# Presentation: 895544

## Preliminary Ozone Results from the 

** **
**Preliminary Ozone Results from the **
**TF HTAP Model Intercomparison**

- HTAP Observations Workshop, WMO, Geneva, January 25, 2007

**Arlene M. Fiore**
**(arlene.fiore@noaa.gov)**

**Kees Cuvelier, Frank Dentener (JRC)**
**and the HTAP Modeling Team**

## Literature Estimates of Surface O3 Enhancements at Northern Mid-latitudes from Hemispheric Transport

**Difficult to conduct meaningful assessment due to differences in:**
**1) methods  2) regional definitions 3) reported metrics **

**           ****USA  ****	****                 EU****	****          ASIA**

**Estimates are from studies cited in current draft of Interim report Ch5 Section B,**
**updated from tables in *****Holloway et al*****., *****ES&T*****, 2003 and *****Fiore et al*****., *****EM*****, 2003**

**RECEPTOR REGIONS**

**SOURCE REGIONS:  ****N. AMERICA****   ****EUROPE****   ****ASIA****   ****BACKGROUND**

## Overview of HTAP Model Intercomparison for Ozone 

**20% decreases in:**
** ****anthrop. emis. in HTAP regions for NO****x****, CO, NMVOC individually**
** ****anthrop. emis. of all O****3**** and aerosol precursors in HTAP regions **
** ****global CH****4**** **

_**OBJECTIVES**_**: Quantify source-receptor relationships for HTAP regions and assess uncertainties in these estimates**

_**APPROACH**_**: Conduct base simulation with 3-D models **
**	******** ****horizontal resolution of 4****°****x5****°**** or finer**
**	******** ****2001 meteorology**
**	******** ****each group’s best estimate for emissions in 2001**
**	******** ****methane set to a uniform value of 1760 ppb**
**	****Conduct sensitivity simulations (17 total)**

**~ 14 modeling groups have already delivered results for Experiment 1**

## Seasonal Cycles in Simulated Surface O3 over HTAP Regions: Results from Individual Models

## Previous ACCENT Multi-model Surface O3 vs. Observations in HTAP Regions: NA and EU

**Ellingsen et al., in prep**

- Europe and North Africa

**SW US: 11 sites**

**SE US: 12 sites**

**US Great Lakes: 13**

**C. Mediterranean: 21**

**C. Europe: 101 sites**

**Middle East: 1 site**

## OBSERVATIONAL DATASETS FOR 2001
Field campaigns (TRACE-P, ACE-Asia, PHOBEA-II, CONTRACE, STACCATO)

Vertical profiles (e.g. sonde network, MOZAIC, long-term sites)

Satellites

Surface monitoring networks (CASTNet/AIRS; EMEP; EANET)

Event-based analysis at sites where long-range transport has been detected?

Others?

- OBSERVATIONAL DATASETS FOR 2001
- Field campaigns (TRACE-P, ACE-Asia, PHOBEA-II, CONTRACE, STACCATO)
- Vertical profiles (e.g. sonde network, MOZAIC, long-term sites)
- Satellites
- Surface monitoring networks (CASTNet/AIRS; EMEP; EANET)
- Event-based analysis at sites where long-range transport has been detected?
- Others?

** ****Signatures of intercontinental transport in tracer correlations?**
** ****Observation-based estimates of HTAP?**

## Annual Mean Surface O3 Decrease in HTAP Receptor Regions from 20% Reductions of O3 Precursors

**NA contributes most**

**Multi-model means indicate:**

**EU********EU 0.5              0.4             0.1             1.0   ppbv  (multi-model mean)  **

## Annual Mean Surface O3 Decrease in HTAP Receptor Regions from 20% Reductions of O3 Precursors

**EU contributes most**
**EA contribution ****≈ NA**

**EU and NA NO****x**** contribute similarly but stronger EU**
**VOC influence**
**EU and NA > SA**

**Multi-model means indicate:**

**Does response to 20% reductions scale linearly to other magnitudes? **

**SA********SA 1.1             0.2             0.2            1.1   ppbv**

**EA********EA 0.6            0.2             0.2            0.9   ppbv**

## Surface Ozone Decreases Similarly in all HTAP Regions When Global Methane is Reduced

** ****1 ppbv O****3**** decrease over all NH receptor regions**
** ****Consistent with prior studies**

**What causes the ~1 ppb range across individual models?  **
**	****-- examine ozone production efficiency; NO****x****:VOC ratios**
**Is there seasonality in the response?**

## Tropospheric O3 Responds Approximately Linearly to Anthropogenic CH4 Emission Changes Across Models

**Tropospheric O****3**** Responds Approximately Linearly to Anthropogenic CH****4**** Emission Changes Across Models**

**Anthropogenic CH****4**** contributes ~50 Tg (~15%) to tropospheric O****3**** burden**
**	****	****	****            ****~5 ppbv to surface O****3**

## Annual Mean Surface O3 Response to Global CH4 Decrease of 20% in HTAP Models

**Annual Mean Surface O****3**** Response to Global CH****4**** Decrease of 20% in HTAP Models**

****** ****Likely reflects model differences in NO****x****; transport patterns also?**

## Example Analysis From One Model: Impact of a 20% Decrease in NA Anthropogenic NOx to EA Surface O3 (Jun 1 - Aug 31 2001)

**0.5**
**0.0**
**-0.5**
**-1.0**
**-1.5**

**0           20         40         60         80         100      120**

**Example Analysis From One Model: Impact of a 20% Decrease in NA Anthropogenic NO****x**** to EA Surface O****3**** (Jun 1 - Aug 31 2001)**

**MOZART-2 model at GFDL**

**Mean of 10 ppb bins**

**Base case daily max 8-hr O****3**** (ppbv)**

**Change**
**in ozone**
**(ppbv)**

**Each point is 1 daily max 8-hr avg surface O****3**** in 1 model grid cell **

## What Next?

- JRC will distribute a visualization tool
- Normalize by applied emissions perturbations
- Examine seasonality of hemispheric transport of O3
- Impacts on deposition
- Any obvious dependence on horizontal resolution?
- Can we scale to reductions of different magnitude?
- Contribution to O3 episodes, clean conditions, e.g. compare intercontinental contribution to O3 at the 10th, 50th, 90th percentiles of O3 distribution for a given season

## Preliminary (!) Conclusions on HTAP Source-Receptor Relationships

- Range of estimates narrows from that in the literature under a coherent modeling framework.
- 20% decreases of NOx, NMVOC, CO individually in an HTAP region reduce annual mean surface O3 over receptor regions by <0.2 ppbv.
- 	-- Largest contributions from NOx everywhere, and European NMVOC
- 20% reductions of NOx+NMVOC+CO in HTAP regions yield responses over the receptor regions that are ~20% of the decrease from equivalent reductions in domestic emissions.
- 20% reductions in global CH4 abundances yield ~1 ppbv (0.7-1.8 range from individual models) decrease in annual mean surface O3 over HTAP receptor regions.
- Reductions in individual O3 precursors appear to be fairly additive (to within 20-30%).