Ultraviolet radiation in the Atacama Desert

Abstract

The world's highest levels of surface ultraviolet (UV) irradiance have been measured in the Atacama Desert. This area is characterized by its high altitude, prevalent cloudless conditions, and a relatively low total ozone column. In this paper, we provide estimates of the surface UV (monthly UV index at noon and annual doses of UV-B and UV-A) for all sky conditions in the Atacama Desert. We found that the UV index at noon during the austral summer is expected to be greater than 11 in the whole desert. The annual UV-B (UV-A) doses were found to range from about 3.5 kWh/m (130 kWh/m) in coastal areas to 5 kWh/m (160 kWh/m) on the Andean plateau. Our results confirm significant interhemispherical differences. Typical annual UV-B doses in the Atacama Desert are about 40% greater than typical annual UV-B doses in northern Africa. Mostly due to seasonal changes in the ozone, the differences between the Atacama Desert and northern Africa are expected to be about 60% in the case of peak UV-B levels (i.e. the UV-B irradiances at noon close to the summer solstice in each hemisphere). Interhemispherical differences in the UV-A are significantly lower since the effect of the ozone in this part of the spectrum is minor.

Ozone—climate interactions and effects on solar ultraviolet radiation

“…144 In the tropics, the annual dose reaches about 1.75 MJ m −2 near sea-level, which corresponds to an average daily dose of 4.8 kJ m −2 . At high altitude sites, much higher doses were measured at the Atacama Desert, Chile (5.2 km altitude), 145 which correspond to about 2.4 MJ m −2 of erythemal irradiance. For fair-skinned individuals (skin type I), the minimal erythemal dose (MED) leading to reddening of the skin is about 0.2 kJ m −2 .…”

Extreme environments: microbiology leading to specialized metabolites

“…Several pilot studies have been carried out to establish the microbial flora of nonpolar deserts (Kurapova et al 2012;Tiwari et al 2015;Ouchari et al 2018) but the most extensive studies of cultivable microbial diversity in desert biomes have been focused on sites in the Atacama Desert in Northern Chile (Bull et al 2016(Bull et al , 2018aBull and Goodfellow 2019). The location and abiotic conditions associated with this temperate, nonpolar desert have been the subject of several reviews (Azua-Bustos et al 2012;Cordero et al 2018) and its uniqueness highlighted (Bull et al 2016). Microbial surveys of Atacama Desert soils and regoliths have been focused on the isolation and characterization of microorganisms, notably actinobacteria, from hyperarid and extreme hyperarid regions where the mean annual rainfall to mean annual evaporation is 0Á05 and 0Á02% respectively (Houston 2006).…”

Atmospheric Nitrate as a Potential Nutrient for Life on Mars

“…Within the hyperarid core, Yungay region is studied the most as a dry limit of life with the mean annual precipitation as low as 0.7 mm during typical dry years (1994)(1995)(1996)(1997)(1998) [6]. In addition, both the high and low altitude Atacama Deserts are exposed to extreme surficial UV irradiation as high as ~150 kWh/m 2 in the UV-A (315-400 nm) and ~5 kWh/m 2 in the UV-B (280-315 nm), more than 40% greater than the average UV-B intensity in northern Africa [10]. UV irradiation in these bands can both destroy organic matter [11,12] and photochemically produce oxyanions such as nitrate [4,13].…”