Turbulence Over Large Spatial Scales
Wide Emission Angle
Easy to Set Up, Align and Operate
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Large Aperture Scintillometers

The Scintec BLS Series Scintillometers measure atmospheric turbulence, heat flux and crosswind over large spatial scales. Various versions are available for path lengths between 100 m and 12 km. With complementing meteorological sensors they can also be used to determine the evaporation or evapotranspiration over extended areas.

The models of the Scintec BLS Series are so-called large aperture scintillometers. Large transmission and reception areas reduce the scintillation and allow for measurement ranges of several kilometers without saturation of scintillation. This compares to laser scintillometers where the transmitter-to-reveiver distance is limited to a few hundred meters due to saturation.

Note that generally, large apertures scintillometers cannot measure the so-called inner scale of turbulence. For the measurement of the turbulent fluxes, separate wind measurements are required therefore. See the Scintec SLS Series for purely optical measurements of the turbulent fluxes.

All BLS Series Scintillometers use LED arrays as transmitters. Wide emission angles virtually eliminate the need for transmitter alignment and maintain high data accuracy even when installed on drifting mounts or on towers which are prone to vibration.

Large Aperture Scintillometer BLS450

The BLS450 uses one radiating disk, which makes it the most economical and lightest of the BLS series.

maximum path length 6000 m
LED array eases transmitter alignment
built-in Receiver Alignment Monitor
LED array allows transmitter to be mounted on vibrating towers
Large Aperture Scintillometer BLS900
Dual-Disk Design

The Dual-Disk Design of the BLS900 provides for instantaneous corrections of absorption fluctuations, saturation of scintillation and outer scale effects.

maximum path length 6000 m
Dual-Disk Design for unrivalled accuracy
crosswind measurement capability
built-in Receiver Alignment Monitor
Large Aperture Scintillometer BLS2000
Dual-Disk Design

The Large Aperture Scintillometer with Dual-Disk Design for very long paths

maximum path length 12 km
Dual-Disk Design for unrivalled accuracy
crosswind measurement capability
built-in Receiver Alignment Monitor
Competitive Advantages
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 stabilty..
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. The adjacend graph shows an example: The SLS20 Scintillometer resolves a reduction in turbulent heat flux caused by a cloud-related drop in solar radiation. A single eddy-correlation sensor does not.
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 functions of a scintillometer reaches zero at the transmitter and receiver positions. So there is virtually no distortion of the turbulent flow casued by the instruments themselves. This compares to point sensors, where a flow distortion correction is needed and often essential.
Wide Emission-Angle
All BLS Series transmitters use multiple LEDs with wide emission angles. This drastically simplifies the alignment compared to telescope-based transmitters. It also allows operation of the transmitter from vibrating platforms such as towers or tripods in strong wind. Power consumption is still low with the optional pulsed modes.
Dual-Disk Design
The BLS900 and BLS2000 use dual transmitting disks. In this way, they can eliminate intensity fluctuations caused by absorption changes instead of temperature fluctuations. This is especially important in conditions of weak thermal turbulence. In strong thermal turbulence, the dual-disk design allows the instrument to operate deeper into saturation since a saturation correction is applied. Altogether, the dual-disk design gives accuracy advantages in both, weak and strong turbulence conditions.
Crosswind Measurement Capacity
The Scintec BLS900, BLS2000 and all SLS Series Scintillometers can measure crosswind. This includes the sign or direction of the crosswind. So these instruments can also reliably measure crosswind with winds near the direction of the optical propagation paths.
Position-Sensitive Detector for Receiver Alignment
All receivers of the Scintec BLS Series contain a position-sensitive detector indicating incorrect receiver alignment before measurement errors occur.
Separate Storage Unit for Easy Data Access
All Scintec BLS and SLS 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. Note that the receiver must be mounted so it points to the transmitter, usually on a tripod or another elevated platform, and may not be in easy reach.
Large Data Storage Capacity
All Scintec BLS and SLS 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.