In:
Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 18, No. 20 ( 2018-10-29), p. 15515-15534
Abstract:
Abstract. Stratosphere-to-troposphere transport (STT) is an important 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 4 to 9 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 vapour. 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 3 days in advance by the 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 it is 0.04 and 0.19, highlighting the contribution of data
assimilation, which in most cases improves the model performance. Finally, the
meteorological and 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.
Type of Medium:
Online Resource
ISSN:
1680-7324
DOI:
10.5194/acp-18-15515-2018
DOI:
10.5194/acp-18-15515-2018-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2018
detail.hit.zdb_id:
2092549-9
detail.hit.zdb_id:
2069847-1