# Presentation: 421718

## AURA Science Meeting

- The Hague, The Netherlands, November 7 – 10, 2005

- Institute of Environmental Physics and
- Institute of Remote Sensing
- University of Bremen

**Results from one decade of measurements ****from GOME and SCIAMACHY**

**Andreas Richter, Oluyemi Afe, Andreas Heckel, Folkard Wittrock, and John P. Burrows**

## Overview

**Introduction**
**NO****2**** :**
- NOx emissions from ships
- emission changes
- validation
**BrO:**
- polar BrO release
- BrO from volcanoes
**SO****2**
- global distribution
- comparison with aircraft measurements
**OClO:**
- Split Vortex event 2002
- SCIAMACHY outlook

## SCIAMACHY Tropospheric NO2

- SCIAMACHY Tropospheric NO2

## SCIAMACHY NO2: Shipping Emissions

**Ship emissions:**
- large source of NOx, SOx and aerosols
- relevant input into marine boundary layer
- well defined NO2-patterns in Red Sea and Indian Ocean in SCIAMACHY data
- consistent with pattern of shipping emissions

- With estimate of NO2 lifetime, NOx emissions can be estimated => agreement within error bars.
- But: error bars still large (mainly from lifetime)

- A. Richter et al., Satellite Measurements of NO2 from International Shipping Emissions, *Geophys. Res. Lett.*, **31**, L23110, doi:10.1029/2004GL020822, 2004

- NO2 reductions in Europe and parts of the US
- strong increase over China
- consistent with significant NOx emission changes

- 7 years of GOME data
- DOAS retrieval + CTM-stratospheric correction
- seasonal and local AMF based on 1997 MOART-2 run
- cloud screening

- NO2 trends from GOME

- A. Richter et al., Increase in tropospheric nitrogen dioxide over China observed from space, *Nature*, **437**** **2005** **

## Validation of Tropospheric NO2

**NO****2**** distribution characteristic:**
- Important sources are close to the ground
- Lowermost 1.5km make up to 50% of the tropospheric NO2 column
- High spatial (horizontal AND vertical) variability
**Characteristics of in-situ aircraft measurements:**
- Only few measurements close to the ground
- These measurements are in clean regions
- Interpolation and extrapolation of data gaps is critical below 1.5km altitude
- Spirals usually cover 2-4 satellite pixels
- Slant ascents and descents cover a much larger area, but only in one dimension
**Satellite measurement characteristic:**
- large ground pixel
- tropospheric column
- limited sampling

## NO2 validation using airborne in-situ measurements

- in-situ measurements on DC8 during ICARTT (data  R. Cohen)
- SCIAMACHY limb-nadir tropospheric NO2
- Difficult to find comparable measurements
- Strong dependence on the integration of the in-situ profiles
- spatial variability is a major problem

**=> overall: good agreement**

## NO2 validation using AMAXDOAS measurements

- Multi-Axis DOAS measurements on DLR-Falcon (SCIAVALUES campaign) over Alps & Po-valley
- direct comparison of tropospheric columns
- not completely independent (similar technique)
- smaller footprint of AMAXDOAS instrument
**=> good agreement**

- Heue, K.-H., et al., Validation of SCIAMACHY tropospheric NO2-columns with AMAXDOAS measurements, *Atmos. Chem. Phys., ***5, 1039-1051, 2005**

## NO2 validation using surface measurements

- GOME NO2
- 1996 – 2002
- comparison to measurements of 100 in-situ measurement stations of ARPA in the Lombardy region, Italy
- computation of tropospheric columns using model profile
- correction of in-situ measurements for PAN and HNO3 interference
- analysis of groups with different pollution levels

- Ordóñez C. et al., Comparison between 7 years of satellite-borne and ground-based tropospheric NO2 measurementsaround Milan, Italy, *submitted to J. Geophys Res.*, 2005

## NO2 validation using surface measurements

- NO2 validation using surface measurements

**annual cycle**

**weekly cycle**

**GOME**

**in-situ**

**=> good agreement in values, seasonality and weekly cycle, but large spatial variability**

## NO2 validation using MAXDOAS measurements

- NO2 validation using MAXDOAS measurements

**Analysis:**
- MAXDOAS measurements in Cabauw during the DANDELIONS campaign
- May – July 2005
- tropospheric column determined from off-axis viewing directions
- Bremen SCIAMACHY tropospheric NO2 product
- closest value within 50 km radius selected
- 20 overpasses with cloud fraction < 30%

