Diurnal warm-layer events in the western Mediterranean and European shelf seas

Merchant, C. J. ORCID: https://orcid.org/0000-0003-4687-9850, Filipiak, M. J., Le Borgne, P., Roquet, H., Autret, E., Piolle, J.-F. and Lavender, S. (2008) Diurnal warm-layer events in the western Mediterranean and European shelf seas. Geophysical Research Letters, 35 (4). L04601. ISSN 0094-8276 doi: 10.1029/2007GL033071

Abstract/Summary

We characterize near-surface ocean diurnal warm-layer events, using satellite observations and fields from numerical weather forecasting. The study covers April to September, 2006, over the area 11°W to 17°E and 35°N to 57°N, with 0.1° cells. We use hourly satellite SSTs from which peak amplitudes of diurnal cycles in SST (dSSTs) can be estimated with error ∼0.3 K. The diurnal excursions of SST observed are spatially and temporally coherent. The largest dSSTs exceed 6 K, affect 0.01% of the surface, and are seen in the Mediterranean, North and Irish Seas. There is an anti-correlation between the magnitude and the horizontal length scale of dSST events. Events wherein dSST exceeds 4 K have length scales of ≤40 km. From the frequency distribution of different measures of wind-speed minima, we infer that extreme dSST maxima arise where conditions of low wind speed are sustained from early morning to mid afternoon.