The Hillarys Transect (3): Optical and chlorophyll relationships across the continental shelf off Perth

Fearns, Peter; Twomey, Luke; Zakiyah, Umi; Helleren, S.; Vincent, Wilma J; Lynch, M.

doi:10.1016/j.csr.2007.02.004

Cited by 9 publications

(3 citation statements)

References 33 publications

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“…For such an assessment to be of value to future inferences of phytoplankton productivity (e.g., hotspots or anomalous productivity events) from satellite-derived surface chlorophyll data, it is imperative to ensure that depthintegrated values capture DCMs and that satellite remote sensing accurately reflects in situ conditions. While previous studies have touched on these topics, they were either spatiotemporally restricted (e.g., Hanson et al, 2005aHanson et al, , b, 2007Fearns et al, 2007;Twomey et al, 2007;Koslow et al, 2008;Chen et al, 2019) or based on discontinued satellite data (i.e., SeaWIFS, concluded in 2010; Koslow et al, 2008). Hence, this study assessed temporal patterns in water column stratification, DCM formation, and DCM characteristics (i.e., type, depth, width); analysed the relationship between surface and depth-integrated chlorophyll values; and validated satellite-derived against in situ chlorophyll measurements.…”

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confidence: 99%

Including the invisible: Deep depth-integrated chlorophyll estimates from remote sensing may assist in identifying biologically important areas in oligotrophic coastal margins

Schoeman,

Erbe,

McCauley

2024

Preprint

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Abstract. Deep chlorophyll maxima (DCM) are common in stratified water columns and may support higher trophic levels. Yet, it is challenging to include DCM contributions in studies aiming to identify marine animal foraging habitats and hotspots, because these studies often rely on satellite remote sensing data restricted to the surface. Previously established quantitative relationships between surface and depth-integrated chlorophyll within the euphotic zone of the open ocean and a eutrophic coastal margin encouraged us to assess whether such relationships are also present within the Western Australian intermittent-oligotrophic coastal margin. We also assessed whether the relationships could be extended to greater depths to capture DCMs below the euphotic zone. Based on ~9600 ocean glider profiles, our analyses demonstrate that such a relationship similarly exists off Western Australia and can be extended to twice the euphotic zone depth. Regression parameters were fine-tuned for three different conditions: 1) stratified waters in summer-transition months (September–April), characterised by relatively deep biomass maxima; 2) stratified waters in mid-winter (May–August) in which DCMs were less common and more likely a photo-acclimation maximum; and 3) mixed waters. While mean absolute errors increased in relationships over twice the euphotic zone depth (i.e., for estimates of deep depth-integrated chlorophyll), they remained low (i.e., max 16.5 %). These results and an observed chlorophyll increase in summer, unique to deep depth-integrated values, highlight the necessity to include deep depth-integrated chlorophyll estimates from satellite remote sensing in studies that aim to identify biologically important areas and productivity anomalies in (intermittent) oligotrophic environments.

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confidence: 99%

Including the invisible: Deep depth-integrated chlorophyll estimates from remote sensing may assist in identifying biologically important areas in oligotrophic coastal margins

Schoeman,

Erbe,

McCauley

2024

Preprint

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“…The good knowledge of the AOPs and IOPs of the water under investigation is necessary in the study of its bio-optical state and hereafter its color identity. Spectral variations in the optically marine constituents coupled with changes in distribution and abundance of each, lead to variations in the color of the ocean (Fearns et al, 2007). The basic classification of the seawater in Case-1 and Case-2 waters leads to an inaccurate bio-optical estimation of the marine environment, so as suggested by Mobley et al (2004), it is time to drop the above classification and focus on modeling water bodies according to whatever constituents are in the water column.…”

Section: Discussionmentioning

confidence: 99%

Improvement of the assessment of the marine environment of the Aegean Sea with optical measurements

