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