Sensitivity of UV-B Irradiance to Cloud Optical Depth and Droplets Equivalent Radii

The DIScrete Ordinate Radiative Transfer (DISORT) and the delta-Eddington models were used to evaluate the relationship between cloud optical depth, tc and direct, diffuse and global transmitted irradiances in the UV-B region for various solar zenith angles (SZAs), two values of cloud droplet equivalent radius, re (7mm and 10mm) and two cases of low (? = 0.05) and high (? = 0.75) albedos under overcast conditions. The study shows that the delta-Eddington model is not suitable for calculating direct and diffuse components separately but it is suitable for calculating diffuse irradiances for overcast conditions for two cases only at northern latitudes where SZAs are large and at southern Canada wheretc values are always greater than 10. The delta-Eddington model is accurate when calculating the global fluxes anywhere, although it overestimates by an average of 6%. Global transmittance is greater by 7% for smaller droplet sizes (re = 7µm) for both cases of low (? = 0.05) and high (? = 0.75) albedos.

• Publication year

  2015

• Venue

  Earth Science Research

• Publication date

  2015-01-10

• Fields of study

  Physics, Environmental Science

• Identifiers
  DOI 10.5539/ESR.V4N1P68
• External record

  Open on Semantic Scholar

• Source metadata

  Semantic Scholar

• No claims are published for this paper.

• No concepts are published for this paper.

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