 |
| Titel |
Screen-level non-GTS data assimilation in a limited-area mesoscale model |
| VerfasserIn |
M. Milelli, M. Turco, E. Oberto |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1561-8633
|
| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 10, no. 6 ; Nr. 10, no. 6 (2010-06-10), S.1129-1149 |
| Datensatznummer |
250008222
|
| Publikation (Nr.) |
 copernicus.org/nhess-10-1129-2010.pdf |
|
|
|
|
|
| Zusammenfassung |
| The forecast in areas of very complex topography, as for instance the Alpine
region, is still a challenge even for the new generation of numerical weather
prediction models which aim at reaching the km-scale. The problem is enhanced
by a general lack of standard observations, which is even more evident over
the southern side of the Alps. For this reason, it would be useful to
increase the performance of the mathematical models by locally assimilating
non-conventional data. Since in ARPA Piemonte there is the availability of a
great number of non-GTS stations, it has been decided to assimilate the 2 m
temperature, coming from this dataset, in the very-high resolution version of
the COSMO model, which has a horizontal resolution of about 3 km, more
similar to the average resolution of the thermometers. Four different weather
situations have been considered, ranging from spring to winter, from cloudy
to clear sky. The aim of the work is to investigate the effects of the
assimilation of non-GTS data in order to create an operational very
high-resolution analysis, but also to test the option of running in the
future a very short-range forecast starting from these analyses (RUC or Rapid
Update Cycle). The results, in terms of Root Mean Square Error, Mean Error
and diurnal cycle of some surface variables such as 2 m temperature, 2 m
relative humidity and 10 m wind intensity show a positive impact during the
assimilation cycle which tends to dissipate a few hours after the end of it.
Moreover, the 2 m temperature assimilation has a slightly positive or
neutral impact on the vertical profiles of temperature, eventhough some
calibration is needed for the precipitation field which is too much perturbed
during the assimilation cycle, while it is unaffected in the forecast period.
So the stability of the planetary boundary layer, on the one hand, has not
been particularly improved by the new-data assimilation, but, on the other
hand, it has not been destroyed. It has to be pointed out that a correct
description of the planetary boundary layer, even only the lowest part of it,
could be helpful to the forecasters and, in general, to the users, in order
to deal with meteorological hazards such as snow (in particular snow/rain
limit definition), or fog (description of temperature inversions). |
| |
|
| Teil von |
|
|
|
|
|
|
|
|