Spatial distribution and precipitation intensity of supercells: Response to terrain asymmetry in the Western Carpathians, Central Europe
Abstract
Empirically based research presents a challenge posing a question as to how much the complex terrain affects the behavior of actual supercell storms. An investigation took place in the Western Carpathians in Central Europe during warm seasons over a period of 5 years.
The occurrence of 62 supercells was identified by mesocyclone/supercell features in two-dimensional radar products. Specifically, in the fields of Doppler radial velocity and reflectivity factor.
Statistical qualities of radar reflectivity at 2-6 km above mean sea level and around approximate mesocyclone centers within 5, 10 and 15-km radius were perceived as an estimated precipitation intensity descriptor. Reflectivity data were compared with several terrain attributes such as elevation, slope angle and curvature.
Results suggest that supercells were spatially bonded to the mountains, e.g., through initiation sites that were predominantly placed over leeward slopes. A mountain-related propagation pattern of storms based on their translation speed was observed as well.
Overall, storms did not appear to be unable to traverse significantly higher terrain, and they did not become stronger or weaker while doing so. Most of their maximum precipitation intensity was situated in the lowlands.
The accumulation of precipitation intensity revealed, though, that the largest values were concentrated over two elevated regions. The general relation between changing precipitation intensity and the terrain was not found and remained insignificant, suggesting that terrain-related effects may impact the precipitation intensity of storms rather on a case-by-case basis.
The strongest, if moderate positive correlation of 0.4 was assigned to the pairs of fast-moving supercells and current elevation of the ground within 15-km radius along the paths of the storms.