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Global primary productivity and the role of climate modes of variability

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thesis
posted on 28.03.2022, 14:28 by André David Belo do Couto
Phytoplankton are a unique group of organisms, mostly due to their exclusive capacity to photosynthesise inorganic matter into highly energetic organic compounds. Consequently phytoplankton growth, i.e., primary productivity, fuels almost all life in the global ocean and plays a crucial role in biogeochemical cycles and climate processes. Although it is commonly known that phytoplankton primary productivity is highly variable at intra-annual scales, inter-annual patterns of variability have only relatively recently been observed with the advent of remote sensing technology. Satellite instruments detect and estimate chlorophyll, a molecule present in all phytoplankton, and primary productivity rates, at a global scale. Here, we use remote sensing products to assess net primary productivity and surface chlorophyll-a patterns of variability from intra- to multi-annual, and global to regional scales, and evaluate its physical forcing mechanisms. We aim to assess the connections between large-scale climate variability and inter- and multi-annual phytoplankton patterns of variability via empirical analysis of satellite derived Chl and various geophysical parameters. The main methodology utilised to this end is the Empirical Orthogonal Function (EOF) for detecting standing signals and its extended form to isolate propagating features. Our findings include a much higher percentage of NPP variability at seasonal scales (~90%) than previously acknowledged, an anomalous change of 90 Pg.C (Pg = 1015g) in the last decade coupled to the classic El Niño - Southern Oscillation (ENSO) regional climate phenomenon, and an extra 18 Pg.C fixed in the ocean which can be attributed to the influence of the past decade's trend found in a controversial second main mode of variability. Further, we use extended EOF (EEOF) to isolate and analyse propagating features of surface chlorophyll-a across the global ocean and link them to regional climate modes of variability. We then focus on the Tropical and South Pacific regions, characterizing the seasonal atmosphere and ocean dynamics and isolating the regional propagating inter-annual features. Finally, we assess the influence of the East Australian Current on regional remotely sensed chlorophyll, and investigate the role of large-scale regional climate modes of variability on chlorophyll patterns.

History

Table of Contents

1. Introduction -- 2. Data and methods -- 3. Global patterns of NPP -- 4. Global proapting interannual features of Chl -- 5. South Hemisphere interannual patterns of Chl -- 6. Tropical and South Pacific seasonality -- 7. Tropical and South Pacific ENSO propagating variability -- 8. EAC patterns of Chl -- 9. General discussion and conclusions.

Notes

"June 2011" Thesis by publication. Includes bibliographical references

Awarding Institution

Macquarie University

Degree Type

Thesis PhD

Degree

PhD, Macquarie University, Faculty of Science, Department of Environment and Geography

Department, Centre or School

Department of Environment and Geography

Year of Award

2012

Principal Supervisor

Neil J. Holbrook

Additional Supervisor 1

Angela Maharaj

Additional Supervisor 2

Kevin Cheung

Rights

Copyright disclaimer: http://www.copyright.mq.edu.au Copyright André David Belo do Couto 2012.

Language

English

Extent

1 online resource (x, 207 pages) illustrations, maps

Former Identifiers

mq:30377 http://hdl.handle.net/1959.14/284147 2083268