Skip to data content Skip to data search

North Pole Environmental Observatory (NPEO) Nutrient, Chlorophyll, and Hydrographic Profiles



This project began an evaluation of nutrients and phytoplankton standing stocks in the central Arctic Ocean based on sampling at the North Pole Environmental Observatory (NPEO). The first sampling occurred in April 2005, the second in April 2006, where eight vertical profiles of hydrographic properties (salinity, temperature, sigma-t), in-situ fluorescence, and nutrients in the region of the NPEO were determined.

Vertical profiles of hydrographic, fluorescence, and nutrients over the upper 150 m were obtained using a Sea-Bird SBE-19 CTD (serial number 1923347-2995) combined with a Wetstar model WS3S miniature flow-through fluorometer (serial number 646P), which had an excitation wavelength of 460 nm and an emission wavelength of 695 nm. The continuous CTD profiles were processed using standard SeaSoft software with the results being binned into 0.5 m depth intervals. The fluorometer was calibrated in the laboratory with aqueous solutions of resorufin (Christensen, 2006a). The fluorescence of resorufin was compared with the fluorescence of purified chlorophyll-a (from the algae Anacystis nidulans) dissolved in buffered acetone (10 ml of 1% (weight per volume) magnesium carbonate per L of 90% acetone). These chlorophyll solutions showed a fluorescence of 40.0 times that of resorufin for the same molar concentrations. The output of the fluorometer was first converted to fluorescence of resorufin (mmol/L) and then to that of chlorophyll-a (expressed in microgram-chl/L) using this factor and the molecular weight of chlorophyll-a (893.5 g/mole).

Data access

Additional information

  • 1.0 (2009-06-18)
Subscribe Subscribe to receive email when new or updated data is available.
Related projects
Spatial Type point
Frequency continuous
Language English
Grant Code 0352641, 0352656
ISO Topic Categories
  • oceans
GCMD Science Keywords Expand keywords
Related links

Temporal coverage

Begin datetime 2005-04-18 00:00:00
End datetime 2006-04-22 23:59:59

Spatial coverage

Map data from IBCSO, IBCAO, and Global Topography.

Maximum (North) Latitude: 90.00, Minimum (South) Latitude: 88.50
Minimum (West) Longitude: -180.00, Maximum (East) Longitude: 180.00

Primary point of contact information

John P. Christensen <>

Additional contact information


Christensen, J., Pegau, S., Christensen, J. 2009. North Pole Environmental Observatory (NPEO) Nutrient, Chlorophyll, and Hydrographic Profiles. Version 1.0. UCAR/NCAR - Earth Observing Laboratory. Accessed 23 Jun 2024.

Today's date is shown: please replace with the date of your most recent access.

Additional citation styles

The citation text below is from the DataCite Content Resolver service and may take a few seconds to load. The styles and locales are obtained from CrossCite, which also provides a citation formatter. See ReFindit for another alternative. Formatting is not perfect: please verify and edit before use. Today's date is shown: please replace with the date of your most recent access.

Style: Locale:

Ancillary information

Metadata download

Note that your browser may not display the above metadata links, but automatically save them as files in a folder such as "Downloads"