Estimating labile particulate iron concentrations in coastal waters from remote sensing data

Abstract

[1] Owing to the difficulties inherent in measuring trace metals and the importance of iron as a limiting nutrient for biological systems, the ability to monitor particulate iron concentration remotely is desirable. This study examines the relationship between labile particulate iron, described here as weak acid leachable particulate iron or total dissolvable iron, and easily obtained bio-optical measurements. We develop a bio-optical proxy that can be used to estimate large-scale patterns of labile iron concentrations in surface waters, and we extend this by including other environmental variables in a multiple linear regression statistical model. By utilizing a ratio of optical backscatter and fluorescence obtained by satellite, we identify patterns in iron concentrations confirmed by traditional shipboard sampling. This basic relationship is improved with the addition of other environmental parameters in the statistical linear regression model. The optical proxy detects known temporal and spatial trends in average surface iron concentrations in Monterey Bay. The proxy is robust in that similar performance was obtained using two independent particulate iron data sets, but it exhibits weaker correlations than the full statistical model. This proxy will be a valuable tool for oceanographers seeking to monitor iron concentrations in coastal regions and allows for better understanding of the variability of labile particulate iron in surface waters to complement direct measurement of leachable particulate or total dissolvable iron.Citation: McGaraghan, A. R., and R. M. Kudela (2012), Estimating labile particulate iron concentrations in coastal waters from remote sensing data,

Phytoplankton and microbial abundance and bloom dynamics in the upwelling shadow of Monterey Bay, California, from 2006 to 2013

“…Contrary to other evidence that indicates chl a is increasing in the CCS (Anderson et al 2008, Kim et al 2009, McGaraghan & Kudela 2012, Kahru et al 2012, our weekly 7-yr time series from the SCMW did not show an increase in bloom magnitude over the time period examined in this study (Kendall's tau Month is shown on the x-axis and year on the y-axis. The marker size is related to bloom duration, which ranges from 1 to 4, and the color indicates average concentration over the bloom period p = 0.47).…”

Effect of continental shelf canyons on phytoplankton biomass and community composition along the western Antarctic Peninsula

“…Future efforts could focus on specific ocean color derived products (e.g. Behrenfeld et al 2009, McGaraghan & Kudela 2012 and can be coupled with in situ trace metal chemistry and ongoing incubation experiments to determine nutrient sour ces (e.g. UCDW, glacial melt, resuspended sediments) and phytoplankton responses.…”

Evaluation of Satellite Retrievals of Ocean Chlorophyll-a in the California Current

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