P18

• Nitrate (Mordy, Zhang - NOAA)
• Phosphate (Mordy, Zhang - NOAA)
• Silicate (Mordy, Zhang - NOAA)
• Oxygen (Mordy, Zhang - NOAA)
• TCO₂(Feely - PMEL) - No adjustment recommended.
• Crossovers:
  

  Crossing #	Old #	Latitude	Longitude	Cruise 1	Cruise 1 Sta	Cruise 2	Cruise 2 Sta	Delta	Stdev
  73	32	5° N	110° W	P18	155,159	EQS92	6	-7.5	4.9
  74	36	17° S	103° W	P18	105,106	P21	77	-2.7	1.5
  76	35	32° S	103° W	P18	73	P6	56,58	-0.5	0.4
  77		52° S	103° W	P18	37	P17E19S	194	3.4	0.8
  78	34	67° S	103° W	P18	10,11	S4P	711,712,713	-1.2	0.4
  MEAN								-1.7	3.9

• Precision of Duplicate Measurements - Precision for 100 duplicates was ± 0.014%
• CRM Results - Shipboard measurements off by -1.3 ± 1.4.
• Keeling Replicates - Mean difference for 28 samples was -0.43 ± 2.04.
• Multiparameter Analysis (details) - Mean Difference (estimated - measured) = -2.8 ± 2.6 Note: Analysis only considered stations north of equator.
• Alkalinity(Millero - RSMAS) - No adjustment recommended.
• Crossovers:
  

  Crossing #	Old #	Latitude	Longitude	Cruise 1	Cruise 1 Sta	Cruise 2	Cruise 2 Sta	TALK Delta Stdev
  73	32	5° N	110° W	P18	155,159	EQS92	6	-0.4 ± 1.0 (graph)
  74	36	17° S	103° W	P18	105,106	P21	77	-0.5 ± 2.8 (graph)
  77		52° S	103° W	P18	37	P17E19S	194	4.5 ± 1.8 (graph)
  78	34	67° S	103° W	P18	10,11	S4P	711,712,713	1.0 ± 1.3 (graph)
  AVERAGE								1.2 ± 2.3

• Precision of Duplicate Measurements - No Information.
• CRM Results - No Information.
• Multiparameter Analysis (details) - Mean Difference (estimated - measured) = 2.3 ± 7.1 Note: Analysis only considered stations north of equator.
• Internal Consistency Analysis (details) - Measured Alkalinity - calculated(pH&TCO₂) = -2.5 ± 4.6
  Measured Alkalinity - calculated(fCO₂&TCO₂) = -1.7 ± 4.9
• fCO₂ (Wanninkhof - AOML) - No adjustment recommended.
• Crossovers:
  

  Crossover	Longitude	Latitude	Cruise-1	Stations-1	Cruise-2	Stations-2	Δ Salinity	Δ O2	ΔfCO2	Feely et al. #
  73	110° W	0° N	P18	144	EQS92	14	-0.012 ± 0.012	0.6 ± 6.0	-28.7 ± 41.5	30
  73	110° W	0° N	P18	144	EQF92	62	0.018 ± 0.022	-3.2 ± 1.6	-12.9 ± 25.1	31
  73	110° W	5° N	P18	158	EQS92	6	-0.006 ± 0.004	-5.1 ± 1.5	67.1 ± 10.9	32
  73	110° W	5° N	P18	158	EQF92	53	-0.001 ± 0.004	3.7 ± 6.6	34.0 ± 74.1	33
  78	103° W	67° S	P18	10,11	S4P	711,712,713	0.002 ± 0.002	-5.1 ± 3.9	-8.0 ± 5.5	34

  From Feely et al., 1999, ORNL/CDIAC-115 (Δ = Cruise 1 - Cruise 2)
• Precision of Duplicate Measurements - Precision for 52 duplicates was ± 0.2%.
• CRM Results - No Information.
• pH(Byrne - USF) - We recommend adjusting all spectrophotometric pH values upward by 0.0047 to be internally consistent with the other carbon parameters.
• Crossovers - No Information.
• Precision of Duplicate Measurements - No Information.
• CRM Results - No Information.