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

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

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

Microwaves are usually denoted by frequency (gigahertz) Visible and IR are usually denoted by wavelength (microns or nanometers) http://physics.uoregon.edu/~jimbrau/BrauImNew/Chap03/FG03_09.jpg

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.

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

Ocean Color Observations History / Impact EM Radiation Ocean Features Orbits / Satellites / Sensors Trends Ocean Color Observations http://seawifs.gsfc.nasa.gov/SEAWIFS/IMAGES/IMAGES.html

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

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

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

History / Impact EM Radiation Ocean Features Orbits / Satellites / Sensors Trends Coccolithophorids http://oceancolor.gsfc.nasa.gov/cgi/image_archive.cgi Shells composed of calcium coccoliths – milky white appearance Able to thrive in nutrient-poor conidtions Photo by Kurt Buck, 1995 http://www.mbari.org/~reiko/work/phyto.htm

Coccolithophore blooms off of Iceland TERRA MODIS, 21 JUN 04: Coccolithophore blooms off of Iceland http://visibleearth.nasa.gov 50 km

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

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 (50-200 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).

Links Imagery from NASA Imagery from NOAA Visible Earth: http://visibleearth.nasa.gov/ Earth Observatory (including “Image of the Day”): http://earthobservatory.nasa.gov/ Imagery from NOAA Geostationary Satellite Server: http://www.goes.noaa.gov/ CoastWatch: http://coastwatch.noaa.gov/cw_index.html NOAA NESDIS Education and Outreach http://www.nesdis.noaa.gov/outreach_edu.html NASA Remote Sensing Tutorial http://rst.gsfc.nasa.gov/ Visualization of Satellites on Orbit http://science.nasa.gov/Realtime/jtrack/3d/JTrack3D.html

Links Ocean Color Sea Surface Temperature, Topography, Winds Brief Overview: http://disc.gsfc.nasa.gov/oceancolor/index.shtml Data and Imagery Gallery: http://oceancolor.gsfc.nasa.gov/ http://nasascience.nasa.gov/earth-science/oceanography/living-ocean/remote-sensing Sea Surface Temperature, Topography, Winds NASA JPL: http://podaac-www.jpl.nasa.gov/ Overview of POES and GOES (NOAA) http://www.nesdis.noaa.gov/satellites.html DMSP Program Historical Overview: http://www.aero.org/publications/crosslink/winter2005/02.html Data Archive, Research, Products: http://www.ngdc.noaa.gov/dmsp/index.html NPOESS Program http://www.npoess.noaa.gov/ CORONA Program http://www.nro.gov/corona/facts.html