Παπαδοπούλου¹

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Με την παρούσα προτεινόμενη έρευνα, προτείνεται η βελτίωση της δυνατότητας εκτίμησης παραμέτρων της ποιότητας του θαλάσσιου περιβάλλοντος με χρήση οπτικών μετρήσεων. Η Ανατολική Μεσόγειος θάλασσα είναι ιδιαίτερα ολιγοτροφική σε σχέση με τον παγκόσμιο Ωκεανό, με αποτέλεσμα να χαρακτηρίζεται από (α) πολύ χαμηλές συγκεντρώσεις φυτοπλαγκτού, (β) πολύ υψηλή διαύγεια του νερού, και (γ) 'διαμονή' του Βαθιού Μέγιστου της Χλωροφύλλης σε μεγάλα σχετικά βάθη. Οι παραπάνω ιδιαιτερότητες υπαγορεύουν την επαναξιολόγηση των διαφόρων βαθμονομήσεων οπτικών μεθόδων που έχουν βασιστεί σε ωκεάνειες μετρήσεις, ειδικά της δορυφορικής εκτίμησης της συγκέντρωσης χλωροφύλλης στα επιφανειακά ύδατα. Πιο αναλυτικά, το Κεφάλαιο 1 αναφέρεται σε μια επισκόπηση των βασικών στοιχείων της θεωρίας της οπτικής ωκεανογραφίας, το Κεφάλαιο 2 εστιάζει στα μεθοδολογικά βήματα που ακολουθούνται για την αξιολόγηση του χρώματος του θαλασσινού νερού στο Βόρειο Αιγαίο, το Κεφάλαιο 3 παρουσιάζει τα αποτελέσματα της εκτίμησης του χρώματος της θάλασσας στο Βόρειο Αιγαίο μέσω της μελέτης των αγενών και εγγενών οπτικών ιδιοτήτων του θαλασσινού νερού και τέλος στο Κεφάλαιο 4 παρουσιάζονται τα τελικά συμπεράσματα της έρευνας αυτής, όπου από τη σύγκριση μεταξύ των δορυφορικών συγκεντρώσεων χλωροφύλλης και των δορυφορικών βαθών της εύφωτης ζώνης με αντίστοιχα δεδομένα πεδίου προκύπτει υπερεκτίμηση της επιφανειακής συγκέντρωσης της χλωροφύλλης και υποεκτίμηση του βάθους της εύφωτης ζώνης στο Βόρειο Αιγαίο.

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“…It concludes with a brief evaluation of the suitability of the data set for the validation of satellite SSST imagery, A more thorough description of the SST measurement component of the Hillarys Transects in given in [2]. Other elements of the cruise are discussed more fully in associated literature; the general oceanography in [1]; the optical and chlorophyll measurement programs for monitoring nutrients and validating satellite ocean colour imagery in [3] and [4]; numbers and distribution of fish larvae in [5] and [6].…”

Section: Introductionmentioning

confidence: 98%

The Hillarys Transect sea surface temperature measurement and validation program

McAtee

Lynch

Pearce

IGARSS 2001. Scanning the Present and Resolving the Future. Proceedings. IEEE 2001 International Geoscience and Remote Sensing

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There has been a heightened interest in sea surface temperature (SST) measurements during the past two decades, particularly on a global scale, due largely to the advent of several El Nino episodes and increasing worldwide concern about global warming.Because of the continuous global measurements of SST that satellites can provide they play a fundamental role in acquiring the data sets necessary for studies of such global processes. However, the satellite data still need to be validated against in-situ measurements in order to assess the accuracy of satellite SST retrieval algorithms.Since 1997 radiometric sea surface skin temperatures have been recorded monthly using a TASCO radiometer along a cross shelf transect extending 40 km offshore from a coastal location north of Perth, Western Australia.This SST measurement program is one component of the Hillarys Transect, an ongoing multidisciplinary oceanographic study which aims to quantify the seasonal variation of physical and biological variables in the coastal Indian Ocean.Validation of satellite SST retrieval algorithms is the primary aim of the SST measurement program component of the Hlllarys Transect, which also aims to develop a data set which captures the seasonal variation of SST off the coast of southern Western Australia.The radiometric SST measurements are made at 9 stations along the transect and each measurement is calibrated using a portable water-filled blackbody unit. Though the study is low budget, the seasonal variation in SST is clearly captured by the data set and good agreement between in-situ and satellite SST estimates are obtained. Calibration of the radiometer will be dkcussed along with the seasonal cycle of SST off the WA coast and the suitability of the instrumentation for validation of remotely sensed SST.

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The Hillarys Transect (3): Optical and chlorophyll relationships across the continental shelf off Perth

Cited by 9 publications

References 33 publications

Including the invisible: Deep depth-integrated chlorophyll estimates from remote sensing may assist in identifying biologically important areas in oligotrophic coastal margins

Including the invisible: Deep depth-integrated chlorophyll estimates from remote sensing may assist in identifying biologically important areas in oligotrophic coastal margins

Improvement of the assessment of the marine environment of the Aegean Sea with optical measurements

The Hillarys Transect sea surface temperature measurement and validation program

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