Measurement of eddy dissipation rate by a mini-sodar for aviation application: comparison with tower measurement

Low-level turbulence is a hazardous weather phenomenon for arriving and departing aircraft at the airport. In aviation meteorology, turbulence is quantified in terms of eddy dissipation rate (EDR), which is equal to 1/3 power of the turbulent kinetic energy dissipation rate. Continuous measurement of EDR in the atmospheric boundary layer helps the timely issuance of low-level turbulence alerts for the aircraft.

Due to height restriction requirements of the airport and potential interference with the air navigation signals, it is not practical to set up a meteorological tower of a few tens of metres near the runway to make in situ measurement of turbulence. Remote sensing devices, such as sodars, may be viable alternatives.

This paper describes the use of a 4.5 kHz mini-sodar to measure EDR directly in a field study in Hong Kong from December 2003 to May 2004. During the study period, turbulence was mainly light to moderate, with the EDR ranging between 0.1 and 0.3. These data are compared with the sonic anemometer measurements at 30 m and 50 m on a meteorological tower in the vicinity of the mini-sodar. They are found to correlate well in general, with a correlation coefficient greater than 0.65. The mini-sodar appears to have the potential of providing reasonably accurate EDR data for the monitoring of low-level turbulence at the airport in light to moderate turbulence conditions.