Time-series analysis of remote-sensed chlorophyll and environmental factors in the Santa Monica–San Pedro Basin off Southern California Nikolay P. Nezlin a,b, * , Bai-Lian Li b a Institute of the Environment, UCLA, Los Angeles, CA, USA b Department of Botany and Plant Sciences, UCR, USA Received 1 July 2002; received in revised form 16 October 2002; accepted 18 December 2002 Abstract The time-series of remote-sensed surface chlorophyll concentration measured by SeaWiFS radiometer from September 1997 to December 2001 and the relevant hydrological and meteorological factors (remote-sensed sea surface temperature, atmospheric precipitation, air temperature and wind stress) in Santa Monica Bay and adjacent waters off southern California were analyzed using wavelet and cross-correlation statistical methods. All parameters exhibited evident seasonal patterns of variation. Wavelet analysis revealed salient long-term variations most evident in air temperature during El Nin ˜ o 1997 – 1998 and in wind stress during La Nin ˜a 1998 – 1999. Short-period (<100 days) variations of remote-sensed chlorophyll biomass were mostly typical to spring seasons. Chlorophyll biomass was significantly correlated with air temperature and wind stress: an increase of chlorophyll biomass followed with 5 – 6-day time lag an increase of wind stress accompanied by a simultaneous decrease of air temperature. The mechanism of these variations was an intensification of phytoplankton growth resulting from the mixing of water column by wind stress and entrainment of nutrients into the euphotic layer. D 2003 Elsevier Science B.V. All rights reserved. Keywords: Remote sensing; Photosynthetic pigments; Environmental conditions; Time-series analysis; USA; California; Southern California Bight; 33 – 34.5jN; 119 – 118jW 1. Introduction One of the most important problems in studying phytoplankton dynamics in the ocean is the analysis of environmental factors controlling phytoplankton growth (Raymont, 1980). Various methods, including laboratory experiments and mathematical simulation, are used to estimate the mechanism of this influence. However, a statistical analysis of extensive time-series data from field observations is also important. It can reveal correlations between the dynamics of phyto- plankton biomass and environmental characteristics. Based on these correlations, we could hypothesize the mechanisms of environmental control of the biolog- ical processes. The most important limitation of this analysis is that the number of measurements is usually insufficient for statistical analysis because oceano- 0924-7963/03/$ - see front matter D 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0924-7963(03)00030-7 * Corresponding author. Southern California Coastal Water Research Project, 7171 Fenwick Lane, Westminister, CA 92683, USA. Tel.: +1-714-372-9227; fax: +1-714-894-9699. E-mail address: nikolayn@sccwrp.org (N.P. Nezlin). www.elsevier.com/locate/jmarsys Journal of Marine Systems 39 (2003) 185 – 202