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Laser

Laser wavelength 532 nm Laser energy per pulse 50-80 uJ Laser pulse repetition freq. >100 Hz Detector Photoncounting. Ocean Lidar Development. Remote sensing of upper ocean physical and biological properties. Laser. M. Behrenfeld, J. Rall, C. Koblinsky, et al. Telescope.

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Laser

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  1. Laser wavelength 532 nm Laser energy per pulse 50-80 uJ Laser pulse repetition freq. >100 Hz Detector Photoncounting Ocean Lidar Development Remote sensing of upper ocean physical and biological properties Laser M. Behrenfeld, J. Rall, C. Koblinsky, et al Telescope Scattered Light Beam-c

  2. Science Objectives • Ocean circulation and ecosystem response • Physical Oceanography • Mixed Layer depth critical variable in ocean-atmosphere coupling. • Ocean biology and carbon • Mixing depth key to understanding upper ocean productivity.

  3. 2001 Progress • Oregon State Univ. develop advanced ray tracing model funded by NASA HQ Ocean program • DDF and IR&D support development of “bench lidar” system for laboratory validation of fundamental ray tracing model. • GSFC ocean biogeochemistry laboratory starts photo-acclimation experiments. • GSFC ISAL study of advanced Mixed Layer Lidar concept for aircraft. • Mixed layer modeling post-doc hired. • TRL 1 seeks to become TRL 2-3.

  4. Ocean Productivity Satellites now provide global surface chlorophyll concentrations Photosynthesis per unit chlorophyll varies primarily with mixed layer light levels and in proportion to algal carbon to chlorophyll ratios Algal carbon concentration is highly correlated with particulate attenuation or scattering Particulate scattering or attenuation can potentially be measured actively or passively from space Particulate Carbon Total Particulate Scattering

  5. Ocean Biogeochemistry Laboratory NASA GSFC, Building 22 Laboratory Focus: Characterizing the effects of light and nutrient stress on the ratio chlorophyll to photosynthetic carbon fixation Photo acclimation in 23 algal species Chlorophyll : Photosynthesis Growth Irradiance

  6. Requirement: Remote Sensing: SeaWiFS/MODIS data Light Model SeaWiFS/MODIS data Ocean Optical Model Wind Stress (QuikScat) Direct Measurement? Cloud-corrected Irradiance Light Attenuation Mixed Layer Depth Modeling Photoacclimation

  7. Technology Development • Lead: Jonathan Rall/Code 924 • Microchip laser (1-2 uJ/pulse at 532 nm 2-3 kHz pulse repetition rate), photon counting detectors. • Controlled experiments at David Taylor Model Basin for transmission, reflection, scattering, and refraction effects of incident laser pulse with wavey surface. • Test GSFC and OSU ray-trace models. • Ship board lidar (30-40 uJ/pulse at 532nm) for open ocean demonstration later this year.

  8. Challenges • Link between scattering layer and mixed layer depth. • Lidar remote sensing for ocean biology. • Quantification of the ray tracing model with hardware. • Identify candidate lidar concepts and technologies.

  9. Summary Slide

  10. Challenges Link between scattering and mixed layers – ray tracing model. Quantify model with laser system. Implications for biology. Identify candidate lidar concepts and technologies. Ocean Lidar Development • Lidar remote sensing of upper ocean mixing and biology • Air-sea exchange & climate • Ocean productivity & carbon • TRL 1 moving toward TRL 2-3 • 2001 Activities • New Ocean Biogeochemistry Lab in Bldg 22 begins photoacclimation experiments. • IRD, DDF laser development • Ray tracing model improvement • ISAL study of future aircraft system Mike Behrenfeld, Chet Koblinsky, Code 971, Jonathan Rall, Code 924

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