1. History / Impact EM Radiation Ocean Features Orbits / Satellites / Sensors Trends
Earth Remote Sensing*
Definition: The use of electromagnetic radiation (EMR) to acquire information about the ocean, land and atmosphere without being in physical contact with the object, surface, or phenomenon under investigation (Martin, 2004).
Unlike in situ measurements, the geophysical quantity of interest derived from remote sensing is inferred from the properties (intensity, polarization, spectral signatures) of the reflected or emitted radiation.
…inferred from the properties of the sensed radiation, such as intensity, frequency distribution, and polarization.
* The term ”Remote Sensing” was coined by Dr. Evelyn Pruitt, ONR, in the 1940s

2. Active sensors are both source and receiver of the radiation
History / Impact EM Radiation Ocean Features Orbits / Satellites / Sensors Trends
Satellite-borne sensors record emitted and/or reflected radiation, and ocean features are inferred from the radiation measurements
Ocean color
Ice concentration
Ship wakes
Oil slicks
Coral reefs
Passive
Reflected
Sea surface temperature
Surface wind speeds
Ice concentration
Night time lights
Emitted
Transmitted
Sea sfc height
Surface winds
Wave heights
Ice conc., age
Oil slicks
Ship wakes
Reflected
Active
Active sensors are both
source and receiver of the radiation

3. Electromagnetic Radiation (EMR)
History / Impact EM Radiation Ocean Features Orbits / Satellites / Sensors Trends
Ocean Remote Sensing
What are we sensing?
Electromagnetic Radiation (EMR)
What phenomena do we infer
from the radiation measurements?
Chlorophyll, Sea Ice
Oil Slicks, Shoals
visible
infrared
Surface Temperature
Ice Concentration
Surface Winds
Sea Level
Wave Heights
microwave
We use the visible, infrared, and microwave
portions of the electromagnetic spectrum

4. Microwaves are usually denoted by frequency (gigahertz)
Visible and IR are usually
denoted by wavelength
(microns or nanometers)

5. History / Impact EM Radiation Ocean Features Orbits / Satellites / Sensors Trends
Satellite-borne sensors record emitted and/or reflected radiation, and ocean features are inferred from the radiation measurements
Passive
Visible solar radiation
reflects from Earth’s surface
and from particles and organisms in the ocean.
The Earth (land, ocean, and atmosphere) emits infrared and
microwave radiation.
Active
Most active sensors transmit microwave radiation and receive some of the energy which reflects back from Earth’s surface.
There are two new satellites (ICESat and CALIPSO) which use lidar (visible and infrared lasers) for Earth remote sensing.

6. Oceanographic Applications and Primary Satellites / Sensors
History / Impact EM Radiation Ocean Features Orbits / Satellites / Sensors Trends
Oceanographic Applications and Primary Satellites / Sensors
Application
Sensor Type
Satellite / Sensor
Sea Surface Temperature
Infrared Radiometer
(passive)
POES / AVHRR
Aqua / MODIS
Ocean Color
Multispectral Radiometer
SeaWiFs
Sea Surface Height
Altimeter
(active)
JASON-1
ENVISAT / RA-2
GFO
Ocean Surface Winds
Scatterometer (active), Polarimetric Radiometer
QuikScat
Coriolis / Windsat
Sea Ice
Microwave Radiometer
Synthetic Aperture Radar
DMSP / SSM/I
POES / AMSU-B
Radarsat-1

7. Ocean Color Observations
History / Impact EM Radiation Ocean Features Orbits / Satellites / Sensors Trends
Ocean Color Observations

8. Visible light emitted from the sun reflects off suspended particles
Based on the nature and quantity of this reflected light, we can make estimates of chlorophyll concentration (primary productivity) and water clarity
Coastal Upwelling
Oregon & California
6 October 2002
NASA / Terra MODIS

9. Diatoms Most abundant plankton Nutrient rich, high latitudes 2-1000 m
History / Impact EM Radiation Ocean Features Orbits / Satellites / Sensors Trends
Diatoms
From
Most abundant plankton
Nutrient rich, high latitudes m
autotrophic
chlorophyll in chloroplasts – absorb red and blue
Appear yellow-brown (“Golden Algae”)
Diatom Bloom off mid-Atlantic coast
(from

10. Dinoflagellates Unicellular Autotrophic, heterotrophic or mixotrophic
History / Impact EM Radiation Ocean Features Orbits / Satellites / Sensors Trends
Dinoflagellates
Unicellular
Autotrophic, heterotrophic or mixotrophic
Rapid reproduction can lead to red tides
Some produce neurotoxins
Ceratium
50 mm
Red Tide

11. History / Impact EM Radiation Ocean Features Orbits / Satellites / Sensors Trends
Coccolithophorids
Shells composed of calcium coccoliths – milky white appearance
Able to thrive in nutrient-poor conidtions
Photo by Kurt Buck, 1995

12. Coccolithophore blooms off of Iceland
TERRA MODIS, 21 JUN 04:
Coccolithophore blooms off of Iceland
50 km

13. Ocean Color Applications
History / Impact EM Radiation Ocean Features Orbits / Satellites / Sensors Trends
Ocean Color Applications
Ocean Color features are caused by scattering and absorption of visible wavelengths by:
Plankton (also emit certain wavelengths)
Represent 25% of global vegetation
Provide food for zooplankton and fish
Convert CO2 into carbon; important in global carbon cycle
Harmful Algal Blooms
Colored Dissolved Organic Matter (CDOM) or “Gelbstoff” – organic runoff, detritus, decaying matter
Sediments, Pollutants
Ocean optical properties (scattering and absorption) affect swimmer visibility, submarine vulnerability, and performance of electro-optical systems (underwater video, laser)
Features indicate positions of fronts, eddies, and direction of currents

14. Oceanographic Remote Sensing
History / Impact EM Radiation Ocean Features Orbits / Satellites / Sensors Trends
Oceanographic Remote Sensing
Satellite remote sensing has revolutionized oceanography, opening our eyes to energetic small scale ( km) processes
A wide variety of observations are available
Some observations, such as sea ice concentration, are now available for relatively long periods of time (~30 years)
Applications support scientific, commercial and military interests
Walter Munk: “1 + 1 = 3” (When satellite data is combined with in situ ocean observations, the resulting info is worth more than the sum of two separate measurements).

15. Links Imagery from NASA Imagery from NOAA
Visible Earth:
Earth Observatory (including “Image of the Day”):
Imagery from NOAA
Geostationary Satellite Server:
CoastWatch:
NOAA NESDIS Education and Outreach
NASA Remote Sensing Tutorial
Visualization of Satellites on Orbit

16. Links Ocean Color Sea Surface Temperature, Topography, Winds
Brief Overview:
Data and Imagery Gallery:
Sea Surface Temperature, Topography, Winds
NASA JPL:
Overview of POES and GOES (NOAA)
DMSP Program
Historical Overview:
Data Archive, Research, Products:
NPOESS Program
CORONA Program