Characteristics of convection investigated during NAMMA (2006) using a dual-frequency airborne precipitation radar

One of the primary goals of the NASA African Monsoon Multidisciplinary Analyses Experiment (NAMMA, 2006) is to examine the differences between developing and non-developing easterly waves leaving the West African coast. During the experiment, research flights were conducted in 7 waves, ranging from non-developing to weak tropical cyclone. Staged from Sal, Cape Verde, the NASA Jet Propulsion Laboratory (JPL) next generation Airborne Precipitation Radar (APR2) aboard the NASA DC-8 provides an opportunity to examine and compare characteristics of raining areas associated with NAMMA waves. The APR2 is a dual-frequency (14 and 35 GHz) profiling radar; post-processed data include reflectivity, Doppler velocities of rain and snow and linear depolarization ratio (LDR). These attributes make it a capable platform for evaluating precipitation processes and microphysics.

Convection associated with a variety of easterly wave scenarios are compared: an already developed wave (2 - Debby), a developing wave (7 – Helene), two non-developing waves (3 and 6) with well-defined centers, two weak waves (1 and 4) with primarily ITCZ related convection and poorly defined centers, as well as a wave that does not immediately develop but has a well-defined vorticity center (5). Utilizing the APR2 data, the comparison includes the percentage and characteristics of convective and stratiform profiles, vertical velocity, and cumulative frequency by altitude diagrams of reflectivity. Supplementing the APR2 will be microwave, IR and TRMM PR overpasses, which provide an additional context for convective differences between the waves. The goal is to elucidate differences between convective intensity, the area of convective and stratiform rain, the location of the raining area relative to the vorticity maximum associated with the wave as well as the nature of the organization (i.e. isolated convective cells, large stratiform only areas, stratiform with embedded convective cells, or squall-line).