Ecology, Climate, Physical Oceanography

Multi and Hyperspectral Remote Sensing for Marine and Coastal

Applications

Bering Sea, AlaskaSeaWifs Image (Norman Kuring image, NASA, April 25, 1998)

Turquoise = phytoplankton bloom

Chlorophyll concentrationsProductivityCarbon cyclingWater clarity and suspended sedimentOcean colorFisheries managementCurrentsSearch and RescueDeep sea drilling, etc.

Some marine applications

Chlorophyll is used by plants to trap light energy which then drives photosynthesis

Amount of chlorophyll related to amt. of photosynthesisOcean productivityCarbon cyclingOcean ecology – food webs/fisheries

Can estimate amount of chlorophyll in oceans using spectral data and models

Ocean chlorophyll concentrations

Upwelling off coast of California

Phytoplankton spectral reflectance similar to that of land plants in the visible part of the spectrumChlorophyll reflects more green visible than

blue or redCan also measure amount of fluorescence with

some sensors (e.g., MODIS)IR light almost all absorbed by water and not

a strong part of the ocean phytoplankton signature

Spectral properties of ocean phytoplankton

Visible Wavelengths NIR Wavelengths

2004 “Red Tide” off coast of Florida with SeaWiFS chlorophyll and MODIS flourescence

Red Tide – La Jolla, California (from Wikipedia)

Measured by the net amount of carbon “fixed” by biota in the oceansCan’t be directly measured—must be modeled

using remotely sensed data as inputsFunction of amount of chlorophyll, ocean

temperature, amount of incoming solar radiation, and mixing models to deal with 3-dimensional ocean (it has depth)

Oceans are net sinks for carbon – remove SOME carbon from the atmosphere each year (but less than enters the atmosphere).

Ocean productivity

From IPCC AR4 (2007)

Ocean plants need sunlight as do land plants – productivity drops off with depth. So does our ability to remotely sense chlorophyll.

Ocean productivity Oct 2002 – note near-shore environments

Open ocean water nearly sediment free – perfectly clear

Near-shore water holds variable sediment loads and is more turbidTurbid water coincides with more productive

parts of ocean near shore due to input of sediment by rivers and shallower water

Turbidity can cause erroneous chlorophyll (and productivity) measurements from RS

Important to know where ocean is turbid so that you can be careful about predicting chlorophyll there.

Water clarity and suspended sediment

Turbidity near Mississippi delta in near-shore Louisiana

Turbid waters are more reflective than clear water

Peaks in spectral response depend on:Amount of sedimentDepth profile of sedimentType of sediment (mineralogy, etc.)

Turbidity can be a temporal phenomenon – sediment input by rivers after floods, stirred up by hurricanes and other wind events, etc.

Spectral properties of turbid water

Change in spectral curves with time in turbid water during settling: 575 nm spectral peak declines with reduced turbidity

Ocean fisheries are most productive where ocean productivity is highHigh chlorophyll content relates to high

productivityBut…too much productivity or harmful blooms

(e.g., red tides) can harm fisheriesOcean currents, climate change, nutrient

inputs from land, etc. affect fisheriesPollution can harm fisheries especially near

shoreAll of these things can be monitored with

remote sensing and other geospatial tools

Fisheries

Global FisheriesTheglobaleducationproject.org

SeaWiFS (Sea-viewing Wide Field of view Sensor)Flies on the OrbView-2 platformDesigned to monitor ocean color

MODISFlown on the Aqua and Terra platformsPhotosynthetic activity of marine organisms

Related to carbon cycle in oceansSome MODIS bands designed for ocean RS

Satellites for Marine Remote Sensing

SeaWiFS specifications

Bands: Visible and NIR1 km pixelsDaily return

Coastal erosion monitoring

Hurricane damage assessment

Estuarine ecologyCoastal geomorphologyCoastal ecologyHuman impacts

Coastal applications of optical RS

“…to detect, assess, and predict the effects of weather, climate, natural hazards, and human activities on the state of the coastal ocean, its ecosystems and living resources, and the U.S. economy. It consists of both a national backbone and regional coastal ocean observing systems…”

Coastal Monitoring Goals…

Chesapeake Bay is the largest estuary in the U.S.

Important fishery (fish, crabs, oysters, etc.)Hammered by pollution from major East Coast

rivers and urban inputs E.g., Susquehanna River, Potomac River,

Washington/Baltimore, etc.Nutrient inputs, pesticides, industrial chemicals, etc.

Very populated coastal zone with vulnerability to erosion, sea level rise, hurricanes, etc.

Many issues common to coastal zones globally

Case Study: Chesapeake Bay

Airborne and satellite imagery used to:

Monitor chlorophyll concentrationsMonitor sediment loadsModel ecosystemsModel pollutionManage fisheryTrack coastal erosionContribute to near shore land use

planning

Remote sensing in Chesapeake Bay

Hurricane Isabel 2003Extensive damage to human structures, coastal erosion and temporary changes in water quality

Ganges Delta, Bangladesh. Coastal zones are often densely populated and vulnerable. Will be a focus of remote sensing for years to come.

Most Chesapeake Bay slides/figures from presentations at a Smithsonian Environmental Research Center symposium.

Acknowledgements