A comparison of the microphysical and kinematic characteristics of mid-latitude and tropical convective updrafts and downdrafts

Airborne measurements of updraft speeds, liquid water content and other microphysical parameters were measured in convective storms during two mid-latitude summers in North Dakota, USA, and in two tropical locations (the continental Amazon region in tropical South America and Kwajalein in the tropical central Pacific Ocean). Data representing 0.5 km averages of data collected from a large number of clouds sampled during the field seasons are examined. In the North Dakota clouds, updraft values of a given magnitude were found about as often as downdrafts of similar magnitude in midlevels of the clouds, while lower levels favored downdrafts and upper levels favored updrafts. Drafts in tropical clouds were much weaker and favored updrafts in mid to upper regions of the clouds (the lower levels were not sampled). In two temperature regions (- 5 to - 12 °C and - 12 to - 20 °C), there was little difference in the frequency of occurrence of liquid water content values in the North Dakota clouds, while in the tropical clouds, higher liquid water contents were less likely to be found in the colder temperature intervals. The particle concentrations measured by FSSP instruments were similar in lower and midlevels of the North Dakota clouds, and decreased in upper levels. In the tropical clouds, the concentrations were similar in the mid and upper regions of the clouds. These results are discussed in terms of previous measurements of midlatitude and tropical clouds.