In Situ Matchup Comparison

Below are the comparisons of SeaWiFS to the in situ validation data set for Reprocessing #4. For comparison, the Reprocessing #3 results are shown as well. The comparisons are made for water-leaving radiances corrected for the cosine of the solar zenith angle. The ultimate goal of the validation process is to determine if SeaWiFS is meeting the pre-launch stated goals of +/- 5% for water-leaving radiances, and +/- 35% for chlorophyll.

The values listed as '% diff.' in Tables 1 - 3 are the average percent difference between SeaWiFS and the in situ data. This implies that in situ is truth, i.e. error free. However, the in situ data do have some associated uncertainty. A conservative estimate of this uncertainty is on the order of 5%, it may be more, but is unlikely to be less.

For the chlorophyll comparison plots below, the dashed lines show the bounds of the data set that was used to develop the OC4v4 algorithm. The vast majority of the SeaWiFS chlorophyll retrievals fall within these bounds.

Both set of results presented below draw from the same in situ water-leaving radiance and chlorophyll measurement data set. This data set currently consists of 2607 water-leaving radiance records and 5326 chlorophyll measurements. For water-leaving radiance validation, only about 6% of the in situ measurements result in a validation data record. This is primarily the result of the exclusion criteria applied to the satellite data. See the following for a brief description of the validation procedure:

Validation Strategy

Operational (Reprocessing #3) Results

Table 1
	SeaWiFS/In Situ	std. dev.	% diff.	CoV	N	In Situ Range	SeaWiFS Range
Lw(412)	0.7668	0.4790	23.09	0.625	144	0.1287 - 2.630	-0.4529 - 2.298
Lw(443)	1.0223	0.3363	14.00	0.329	143	0.2044 -2.313	0.0474 - 2.341
Lw(490)	1.0896	0.2997	12.39	0.275	143	0.2953 - 2.960	0.4113 - 3.134
Lw(510)	1.1576	0.3714	16.44	0.321	138	0.2379 - 2.923	0.3465 - 3.168
Lw(555)	1.2684	0.5202	21.47	0.410	143	0.0862 - 2.494	0.1365 - 3.087
Chlorophyll	1.6353	2.0306	36.44	1.242	246	0.010 - 174.1	0.0299 - 64.767

Figure 1: Reprocessing #3 matchup comparisons

Reprocessing #4 Results

Table 2
	SeaWiFS/In Situ	std. dev.	% diff.	CoV	N	In Situ Range	SeaWiFS Range
Lw(412)	1.0117	0.3442	12.44	0.340	162	0.1287 - 2.831	-0.0828 - 2.341
Lw(443)	1.0536	0.2987	11.16	0.284	175	0.1790 - 2.604	0.2030 - 2.070
Lw(490)	1.0379	0.2464	8.53	0.237	178	0.2186 - 2.960	0.3181 - 2.775
Lw(510)	1.0474	0.2676	11.18	0.255	156	0.1878 - 2.923	0.3339 - 2.682
Lw(555)	1.1201	0.3293	12.91	0.294	146	0.1069 - 2.059	0.1544 - 2.017
Chlorophyll	1.2028	1.1779	23.77	0.979	208	0.0100 - 23.46	0.0345 - 20.94

Figure 2: Repocessing #4 matchup comparisons

Operational (Reprocessing #3) Results

Points in common with Reprocessing #4

Table 1
	SeaWiFS/In Situ	std. dev.	% diff.	CoV	N	In Situ Range	SeaWiFS Range
Lw(412)	0.8205	0.4304	19.94	0.525	104	0.1287 - 2.630	-0.2661 - 2.298
Lw(443)	1.0245	0.3385	14.19	0.330	112	0.2044 -2.313	0.0474 - 2.341
Lw(490)	1.0697	0.3009	12.71	0.281	115	0.3469 - 2.960	0.4113 - 3.134
Lw(510)	1.1189	0.3453	16.37	0.309	107	0.2379 - 2.923	0.3465 - 3.168
Lw(555)	1.1407	0.3741	16.22	0.328	94	0.1069 - 2.059	0.1487 - 1.824
Chlorophyll	1.4558	1.6044	29.34	1.102	119	0.010 - 23.459	0.0299 - 19.78

Reprocessing #4 Results

Points in common with Reprocessing #3

Table 2
	SeaWiFS/In Situ	std. dev.	% diff.	CoV	N	In Situ Range	SeaWiFS Range
Lw(412)	1.0372	0.3550	13.15	0.342	104	0.1287 - 2.630	-0.0826 - 2.278
Lw(443)	1.0856	0.2798	9.76	0.258	112	0.2043 - 2.313	0.3043 - 2.011
Lw(490)	1.0608	0.2251	7.69	0.212	115	0.3469 - 2.960	0.3906 - 2.777
Lw(510)	1.0652	0.2515	11.08	0.236	107	0.2379 - 2.923	0.4024 - 2.677
Lw(555)	1.1409	0.3002	13.75	0.263	94	0.1069 - 2.059	0.1542 - 2.015
Chlorophyll	1.3674	1.4991	31.35	1.096	119	0.0100 - 23.46	0.0345 - 20.94

Reprocessing #4 with enhanced exclusion criteria

The following are matchup comparisons for reprocessing #4 using additional exclusion criteria. The addional criteria are:

Smaller time window: +/- 30 minutes
Case 1 waters only: excluded records if the turbid water flag was set
LAC resolution: excluded records if the matchup was done at GAC resolution

Table 3
	SeaWiFS/In Situ	std. dev.	% diff.	CoV	N	In Situ Range	SeaWiFS Range
Lw(412)	0.9798	0.2565	9.21	0.262	50	0.3019 - 2.3422	0.2002 - 2.279
Lw(443)	0.9933	0.2630	0.901	0.265	58	0.2479 - 2.0185	0.2030 - 2.012
Lw(490)	1.0062	0.2134	8.06	0.212	59	0.3816 - 1.2701	0.3181 - 1.291
Lw(510)	1.0272	0.2600	9.39	0.253	52	0.3853 - 0.9345	0.3363 - 1.027
Lw(555)	1.0671	0.2564	13.61	0.240	48	0.1429 - 0.7883	0.1903 - 0.7718
Chlorophyll	1.1764	0.9423	27.64	0.801	41	0.0668 - 4.392	0.0489 - 4.163

Figure #3: Reprocessing #4 matchup results - enhanced exclusion criteria