scope:

Introduction

The guideline series VDI 3786 is divided into several parts. Some of these parts present schemes for the remote determination of the vertical profile of the wind vector.

Radar (an acronym of Radiowave Detection And Ranging) is a family of methods that provide information about atmospheric properties in a well-defined volume in space. The information is obtained from the scattered part of electromagnetic radiation previously transmitted into the atmosphere. The location of the scattering volume is inferred from the direction into which the radiation was transmitted and the delay time between the transmitted and received signals. Strictly speaking, the notion of "radar" is confined to methods that use radiation in the wavelength range between millimeters and meters. Lidar, as opposed to radar, works at optical wavelengths, and sodar uses acoustic waves. These two types of methods are described in guidelines VDI 3786 Part 11 (Doppler sodar) and VDI 3786 Part 14 (Doppler lidar).

In the present guideline the determination of the vertical profile of the wind vector using wind profiler radars (WPRs) is presented. In addition to the wind vector, WPR systems provide other information on the physical state of the atmosphere as well such as turbulence, precipitation, and the height of the planetary boundary layer [1]. The measurement of these data is also described in the present guideline.

For the definition of the target variable wind, this guideline refers to guideline VDI 3786 Part 2. The definition of the averaging time is based on guideline VDI 3786 Part 1. Use is also made of guideline VDI 3786 Part 8. Safety aspects are not treated here; instead, reference is made to the corresponding standards and regulations (26. BImSchV; BEMFV; BGV B 11; BGR B 11; DIN VDE 0848). In addition, the national regulations on the allocation of operating frequencies shall be observed when using radar systems. For Germany, this is the standard RegTP 321 ZV 044 in which reference is made to certain international regulations as well.

WPR systems have successfully been used for many years for the remote determination of wind-vector vertical profiles. WPRs complement conventional instruments as they lend themselves to a large number of measurement tasks that cannot be fulfilled adequately with in-situ or point measurement devices [2] or in cases where masts or towers can not be used due to technical, administrative or economical reasons.

The use of WPRs is particularly advantageous for

• measurements close to the ground as well as in higher layers of the atmosphere

• measurements under all weather conditions

• measurements with high temporal resolution

• automated measurements

The following applications are of special importance:

• routine wind measurements at aerological stations

• flight safety, aviation weather services

• production of data for the use of dispersion models, e.g., in connection with licensing procedures under BImSchG, 9. BImSchV und TA Luft: time series calculation (TA Luft, Annex 3, Clause 1), Monin-Obukhov length (TA Luft, Annex 3, Clause 8.4), height of the mixing layer (TA Luft, Annex 3, Clause 8.5)

• monitoring of installations and facilities during regular and irregular operation

• future measurement of the turbulent exchange in the troposphere and up to the lower stratosphere

Section 5 describes some examples of the application of WPRs in these fields.