 |
| Titel |
Polarimetric radar observations during an orographic rain event |
| VerfasserIn |
M. Frech, J. Steinert |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1027-5606
|
| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 19, no. 3 ; Nr. 19, no. 3 (2015-03-02), S.1141-1152 |
| Datensatznummer |
250120643
|
| Publikation (Nr.) |
 copernicus.org/hess-19-1141-2015.pdf |
|
|
|
|
|
| Zusammenfassung |
| An intense orographic precipitation event on 5 January 2013 is analyzed using
a polarimetric C-band radar situated north of the Alps. The radar is operated
at the meteorological observatory Hohenpeißenberg (MHP, 1006 m a.s.l. – above
sea level) of the German Meteorological Service (DWD). The event
lasted about 1.5 days and in total 44 mm precipitation was measured at
Hohenpeißenberg. Detailed high resolution observation on the vertical
structure of this event is obtained through a birdbath scan at 90°
elevation which is part of the operational scanning. This scan is acquired
every 5 min and provides meteorological profiles at high spatial resolution
which are often not available in other radar networks. In the course of this
event, the melting layer (ML) descends until the transition from rain into
snow is observed at ground level. This transition from rain into snow is well
documented by local weather observers and a present-weather sensor. The
orographic precipitation event reveals mesoscale variability above the
melting layer which can be attributed to a warm front. This variability
manifests itself through substantially increased hydrometeor fall velocities.
Radiosounding data indicate a layered structure in the thermodynamic field
with increased moisture availability in relation to warm air advection. Rimed
snowflakes and aggregation in a relatively warm environment lead to a
signature in the radar data which is attributed to wet snow. The passage of
the warm front leads to a substantial increase in rain rate at the surface.
We use the newly implemented hydrometeor classification scheme "Hymec" to
illustrate issues when relating radar products to local observations. For
this, we employ data from the radar near Memmingen (MEM, 65 km west of MHP,
600 m a.s.l.) which is part of DWD's operational radar network. The
detection, in location and timing, of the ML agrees well with the
Hohenpeißenberg radar data. Considering the size of the Memmingen radar
sensing volume, the detected hydrometeor (HM) types are consistent for
measurements at or in a ML, even though surface observations indicate for
example rain whereas the predominant HM is classified as wet snow. To better
link the HM classification with the surface observation, either better
thermodynamic input for Hymec or a statistical correction of the HM
classification similar to a model output statistics (MOS) approach may be
needed. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|