Monitoring volcanic haze from space: the Bárðarbunga fissure eruption OMI Science Team Meeting 31 August – 2 September 2015, KNMI, de Bilt Image: VIIRS volcanic ash & SO2 RGB, 23 September 2014, 12:20 UTC

Monitoring volcanic haze from space: the Bárðarbunga fissure eruption [Bárðarbunga aka Holuhraun !!!] Jos de Laat (KNMI) Sophie Smits (TU Delft, M.Sc) Martin de Graaf (TU Delft/ KNMI)

Bárðarbunga eruption Aug March 2015

Factsheet Bárðarbunga - Late August 2014 to early March Fissure eruption, fairly constant lava flow rate ± 0.3 km 3 of lava produced, 5-11 Mt SO 2 [Gíslason et al., 2015] - Strength 5-10% of Laki 1783 (= ~ 100 Mt SO 2, ~ 15 km 3 of lava) [Stevenson et al., 2003; Gíslason et al., 2015] - Air quality standards on Iceland frequently exceeded - Occasional transport towards western Europe - Few problems with air quality in western Europe and Scandinavia

What made Bárðarbunga special? - many recent eruptions with lots of SO Soufrière Hills (Montserrat, Caribic) 2008 Kasatochi (Alaska, Aleutian Islands)  2009 Sarychev (Kamtjatska, Kuril Islands) 2010 Eyjafjallajokull (Iceland) 2010 Merapi (Indonesia) 2011 Grimsvotn (Iceland) 2011 Nabro (Ethiopia) 2011 PuyeHue Cordon-Caulle (Chile) - all explosive eruptions, free tropospheric SO 2 - Bardarbunga: to our knowledge the first time satellite history eruption of this combined type, strength and duration. This type = fairly constant surface emissions, long duration of eruption

Bárðarbunga impact - formation of volcanic haze (“vog”) - SO 2 transformed into sulfuric acid (H 2 SO 4 ) - damaging to plants, affects the respiratory system in animals and humans. - Laki 1783: thousands of deaths on Iceland, failed crops - many more casualties throughout Europe, either directly or due to crop failure, famines or climatic effects (coldness)

Bárðarbunga: observing VOG formation [1] Research Questions: - Can we observe particle formation from SO 2 with satellites? - Is there a relation between SO 2 and aerosols? - What are the complexities of satellite observations of SO 2 and aerosols? clouds, strong winds & fast transport, time difference MODIS & OMI observations - Is there added value in monitoring aerosols for such an eruption?

24 September October 2014 Bárðarbunga eruption, SO 2 and aerosol formation Large image: MODIS AOT (NASA), insert: OMI SO2 (TEMIS KNMI/BIRA)

Bárðarbunga: observing VOG formation [2] Method: - Analyze OMI SO 2 and MODIS AOT - similar spatial resolution (OMI 13×24 km 2 vs MODIS 10×10 km 2 ) - good coverage of Iceland region (multiple scenes per day from OMI) - OMI OMSO2 boundary layer SO 2 product - MODIS AOT and MODIS AOT Fine Mode Fraction (FMF) (OCEAN ONLY !!!) - all days in September and October (not later due to Polar winter)

Example: 5 September enhanced AOT - high value MODIS FMF (Small Ratio) - aerosols from SO 2 are expected to be small Complications: OMI row anomaly enhanced non-SO 2 AOT elsewhere clouds

Analysis - 61 days to check - 14 days (26 cases) of either AOT or SO cases with low AOT, little SO cases with high AOT, little SO cases with low AOT, high SO cases with high AOT, high SO 2 Explanations: - time difference & plume displacement - other aerosols sources Much AOTOLRR2R2 SO 2 maxAOTmaxN Much SO V I 2.3 ± ± ± ± Little AOTOLRR2R2 SO 2 maxAOTmaxN Much SO II IV II -1.1 ± ± ± Little AOT OLRR2R2 SO 2 maxAOTmaxN Little SO I I III I II I I II 3.2 ± ± ± ± ± ± ± ± ± ± ± ± Much AOTOLRR2R2 SO 2 maxAOTmaxN Little SO II III VII I II ± ± ± ± ± ± ±

Plume displacement thingy … 2 September 2014 case: -no correlation SO 2 & AOT -time difference 41 min -fresh plume -small change wind direction Colors indicate distance from volcano (blueish 500 km) Estimated OMI SO2 uncertainty 5 DU

Cases: the good, the bad, the ugly … REMOVE ALL SO 2 MEASUREMENTS < 5 DU

The golden case (5 Sep 2014) … -good correlation (R 2 = 0.46) -R 2 = 0.61 for distances up to 650 km (blueish) -R 2 = 0.68 for distances beyond 650 km (redish) -Plume aging, dispersion: SO 2, AOD ???

Summary - compared OMI SO 2 and MODIS AOT for Bárðarbunga eruption Sep-Oct reduced number of useful cases due to clouds, OMI row anomaly - even fewer useful cases due to plume displacement (obs. times differ) Conclusions - clear evidence of enhanced AOT due to conversion SO 2 into particles - one golden case: good correlation between AOT and SO 2 - some evidence for plume aging effects (lifetimes, dispersion, chemistry ??) - there is added value in monitoring AOT for such eruptions (despite complications of collocating SO 2 and AOT measurements)  cloudy region, any information is welcome … paper in preparation: de Laat et al. 2015

That’s all