UW Ocean Modeling Group

UW OCEAN GBC MODELING GROUP

Assimilation of chlorophyll and nutrients into a 3-D marine carbon cycle model (NASA-Carbon cycle)

11 section parameter optimizations

In these experiments, ecosystem parameters are varied seasonally and regionally to fit the SeaWiFS chlorophyll data. For this purpose the ocean model domain is divided into eleven sections.

ocean sections

Figure 1 Plot of global ocean regions based in ocean basin distribution

The regional variation of ecosystem parameters resulted in a better performance of the carbon cycle model with a significantly reduced misfit between the simulated and the observed chlorophyll concentration. The a posteriori model-data misfit in the Southern Ocean remains relatively high in the Spring season assimilation (Figure 2c). The optimization also improves the chlorophyll simulation in the equatorial Atlantic and Indian Ocean, as well as in the southern Indian Ocean. A distinguishable improvement also occurred in the North Pacific region where the a posteriori chlorophyll concentration increased significantly. The optimized ecosystem parameters are listed in Table 1. Almost all of the assimilation experiments yielded lower zooplankton grazing rates.

Pi		NOPA	NOAT	MIPA	MIAT	EQIN	EQPA	EQAT	SOIN	SOPA	SOAT	SOOC	NOPA	NOAT	Mean	Var
P1	Spring	1.05	1.00	1.00	1.00	1.00	1.00	1.01	1.00	1.01	1.00	1.00	1.05	1.00	1.01	0.00
P2		2.15	1.00	1.07	1.04	1.10	1.02	1.64	1.11	1.11	1.11	1.03	2.15	1.00	1.22	0.13
P3		0.00	0.99	0.99	0.97	1.00	1.00	1.07	0.99	1.00	1.00	1.00	0.00	0.99	0.91	0.09
P4		0.00	0.78	0.71	0.69	0.97	0.99	0.95	0.88	0.90	0.90	0.91	0.00	0.78	0.79	0.08
P5		0.00	0.99	0.83	0.90	0.94	0.98	0.09	0.93	0.92	0.86	1.05	0.00	0.99	0.77	0.13
P6		0.00	0.99	0.87	0.91	0.92	0.99	0.48	0.87	0.91	0.88	0.95	0.00	0.99	0.80	0.09
P7		0.00	0.99	0.86	0.91	0.85	0.99	0.00	0.94	0.89	0.89	1.04	0.00	0.99	0.76	0.14
P8		1.23	1.00	1.01	1.01	1.02	1.00	1.13	1.02	1.02	1.02	1.00	1.23	1.00	1.04	0.01
P9		1.03	1.00	1.00	1.00	1.01	1.00	1.02	1.00	1.00	1.00	1.00	1.03	1.00	1.01	0.00
P10		2.45	1.02	1.06	1.05	1.04	1.01	1.21	1.03	1.08	1.02	1.00	2.45	1.02	1.18	0.18
P11		3.56	1.12	1.01	1.04	0.90	1.00	0.81	1.13	1.01	1.05	1.12	3.56	1.12	1.25	0.60
P12		0.00	0.99	1.00	0.79	1.03	0.92	0.82	0.02	0.66	0.74	0.00	0.00	0.99	0.63	0.18
P1	Fall	1.00	1.00	1.01	1.00	1.00	0.99	1.01	1.00	1.00	1.00	1.00	1.00	1.00	1.00	0.00
P2		2.30	1.07	2.13	1.15	1.08	1.19	1.30	1.05	1.00	1.11	0.98	2.30	1.07	1.31	0.21
P3		0.72	0.11	0.83	0.99	1.00	1.00	1.02	1.02	1.00	1.05	1.01	0.72	0.11	0.89	0.08
P4		0.00	0.78	0.63	0.78	0.97	0.95	0.99	1.12	1.01	1.31	1.11	0.00	0.78	0.88	0.12
P5		0.57	0.94	1.15	0.91	0.90	0.96	0.76	0.92	1.00	0.83	1.06	0.57	0.94	0.91	0.02
P6		0.00	0.83	0.43	0.77	0.94	0.88	0.77	0.94	1.00	0.70	1.05	0.00	0.83	0.76	0.09
P7		0.01	0.96	1.11	0.93	0.91	1.01	0.61	0.94	1.00	0.88	1.05	0.01	0.96	0.86	0.09
P8		1.25	1.01	1.20	1.03	1.02	1.03	1.07	1.01	1.00	1.02	1.00	1.25	1.01	1.06	0.01
P9		1.10	1.00	1.17	1.00	1.00	0.96	1.02	1.00	1.00	1.00	1.00	1.10	1.00	1.02	0.00
P10		1.02	1.00	1.11	1.01	1.01	0.94	1.10	0.99	1.00	0.92	0.98	1.02	1.00	1.01	0.00
P11		2.02	1.23	0.40	1.31	0.96	1.30	0.84	0.98	1.00	0.97	0.96	2.02	1.23	1.09	0.16
P12		0.00	0.00	2.82	0.00	1.07	0.00	0.90	1.22	1.00	1.10	0.00	0.00	0.00	0.74	0.76

Table 1. A posteriori ecosystem parameter values with mean and variance resulting from the assimilation with regionally varying control variables for Spring and Fall season integrations.

Figure 2. SeaWiFS chlorophyll-a data for Spring (A) and Fall (B) seasons in comparison to the respective model a posteriori simulation of surface chlorophyll concentration for Spring (C) and Fall (D). Ecosystem parameters are varied by the optimization in different ocean sections.