|
|
 |
 |
|
The HYDROLIGHT radiative transfer numerical model computes radiance distributions and related quantities (irradiances, reflectances, diffuse attenuation functions, etc.) in the ocean. Users can specify the water absorption and scattering properties, the sky conditions, and the bottom boundary conditions in various ways: by selection of built-in defaults, by reading in user-supplied data (such as WETLabs® ac-9 data), or by writing their own Fortran subroutines to define their input. HYDROLIGHT then computes the in-water light field and other quantities of interest to optical oceanographers, such as the water-leaving radiance and remote-sensing reflectance. Output is presented as ASCII printout, as Excel® spreadsheets, or as digital files designed for plotting and analysis using IDL®. HYDROLIGHT is used in various ways:
As a predictive tool
What will the oceanic light field be at some time in the future?
Given a prediction of water absorption and scattering properties, HYDROLIGHT can use that information to predict the corresponding light field. HYDROLIGHT can even become the optics component of a coupled biological-physical-optical ecosystem model.
As a data analysis tool
What was the ambient light field when the data were taken?
For example, when imaging an underwater object in the daytime, the ambient daylight may contribute noise (in this case, path radiance) to the signal of interest (the light propagating from the target to the sensor). HYDROLIGHT can compute the ambient daylight field so that it can be subtracted from the total signal received at the sensor to improve the signal-to-noise ratio of the detected signal.
As a system design tool
How would a proposed system perform under different environmental conditions?
HYDROLIGHT can serve as a controlled environment to predict what the light field received by a sensor would be under a wide range of conditions. Such control of the environment and of simulated noise cannot be obtained in the field, which is best used for final testing and evaluation of sensors that were first designed using numerical simulations.
As a teaching tool
How can someone new to the field of optical oceanography most quickly build up "intuition" or a "working knowledge" about the marine optical environment? The best way to gain such knowledge is of course to spend 20 years working as an optical oceanographer. The next best way is to use HYDROLIGHT to study how oceanic light fields depend on various environmental parameters.
Related Links
|
|
|
|  | | Holographic Camera |  | | Sequoia announces that it has acquired a license from University of Plymouth (UK) for manufacture of a Holographic camera developed by Dr. Alex Nimmo Smith, for observation of large particles. The camera also has the potential to measure settling velocity. | |  | |  | | | |
|