Publication Date:
2015-01-24
Description:
Three months of profiler observations from Darwin, Australia are separated into seven cloud types (shallow, mid-level, and deep convective; weak and robust stratiform rain; and transitional and ice-only anvil) to provide vertical velocity statistics on the full spectrum of tropical convective clouds over the course of a monsoon season. Consistent with past studies, convective updrafts increase in height and magnitude as the convective cloud height increases. Shallow/mid-level/deep convection has a mean maximum value of 0.3 m s −1 at 3 km/0.6 m s −1 at 5 km/2.5 m s −1 at 8 km. Deep convective extremes approach 18 m s −1 above 8 km while downdrafts in all convective cloud types are maximum below 4 km. Stratiform vertical velocities are weaker and less varied than in active convection, with maximum mean values 〈 0.25 m s −1 . However, stratiform rain regions associated with larger near-surface reflectivities (and thus rain rates) have stronger mesoscale up and downdrafts than weaker stratiform rain regions. Anvil cloud with little or no rain near the surface also exhibits mesoscale up and downdrafts, but the vertical velocity profile is shifted up in height by at least 2 km. In addition, anvil updrafts were only 20 to 50% of the magnitudes in the stratiform rain region. Overall, the vertical motion statistics were similar across the pre-, active, and suppressed monsoon periods. The vertical velocity distributions for each cloud type were also generally consistent with the reflectivity distributions (i.e., the strongest updrafts were often linked to the largest reflectivities), allowing for some linkages between the dynamical and microphysical cloud properties. For example, strong updrafts above the 0 ° C level in deep convection are associated with strongly sloping reflectivity profiles supporting the importance of cold rain growth processes and stronger vertical motions are associated with stratiform rain that has a robust bright band.
Print ISSN:
0035-9009
Electronic ISSN:
1477-870X
Topics:
Geography
,
Physics
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