1. 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

2. Status  Completed 1995-1999 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

3. Model structure

4. Surface - Nitrogen

5. Surface - Phytoplankton

6. Transect - Phytoplankton

7. Model skills Degree of agreement: (Willmott, 1981)

8. Model vs data on GB N

9. P

10. N

11. P

12. Model vs data in Basins Jordan Basin Wilkinson Basin

13. Model vs data at CMO

14. Sensitivity to IC (GB crest) N P

15. Sensitivity to IC (Wilkinson Basin) N P

16. Sensitivity to BC (Scotian Shelf) N P

17. Sensitivity to BC (Wilkinson Basin) (GB crest)

18. Nitrogen cycle Redline from Pastsuzak et al., 1982

19. 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)

20. Modeled N flux on GB Summertime new N supply 0.23x10 3 mol N s -1 Summertime f ratio = 0.18

21. Response to bottom N change

22. Bloom - freshening

23. Bloom “propagation”

25. Timing-SSS anomaly

26. Magnitude/NPP

27. 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