Development and validation of tools for the implementation of european air quality policy in Germany (Project VALIUM)
In the framework of the German Atmospheric Research Program AFO-2000 a system of consistent coupled numerical models has been developed. The purpose of the model system is to serve as a tool for the execution of European urban air quality regulations. A consortium with the acronym VALIUM was formed, which consisted of German research institutes, environmental consultancies and an environmental agency. A substantial part of the VALIUM program was devoted to the generation of a set of high quality data for the validation of the numerical model system. The validation data are based on a combination of field studies, tracer experiments and corresponding wind tunnel experiments. The field experiments were carried out inside and around a street canyon in a city district of Hanover/Germany. After a brief introduction to the VALIUM project a summary of the main results will be given.
Atmospheric boundary-layer structure from simultaneous SODAR, RASS, and ceilometer measurements
A comparison of the determination of boundary-layer structures by a SODAR, by a RASS, and by a ceilometer is presented. One important structure is the mixing-layer height (MLH). The comparison is focused on 3 days with an evolution of a convective boundary layer over a larger city in Germany. The three instruments give information that partly agree and partly complement each other. By this, a picture of the diurnal evolution of the vertical structure of this urban boundary layer is presented. The ceilometer gives information on the aerosol content of the air and the RASS provides a direct measurement of the vertical temperature distribution in the boundary layer. The RASS and the ceilometer add information on the moisture structure of the boundary layer that is not detected by the SODAR. On the other hand this comparison validates known techniques by which the MLH is derived from SODAR data. Especially the temperature information from the RASS agrees well with lifted inversions derived from the analysis of the SODAR data. The ceilometer, being the smallest instrument, has a potential to be used in future MLH studies.
Remote sensing of tropospheric temperature and water vapor by integrated observing systems : The remote sensing lecture
In the last decade, substantial advances have been made in the remote sensing of tropospheric temperature and water vapor. Techniques include measurement of virtual temperature by Radio Acoustic Sounding Systems (RASS), the combination of RASS with satellite soundings, the measurement of precipitable water vapor by Global Positioning Systems, the measurement of water vapor profiles by Raman and differential absorption lidar, and the measurement of both temperature and water vapor profiles by Fourier Transform Infrared Radiometers. However, none of the techniques, by itself, is capable of satisfying most meteorological and climate needs. Thus, determination of profiles from combinations of data and sensors is the only practical way of satisfying these needs. In this paper, some of the techniques used for combining remote sensor data are outlined, some of the current sensors are described, and then examples of data derived from these combinations are presented. The role of the radiosonde in remote sensor evaluation, retrievals, and calibration is discussed. Finally, some of the new possibilities for combined remote sensors are presented.