1. Tropospheric Ozone Assessment Report (TOAR)
Global metrics for climate change, human health and
crop/ecosystem research
Presentation is based on the input from O. Cooper and M. Schultz
And outcome of the TOAR workshop April 2015 in AEMET
Stakeholders:

2. >160 scientists from 33 nations, representing all 7 continents
Mission:
Provide the research community with an up-to-date global assessment of tropospheric ozone’s distribution and trends from the surface to the tropopause.
Facilitate access to the ozone metrics necessary for quantifying ozone’s impact on human health and crop/ecosystem productivity.
>160 scientists from 33 nations, representing all 7 continents

3. TOAR Member Nations

4. TOAR Organization
TOAR is a science effort initiated by IGAC, and developed by an international team of experts.
TOAR receives financial and logistical support from
- IGAC
- The World Meteorological Organization
- US National Oceanic and Atmospheric Administration (NOAA)
Coordinated by an eleven-member Steering Committee
The assessment report will be published as a series of 8 stand-alone chapters in a special issue of a peer-reviewed, open-access journal.

5. Tropospheric ozone data for use in TOAR analyses
Global database of (hourly) surface ozone observations (Forschungszentrum Jülich)
Ozone sonde records (WOUDC, NILU)
MOZAIC/IAGOS; other aircraft data(?)
Satellite data
FTIR, LIDAR, DOAS, …
surface
free troposphere

6. The TOAR (surface stations) database
Airbase (Europe): ~3500 ozone records, earliest data from 1990
CaPMon (Canada): 19 ozone records, earliest data from 1995
CASTNET (US): 79 ozone records, earliest data from 1987
EANET (Asia): 16 ozone records, earliest data from 2000
EMEP (Europe)1: 196 ozone records, earliest data from 1977
GAW2 (global): 112 ozone records, earliest data from 1971
UBAG3 (Germany): 599 ozone records, earliest data from 1990 (19694)
US AQS (US): ~2000 ozone records, earliest data from 1980
1 some data also contained in Airbase
2 some data also contained in Airbase, CaPMon, EMEP, or EANET
3 more recent data also contained in Airbase or EMEP
4 collection by H. Geiß

7. Data quality control
Standardized „reports“ with plots and statistical analysis
Outlier filter program
Expert knowledge, i.e. discussion with community(!)
Database allows to set status of a data series and flag each individual data value (WMO standard flagging scheme)

8. TOAR Database is up and running

10. TOAR Ozone Metrics
The TOAR database will contain various ozone metrics at thousands of surface sites around the world. The full suite of metrics is still being developed but some key metrics that will be included are:
Human Health:
- Maximum daily 8-hour average
  - Maximum daily 1-hour average
Vegetation:
- Cumulative Exposure Index: W126
- Cumulative Exposure Index: AOT40
- Flux-Based Index: PODy (will only be calculated for a limited number of sites due to the need for additional meteorological and soil parameters)
Climate Change:
- Monthly means, medians and various percentiles at rural sites
- Monthly and seasonal mean vertical profiles where data are available

11. Summary (statistics group)
Decision to use „at least 3 years between 2009 and 2013“ as the basis for characterizing present-day distributions (don‘t focus on mean values only!)
Choose a second reference period to allow for „change detection“ (not to be confused with trend analysis) – again: don‘t focus only on mean values, but consider also the changes in the frequency distributions.
As a default, use non-parametric Mann-Kendall test to identify significant trending and Sen-Theil to estimate magnitude of trend, and also include parametric (linear/quadratic) test results for trends if statistical assumptions are met.

12. Summary …
Assess trends over different time periods to investigate varying trending patterns
One example is to perform trending over each running 15-year period to obtain a rate of change for each period using the Mann-Kendall/Sen-Theil approach. Using a modified Mann-Kendall approach, test overall whether the magnitude of the trend is increasing, decreasing, or not changing.
Another approach is to use the quadratic linear regression approach assuming the regression satisfies assumptions

13. Summary …
Some more discussions and analysis needed to decide on minimum data capture requirements and uncertainty estimates (default: use 75% because of historical application by various governments) – data capture requirement may vary depending on selected metrics.
Example: Slope statistics based on 80% complete data series
6-year time series
15-year time series

14. Timeline December 2014: TOAR Workshop 1.01 in Boulder
February – March, 2015: Preliminary organization of TOAR chapter author teams and working groups.
February – December 2015: Collect ozone observations and populate TOAR database, begin work on calculating ozone metrics around the world
April 28-30, 2015: TOAR Workshop 1.02, Madrid, Spain
December 2015: Produce first draft of assessment report
January 2016: Workshop 1.03 – location to-be-determined
December 2016: Submit assessment report to a peer-reviewed journal and perform any necessary updates to the ozone metrics on the database

15. TOAR Workshop 1.02
April 28-30, 2015
Agencia Estatal de Meteorología (AEMET), Madrid, Spain