Modeling the influence of local/external Modeling the influence of local/external processes on nitrogen and phytoplankton processes on nitrogen and phytoplankton dynamics in the GoM/GB region dynamics in the GoM/GB region

R. JiR. Ji

With help from:With help from: PI team: Davis, Chen, Beardsley, Townsend, Durbin, Runge, FlaggPI team: Davis, Chen, Beardsley, Townsend, Durbin, Runge, FlaggUMASS-D modeling group: Q. Xu, G. Cowles, R. Tian, S. Hu, D. StuebeUMASS-D modeling group: Q. Xu, G. Cowles, R. Tian, S. Hu, D. StuebeNMFS: D. Mountain, J. Hare, M. TaylorNMFS: D. Mountain, J. Hare, M. Taylor

StatusStatus

Completed 1995-1999 continuous run for Completed 1995-1999 continuous run for FVCOM+NPZD; comparing data/model resultsFVCOM+NPZD; comparing data/model results

Completed 1995 Completed 1995 PseudocalanusPseudocalanus model run; model run; using “stage with mean age” method; Testing using “stage with mean age” method; Testing different implementation of CPDdifferent implementation of CPD

Examining effect of freshening on phytoplankton Examining effect of freshening on phytoplankton dynamics (data analysis + numerical exp.)dynamics (data analysis + numerical exp.)

1 ms. submitted to JMS + 1 ms. to be submitted 1 ms. submitted to JMS + 1 ms. to be submitted to GRL + 1 new babyto GRL + 1 new baby

Model structureModel structure

Surface - NitrogenSurface - Nitrogen

Surface - PhytoplanktonSurface - Phytoplankton

Transect - PhytoplanktonTransect - Phytoplankton

Model skillsModel skills

Degree of agreement: (Willmott, 1981)

2

1

2

1

( )1

N

i ii

N

i ii

M O

M O O O

Model vs data on GBModel vs data on GB

NN

Model vs data on GBModel vs data on GB

PP

Model vs data on GBModel vs data on GB

NN

Model vs data on GBModel vs data on GB

PP

Model vs data in BasinsModel vs data in Basins

Jordan BasinJordan BasinWilkinson BasinWilkinson Basin

Model vs data at CMOModel vs data at CMO

Sensitivity to ICSensitivity to IC(GB crest)(GB crest)

NN PP

Sensitivity to ICSensitivity to IC(Wilkinson Basin)(Wilkinson Basin)

NN PP

Sensitivity to BCSensitivity to BC(Scotian Shelf)(Scotian Shelf)

NN PP

Sensitivity to BCSensitivity to BC

(Wilkinson Basin)(Wilkinson Basin) (GB crest)(GB crest)

Nitrogen cycleNitrogen cycle

Redline from Pastsuzak et al., 1982

N demand and supply on GBN demand and supply on GB

70° 0' 68° 0' 66° 0' 40° 0'

41° 0'

42° 0'

43° 0'

Total N demand: ~1.26x103 mol N s-1 (Horne et al., 1989)New N supply: ~0.48x103 mol N s-1 (Townsend & Pettigrew, 1997) ~5x103 mol N s-1 (Horne et al., 1989)

Modeled N flux on GBModeled N flux on GB

Summertime new N supply 0.23x103 mol N s-1 Summertime f ratio = 0.18

Response to bottom N changeResponse to bottom N change

Bloom - fresheningBloom - freshening

Bloom “propagation”Bloom “propagation”

Bloom “propagation”Bloom “propagation”

Timing-SSS anomalyTiming-SSS anomaly

Magnitude/NPPMagnitude/NPP

Issues Issues

Huge amount of model output, Huge amount of model output, OO((TBTB)) Very limited availability of data in Very limited availability of data in

GoM during GLOBEC year (N, GoM during GLOBEC year (N, Vertical profile)Vertical profile)

Boundary conditions (N/P/Z/D, T/S)Boundary conditions (N/P/Z/D, T/S) Need free grad studentsNeed free grad students