Skip to main content

Satellite ocean-colour remote sensing of the Hauraki Gulf Marine Park

On this page: abstract, table of contents

Report: TR 2013/51

Author: M Pinkerton, S Wood, J Zeldis, M Gall (National Institute of Water & Atmospheric Research Ltd)


Waikato Regional Council seeks to use satellite remote sensing methods to provide spatial data on ocean colour, to help management of the Hauraki Gulf region.

Coastal waters exhibit high natural variability in their characteristic properties, both spatially and seasonally. Observations of the ocean from optical sensors on satellites can complement measurements of water properties from boats and moorings, and provide synoptic distributions of these properties over large areas, at daily and longer timescales.

Local (regional) validation and tuning of processing methods is required to use satellite observations. In-water measurements of total suspended matter (TSM) and chlorophyll-a (chl-a) concentration (a proxy for phytoplankton biomass) in the Hauraki Gulf region were assembled to assess and develop “locally-tuned” satellite processing methods.

These locally-tuned algorithms were applied to more than a decade of satellite observations from the NASA MODIS-Aqua sensor, in order to assess typical conditions and characterise variability of water constituents.

Satellite ocean-colour remote sensing of the Hauraki Gulf Marine Park (1mb)

Table of contents

  Executive summary 5
1 Introduction 6
1.1 Background 6
1.2 Coloured water constituents 7
1.3 Remote sensing of ocean colour 8
1.4 Objectives 9
1.5 Structure of report 10
 2 Objective 1: Evaluation of satellite products 10
2.1  Source of satellite data 10
2.2 Atmospheric correction 10
2.3 Satellite data grid 10
2.4 Testing and tuning satellite in-water algorithms 11
2.5 Long-term median, high and low satellite data values 11
2.6 In situ data available 12
2.7 Satellite algorithms for total suspended matter (TSM) 12
2.8 Satellite algorithms for chlorophyll-a concentration (chl-a) 14
2.8.1 Band-ratio chl-a algorithm (CHL) 16
2.8.2 Fluorescence line height (FLH) 16
2.8.3 QAA phytoplankton absorption product (APH-QAA) 16
2.8.4 GSM phytoplankton absorption production (APH-GSM) 17
3 Objective 2: Satellite total suspended matter 18
4 Objective 3: Satellite chlorophyll-a concentration 21
5 Discussion 24
6 Acknowledgements 26
7 References 27
  Appendix A: Number of pixels used in data compilations 30