Combined effects of mesoscale processes and atmospheric high-frequency variability on the spring bloom in the MEDOC area

A number of processes are proposed to explain the time and space variabilit y of the onset and decay of the spring phytoplankton bloom. This is done in the modeling framework of a case study most representative of the northwes tern Mediterranean Sea (MEDOC area). The strategy followed is to isolate th e different possible sources of variability (oceanic mesoscale dynamics, sp ring warming, wind bursts) in a series of process experiments (no flux, war ming and wind experiments). The analysis of these experiments provides info rmation for the analysis of a more realistic experiment, forced with daily atmospheric data (high-frequency experiment). On the basis of this study, w e propose a categorization of the processes that control the spring bloom, in terms of their impact on the onset and decay of the bloom, and of the ti me and space scales on which they apply. (C) 1999 Elsevier Science Ltd. All rights reserved.