Assimilation of water-vapour airborne lidar observations

Autor(en)

S. Bielli, M. Grzeschik, E. Richard, C. Flamant, C. Champollion, C. Kiemle, M. Dorninger, P. Brousseau

Abstrakt

The Convective and Orographically-driven Precipitation Study (COPS) carried out in summer 2007 over northeastern France and southwestern Germany provided a fairly comprehensive description of the low-troposphere water-vapour field, thanks in particular to the deployment of two airborne differential absorption lidar systems. These lidar observations were assimilated using the 3D-Var assimilation system of the Application of Research to Operations at MEsoscale (AROME) numerical weather prediction mesoscale model. The assimilation was carried out for the period 4 July-3 August by running a three-hour forward intermittent assimilation cycle. First, the impact of the lidar observations was assessed by comparing the analyses with a set of more than 200 independent soundings. The lidar observations were found to have a positive impact on the analyses by reducing the dry bias in the first 500 m above ground level and by diminishing the root-mean-square error by roughly 15% in the first km. Then the impact of the lidar observations was assessed by comparing the precipitation forecasts (obtained with and without the lidar observations for the period 15 July-2 August) with the gridded precipitation observations provided by the Vienna Enhanced Resolution Analysis. In general, the impact was found to be positive but not significant for the 24 h precipitation and positive and significant for the 6 h precipitation, with an improvement lasting up to 24 h. Some selected case studies show that the improvement was obtained through a better depiction of convection initiation or through a more accurate positioning of the precipitation systems.

Organisation(en)

Institut für Meteorologie und Geophysik

Externe Organisation(en)

Université Toulouse III Paul Sabatier, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université Paul-Valéry Montpellier 3, Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), Centre national de recherches météorologiques (CNRM)

Journal

Quarterly Journal of the Royal Meteorological Society

Band

138

Seiten

1652-1667

Anzahl der Seiten

16

ISSN

0035-9009

DOI

https://doi.org/10.1002/qj.1864

Publikationsdatum

12-2011

Peer-reviewed

Ja

ÖFOS 2012

105206 Meteorologie

Schlagwörter

ASJC Scopus Sachgebiete

Atmospheric Science

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/assimilation-of-watervapour-airborne-lidar-observations(47354f8c-45f5-4259-8796-e3fb0303abe5).html