LiDAR Raw Data
This data product is a raw measurement of the absorption length and scattering properties at Cascadia Basin in order to complement the STRAW measurements using an alternative approach. The basic concept of this ultra-low energy LiDAR system is to send out short pulses (~10 ns) of light into the water that are emitted into a narrow beam by a laser diode. A small part of the light is back-scattered in water and sent back towards the module. The LiADR then uses a lens as optical receiver and a photomultiplier tube (PMT) in order to measure the intensity as a function of time=distance by single photon counting in the TRB. The LiDAR is mounted on a motorized gimbal stage that allows the laser to be pointed anywhere into ~2π sr (upper hemisphere).
Oceans 3.0 API filter: dataProductCode=LIDARRD
Format
HLD
The raw data format is the binary HLD format that is used by the HADES collaboration and which is the default format into which the DAQ program DABC for the TRB is writing the data. In this case post-processing with the Go4 program that allows to extract the timestamps into different formats, such as ASCII or ROOT files. The second step of post-processing, which is highly LiDAR specific, is to create and fill a histogram with time delays between the time of firing the laser and the arrival of the photons at the detector. From this histogram one can then compute the attenuation length.
Oceans 3.0 API filter: extension=hld