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- Title
A deep stratosphere-to-troposphere ozone transport event over Europe simulated in CAMS global and regional forecast systems: Analysis and evaluation.
- Authors
Akritidis, Dimitris; Katragkou, Eleni; ZanisIoannis, Prodromos; Pytharoulis, Ioannis; Melas, Dimitris; Flemming, Johannes; Inness, Antje; Clark, Hannah; Plu, Matthieu; Eskes, Henk
- Abstract
Stratosphere-to-troposphere transport (STT) is the dominant natural source of tropospheric ozone, which can occasionally influence ground-level ozone concentrations relevant for air quality. Here, we analyse and evaluate the Copernicus Atmosphere Monitoring Service (CAMS) global and regional forecast systems during a deep STT event over Europe for the time period from 04 to 09 January 2017. The predominant synoptic condition is described by a deep upper level trough over eastern and central Europe favouring the formation of tropopause folding events along the jet stream axis and therefore the intrusion of stratospheric ozone into the troposphere. Both global and regional CAMS forecast products reproduce the hook-shaped streamer of ozone-rich and dry air in the middle troposphere depicted from the observed satellite images of water vapor. The CAMS global model successfully reproduces the folding of the tropopause at various European sites, such as Trapani (Italy), where a deep folding down to 550 hPa is seen. The stratospheric ozone intrusions into the troposphere observed by WOUDC ozonesonde and IAGOS aircraft measurements are satisfactorily forecasted up to three days in advance by CAMS global model in terms of both temporal and vertical features of ozone. The fractional gross error (FGE) of CAMS ozone Day-1 forecast between 300 and 500 hPa is 0.13 over Prague, while over Frankfurt is 0.04 and 0.19, highlighting the contribution of data assimilation which in most cases improves the model performance. Finally, the meteorological/chemical forcing of CAMS global forecast system in the CAMS regional forecast systems is found to be beneficial for predicting the enhanced ozone concentrations in the middle troposphere during a deep STT event.
- Subjects
EUROPE; OZONE layer; TROPOSPHERIC ozone; WEATHER forecasting; COMPUTER simulation; AIR quality
- Publication
Atmospheric Chemistry & Physics Discussions, 2018, p1
- ISSN
1680-7367
- Publication type
Article
- DOI
10.5194/acp-2018-488