Dataset: Nutrient and chlorophyll analyses from surface samples collected underway on board container ships during basin-wide transects of the North Pacific Ocean from Hong Kong to Long Beach, CA from 2009-2012

Samples were collected from shipboard seawater intake (10 m depth) on basin-wide transects of the North Pacific between Hong Kong and Long Beach, California onboard the M/V OOCL Tianjin and the M/V OOCL Tokyo (each individual transect has a unique Cruise ID). Sea surface temperature and salinity at the time of sample collection were determined using a Sea-Bird Electronics SBE45 thermosalinograph installed in the ship’s seawater intake. To prevent biofouling that could cause respiration in the ship’s seawater lines [Juranek et al., 2010], intake lines between the anticorrosive sea chest and the sampling port were purged with bleach and freshwater between every cruise.  Since the samples were collected underway on a vessel moving ~24 knots and samples for all parameters were collected by a single shiprider, ship transit from the time that the location coordinates were recorded to the time of actual sampling could reflect a transit distance offset from the recorded location of up to 40 kilometers.

Details of collection event issues (dataset Notes field):

• Missing info on duplicate:  A number of data entries are missing timestamp and location information for duplicates because separate times were not recorded at the time of collection.  Since the ship moves at ~24 knots, differences between the duplicate samples may represent real spatial variations between the times the duplicate samples were collected.
• Intake temp issue:  The intake temperature was not working until 2010-02-17 on the TJ9 cruise, so 23 of the reported temperatures are derived from TSG -0.3 (approximate correction for inline warming)
• Missing TSG data and/or GPS signal: On the Tokyo_0 cruise, 7 entries are missing TSG data and 2 additional are missing GPS information as well as TSG data. 
• No GPS data: On the Tianjin_1 cruise, six entries did not have GPS available.