Proceedings with Extended Abstracts (single PDF file) - Radio ...

Fig. 14 Distributions of phase centers in vertical direction for range gates 5.0 -6.2 km observed with the Chung-Li VHF radar in the combined SDI-FDI method(same procedure as in Fig. 13). The center panels show that the “width” can be as“thin” as some 50-80 m, and that the mean position changes as function of time.The upper and lower panel show much more irregular variations of the positions.This presented SDI-FDI method does not need any assumptions, such as other methods whichare frequently applied for atmospheric radar imaging (e.g., Chilson et al., 2003). It is furtherquite simplistic and yields the maximum, undistorted and unbiased information available fromthese observations. We can well qualify the characteristics of the radar echo, such as meanposition, its variability and variation as function of time, reflectivity and velocity distributions,and the “width” of structures. To quantify these needs careful piece-by-piece interpretation.Another versatile method, pulse scanning, was only applied once (Röttger and Schmidt, 1979).This allows higher resolution than the pulse width by applying complex deconvolution. It wasshown that this yields an almost three times resolution improvement. One can also apply shortcoded pulses, which requires broader-band transmitters and antennas than used so far.Possible answers to the initially asked questions:(1) Most of the echoes detected by VHF MST radars cannot be described by a Gaussianprocess but are often highly deterministic.(2) The morphology of these echoes is extensive, which means that standard analysismethods have to be adopted with greatest care.(3) Mostly the spatial and temporal coherency of the echoes cannot be explained byisotropic, homogeneous turbulence.(4) We prefer the quantification into Bragg scatter, Fresnel scatter and Fresnel reflection(Fig. 14, Table 1). Fresnel scatter may most often occur, which is the composite ofspecular-type reflection from several smaller-scale rough sheets or laminae.However,discriminating clearly between these is rather complex still.(5) Apply most unsophisticated analysis methods. Each assumption (how does it replicatenature?) introduces further uncertainties. Nature already confronts us with quite someperplexity, which we cannot disentangle by further conjectures.457