AOLFL
in scheme: instruments
definition: The NASA Airborned Oceanographic Lidar (AOL) Fluorosensor (AOLFL) is a laser fluorospectrometer (and associated instruments) which is carried onboard a NASA P-3B or NASA C-130 aircraft. The AOLFL measures a variety of reflected and induced light properties, from which a number of oceanographic surface water properties can be derived. These properties include ocean color and phytoplankton pigment concentrations. The primary AOLFL sensor is a dual wavelength laser fluorospectrometer. This sensor transmits two laser wavelengths, one UV (355nm) and one green (532nm) to the ocean surface from the aircraft. These laser frequencies interact with the water molecules, causing a shift in the laser frequency. This Raman shift of the 355nm and 532 nm laser radiation allows normalization of other light measurements to compensate for changes in water clarity. If biological organisms containing chlorophyll and/or phycoerythrin are present in the water, the 532nm laser light is absorbed, and reemitted as particular bands of fluorescence. These fluorescent signals can be normalized to the water Raman signal, and have been shown to agree well with shipboard measurements of the same pigments. The 355nm laser radiation causes fluorescence of some of the dissolved organic material in the water. The water Raman normalized of this dissolved organic material is labeled CDOM (chromophoric dissolved organic matter). The AOLFL also carries several spectrometers which measure the downwelling sunlight incident on the top of the aircraft, and the reflected sunlight from the ocean surface. From these measurements, various algorithms can determine chlorophyll concentrations in the same manner as CZCS satellite. The ability of the AOLFL sensors to make oceanographic optical component measurements by both laser fluorescence techiques and by reflected spectra techniques allows the validity of each technique to be tested. [This sensor description was derived from the WWW pages of the Airborne Oceanogr…
type: Concept

Lidar/Laser Spectrometers
type: Concept