Seasonal variability of chlorophyll a in the Mid-Atlantic Bight

Yi Xu, Robert Chant, Donglai Gong, Renato Castelao, Scott Glenn, Oscar Schofield

Research output: Contribution to journalArticlepeer-review

43 Scopus citations

Abstract

For this manuscript we use a 9-year time series of Sea-viewing Wide Field of view Sensor (SeaWiFS), HF radar, and Webb Glider data to assess the physical forcing of the seasonal and inter-annual variability of the spatial distribution in phytoplankton. Using Empirical Orthogonal Function (EOF) analysis, based on 4-day average chlorophyll composites, we characterized the two major periods of enhanced chlorophyll biomass for the MAB in the fall-winter and the spring. Monthly averaged data showed a recurrent chlorophyll biomass in the fall-winter months, which represented 58% of the annual surface chlorophyll for the MAB. The first EOF mode explained ~33% of the chlorophyll variance and was associated with the enhanced phytoplankton biomass in the fall-winter found between the 20 and 60. m isobaths. Variability in the magnitude of the enhanced chlorophyll in fall-winter was associated with buoyant plumes and the frequency of storms. The second EOF mode accounted for 8% of the variance and was associated with the spring time enhancements in chlorophyll at the shelf-break/slope (water depths greater than 80. m), which was influenced by factors determining the overall water column stability. Therefore the timing and the inter-annual magnitude of both events are regulated by factors influencing the stability of the water column, which determines the degree that phytoplankton are light-limited. Decadal changes observed in atmospheric forcing and ocean conditions on the MAB have the potential to influence these phytoplankton dynamics.

Original languageEnglish (US)
Pages (from-to)1640-1650
Number of pages11
JournalContinental Shelf Research
Volume31
Issue number16
DOIs
StatePublished - Oct 15 2011

All Science Journal Classification (ASJC) codes

  • Oceanography
  • Aquatic Science
  • Geology

Keywords

  • Mid-Atlantic Bight
  • Ocean color
  • Phytoplankton

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