Airborne Remote Sensing of the Ocean Why Ocean is big ships are slow satellites are far away Also Jim Churnside NOAA Environmental Technology Laboratory http www etl noaa gov fishlidar Candidate Sensors Acoustic 99 9999 of energy lost in 2way propagation through sea surface Radio large antennae impractical for aircraft Microwave both active and passive used Optical both active and passive used Microwave Radars Altimeters surface height Scatterometers sea surface roughness wind Imaging Radars ice surface roughness currents Radar Scattering Mechanisms Specular Kirkhoff approximation reflection from wave facets perpendicular to radar beam polarization independent Bragg reflection from waves at radar wavelength on surface and in radar direction favors vertical polarization Low grazing angle breaking waves Scanning Radar Altimeter Scanning Radar Altimeter Distance to surface corrected for aircraft altitude and attitude using GPS data to get surface elevations Scattering is by normal wave facets Kirchoff Scanning Radar Altimeter Elevation maps and directional wave spectra Hurricane Bonnie August 1998 Wind from Surface Roughness Mean square slope Scatterometer winds in hurricane vs wind speed Imaging Radar Real aperture uses long antenna to get spatial resolution along flight track SAR uses multiple pulses as aircraft moves to get the resolution of a long antenna Both use short pulse to get spatial resolution across flight track Bragg Real Aperture Stable Atmosphere VV HH Real Aperture Unstable Atmosphere VV HH NASA AirSAR Internal Wave Philippines Internal Waves on Pycnocline surface Surface water warm fresh poor in nutrients highly variable Deep water cold saline rich in nutrients very stable pycnocline IW generated by tides modulate surface roughness Microwave Emission Thermal emission microwaves slope 4 Planck function X surface emissivity Emissivity depends on wavelength polarization view angle surface roughness temperature salinity oils and foam Generally 1 10 8 GHz Example Wind from Surface Roughness Mean square slope Scatterometer winds in hurricane vs wind speed Wind Direction Salinity Measurements 1 43 GHz Scanning Low Frequency Microwave Radiometer SteppedFrequency Microwave Radiometer Surface Salinity near Mouth of Chesapea ke Bay Thermal Emission Also Planck function X emissivity At 10 near nadir emissivity 0 99 SST Example Thermal Imager Thermal Imagery Thermal image whale wakes Thermal image sea lions Thermal image birds Thermal image alcids Fish LIDAR Ocean OceanColor Color Chlorophyll Example Visible Imagers Wide search area High resolution Feature tracking Target detection Target identification Simple installation Expensive High maintenance NOAA Visual Surveys marine mammals sea turtles sea birds Navy Hyperspectral Imager Ocean Portable Hyperspectral Imager for Low Light Spectroscopy 128 spectral bands 4 6 nm wide 380 1000 nm NOAA Fish LIDAR Photo and Echogram of Mullet Sardine Returns T 1 T 2 School at right 20 m deep 5 m thick and 130 m long Thin Layers Off Shore Night Plankton and Mackerel Distributions in the Norwegian Sea Internal Waves Power Spectra Average slope 1 5 Fractal dim 1 75 Slope 1 56 E W transects off Pacific NW coast Depths 5 20 m depth 15 m slope 1 56 Imaging Lidar Imaging Lidar Shadow Salmon in Kodiak Single Frame Laser Eye Safety Our laser beam meets ANSI Z136 1 1993 standard for occupational exposure at the surface We have calculated equivalent standards for various marine mammals Our laser beam is a fraction 1 3 to 16 7 of that standard for all marine mammal species investigated Hawaiian Monk Seal Protected Sea Birds And Turtles Coral Damage Ocean Currents of the North Pacific GhostNet Flight Track and Debris Sightings Eddy E August 1 2003 NOAA CoastWatch AVHRR SST Image of Eddy E July 23 2003 GhostNet Aircraft Instruments Infrared Imager Visible RGB Camera Green laser 532 nm imaging LIDAR Computer with anomaly detection Visual search Infrared Radiometer SST MicroSas Optical Sensor OCR 507 Visible Video Clip Conclusions A wide variety of airborne remote sensors exist for observations of the upper ocean Aircraft cover a range of space time scales not available from satellites ships or moorings Multiple sensors on multiple platforms are necessary to understand monitor and ultimately predict the state of the ocean