A scintillometer is a

scientific Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earliest archeological evidence for ...

device used to measure

turbulent In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to a laminar flow, which occurs when a fluid flows in parallel layers, with no disruption between ...

fluctuations of the

refractive index In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, or ...

air The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing f ...

caused by variations in temperature, humidity, and pressure. It consists of an

optical Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultravio ...

or radio wave transmitter and a receiver at opposite ends of an atmospheric propagation path. The receiver detects and evaluates the intensity fluctuations of the transmitted signal, called scintillation. The magnitude of the refractive index fluctuations is usually measured in terms of

C_n^2

, the structure constant of refractive index fluctuations, which is the spectral amplitude of refractive index fluctuations in the inertial subrange of turbulence. Some types of scintillometers, such as displaced-beam scintillometers, can also measure the inner scale of refractive index fluctuations, which is the smallest size of eddies in the inertial subrange. Scintillometers also allow measurements of the transfer of heat between the Earth's surface and the air above, called the

sensible heat flux Sensible heat is heat exchanged by a body or thermodynamic system in which the exchange of heat changes the temperature of the body or system, and some macroscopic variables of the body or system, but leaves unchanged certain other macroscopic vari ...

. Inner-scale scintillometers can also measure the dissipation rate of turbulent kinetic energy and the momentum flux.

References

External links

The scintillation method
by W.M.L. Meijninger, Wageningen University, The Netherlands
A review of the relationships describing the signal of a Large Aperture Scintillometer
- by A.F. Moene, W.M.L. Meijninger, O.K. Hartogensis, W. Kohsiek, H.A.R. de Bruin, Wageningen University, The Netherlands Interferometry {{climate-stub

See also

References

External links