**very nice agreement in spite of large uncertainties**
**good spatial matching crucial**

## Bromine Oxide (BrO) Release in Polar Spring

- Each year, large BrO columns are observed in polar spring over sea ice
- Bromine source is sea water, but release mechanism is not fully understood
- Correlation of GOME and SCIAMACHY BrO with areas with high probability for frost flower formation is indication for central role of frost flowers in bromine release

- L. Kaleschke et al., Frost Flowers on Sea Ice as a Source of Sea Salt and their, Influence on Tropospheric Halogen Chemistry,
-  GRL , 31, L16114, doi:10.1029/2004GL020655, 2004.

## BrO Release from Volcanoes

- the ratio SO2 / BrO was about 1000 at Soufriere Hills
- do satellite measurements show the same behaviour?
- satellites mainly detect large eruptions => search for large signals to get best SNR

- Bobrowski, N. et al., (2003), Detection of bromine monoxide from a volcanic plume *Nature*, 423, 273-276.

## BrO Release from Volcanoes: GOME / SCIAMACHY

- Summit elevation 3,058m

## BrO Release from Volcanoes

- Afe, O. T., et al., BrO Emission from Volcanoes - a Survey using GOME and SCIAMACHY Measurements, *Geophys. Res.Lett.*, **31, L24113, doi:10.1029/2004GL020994, 2004**

**=> no indication for 1:1000 BrO / SO****2**** emissions during large volcanic eruptions; difference to degassing?**

## SCIAMACHY SO2 measurements

**Andreas.Richter@iup.physik.uni-bremen.de**

## SCIAMACHY SO2: Volcanic Emissions

## SCIAMACHY SO2 : Volcanic Emissions

## SCIAMACHY SO2:Pollution

- SCIAMACHY SO2:Pollution

## SCIAMACHY SO2: Pollution

## SCIAMACHY SO2: Fire in Sulphur Plant

**LARGE**** **SO2 plume over Middle East in June / July 2003
- no matching NO2 plume

- Fire in a sulphur plant in Qayyarah, Iraq

## GOME SO2 : Pollution in Eastern US

## Comparison with RAMMP in-situ Measurements

****** ****[SO****2****]dz ******** 1 DU**

- air-borne in-situ measurements from Dickerson et al., University of Maryland
- flight from August 8, 2001
- vertical profile agrees well with assumptions in GOME analysis
- integrated column agrees well with GOME measurements
- more detailed comparisons are under way

## GOME Observations of Split Vortex Event 2002

**NO****2**

**OClO**

**O****3**

**PV**

**T**

## Chlorine Activation (OClO)

**Southern Hemisphere**

**Northern Hemisphere**

- small variability from year to year
- instability and early and rapid end of activation in 2002

- large variability from year to year
- lower activation even in coldest years

- Richter, A., et al., GOME observations of stratospheric trace gas distributions during the splitting vortex event in the Antarctic winter 2002 Part I: Measurements, *J. Atmos. Sci.*, 62 (3), 778-785, 2005

## Denoxification / Denitrification (NO2)

**Southern Hemisphere**

**Northern Hemisphere**

- small variability from year to year
- very large values in Sep / Oct 2002
- early recovery but not exceptional

- little variability from year to year
- no large excursions in spring
- recovery 1 month earlier than in SH

- Richter, A., et al., GOME observations of stratospheric trace gas distributions during the splitting vortex event in the Antarctic winter 2002 Part I: Measurements, *J. Atmos. Sci.*, 62 (3), 778-785, 2005

## Stratospheric OClO SCIAMACHY

## Summary

- GOME and SCIAMACHY provide a valuable long-term record of tropospheric and stratospheric measurements
- the long time series facilitates first “trend” studies
- long time series also improve sensitivity through averaging
- long time series are useful to detect rare events
- validation still is an issue, in particular for tropospheric products
**OMI and GOME-2 will continue and improve the existing data sets**