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instruments:scintillometer:scintillometer

Scintillometer

Principle

The Large Aperture Scintillometer (LAS) is an instrument designed for measuring the path-averaged structure parameter of the refractive index of air (Cn^2) over horizontal path lengths from 250m to 4,5km. Structure parameter measurements obtained with the LAS and standart meteorological observations (air temperature, wind speed and air pressure) can be used to derive the surface sensible heat flux (H).

The LAS optically measure intensity fluctuations (known as scintillations) using a transmitter and receiver horizontally separated by several kilometers. The scintillations seen by the instrument can be expressed as the structure parameter of the refractive index of air(Cn^2). The light source of the LAS transmitter operates at a near-infrared wavelength of 880nm. At this wavelength the observed scintillations are primarily caused by turbulent temperature fluctuations. Therefore Cn^2 measurements obtained with the LAS can be related the sensible heat flux.

Instrument


Test setup in Cologne: Scintillometer (receiver) on the roof of IGM-Cologne.

History

Period Place Project
23.03.10 - 19.9.2013 IGMK, Germany TR32

Data

The instrument is currently inactive.

Data of the test run

Specifications

Parameter Specification
Operating temperature -20° to 50°C
Humidity 0 - 100% RH (IP66)
Voltage 12 VDC nominal (10.5V to 15V)
Power 0.5 A max ( path length dependant ) 3 A with heater
Optical Wavelength of LED 880 nm spectral bandwidth at 50% ~ 80nm
Modulation frequency ~7kHz
Beam width ~1 m at 100 m distance
Physical dimensions (including pan and tilt adjusment)
Length 0.37 m
Width 0.23 m
Height 0.32 m
Weight 13.5 kg
instruments/scintillometer/scintillometer.txt · Last modified: 2016/08/31 09:10 by uli