High penetration of ultraviolet radiation in the south east Pacific waters

Marc Tedetti (1) , Richard Sempere (1) , Alexander Vasilkov , Bruno Charrìère (1) , David Nerini (1) , William L. Miller , Kimitaka Kawamura (2) , Patrick Raimbault (1)

1 MIO - Institut méditerranéen d'océanologie
2 Institute of Low-Temperature Science

[1] We investigated the penetration of solar ultraviolet radiation (UVR) in the surface waters of the south east Pacific (08-35°S, 142-73°W) from October to December 2004 during the BIOSOPE cruise. In the hyper-oligotrophic waters of the South Pacific Gyre (near Easter Island), diffuse attenuation coefficients for downward irradiance, K d (l), at 305 nm (UV-B), 325, 340 and 380 nm (UV-A) were 0.083, 0.055, 0.039 and 0.021 m À1 , respectively. The corresponding 10% irradiance depths, Z 10% (l), were 28, 42, 59 and 110 m, respectively. These UVR penetrations are the highest ever reported for oceanic waters and are equal to those measured in the clearest fresh waters. UV-extended inherent optical property (IOP) and radiative transfer (RT) models allowed reliable estimations of K d (l) with the Case 1 water assumption when two values of chromophoric dissolved organic matter (CDOM) absorption spectral slope coefficient (S) were used, i.e. 0.017 nm À1 at 325, 340 and 380 nm, and 0.023 nm À1 at 305 nm. Citation: Tedetti, M., R. Sempéré, A. Vasilkov, B. Charrière, D. Nérini, W. L. Miller, K. Kawamura, and P. Raimbault (2007), High penetration of ultraviolet radiation in the south east Pacific waters, Geophys.

Domaines: Océan, Atmosphère

Marc Tedetti, Richard Sempere, Alexander Vasilkov, Bruno Charrìère, David Nerini, et al.. High penetration of ultraviolet radiation in the south east Pacific waters. Geophysical Research Letters, 2007, 34 (12), ⟨10.1029/2007gl029823⟩. ⟨hal-01991643⟩