Le projet WISE-Man : réalisations et premiers résultats

Simon Bélanger

C. Araujo, J-P Ardouin, P. Bernatchez, C.Blot, R. Côté, M. Cusson, F. Danhiez, J. Desrochers, C.G. Fichot, G. Fournier, Y. Gendreau, J. Harrington, J. Hedley, G. Ifimov, J. Laliberté, M-F Lavoie, B. Légaré, R. Léger-Daigle, J. Lemarchand, R.

Mabit, J. Mayrand, S. Mukherjee, F. Noisette, C. Nozais, A-S Sean, R. Soffer, S. Velasquez, M. Wieser

WaterSat Imaging Spectrometer Experiment (WISE) for optically shallow coastal waters

assessmentThe WISE-Man project

The overall long-term objective wasto demonstrate the potential of WISE, and more generally hyperspectral imagery, for

coastal ecosystem mapping: • bathymetry,

• water column quality (or inherent optical properties) and • bottom properties

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Landsat-8

Radiative Transfer Equations (RTE)

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Should you have any questions, please ask Soham Mukherjee, PhD student

2019 Fieldwork at a glance

• July 30th to August 26th in Baie-Comeau/Manisouagan• 30 participants including, ~ half students• Four boats (FJ Saucier, Kildir, Machiatic, small zodiac)• 1 lab team in CEGEP de Baie-Comeau• 6 professional divers• NRC’s flight team with a Twin Otter and two hyperspectral

cameras (WISE and CASI-1500)• > 6 hours of flights with simultaneous in situ observations• > 50 stations and 84 water samples for constituents

(pigments, carbon, nuts, etc) • 1 Special « optical » experiment in optically-shallow water

with all boats

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Flight plan

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High tide Low tide

High Altitude (3000 m) => 1.5-m pixels resolution

Low Altitude (1000 m) => 0.5-m pixels resolution

High Tide WISE acquisition (18/08)

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• Clear sky• No wind• 29 stations for sampling and

optics• Transects with hydroball +

HOCR + BB3 (bathy, opticalproperties) in opticallyshallow waters

19:40:15SZA=51.5°AZI=241.5°

21:24:10SZA=68.1°AZI=264.5°

Low tide flight (20/08)

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• Moderate to strong wind• 19 stations• Hydroball transect in River

Important geometric corrections required

Shallow water experiment

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Challenge : bottom reflectance measurement, Rb

• Spectroradiometer deployed by divers (SVC)

• Compact Optical Profiling System (C-OPS)

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Divers in work…

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Diver

Cops

COPS profiles in shallow waters

Video 1

looking up

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Downwellingirradiance profiles

• Decreasing with depth, positive Kd ~dEd/dz

• Variability just above the bottom due to depth, water column IOPs and surface variability

• Green light survival

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Downwelling irradiance at each wavelength in Zostera M.

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COPS profiles in shallow waters

Video 2

looking down

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Upwelling radiance

above bottom

• Increasing or decreasing with depth

• Large variability if seagrass is absent or present

• Absorbed PAR quantification

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Sand

Zostera Marina

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Upwelling radiance at each wavelength above Zostera M.

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Upwelling radiance at each wavelength above sand

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Bottom reflectance method comparison

RrsCOPS_Eu= Eu/Ed Rrs

COPS_Lu= pi*Lu/Ed RrsSVC= pi*Lu/Lpanel

Chlorophyll a

Take home messages

• Light transmission and reflection in optically-shallow is not intuitive and complex: – Theory versus measurements still required

– Great potential for quantification of PAR absorbed by vegetation => net primary production

• Flights and fieldwork conducted in August 2019 was a great success, surpassing the initial objectives of the project (e.g., high versus low tide; the experiment with divers)

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Fieldwork team*

* Excluding some members of the inter-tidalteam Forum des Sciences de la Mer 21

!! Announcement !!

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Summer school in Optical remote sensing of coastal waters

and littoral habitats

In august 2020 in Ile VerteWelcome to HQPs from QO