In Europe (EU25) about half a million skin cancer cases are occurring per year and this is strongly associated with personal habits in relation to sun exposure and its UV component. Within the frame of the European GMES-Program (GMES=Global Monitoring for Environment and Security) the ESA-GSE Project PROMOTE addresses this problem by developing and implementing a UV information service that aims to reach as many as possible citizens of Europe (EU25). The overall PROMOTE UV service contains forecast and monitoring products. The underlying methods, the use of satellite data, the various UV products including related user interfaces, as well as accuracy aspects are described. One central ambition of the PROMOTE project is the close interaction between providers and users. Experiences that have been made and will be made during the different stages of the PROMOTE project contribute significantly to the further up-grading of the services.
An Antarctic UV-monitoring network established in 1999 as a Spanish-Finnish-Argentinian co-operation consists of multiband filter radiometers located at Belgrano, Marambio, and Ushuaia. To provide with quality controlled and assured calibrated groundbased Antarctic UV data, bi-weekly lamp tests were used on every site and visits of travelling reference instruments on two of the sites. Along the six years of operation, the sensitivity in some of the instrument channels was found to drift up to 61%. In both stations, always the same channels showed the best stability or worst instability. The rigorous quality assurance programme ensured that reliable time series of solar data could be produced, however. The most recent Antarctic ozone depletion period of 2005/2006 was studied by comparing OMI satellite-based erythemally weighted daily doses with the measured polynomial corrected data for August 2005-March 2006 for Ushuaia and Marambio. The root mean square (RMS) of difference between the groundbased and satellite-retrieved daily doses was on monthly basis smaller for Ushuaia (19 - 28 %) than for Marambio (17-58 %), possibly due to e.g. bigger heterogeneity of the ground albedo, and variability of the cloudiness. Our final task of combining the polynomial corrected lamp calibration factors and the traveling reference calibration factors, to produce the final calibrated Antartic UV data, is discussed, too.
Monitoring of the terrestrial solar ultraviolet irradiance by using a radiometer is often considered as expensive
and laborious or the data collected as insufficient in spatial coverage and in some cases in its temporal
resolution, too. Therefore, alternative methods, all relying on modelling in one way or the other, have been
developed. They differ in which input they receive, either standard meteorological information, space-based
radiance measurements or ground-based irradiances from broadband or multiband UV radiometer or from
pyranometer. A comparison of performance is presented between three methods during a 15-month period.
The ground reference instrument is the Brewer Mk-III #107 spectroradiometer of the Observatory of
Jokioinen, Finland. Compared to the reference, the space-based method overestimates the UV irradiance at
noon by 14.6% and the pyranometer-based by 0.9% with root-mean-square differences of 35.5% and 10.4%,
respectively. Daily erythemal doses agree by 3.8% for the space-based and 0.4% for the pyranometer-based
method with a scatter of 16.5% and 4.6%, respectively. Spectral irradiances generated by the pyranometerbased
model agree within 0.4% on average with a standard deviation of 17%. A rough estimate on the cost of
each approach suggests that none of them is clearly superior to the others and the actual nature of the data
needed may be used in decision making concerning monitoring strategies.
The seasonal variation of the surface albedo, due to snow or ice, complicates satellite estimation of the high-latitude surface UV irradiance. The TOMS instrument, that measures the backscattered radiances from the Earth's atmosphere and surface, does not distinguish cloud backscattering from surface backscattering. When the TOMS UV algorithm is used, false interpretation of the measured high reflectivity as thick cloudiness leads to substantial underestimation of the surface UV irradiance. While the largest UV irradiance is usually received during the summer, the spring exposure to UV radiation is the main concern in high-latitudes
since the sensitivity of some biological organisms to UV radiation
is more pronounced at low temperatures, and snowcover enhances
the surface UV irradiance. This paper presents a new method for estimation of the surface reflectivity. The method is based on analysis of the TOMS Lambertian equivalent reflectivity data
using the moving time-window technique. The new method treats the measured reflectivity data as samples from a distribution
whose lower tail corresponds to surface albedo. The basic
method assumes that the distribution is homogeneous, i.e. the surface albedo is constant within the window. Adequate statistics is achieved only by using a wide time-window which, unfortunately, leads to underestimation of the surface albedo during spring and autumn transitions. Therefore, the method was developed further to account for transitions. The feasibility of the new method has been studied globally for high-latitude regions, and it is expected to improve springtime UV irradiance estimates of polar regions.