Assessment of turbulence intensity retrieval techniques by using a polarimetric precipitation profiling radar

Abstract

In this presentation a few turbulence intensity retrieval techniques are assessed by estimation of their accuracy and validated by in-situ measurements by using a polarimetric precipitation profiling radar. The turbulence intensity retrieval techniques considered include both (1) a classical approach based on analytical formulas and the assumption of independent contributions to the radar spectral width of the formula parameters (fall speed spectral width, turbulence, etc.) and as well (2) a new approach using model based estimation of radar observables that includes the inertia effect of the scatterers. The major challenge in the technique proposed is to estimate the drop size distribution from the radar measurements such that it can be used in the retrievals. Consequently the turbulence intensity can be estimated. The proposed retrieval techniques are assessed using data from the S-band profiling polarimetric radar TARA operating at 45 degrees elevation angle at the Cabauw (the Netherlands) research site. At this slant elevation agle the radar observables contain both information on fall speeds of the scatterers via the Doppler effect as well as information on axis ratios of the scatterers via polarimetric variables. The estimated turbulence intensities are compared to in-situ values from a sonic anemometer.