ABSTRACT This paper presents a 21‐year evolution of ultraviolet (UV) aerosol optical depth at 320 nm (AOD 320 ) in Hobart, Australia (42.8806° S, 147.3250° E) and its relationship to bushfire events and relevant climate indices. Daily AOD 320 is obtained from readings of a Brewer MKIII spectrophotometer over the period 2002–2023 and is processed into monthly averages. The evolution shows statistically significant increases of 15.4% per decade, although the series exhibits a large fluctuation with a minimum around April 2006 and a maximum around April 2019. The series also features 9 months where AOD 320 averages are more than twice the monthly standard deviation, with these months being related to major fire events in the Tasmanian region. To identify dominant influences on AOD 320 , stepwise regression analyses were performed between monthly AOD 320 as the dependent variable and various climate indices and fire properties as predictors. Seasonality exerts a strong control on AOD 320 . During summer months, AOD 320 is strongly related to fire Hot Spot numbers, Southern Oscillation Index (SOI), and time, with 58% of the variance accounted for by these three predictors. Spring AOD 320 is related to southerly winds and Pacific Decadal Oscillation (PDO), while winter and autumn AOD 320 are related only to time. The significance of these relationships is discussed within the context of our study region located in the Southern Hemisphere mid‐latitudes.
Nuñez et al. (Fri,) studied this question.