is already returning unprecedented measurements of physical, optical, nutrient, and
oxygen properties. Already, these data have been used to track the seasonal evolution of phytoplankton blooms (Boss and Behrenfeld 2010) and constrain the
upwelling supply of nutrients available for photosynthesis (Johnson et al. 2010), to
name just a few applications. Following the success of the Argo program (Roemmich and Owens 2000), the Bio-Argo program strongly supports development and
deployment of floats equipped with sensors for measuring key biogeochemical
properties, such as Chl fluorescence and particulate backscattering. Similar efforts
are in place to make routine O 2 measurements on profiling float platforms (Gruber
et al. 2007). Inclusion of these capabilities represents the first precursors to NPPenabled floats. Indeed, prototype floats capable of the aforementioned measurements and more (e.g., radiometers) already exist and should enable a single platform to yield a complete suite of data suitable for initial NPP calculations.
Another exciting yet unexploited tool for ocean ecological studies is spacebased lidar (Light Dectection And Ranging) systems. Lidar technology is widely
used in terrestrial and atmospheric disciplines, but ocean applications have been
limited to targeted near-shore and coastal studies using aircraft or ship-based
systems (e.g., Churnside and Wilson 2001). Nevertheless, space-borne LIDAR
assets are available for investigating their application to subsurface ocean retrievals. For example, the CALIOP lidar on the CALIPSO satellite conducts routine
vertical profiling measurements at 532 and 1064 nm. The latter wavelength is too
long to penetrate the ocean surface, but the former should effectively sample near
surface plankton populations. CALIPSO’s stated science objectives are aimed
atmospheric aerosol and cloud science applications. Nevertheless, preliminary
analyses suggest subsurface scattering signals can be detected from the ocean
surface. CALIOP was not designed for ocean applications, but these early results
suggest that a more capable ocean-penetrating space lidar could provide critical
independent constraints on ocean particle pools and perhaps even assessments of
vertical structure in plankton distributions with links to mixed layer depths.
Significant opportunities also exist for realizing major advances in ocean
ecosystem characterization from upcoming passive ocean color sensors designed
with capabilities far exceeding those of our heritage sensors. Technological
developments since the conception of CZCS, SeaWiFS, and MODIS now enable
major improvements in spatial, temporal, and spectral resolution, although not
necessarily all within a single instrument. Increased spectral resolution and
expansion into the near-ultraviolet wavebands (350–400 nm) will allow further
discrimination of different phytoplankton groups and separation of phytoplankton
from other optical constituents (sediments, detritus, dissolved organics). Improved
atmospheric corrections may also be realized by flying an advanced ocean color
sensor with a profiling lidar and multi-angle spectral polarimeter. A satellite
constellation of this sort will not only improve atmospheric corrections for more
accurate water leaving radiance retrievals, but would also provide simultaneous
lidar subsurface retrievals described above and a capacity for discriminating
organic and inorganic particles through the polarimeter measurements (Loisel
et al. 2008).
8 Oceanic Net Primary Production
221
oxygen properties. Already, these data have been used to track the seasonal evolution of phytoplankton blooms (Boss and Behrenfeld 2010) and constrain the
upwelling supply of nutrients available for photosynthesis (Johnson et al. 2010), to
name just a few applications. Following the success of the Argo program (Roemmich and Owens 2000), the Bio-Argo program strongly supports development and
deployment of floats equipped with sensors for measuring key biogeochemical
properties, such as Chl fluorescence and particulate backscattering. Similar efforts
are in place to make routine O 2 measurements on profiling float platforms (Gruber
et al. 2007). Inclusion of these capabilities represents the first precursors to NPPenabled floats. Indeed, prototype floats capable of the aforementioned measurements and more (e.g., radiometers) already exist and should enable a single platform to yield a complete suite of data suitable for initial NPP calculations.
Another exciting yet unexploited tool for ocean ecological studies is spacebased lidar (Light Dectection And Ranging) systems. Lidar technology is widely
used in terrestrial and atmospheric disciplines, but ocean applications have been
limited to targeted near-shore and coastal studies using aircraft or ship-based
systems (e.g., Churnside and Wilson 2001). Nevertheless, space-borne LIDAR
assets are available for investigating their application to subsurface ocean retrievals. For example, the CALIOP lidar on the CALIPSO satellite conducts routine
vertical profiling measurements at 532 and 1064 nm. The latter wavelength is too
long to penetrate the ocean surface, but the former should effectively sample near
surface plankton populations. CALIPSO’s stated science objectives are aimed
atmospheric aerosol and cloud science applications. Nevertheless, preliminary
analyses suggest subsurface scattering signals can be detected from the ocean
surface. CALIOP was not designed for ocean applications, but these early results
suggest that a more capable ocean-penetrating space lidar could provide critical
independent constraints on ocean particle pools and perhaps even assessments of
vertical structure in plankton distributions with links to mixed layer depths.
Significant opportunities also exist for realizing major advances in ocean
ecosystem characterization from upcoming passive ocean color sensors designed
with capabilities far exceeding those of our heritage sensors. Technological
developments since the conception of CZCS, SeaWiFS, and MODIS now enable
major improvements in spatial, temporal, and spectral resolution, although not
necessarily all within a single instrument. Increased spectral resolution and
expansion into the near-ultraviolet wavebands (350–400 nm) will allow further
discrimination of different phytoplankton groups and separation of phytoplankton
from other optical constituents (sediments, detritus, dissolved organics). Improved
atmospheric corrections may also be realized by flying an advanced ocean color
sensor with a profiling lidar and multi-angle spectral polarimeter. A satellite
constellation of this sort will not only improve atmospheric corrections for more
accurate water leaving radiance retrievals, but would also provide simultaneous
lidar subsurface retrievals described above and a capacity for discriminating
organic and inorganic particles through the polarimeter measurements (Loisel
et al. 2008).
8 Oceanic Net Primary Production
221