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contact PIs:Data Object chlorophyll a
| name | title |
|---|---|
| Dr Giacomo DiTullio | Co-Principal Investigator |
| Dr David A. Hutchins | Principal Investigator |
| Dr Steven W. Wilhelm | Co-Principal Investigator |
Fluorometric chlorophyll a estimates from Niskin bottle cast samples
NOTE: station 1- or 2- refers to either cruise leg 1 (Florida to the Azores) or cruise leg 2 (Azores to Iceland)
Only 'surface' samples were taken while dead-heading on leg 1. The surface samples are recorded as being from nominal depth of 3 meters as that was the approximate depth of the ship's underway intake system.
Calibration notes
Instrument was calculated prior to the cruise (~ May 1, 2005) using extracted chlorophyll a standards.
Extracted standards were checked with a spectrophotometer to determine chlorophyll a concentrations.
Extracted standards were used to calibrate the solid standard (Turner Designs).
Solid-standard normalizations were completed each day upon initiation of the fluorometer.
Size-fractionated chl a concentrations were determined on replicate samples collected on 0.22, 2.0, and 20.0 μm nominal pore size, 47 mm diameter polycarbonate filters (Osmonics). Samples were extracted in 90% acetone for 24 h at 4°C and quantified using a solid-standard normalized 10-AU field fluorometer (Turner Designs) using the nonacidification protocol (Welschmeyer 1994).
Welschmeyer NA (1994) Fluorometric analysis of chlorophyll a in the presence of chlorophyll b and phaeopigments. Limnol Oceanogr 39:1985–1992
DMO processing notes:
1. reported longitudes corrected to negative (Western hemisphere)
2. depth_n of 'surface' replaced with a nominal depth of 3 meters (to enable plotting of data)
| Parameter | Description | Units |
|---|---|---|
| station | station identifier (leg-station number optionally followed by a or b) | dimensionless |
| depth_n | nominal (target) depth of sample | meters |
| chl_a | mean chlorophyll a concentration from duplicate samples; fluorometric method with nonacidification protocol (Welschmeyer 1994) | micrograms/liter |
| size | polycarbonate filter pore size in microns; investigators looked at size-fractionated distribution of chlorophyll a | micrometers |
| range_n2 | range of the duplicate samples | dimensionless |
| date | date (GMT) start of sampling (from event log) | dimensionless |
| time | time (GMT) at start of sampling (from event log) | dimensionless |
| lat | latitude, in decimal degrees, North is positive, negative denotes South (from event log) | decimal degrees |
| lon | longitude, in decimal degrees, East is positive, negative denotes West (from event log) | decimal degrees |
| R/V Seward_Johnson SJ0516 |
This document is created from the content of the BCO-DMO metadata database. 2010-02-09 14:57:46
info app: /home/bco/dbase-v2 v.100108 CLC