"ACE 1, Leg 2:   Seawater pH and total ammonia (NHx(s) = NH3(s) + NH4+(s)) measured onboard the Discoverer by NOAA PMEL."

This is the text descriptor file for data contained in the file  SWPHNH3.CSV.
Questions about these data should be directed to Trish Quinn (quinn@pmel.noaa.gov).

"pH was measured with a spectrophotometric technique using an indicator dye (Dickson, 1993, Mar. Chem., 44, 131 - 142)."
"NHx(s) was measured with a fluorescence method (Jones, 1991, Limnol. Oceanogr., 36, 814-819)."

The accuracy of the pH measurements is estimated to be +/- 0.005.
The uncertainty associated with the NHx(s) is estimated to be +/- 5 to 25%.

Columns in the spreadsheet are:

"1, Time (GMT)"
"2, Latitude"
"3, Longitude"
"4, surface seawater pH"
"5, surface total ammonia concentration, NHx(s) = NH3(s) + NH4(s), in umolar."

Codes used in the spreadsheet:

"BDL, below the detection limit for NHx(s) of 0.005 uM."