# 20070423 Polarimetric Observations of a Mesocyclone

In the following plot the color fill is the $\rho_{HV}$ data from the same sweep. (The basic $\rho_{HV}$ values have been scaled up by a factor of 10; 8 = 0.8). One localized $\rho_{HV}$ minimum is found near the Doppler rotation pattern. (Other investigators have found that tornado-lofted debris can cause localized $\rho_{HV}$ minima). However, $\rho_{HV}$ is also lowered in much of the strong outflow area. The $\rho_{HV}$ estimator used in alternating HV mode operation is subject to error when the radial velocity power spectrum within the pulse volume is non-Gaussian. Such ill-behaved spectra (i.e., bi-modal, etc.) may be expected in the storm environment depicted here. Additional data sets are being collected to examine the differences between the $\rho_{HV}$ estimates made under alternating H, V and simultaneous H+V transmission schemes.