD films and exposed for 1 year to an arid climate, and values of $$ \bar{n} $$n¯ and $$ \bar{\sigma } $$σ¯ were investigated. Exposing films to the arid climate for 1 year increased the values of $$ \bar{n} $$n¯ from 1.58 to 2.86 and $$ \bar{\sigma } $$σ¯ from 3.86 to 8.1 mm−1, resulting in a decrease in transmittance from 0.42 to 0.12. Two correlations for predicting the degradation rate of $$ \bar{n} $$n¯ and $$ \bar{\sigma } $$σ¯ for PE-LD covers were developed.