Validity of satellite measurements used for the monitoring of UV radiation risk on health

Abstract

Abstract. In order to test the validity of ultraviolet index (UVI) satellite products and UVI model simulations for general public information, intercomparison involving three satellite instruments (SCIAMACHY, OMI and GOME-2), the Chemistry and Transport Model, Modélisation de la Chimie Atmosphérique Grande Echelle (MOCAGE), and ground-based instruments was performed in 2008 and 2009. The intercomparison highlighted a systematic high bias of ∼1 UVI in the OMI clear-sky products compared to the SCIAMACHY and TUV model clear-sky products. The OMI and GOME-2 all-sky products are close to the groundbased observations with a low 6 % positive bias, comparable to the results found during the satellite validation campaigns. This result shows that OMI and GOME-2 all-sky products are well appropriate to evaluate the UV-risk on health. The study has pointed out the difficulty to take into account either in the retrieval algorithms or in the models, the large spatial and temporal cloud modification effect on UV radiation. This factor is crucial to provide good quality UV information. OMI and GOME-2 show a realistic UV variability as a function of the cloud cover. Nevertheless these satellite products do not sufficiently take into account the radiation reCorrespondence to: F. Jégou (fabrice.jegou@orleans.cnrs.fr) flected by clouds. MOCAGE numerical forecasts show good results during periods with low cloud covers, but are actually not adequate for overcast conditions; this is why Météo-France currently uses human-expertised cloudiness (rather than direct outputs from Numerical Prediction Models) together with MOCAGE clear-sky UV indices for its operational forecasts. From now on, the UV monitoring could be done using free satellite products (OMI, GOME-2) and operational forecast for general public by using modelling, as long as cloud forecasts and the parametrisation of the impact of cloudiness on UV radiation are adequate.

Sex differences in the association of cutaneous melanoma incidence rates and geographic ultraviolet light exposure

“…Daily average UVI was calculated using data collected by the GOME-2 satellite stations (Table 1 and Supplemental Table S2). Ambient UVI was modeled with data collected at noon each day with consideration for the local cloud conditions and was well correlated with ground erythemal UV dose, without distinction of UVA or UVB [11]. The UVI ranged from 1.8 (Finland) to 12.0 (Australia, Northern Territory) and roughly demonstrated a normal distribution (Supplemental Table S3).…”

Comparison of GOME-2 UVA Satellite Data to Ground-Based Spectroradiometer Measurements at a Subtropical Site

“…The application of a correction factor based on the aerosol absorbing optical thickness provided an improvement in the agreement with the difference falling to less than 20% for 90% of the cases [11]. A validation report of offline erythemal UV products from GOME-2 against 15 ground-based stations for data between June 2007 and May 2008 have found a positive bias of 10-20% for daily erythema UV exposures [12], [13]. A smaller, but still positive bias was found for the daily maximum irradiances.…”

Long-term comparisons of UV index values derived from a NILU-UV instrument, NWS, and OMI in the New York area

“…While UVB radiation is heavily absorbed by ozone, UVA radiation suffers relatively little absorption. Thus, UVB radiation is significantly attenuated before reaching the surface of the Earth, while UVA radiation is little affected by the ozone layer [2]. Since UV radiation is harmful to human beings, animals, and plants [3], it is important to monitor the UV exposure.…”