Chlorophyll distribution and primary production on the Grand Banks of Newfoundland investigated by remote sensing

Prasad, Kota Sivaramakrishna (1993) Chlorophyll distribution and primary production on the Grand Banks of Newfoundland investigated by remote sensing. Doctoral (PhD) thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (20MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

A sequence of surface pigment images of the 1980 phytoplankton spring bloom on the Grand Bank of Newfoundland was derived from the Nimbus-7 Coastal Zone Color Scanner (CZCS). This data set is augmented with in situ observations of physical and biological data to examine spatial and temporal variability of the surface pigment fields. The satellite imagery suggests considerable temporal and spatial variability in surface chlorophyll concentrations across the period of investigation. Patterns in near-surface pigment concentrations were associated with the evolution of the spring bloom. -- A semi-empirical model, which is in part physiologically based, is presented which utilizes integral chlorophyll (IC), photosynthetically available radiation (PAR) and light absorption by chlorophyll to predict integral production (IP). A preliminary assessment of the relationship between sea-surface temperature (SST), water column stability (VS), integral chlorophyll (IC), and remote sensing optical depth (1/K490) allows the development of another model based on secondary variables to predict integral production (IP). Simultaneous assimilation of sea surface temperature and optical depth into one model for predicting integral chlorophyll demonstrates the usefulness and need for a thermal channel in future ocean color sensors. -- Water column light utilization index, ψ, varies seasonally over the Grand Banks and cannot be treated as a constant in primary production models. Mean values of ϕc showed a twofold to sixfold variation from spring through summer. A shift in distribution of normalized quantum yield (i.e. ϕc / ϕmax) towards lower values in the upper 20m suggested frequent occurrence of light saturation. -- Chlorophyll determined from satellite imagery is used to calculate the depth-integrated pigment content of the euphotic zone. This value, along with a computed value of chlorophyll-specific cross section and computed values of quantum yield, are used in an algorithm developed to predict annual production on the Grand Banks of Newfoundland. Adjustment of the phytoplankton physiological parameters was necessary to take seasonal variation into account. Mean primary production computed from the algorithm was 194g C m⁻² yr⁻¹ which compared well with the mean shipboard measured value of 186g C m⁻² yr⁻¹. -- The work presented in this thesis represents a significant advance for the synoptic description of oceanography in the Newfoundland area and provides baseline information, for mid-latitude cold oceans, of use in pigment retrieval and production estimation from the proposed ocean color sensor (SeaWiFS) when it becomes available in 1993. The study gives CZCS-derived production estimates which are similar and reasonable in comparison to the few other such studies which have been carried out in the Pacific and Atlantic oceans.

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