In an attempt to achieve a complete drop size distribution in rain, in April 2015, a droplet spectrometer (Meteorological Particle Spectrometer, MPS) was installed next to a 2DVD at a site near Greeley, Colorado. Both instruments were conveniently installed within a 2/3-scaled DFIR double wind-fence, located at about 13 km from the CSU-CHILL S-band polarimetric radar. Very soon after the MPS installation, a long-duration but intermittent rain event occurred at the Greeley location. The event was part of a mid-latitude synoptic scale cyclone that had produced fine drizzle, light precipitation, cold rain, rain bands, stratiform and convective, as well as thunderstorm towards the end of the event. CHILL radar scans were made at regular and closely spaced time intervals comprising VAD, sector, PPI and RHI scans. The LDR VAD scans (10 deg elevation) showed extraordinarily clear melting layer circles' at times.
Whilst the MPS enabled drop concentration measurements down to 0.1 mm, the 2DVD had recorded drops as large as 5 mm associated with the (non-hail producing) thunderstorm. Fall velocities show a clear trend with drop diameter, in agreement with the expected Gunn-Kinzer variation, but with an adjustment factor appropriate for the 1.4 km altitude for Greeley. Further, shape information also confirmed that almost all the hydrometeors were rain drops.
This paper will present a near-complete picture of the DSD spectra (from tiny to large drops) by combining the MPS and 2DVD measurements for the above-mentioned variety of rain-types, and compare the main DSD parameters (such as the mass-weighted mean diameter) with the corresponding CHILL-based estimates. Comments on the S-band dual-polarization rainfall algorithms will also be included for all rain types considered.
- Indicates paper has been withdrawn from meeting
- Indicates an Award Winner