Gerber scientific (GSI) 1000-hz PVM

Both techniques, hot wire and PVM-100, have a tendency to underestimate the total liquid water in large drops or mixed phase clouds. The effective radius Re of the cloud droplets (XGRFF) is given by Re(um) = 30,000 x XGLWC(g/m^3)/XGSFC(cm^2/m^3). As the values of XGLWC and XGSFC approach zero the noise in the calculated values for Re will approach infinity given Re is the ratio of the two quantities.

Thus to get all meaningful values of Re, a conditional statement should be applied to the ratio to avoid excessive noise. The recommended approach is to chose a limiting value of XGLWC below which no value of Re is calculated. With additional care in removing any remaining small offsets in the XGLWC and XGSFC data, the limiting value of XGLWC can be chosen as small as 0.010 g/m^3 for this data set.

XGRFF was calculated with an XGLWC threshold of 0.05 and the additional condition that XGSFC>0 to avoid negative radius value.