The influence of mid-latitude cyclones on European background surface ozone

Transcription

1 1 The influence of mid-latitude cyclones on European background surface ozone K. Emma Knowland (USRA/GESTAR NASA/GMAO) In collaboration with: Ruth Doherty (U. Edinburgh) Kevin Hodges (U. Reading) Lesley Ott (NASA/GMAO)

2 2 The influence of mid-latitude cyclones on European background surface ozone The special issue is open to all publications that inform about the aspects of intercontinental transport of air pollution and provide answers to the HTAP scientific questions: What fraction of air pollution concentrations or deposition can be attributed to sources of contemporary anthropogenic emissions within the region as compared to extra-regional, nonanthropogenic or legacy sources of pollution?

3 Background Question Data & Methods Results Summary 3 Cold front height Warm front Catto et al., 2010, J. Climate (modified from Browning, 1997, Meteorol. Appl.)

4 Background Question Data & Methods Results Summary 4 Cold front height Warm front Catto et al., 2010, J. Climate 1. Storms ventilate the lower atmosphere of pollutants WCB

5 Background Question Data & Methods Results Summary 5 SI Cold front Warm front H height Catto et al., 2010, J. Climate 1. Storms ventilate the lower atmosphere of pollutants WCB 2. Introduce stratospheric air into the troposphere SI

6 6 Questions Do passing cyclones have a detectable impact on surface O3 concentrations? What are the key synoptic features associated with cyclones that impact surface O3 concentrations? Background Question Data & Methods Results Summary k.e.knowland@nasa.gov

7 Two EMEP remote coastal monitoring stations Mace Head, Ireland 53 N, 10 W 7 Hourly observations available from 1 April 1988 until 31 December 2014 Background Question Data & Methods Results Summary k.e.knowland@nasa.gov

8 Two EMEP remote coastal monitoring stations Monte Velho, Portugal 38 N, 9 W 8 Hourly observations available from 1 January 1988 until 31 December 2009 Background Question Data & Methods Results Summary k.e.knowland@nasa.gov

9 Background Question Data & Methods Results Summary ERA-Interim Reanalysis European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis product Available: January 1979 July 2015 (3 months prior to present) 6 hourly resolution Spring (MAM) TRACK Construct cyclone tracks using the objective feature tracking algorithm, TRACK (Hodges 1995, 1999): TRACK identifies cyclones by maxima in 850-hPa relative vorticity (ζ 850 )

10 (Knowland et al., in prep.) 10 Relationship between O 3 at Mace Head and cyclone tracks Mean percent of tracks in a season associated with high O3 Mean percent of tracks in a season associated with low O3 North 51.8% 36.6% 32 Center 51.0% 40.8% 30 South 44.9% 52.7% 25 Mean number of tracks in a season Number of years with more tracks associated with high O3 Number of years with more tracks associated with low O3 North 18 (15) 5 (0) Center 17 (6) 6 (1) South 7 (2) 16 (8) Background Question Data & Methods Results Summary k.e.knowland@nasa.gov

11 MACC Reanalysis Monitoring Atmospheric Composition and Climate O 3 assimilated into an extended version of the ECMWF Integrated Forecast System (IFS) IFS coupled to a Mozart-3 Chemistry Transport Model (CTM) MERRA-2 Reanalysis (Inness et al., 2013, ACP) Modern Era Retrospective analysis for Research and Applications version 2 O 3 assimilated from OMI and MLS since 2004 GEOS-5 model includes simplified O3 chemistry scheme for both the stratosphere and troposphere based on monthly-dependent production/loss rates Background Question Data & Methods Results Summary k.e.knowland@nasa.gov 11 (Gelaro et al., 2017, J.Clim.)

12 (Knowland et al., in prep.) Background Question Data & Methods Results Summary 12 N1 cyclone 4 March UTC

13 (Knowland et al., in prep.) Background Question Data & Methods Results Summary 13 N1 cyclone 4 March UTC

14 (Knowland et al., in prep.) Background Question Data & Methods Results Summary 14 N1 cyclone 5 March UTC N1

15 (Knowland et al., in prep.) N1 cyclone 4 March UTC 15

16 (Knowland et al., in prep.) N1 cyclone 4 March UTC MERRA-2 Reanalysis 16

17 (Knowland et al., in prep.) Background Question Data & Methods Results Summary 17 S1 cyclone 25 April UTC At time of maximum vorticity

18 18 S1 cyclone 25 April UTC

19 (Knowland et al., in prep.) S1 cyclone 25 April UTC MERRA-2 Reanalysis 19

20 S1 cyclone 25 April UTC 20

21 (Knowland et al., in prep.) Background Question Data & Methods Results Summary 21 Summary O3 measurements at Mace Head and Monte Velho are influenced by cyclone tracks passing in the vicinity of the observation sites The relationship between O3 observed and cyclone tracks is dependent on the region, which demonstrates the importance of the associated fronts and conveyor belts The case studies demonstrate The importance of the passage of a cyclone s cold front to surface O3 measurements The ability of cyclones to bring down O3 from the stratosphere Nearby surface high pressure systems also play an important role in the temporal variability of surface O3

22 Thank you! 22