1 research outputs found
Atmospheric circulation patterns, cloud-to-ground lightning, and locally intense convective rainfall associated with debris flow initiation in the Dolomite Alps of northeastern Italy
The Dolomite Alps of northeastern Italy experience debris flows with great
frequency during the summer months. An ample supply of unconsolidated
material on steep slopes and a summer season climate regime characterized by
recurrent thunderstorms combine to produce an abundance of these destructive
hydro-geologic events. In the past, debris flow events have been studied
primarily in the context of their geologic and geomorphic characteristics.
The atmospheric contribution to these mass-wasting events has been limited
to recording rainfall and developing intensity thresholds for debris
mobilization. This study aims to expand the examination of atmospheric
processes that preceded both locally intense convective rainfall (LICR) and
debris flows in the Dolomite region. 500 hPa pressure level plots of
geopotential heights were constructed for a period of 3Â days prior to
debris flow events to gain insight into the synoptic-scale processes which
provide an environment conducive to LICR in the Dolomites. Cloud-to-ground (CG)
lightning flash data recorded at the meso-scale were incorporated to
assess the convective environment proximal to debris flow source regions.
Twelve events were analyzed and from this analysis three common synoptic-scale circulation patterns were identified. Evaluation of CG flashes at
smaller spatial and temporal scales illustrated that convective processes
vary in their production of CF flashes (total number) and the spatial
distribution of flashes can also be quite different between events over
longer periods. During the 60 min interval immediately preceding debris
flow a majority of cases exhibited spatial and temporal colocation of LICR
and CG flashes. Also a number of CG flash parameters were found to be
significantly correlated to rainfall intensity prior to debris flow initiation