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A scalable datalogging system for micrometeorological, fast-response, in situ, and remote sensing applications is presented. The system is based on a standard x86 MINI-ITX computer and the open-source operating system Linux. Real-time access for debugging and remote system control is implemented via a network interface. A 160-GB, 2.5-in. hard disk drive provides extended local storage. The recorded data can alternately be stored at a remote location using the Network File System (NFS) included in Linux. Accurate time stamping of collected data points is implemented using the open-source software Network Time Protocol (NTP) and a global positioning system (GPS) receiver. The operational capability of the system is demonstrated over a period of several weeks with data from seven ultrasonic anemometer-thermometers and a barometer.

The frequency spectrum of angle-of-arrival (AOA) fluctuations of optical waves propagating through atmospheric turbulence carries information of wind speed transverse to the propagation path. We present the retrievals of the transverse wind speed, upsilon b, from the AOA spectra measured with a Schmidt-Cassegrain telescope equipped with a CCD camera by estimating the "knee frequency," the intersection of two power laws of the AOA spectrum. The rms difference between 30 s estimates of upsilon b retrieved from the measured AOA spectra and 30s averages of the transverse horizontal wind speed measured with an ultrasonic anemometer was 11 cm s(-1) for a 1 h period, during which the transverse horizontal wind speed varied between 0 and 80 cm s(-1). Potential and limitations of angle-of-arrival anemometry are discussed.

To predict the performance of coastal and shipborne radars, it is essential to assess the propagation characteristics of electromagnetic waves in the maritime boundary layer. To be independent upon environmental measurements, which are generally not as precise and reliable as they have to be for a proper input to simulation programs, usually based upon parabolic equation models, a method to retrieve the refractive index gradients in the low troposphere is the Refractivity from Clutter (RFC) algorithm. The propagation factor is computed from the received clutter power and is iteratively processed in order to retrieve the refractive index profiles. Under a respective French-German technical agreement a measurement program concerning radar propagation in the maritime boundary layer has been initiated, with contributions from ONERA-CERT, DGA MI/TN, Fraunhofer-FHR and the German Technical Center for Ships and Naval Weapons (WTD 71). The paper gives an overview on the RFC met hod with examples from the previous campaigns. It describes the experimental set-up and its methodology

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