Intercomparison of ocean colour band-ratio algorithms for chlorophyll concentration in the Subtropical Front east of New Zealand

Pinkerton, Matthew H.; Richardson, K.; Boyd, Philip W.; Gall, Mark; Zeldis, John; Oliver, M; Murphy, Richard J.

doi:10.1016/j.rse.2005.05.004

Cited by 26 publications

(23 citation statements)

References 59 publications

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“…The source of this elevated reflectance remains unknown, but appears related to high algal productivity in the largest lakes only. The spatial distribution of chlorophyll a concentration from the MODIS chlorophyll product [ Pinkerton et al , 2005] closely matches that of anomalously high reflectance, suggesting a link between biological activity and reflectance (Figure 3). These six largest lakes have therefore been excluded from our analysis.…”

Section: Methodsmentioning

confidence: 85%

Remote sensing of suspended sediment concentration, flow velocity, and lake recharge in the Peace‐Athabasca Delta, Canada

Pavelsky

Smith

2009

Water Resources Research

126

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[1] The transport of fine sediment, carried in suspension by water, is central to the hydrology, geomorphology, and ecological functioning of river floodplains and deltas. An extensive new field data set for the Peace-Athabasca Delta (PAD), Canada quantifies robust positive relationships between in situ suspended sediment concentration (SSC) and remotely sensed visible/near-infrared reflectance. These relationships are exploited using SPOT and ASTER satellite images to map suspended sediment concentrations across the PAD for four days in 2006 and 2007, revealing strong variations in water sources and flow patterns, including flow reversals in major distributaries. Near-daily monitoring with 276 MODIS satellite images tracks hydrologic recharge of floodplain lakes, as revealed by episodic infusions of sediment-rich water from the Athabasca River. The timing and magnitude of lake recharge are linked to springtime water level on the Athabasca River, suggesting a system sensitive to changes in river flow regime. Moreover, recharge timing differentiates lakes that are frequently and extensively recharged from those recharged more rarely. Finally, we present a first estimation of river flow velocity based on remotely sensed SSC, though saturation may occur at velocities >0.6 m/s. Viewed collectively, the different remote sensing methodologies presented here suggest strong value for visible/near-infrared remote sensing of suspended sediment to assess hydrologic and sediment transport processes in complex flow environments. Field observations including nephelometric turbidity, specific conductivity, water temperature, Secchi disk depth, suspended sediment concentration, and water level are archived at the Oak Ridge National Laboratory Distributed Active Archive Center for Biogeochemical Dynamics (available at

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Section: Methodsmentioning

confidence: 85%

Remote sensing of suspended sediment concentration, flow velocity, and lake recharge in the Peace‐Athabasca Delta, Canada

Pavelsky

Smith

2009

Water Resources Research

126

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“…Data were processed using the SeaDAS v4.7 algorithms [ Hooker et al , 1992; Fu et al , 1998; Murphy et al , 2001] and composited to give 8 day averages. Validation studies indicate that the OC4v4 algorithm gives estimates of chlorophyll to within approximately 30% of that measured by fluorometry using discrete samples in this region [ Richardson et al , 2004; Pinkerton et al , 2005].…”

Section: Methodsmentioning

confidence: 99%

“…Although there is a paucity of physical and biological data for a significant proportion of these water masses [ Longhurst , 1998], the physical environment and seasonal pelagic community structure in each of these water masses off eastern New Zealand has been well characterized [e.g., Bradford‐Grieve et al , 1999; Chiswell , 2002, 2005]. Moreover, the Sea‐viewing Wide Field‐of‐view Sensor (SeaWiFS) ocean color algorithm (OC4v4) has been validated locally for chlorophyll for open ocean waters around New Zealand [ Richardson et al , 2004; Pinkerton et al , 2005], making this a suitable region to study the coupling between surface and deep water processes.…”

Section: Introductionmentioning

confidence: 99%

Temporal coupling between surface and deep ocean biogeochemical processes in contrasting subtropical and subantarctic water masses, southwest Pacific Ocean

et al. 2005

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[1] Surface to deep-ocean coupling was investigated in subtropical (STW) and subantarctic (SAW) waters off eastern New Zealand. Moorings, comprising a near-surface fluorometer, temperature loggers, current meters, and sediment trap at 1500 m depth, were deployed at 41°and 46°40 0 S along 178°30 0 E between October 2000 and October 2001. Locally validated, remotely sensed data provided areal estimates of surface chlorophyll that were representative of 1997-2004 annual cycles. In STW, early spring chlorophyll peaks were coupled with deposition of labile (molar C:N$7-8), bio-siliceous organic matter. Low winter chlorophyll concentrations were associated with high particulate organic carbon (POC) fluxes of moderately refractory material (C:N$9-10). This indicates that winter flux was affected by heterotrophic recycling processes (zooplankton exuviae, fecal pellets) and/or slowly sinking particles from the preceding autumn. Deep-ocean POC fluxes off New Zealand were similar to global estimates and Tasman Sea (0.8 cf. 1.0 g C m À2 yr À1). Elevated biogenic silica and lithogenic fluxes probably reflect processes within a warm-core eddy near an eroding landmass, rather than STW in general. In SAW, POC and biogenic silica flux peaks occurred in spring with moderate surface chlorophyll concentrations. Decoupling between high chlorophyll and low flux in summer may reflect near-surface organic matter recycling by the microbial-dominated ecosystem. In spring, moderate chlorophyll levels in SAW, high POC and silica flux, and high C:N ratios (9-13) indicate some coupling with upper water column processes. SAW, east of New Zealand, was characterized by low POC (0.2 g C m À2 yr À1 ), high biogenic silica, and low carbonate fluxes, unlike other subantarctic sites, which are dominated by carbonate deposition with fivefold higher POC flux.

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“…The feature is seen neither in the other anomalies (the offshore portion appears in the R 412,443,547 531 anomaly) nor in the chlorophyll concentration. It appears to very closely follow the subtropical front (~15°C isotherm in SST, see also Pinkerton et al, 2005), highlighting a particular optical feature of the front. Lower values of R 412,443,547 488 are also observed in Fig.…”

mentioning

confidence: 74%

Remote sensing reflectance anomalies in the ocean

Huot

Antoine

2016

Remote Sensing of Environment

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Intercomparison of ocean colour band-ratio algorithms for chlorophyll concentration in the Subtropical Front east of New Zealand

Cited by 26 publications

References 59 publications

Remote sensing of suspended sediment concentration, flow velocity, and lake recharge in the Peace‐Athabasca Delta, Canada

Remote sensing of suspended sediment concentration, flow velocity, and lake recharge in the Peace‐Athabasca Delta, Canada

Temporal coupling between surface and deep ocean biogeochemical processes in contrasting subtropical and subantarctic water masses, southwest Pacific Ocean

Remote sensing reflectance anomalies in the ocean

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