Obsolete - AFSC/RACE/Eco-FOCI: Chlorophyll: groundtruth data for chlorophyll fluorescence sensors on the moorings.

These data are part of a ocean observation study by Stabeno, Napp, and Whitledge sponsored, in part, but the North Pacific Research Board (Project 410; http://doc.nprb.org). The grant was titled "Long-term observations on the Bering Sea shelf (2004-2005): biophysical moorings at sites 2 and 4 as sentinels for ecosystem change." Moorings were maintained on the southeastern Bering Sea shelf at M2

(56.9B0N, 164.1B0W), and at M4 (57.9B0N, 168.9B0W). Shipboard

measurements of temperature, salinity, nutrients, chlorophyll, fluorescence and

zooplankton were collected around the moorings on two cruises (3MF04 - April 2004 and 8MF04 - September 2004) to ground truth in situ sensors on the moorings. This long-term monitoring supported major findings: (1) The timing of the spring phytoplankton bloom is determined by the presence of ice, with an early bloom occurring if ice is present after mid-March and later bloom occurring if there

is no sea-ice after mid-March; (2) During the last decade, the southeastern Bering Sea

shelf has undergone a marked warming (~3B0C) that is closely associated with a marked

decrease of sea ice over the southeastern shelf; (3) Nutrients supply and summer salinity

over the shelf has not significantly changed during the last three decades; (4) There is an

indication that cold water zooplankton species (e.g Calanus marshallae) are occurring

in reduced abundance in association with the warming. While the warming over the

southeastern shelf is primarily related to the reduction of ice extent, a combination of

other mechanisms are important: the presence over the eastern shelf of a relatively mild

air mass during winter since 2000; a shorter ice season caused by a later fall transition

and/or earlier spring transition; increased flow through Unimak Pass during winter

introducing warm Gulf of Alaska water onto the shelf; and a thermal feedback

mechanism whereby warmer, summer ocean temperatures delay the southward advection

of sea ice during winter.

Chlorophyll samples taken at and around the moorings were obtained as groundtruth data for chlorophyll fluorescence sensors on the moorings. See http://www.pmel.noaa.gov/foci/foci_moorings/foci_moorings.shtml for information on mooring locations, configurations, and data.

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