A set of computer programs is described to process turbulence data as measured along the 200 m high meteorological mast at Cabauw, the Netherlands (Van Ulden et al., 1976; Driedonks et al., 1978).

The following parameters are measured simultaneously at six levels: three wind components, dry bulb temperature Td wet bulb temperature Tw.

Measuring heights are 20, 40, 80, 120, 160, 200 m. Standard sampling rate is 5 Hz.

For wind measurements, trivanes are used (Wieringa, 1967 and 1972), which measure wind speed, azimuth and elevation angle.

Temperature fluctuations are measured with two pair of unventilated thermocouples (dry and wet bulb). (Kohsiek and Monna, 1980).

Registration of the turbulence data is performed by a Hewlett and Packard 21 MX minicomputer, which formats the data on magnetic tape.

For the processing of these data on the Burroughs B6700 computer at the KNMI a series of computer programs has been vritten, This sequence of programs performs the following main actions:

First, the format is checked and calculations are carries out to find possible technical malfunctioning of the instruments. If suitable, corrections can be supplied.

In the second stage, calibration factors are introduced in order to transform the data into SI-units. Then, averal calculationa are performed in order to provide averages over any chosen time interval. Also, the time history of all variables can be plotted.

The third action is to calculate the variances and covariances over any chosen time interval between variables at each level.

Also, the spectral distribution of the variances and covariances can be calculated.

A.G.M. Driedonks, P.A.T.Nieuwendijk and C.J. Goes. A set of computer programs to process turbulence data measured at the 200m mast at Cabauw

KNMI number: WR-80-03, Year: 1980, Pages: 96

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