Towards estimating surface ultraviolet irradiance using dobson ozone spectrophotometer observations

Abstract

A technique is developed to process Dobson Ozone (O3) Spectrophotometer’s raw data to produce UV-B irradiance values using the instrument's A, C, and D wavelength pairs, (305.5, 325.4), (311.5, 332.4) and (317.6, 339.8) nm, respectively. A case study of ultraviolet patterns using January and September values from the six years of data, collected with Dobson O3 Spectrophotometer number 18, located at Chiromo campus, University of Nairobi, Kenya, is presented. Irradiance derived from pair A show a significant inverse relationship with total ozone. Linear regression of the irradiance with irradiance measurements from other stations around the world show a good agreement. However for pair C, a relatively poor correlation is found for January. The corresponding scatter diagrams suggest the presence of two distinct patterns as evidenced by two clearly seperated clusters.