Solar Ultraviolet Radiation Temporal Variability Analysis from 2-Year of Continuous Observation in an Amazonian City of Brazil

Abstract

Solar ultraviolet radiation (UVR) is a highly energetic component of the solar spectrum that needs to be monitored because of the effects on human health and on the ecosystems. In Brazil, few cities monitor UVR, especially in the Amazon region which is particularly poor in observation. This work is the first to address the short-term (2-year) time variability of UVR in Santarém (2°25′ S, 54°44′ W, 51 m) using ground-based measurements. The irradiance in the wavelength range of 250–400 nm was investigated on different time scales. Furthermore, to understand how the UVR varies without the influence of clouds, the hours corresponding to the clear sky condition were analyzed as well as the hours in all sky conditions. Regarding the averages, there is a slight variation over the year. In all sky and clear sky conditions, the dry season had a higher average than the rainy season, despite the slight difference. Also, both in all-sky and clear-sky conditions the maximums occurred around local solar noon, and reached a maximum of 87 in the dry season under the clear sky condition. Further understanding of the radiative effects of the clouds in UVR time variability is considered essential for future research. This study can serve as a reference for UVR levels in this region where no other ground-based UVR measurements are made.

Protective role of melatonin in ultraviolet radiation- induced oxidative stress in human skin photoaging

“…(17,18,59,60) Solar UVR consists of electromagnetic wavelengths between 100 and 400 nm that reach the terrestrial surface and has a direct effect on human health and terrestrial and aquatic ecosystems, as well as material degradation. (61)(62)(63)(64) It is divided into three components, depending on its transmission capability in the atmosphere and its biological effects: UVA (315-400 nm) makes up most of the UVR received on the terrestrial surface; UVB (280-315 nm) which is partially absorbed into the atmosphere, and UVC (100-280 nm) which is completely absorbed by stratospheric ozone. (34,64) Both UVA and UVB wavelengths have been shown to contribute to photoaging, by imbalanced ROS/ RNS production and/or by direct DNA damage.…”

“…(61)(62)(63)(64) It is divided into three components, depending on its transmission capability in the atmosphere and its biological effects: UVA (315-400 nm) makes up most of the UVR received on the terrestrial surface; UVB (280-315 nm) which is partially absorbed into the atmosphere, and UVC (100-280 nm) which is completely absorbed by stratospheric ozone. (34,64) Both UVA and UVB wavelengths have been shown to contribute to photoaging, by imbalanced ROS/ RNS production and/or by direct DNA damage. (34) In Figure 3, it is stated that approximately 95% of UVA reaches the earth's surface and penetrates up to 10 times deeper into the reticular dermis, such that UVA plays a major role in the UVR-induced oxidative damage and the aging process of the skin.…”