A. Eigenheer et al., ON THE SENSITIVITY OF ECOSYSTEM BOX MODEL SIMULATIONS ON MIXED-LAYER DEPTH ESTIMATES, Deep-sea research. Part 1. Oceanographic research papers, 43(7), 1996, pp. 1011-1027
A certain class of pelagic ecosystem box models uses the mixed layer d
epth as the main physical forcing. This paper investigates the influen
ce of the definition and derivation of the mixed layer depth on the si
mulation results. For this investigation the model of Fasham et al. (1
990) (Journal of Marine Research, 48, 591-639) is used to simulate the
phytoplankton bloom during the Fladenground Experiment in spring 1976
(FLEX'76). The time of establishment of the thermocline, the mean dep
th and the temporal variability of the mixed-layer depth differ substa
ntially between the estimates under consideration. Exactly those featu
res influence the model results fundamentally. All processes and state
variables of the ecosystem model examined for a series of representat
ions of mixed layer development during FLEX '76 differ widely from eac
h other and from observations. Temporal variability of the mixed-layer
depth causes a variability of the onset of the plankton bloom of abou
t two weeks. Consequently, this class of ecological models cannot repr
oduce the dynamics of the spring bloom ecosystem appropriately; for th
is purpose vertical mixing processes need to be represented explicitly
. Copyright (C) 1996 Elsevier Science Ltd.