Ground-based remote sensing of wind vector and visibility: latest results from guideline development

The guideline series VDI 3786 'Environmental meteorology; Meteorological measurements' is organized into several parts. The present guideline VDI 3786 Part 14 describes the determination of the three-dimensional wind vector using Doppler LIDAR ('LIght Detection and Ranging' or 'Light Identificaiton, Detection and Ranging'). The guideline refers to guideline VDI 3786 Part 2 with regard to the definition of the measurement variable wind and goes back to the guideline VDI 3786 Part 1 in considering the averaging time. Use is also made of the guideline VDI 3786 Part 8. Safety problems are not treated; reference may be made here to relevant Standards [VBG 93, DIN EN 60825-1]. Wind profiles in the atmospheric boundary layer yield a very important contribution also to the investigation of atmospheric exchange processes. The wind field in the atmospheric boundary layer is highly variable in spatial and temporal scales. For a few applications a more frequeent wind sensing is necessary, i.e. (1) on airports located in low level jet areas, (2) near chemical plants to get information of the transport of toxic gases from leakages, (3) for metrology in general to improve the weather forecast, (4) for environment protection purposes like dispersion studies. The following statements are valid for visibility measurements [visual range LIDAR (VDI 3786 Part 15)]: (1) Lidar can provide the same information of the visibility as conventional sensors, but in addition lidar will provide range resolved measurements. (2) It is possible to shrink a lidar down to the size of binoculars. (3) It is possible to measure local visibility with an eye- safe (class 1) lidar. (4) Layers can be detected up to 250 m distance in approximately 2 s even with a small size instrument.