Heat and Momentum Flux
Measures Purely by Optical Means
Outstanding Temporal Resolution
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Laser Scintillometers

The Scintec SLS ES Series Scintillometers are unique sensors which can measure atmospheric turbulence, heat flux, momentum flux and crosswind by purely optical means. The length of the measurement paths between the transmitter and the receiver can be set up between 50 m and 250 m. Combined with a net radiometer, the SLS ES Series Scintillometers can also be used to determine the evaporation or evapotranspiration over extended areas.

The models of the Scintec SLS ES Series are so-called inner-scale scintillometers. By measuring the spatial turbulence spectrum, they can directly asses the dissipation rate of turbulent kinetic energy. By application of Monin-Obukhov similarity, this directly leads to the turbulent fluxes of heat and momentum without any complementing wind measurements or assumptions on surface roughness. Only the SLS ES Series Scintillometers provide the full set of accessible information purely from optical measurements: the structure function constant of refractive index Cn2, the structure function constant of temperature CT2, the turbulent flux of heat, the turbulent flux of momentum, the inner scale of turbulence, the kinetic energy dissipation rate and the crosswind. If combined with a net radiometer, evaporation or evapotranspiration is also determined.

All SLS ES Series Scintillometers are eye safe Class 1 laser products.

Applications
Air Quality
Climate Research
Meteorological Research
Turbulence and Seeing
Water and Agriculture
Models
Surface Layer Scintillometer SLS20 ES

The Surface Layer Scintillometer for use on stable platforms or heavy tripods on solid ground.

heat flux, momentum flux by purely optical means
suitable for stable and unstable conditions
high temporal resolution
crosswind option available
easy installation and operation
Surface Layer Scintillometer SLS20-A ES

The Surface Layer Scintillometer with beam steering which permits operation when manual beam alignment is undesirable or difficult.

built-in automatic beam steering
heat flux, momentum flux by purely optical means
high temporal resolution
crosswind option available
easy installation and operation
Surface Layer Scintillometer SLS40 ES

The Surface Layer Scintillometer for operation on towers or other platforms prone to vibration.

correction for transmitter vibrations
suitable for stable and unstable conditions
high temporal resolution
crosswind option available
easy installation and operation
Surface Layer Scintillometer SLS40-A ES

The Surface Layer Scintillometer for operation on towers or other platforms prone to vibration or longterm-drift.

built-in automatic beam steering
correction for transmitter vibrations
high temporal resolution
crosswind option available
easy installation and operation
Competitive Advantages
Optical Measurement of Inner Scale and Momentum Flux
The Scintec SLS ES Series Scintillometers form a unique product line. They can optically measure the so-called inner scale of turbulence. Turbulence theory connects the inner scale to the dissipation rate of turbulent kinetic energy. Using Monin-Obukhov similarity, an extensive set of quantities is derived: the structure function constant of refractive index Cn2, the structure function constant of temperature CT2, the turbulent flux of heat, the turbulent flux of momentum, the inner scale of turbulence and the kinetic energy dissipation rate. In combination with a net radiometer, evaporation or evapotranspiration is also assessed. No additional wind measurements or assumptions on the roughness length are needed.
Spatially Representative Data
Scintillometers measure a path average between a transmitter and a receiver. This leads to representative data even in inhomogeneous terrain. The large footprint of a scintillometer contrasts with the small footprint of a conventional point sensor, which is solely determined by the fetch and largely dependent on wind direction and atmospheric stability.
High Temporal Resolution
The path averaging of a scintillometer reduces the need for temporal averaging when comparing to a conventional point sensor. This means that a scintillometer can produce statistically stable averages in much shorter times. As an estimate, one scintillometer can replace about 100 conventional point sensors for a similar statistical significance with identical averaging times.
Double-Ended Remote Sensing
Scintillometers can easily measure over water, across a valley or over urban areas, for example, where the deployment of in-situ sensors would be troublesome.
No Flow Distortion
The path weighting function of a scintillometer reaches zero at the transmitter and receiver positions. So there is virtually no distortion of the turbulent flow caused by the instruments themselves. This compares to point sensors, where a flow distortion correction is needed and often essential.
Crosswind Measurement Capacity
The Scintec BLS900 Neo, BLS2000 Neo and all SLS ES Series Scintillometers can measure crosswind. This includes the sign (direction) of the crosswind. These instruments can also reliably measure crosswind if the wind direction is near the direction of the optical propagation paths.
Automatic Beam-Steering
The Scintec SLS20-A ES and SLS40-A ES have automatic transmitter beam steering. An optical scanning device points the transmitted beam automatically to the receiver. This facilitates the transmitter alignment. It also allows operation from drifting platforms such as tripods on soft ground.
Built-in Vibration Correction
The Scintec SLS40 ES and SLS40-A ES use a duplicate set of detectors in order to quantify and correct for intensity variations caused by high-frequency transmitter movements on vibrating platforms. So the Scintec SLS40 ES and SLS40-A ES can be operated from towers, for example, which are prone to vibration.
Separate Storage Unit for Easy Data Access
All Scintec BLS Neo and SLS ES Scintillometers store their measurement data in a designated Signal Processing Unit (SPU). The SPU is separate from the receiver and can be mounted in a location convenient for access to the data. Since the receiver must be mounted pointing to the transmitter, usually on a tripod or another elevated platform, it may not be in easy reach.
Large Data Storage Capacity
All Scintec BLS Neo and SLS ES Series Scintillometers have a data storage capacity of 6 GB which can hold large amounts of measurement and raw data. The measurement data storage period depends on the individual setting and can range from months to years.