Modelling the timing of major spring bloom events in the central Yellow Sea

Abstract

Spring blooms observed in the Yellow Sea, which contribute the primary production in the local food chain, generally occur in the central part of the Yellow Sea (YS) in the early spring from March to April. In this paper, we use a 3-D physical ocean model and 1-D ecosystem model to explore the timing of the five major spring bloom events observed in the central YS in 2007. The results show that Sverdrup's critical depth model can be applied to simulate the first four spring bloom events in March and April of 2007. Under the conditions when nutrients are sufficient, the timing of the spring bloom events appears to always be controlled by physical processes and the reduction of the wind speed in particular. The magnitude of the bloom events is affected by light and temperature in the euphotic layer. The correlation between the timing of the spring bloom and the reduction of the wind speed is investigated by reversal computations and linear regression, and a critical wind speed of less than 5.7 m s−1 was determined to trigger the bloom.