Availability of vitamin D photoconversion weighted UV radiation in southern South America.

Ultraviolet radiation (UVR) plays a key role in several biological functions, including human health. Skin exposure to UVR is the main factor in vitamin D photoconversion. There is also evidence relating low levels of vitamin D with certain internal cancers, mainly colon, breast and prostate, as well as other diseases.

Quality of UVR exposure for different biological systems along a latitudinal gradient.

The exposure of organisms to ultraviolet radiation (UVR) is characterized by the climatology (annual cycle) and the variance (anomalies) of biologically-weighted irradiances at eight geographical locations in austral South America, from 1995-2002. The net effect of UVR on biological systems is a result of the balance of damage and repair which depends on intensity and duration of irradiance and is modulated by its variability. The emphasis in this study is on day-to-day variability, a time scale of importance to adaptive strategies that counteract UVR damage.

A five-year study of solar ultraviolet radiation in southern Chile (39 degrees S): potential impact on physiology of coastal marine algae?

This study reports 5 years of (1998-2003) data on continuous solar-irradiation measurements from a scanning spectroradiometer (SUV-100) in Valdivia, Chile (39 degrees S), accompanied by evaluation of the impact of ultraviolet radiation (UVR) on marine macroalgae of this site. UVR conditions showed a strong seasonal variation, which was less pronounced toward longer wavelengths. Daily maximum dose rates (clear days) averaged in winter-summer: UV-B(290-315 nm) 0.

Multichannel radiometer calibration: a new approach.

The error in irradiance measured with Sun-calibrated multichannel radiometers may be large when the solar zenith angle (SZA) increases. This could be particularly detrimental in radiometers installed at mid and high latitudes, where SZAs at noon are larger than 50 degrees during part of the year. When a multiregressive methodology, including the total ozone column and SZA, was applied in the calculation of the calibration constant, an important improvement was observed.

[Ultraviolet radiation producing erythema in Valdivia. A comparison among satellite data, a radiative transfer model and ground-based observations].

To evaluate dose rates and daily doses (DDE) at Valdivia in Southern Chile, ultraviolet irradiances recorded every 15 min from 1998 to 2000 with a high resolution spectroradiometer were weighted with an erythemal action spectrum. Exposure times to get one MED (210 J/m2) in Summer are 10, 12, 18 and 24 min for skin types I trough IV respectively. DDE estimations included in NASA Web products overestimate measurements by 16% on average in Summer, with an absolute uncertainty of 980 J/m2 at the 95% level.