Understanding the model representation of clouds based on visible and infrared satellite observations

Autor(en)
Stefan Geiss, Leonhard Scheck, Alberto de Lozar, Martin Weissmann
Abstrakt

Satellite observations provide a wealth of information on atmospheric clouds and cover almost every region of the globe with high spatial resolution. The measured radiances constitute a valuable data set for evaluating and improving clouds and radiation representation in climate and numerical weather prediction (NWP) models. An accurate, bias-free representation of clouds and radiation is crucial for data assimilation and the increasingly important solar photovoltaic (PV) power production prediction. The present study demonstrates that visible (VIS) and infrared (IR) Meteosat SEVIRI observations contain valuable and complementary cloud information for these purposes.

We analyse systematic deviations between satellite observations and convection-permitting, semi-free ICON-D2 hindcast simulations for a 30-day period with strong convection. Both visible and infrared satellite observations reveal significant deviations between the observations and model equivalents. The combination of infrared brightness temperature and visible solar reflectance allowed to attribute individual deviations to specific model shortcomings. Furthermore, we investigate the sensitivity of model-derived VIS and IR observation equivalents to modified model and visible forward operator settings to identify dominant error sources. The results reveal that model assumptions on subgrid-scale water clouds are the primary source of systematic deviations in the visible spectrum. Visible observations are, therefore, well-suited to advance this essential model assumption. The visible forward operator uncertainty is lower than uncertainties introduced by model parameter assumptions by one order of magnitude. In contrast, infrared satellite observations are very sensitive to ice cloud model assumptions. Finally, we show a strong negative correlation between VIS solar reflectance and global horizontal irradiance. This implies that improvements in VIS satellite reflectance prediction will coincide with improvements in the prediction of surface irradiation and PV power production.

Organisation(en)
Institut für Meteorologie und Geophysik
Externe Organisation(en)
Deutscher Wetterdienst, Hans Ertel Centre for Weather Research,
Journal
Atmospheric Chemistry and Physics
Band
21
Seiten
12273-12290
ISSN
1680-7316
DOI
https://doi.org/10.5194/acp-21-12273-2021
Publikationsdatum
07-2021
Peer-reviewed
Ja
ÖFOS 2012
105206 Meteorologie
Link zum Portal
https://ucris.univie.ac.at/portal/de/publications/understanding-the-model-representation-of-clouds-based-on-visible-and-infrared-satellite-observations(059823b3-2a16-4e4a-9990-5b2ec57046c5).html