Flux Measurements of Pulsating Rain with a Disdrometer and Doppler Radar during Phase II of the Joint Tropical Rain Experiment in Malaysia

Multipeak Raindrop Size Distribution Observed by UHF/VHF Wind Profilers during the Passage of a Mesoscale Convective System

“…As in Fig. 5, but for the period corresponding to box 3. other peak, which is at ;1.8-2.2 mm, is consistent with earlier theoretical and experimental results (Steiner and Waldvogel 1987;McFarquhar 2004). Corresponding drop size spectra near the surface (during 2325-2329 LT) also show peak at ;1.8 mm, confirming that the peaks in the distribution are not shifting significantly with altitude.…”

“…This study showed that filament breakup and coalescence of raindrops are responsible for the peaks. Recently, Prat and Barros (2007) presented a discrete numerical model for collisionbreakup and tested their model with the popular coalescence and breakup parameterization schemes available in the literature (Low and List 1982b;McFarquhar 2004). Their analysis shows a bimodal equilibrium distribution with peaks at 0.26 and 2.5 mm, consistent with the results of McFarquhar (2004).…”

“…Later, raindrop measurements with optical probes also show MRDSD similar to those predicted by the models (Willis 1984;Garcia-Garcia and Gonzalez 2000). A recent study employing a new numerical parameterization scheme, which alleviates the shortcomings of Low and List's (1982b) parameterization scheme, has shown a bimodal distribution with peaks at 0.26 and 2.3 mm (McFarquhar 2004). This study showed that filament breakup and coalescence of raindrops are responsible for the peaks.…”

“…Several studies with JW disdrometers also observed peaks similar to those observed in modeling studies (Steiner and Waldvogel 1987;Zawadzki and Antonio 1988;Sauvageot and Koffi 2000), supporting the above processes. McFarquhar and List (1993), however, have shown that the magnitudes of peaks associated with instrumental errors and the observed peaks are of the same order, raising doubts about the role of microphysical processes producing peaks in the distribution. Later, raindrop measurements with optical probes also show MRDSD similar to those predicted by the models (Willis 1984;Garcia-Garcia and Gonzalez 2000).…”

“…This bias may results into MRDSD, particularly for averaged DSDs. The dynamical effects that can produce the MRDSD are associated with the overlapping of rain shafts from contiguous rain cells, present either at the same vertical level with wind shear below that level or overlying one another (Marshall 1953;Atlas and Plank 1953;Gunn and Marshall 1955;Douglas et al 1957;McFarquhar et al 1996). However, these studies have not accounted the changes in DSD due to microphysical processes (e.g., collision-coalescence, breakup, and secondary ice generation) in the falling precipitation.…”