Plenary Lecture

Monitoring the Vertical Mean and Turbulent Structure of the Lower Atmosphere Over Sea and Land
using SODAR Measurements

Professor Costas G. Helmis
Department of Environmental Physics and Meteorology
Faculty of Physics
National and Kapodistrian University of Athens
Building PHYS-5, University Campus, 157 84 Athens, Greece
E-mail: chelmis@phys.uoa.gr

Abstract: The ability of the Acoustic Sounder (SODAR) to measure the mean and turbulent characteristics of the wind flow as well as the thermal structure of the Atmospheric Boundary Layer (ABL), that extends up to the first 1500m of the atmosphere, with high time and space resolution is well known. The SODAR provides information on the horizontal wind speed and direction, the temperature structure parameter (CT2), the surface heat flux (Q0) as well as the atmospheric stability and the mixing height. Furthermore, the estimation of the vertical and the two horizontal wind components, the standard deviations of the three wind components, the Turbulent Kinetic Energy (TKE) and the momentum flux profiles is possible. The spatial and time average of the above mentioned atmospheric parameters is often more appropriate than single point measurements for ABL studies while this real-time information is valuable in a wide range of meteorological and air pollution applications or in environmental policy planning.
In this invited talk a review on the operating parameters, the advantages and disadvantages of SODAR systems and the estimation and evaluation of important atmospheric parameters will be given. Results from previous studies demonstrating the feasibility of SODARS operating over the land, the ocean, a small island or on the shore-line, giving information on the main characteristics of the mean and turbulent vertical structure of the ABL, under different conditions will be presented. This information reveals the variation and the evolution of the ABL, its vertical turbulent characteristics, the shear forcing and the development of wind maxima as well as the transport of momentum, heat and TKE, in response to the background flow and the topography of the experimental area. Finally the evaluation between the estimated mixing height, CT2, heat and momentum fluxes from the SODAR and the corresponding atmospheric parameters which are estimated using in-situ methods will be given and discussed.

Brief Biography of the Speaker:
Studies First Degree: BSc, University of Athens, Faculty of Physics, 1972
Post Graduate Titles: MSc in Electronics, University of Athens, 1975
MSc in Automation, University of Athens, 1976
PhD in Physics, University of Athens, 1981
Academic Positions:
Head of the Dept. of Applied Physics, Faculty of Physics, University of Athens.
Assoc. Professor, Dept. of Applied Physics, Faculty of Physics, University of Athens.
Fields of Scientific activities:
- Atmospheric Physics
- Development of instrumentation for remote and in-situ measurements
- Air Pollution meteorology
- Indoor and Outdoor Air Pollution
He has 92 publications in journals, 167 announcements in conference proceeding, 86 participations in technical reports and 20 other publications. He has participated in the EEA on air quality (ETC/AQ) during 1996-2001 and in 89 research projects, in 37 of the above he acted as the Principal Investigator.