 |
| Titel |
Hail formation in pre-frontal environments: A long-term study over Switzerland |
| VerfasserIn |
Sebastian Schemm, Luca Nisi, Andrey Martynov, Olivia Martius |
| Konferenz |
EGU General Assembly 2015
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250112284
|
| Publikation (Nr.) |
 EGU/EGU2015-15043.pdf |
|
|
|
|
|
| Zusammenfassung |
| This study investigates the formation of hail in environments pre-conditioned by synopticscale
cold fronts. In addition the link of pre-frontal dynamics as trigger for the hail cell initiation is
characterized climatologically over Switzerland. The study is based on a high-resolution analysis
dataset (COSMO-2/-7) for the extended hail season May-September between the years 2002 - 2013
and a radar-based hail identification and tracking scheme. An automated identification method for
fronts is used to compile a climatology of fronts for the COSMO-2 domain, encompassing Switzerland
and parts of its neighboring countries, e.g., the Italian Alpine foothills and the Black Forest in
southwestern Germany. The informations are used to quantify the relative portion of hail cell initiation
in a pre-frontal environment and to study in greater detail the temporal evolution of selected
variables (CAPE, CIN, wind shear) in a 20 hour period prior.
Pre-frontal hail initiations accounts for up to 40% of all hail formation in northwestern Switzerland,
the southern Prealps, and upstream of the Jura and Black Forest mountains.We suggest that
fronts trigger hail formation in particular in regions where hail is less frequently observed (with the
exception of southern Switzerland). Adiabatic cooling due to pre-frontal lifting lead an increase of
CAPE, a reduction of CIN and an increase of the wind shear. Additional lifting by flow convergence
along the Alps or by the front itself above the level of free convection leads to the development of
strong convection. |
|
|
|
|
|
|