Modeling the influence of local/external processes on nitrogen and phytoplankton dynamics in the GoM/GB region R. Ji With help from: PI team: Davis, Chen, Beardsley, Townsend, Durbin, Runge, Flagg UMASS-D modeling group: Q. Xu, G. Cowles, R. Tian, S. Hu, D. Stuebe NMFS: D. Mountain, J. Hare, M. Taylor
Status Completed continuous run for FVCOM+NPZD; comparing data/model results Completed 1995 Pseudocalanus model run; using “stage with mean age” method; Testing different implementation of CPD Examining effect of freshening on phytoplankton dynamics (data analysis + numerical exp.) 1 ms. submitted to JMS + 1 ms. to be submitted to GRL + 1 new baby
Model structure
Surface - Nitrogen
Surface - Phytoplankton
Transect - Phytoplankton
Model skills Degree of agreement: (Willmott, 1981)
Model vs data on GB N
P
N
P
Model vs data in Basins Jordan Basin Wilkinson Basin
Model vs data at CMO
Sensitivity to IC (GB crest) N P
Sensitivity to IC (Wilkinson Basin) N P
Sensitivity to BC (Scotian Shelf) N P
Sensitivity to BC (Wilkinson Basin) (GB crest)
Nitrogen cycle Redline from Pastsuzak et al., 1982
N demand and supply on GB Total N demand: ~1.26x10 3 mol N s -1 (Horne et al., 1989) New N supply: ~0.48x10 3 mol N s -1 (Townsend & Pettigrew, 1997) ~5x10 3 mol N s -1 (Horne et al., 1989)
Modeled N flux on GB Summertime new N supply 0.23x10 3 mol N s -1 Summertime f ratio = 0.18
Response to bottom N change
Bloom - freshening
Bloom “propagation”
Timing-SSS anomaly
Magnitude/NPP
Issues Huge amount of model output, O(TB) Very limited availability of data in GoM during GLOBEC year (N, Vertical profile) Boundary conditions (N/P/Z/D, T/S) Need free grad students