Inspect/
Animate CAPPI's of radar reflectivity at the 2 km level.
This squall line was sampled during TOGA COARE by the MIT and TOGA C-band (5 cm) Doppler radars situated aboard the R/V Vickers and PRC #5 respectively.
Inspect/
Animate CAPPI's of radar reflectivity at the 2 km level.
Figure 1. 9 February 1993 1022 UTC. 3-D image of 5 m/s vertical velocity isosurface (light blue), 40 dBZ reflectivity isosurface (white), and a CAPPI of radar reflectivity on the 1.0 km horizontal plane. The view is from the southeast looking slightly behind the line which is oriented NW-SE. Note the decoupling of 5 m/s updrafts from the heavier precipitation particles situated at lower levels (indicated by the reflectivity core). The top of the 40 dBZ core was at approximately 4-5 km. 5 m/s updrafts extend to greater than 10 km.
The squall line initiated along a gust front boundary that propagated from the southern portion of the intensive flux array toward the northeast. The gust front and convective line were aligned approximately parallel to the deep tropospheric shear vector, with the entire mesoscale feature propagating to the northeast and individual convective cells propagating along the line toward the east-southeast. While the convection exhibited echo tops in excess of 15 km, only one lightning flash was detected by the electric field mill aboard the R/V Vickers, and peak electric fields reached only 5 kV/m over the ocean surface in the vicinity of the ship. The relative absence of lightning is consistent with the overall reflectivity profile observed in the system, which indicated that the bulk of the hydrometeor mass was situated below the height of the -10 C level (~6.7 km). Vertical velocities were generally less than 6 m/s at the -10 C level which suggests that the updraft was not strong enough to loft millimeter-diameter liquid/frozen drops deep into the mixed phase region of the cloud and was also not able to generate a robust mixed phase microphysical environment, thus decreasing the efficiency of any precipitation based charging that may have been present in the cold regions of the cloud.
I will be adding more 3-D images from different stages of the lifecycle as I produce them.
Back to Observations Dr. Walter A. Petersen (970) 491-6944 Dept. of Atmospheric Science walt@olympic.atmos.colostate.edu Colorado State University Fort Collins, CO 80523