Lidar, sonde and aircraft observations of volcanic ash in Switzerland

In-situ, Lidar, sonde and aircraft observations of volcanic ash in Switzerland Dominik Brunner, Empa with contributions from Stephan Henne, Christoph Hüglin, Andrea Ulrich, Brigitte Buchmann Urs Baltensperger,, Nicolas Bukowiecki Paul Zieger Thomas Peter, Frank Wienhold Ralf Kägi Bruno Neininger Barbara Pietragalla Materials Sci ence & Technolog y MeteoSwiss

Volcanic ash measurements in CH Lidar profiles Aircraft (OPC, trace gases) Backscatter sonde profiles Zurich Neuchatel Payerne Jungfraujoch 3600 m Rigi 1030 m Magadino 200 m Pollen filter samples In-situ (SO 2, PM) Lugano 280 m In-situ (chemistry, size distribution, optical analysis) 2

FLEXPART simulations by Empa Our first FLEXPART forecast started noon 16.4. based on GFS forecasts Best estimate FLEXPART simulation based on ECMWF analyses 17 April 12 UTC 17 April 11 UTC Simulations by Stephan Henne, Empa 3

First evidences of the plume in Switzerland Balloon borne backscatter sonde COBALD of ETH Night ascent 17 April 00 UTC Lidar profiles available by 17 April noon Lidar Payerne, MeteoSwiss / EPFL Ash layers in dry air (RH 30-60%) with enhanced color ratio 870:455 nm Aerosol Lidar ETH Zurich 16/04 19:00 17/04 09:00 Plume descending rapidly from 7 km to 3 km 4

First evidences of the plume in Switzerland First plume as observed by ETH Lidar in Zurich EMPA simulation Comparison with FLEXPART simulation by Empa 16 April 17 April 18 April 5

First evidences of the plume in Switzerland Metair Dimona, 2 channel OPC, O 3, CO, CH 4, NO x Ash layer Flight path on 17 April 6

First evidences of the plume in Switzerland In-situ measurements at Jungfraujoch Plume arrived in evening of 17 April SO 2 : maximum 3.8 μg/m 3 PM10: maximum 32 μg/m 3 Mass ratio SO 2 :PM10 ~ 1:10 Aerosol size distribution reveals two distinct modes Plume maximum 7

Volcanic ash particle characterization Volcanic ash sampled on Pollen filter at MeteoSwiss above Zurich. Optical microsopy 600x Dominance of particles in 3-5 μm size range, only very few > 10 μm Birch pollen Particles are transparent Volcanic ash 0 10 20 30 µm 8

Volcanic ash particle characterization Scanning electron microscopy cristalline structures agglomerates of very fine particles approximate elemental analysis with EDX suggests basaltic material mostly < 10 μm and extending into submicron range Jungfraujoch filter sample Rigi rain sample: Particle is probably an agglomerate of several originally smaller ones 9

Volcanic ash particle characterization Preliminary elemental analysis of filter samples by ICP-MS 14 April (before event) 18 April (during event) Transition; 18.9 Alkaline; 9.2 Alkaline; 13.4 REE; 0.05 Main Group; 9.7 Transition; 44.3 Earth Alkaline; 21.9 Earth Alkaline; 62.1 REE; 0.14 Main Group; 20.3 Before event: Alkaline (mainly potassium) and earth alkaline (Ca, Mg) elements dominating. Transition elements dominated by Fe (70%) and Zn (22%) Note: Si not accessible to method During event: Transition (Fe, Ti) and rare elements enhanced. Sodium and Magnesium enhanced in alkaline and earth alkaline fractions, respectively. Titanium 10% of transition elements. 10

Volcanic ash particle characterization Ion chromatography and EC/OC analysis Ion chromatography: SO 4 2- enhanced 90% of SO 4 2- in fine mode (< 1 μm) partly neutralized by NH 4 + (sampling artifact?) Mg 2+ and Ca 2+ enhanced, Ca 2+ with time delay, 30% of Ca 2+ in fine mode Concentration [μg/m3] 3 2.5 2 1.5 1 0.5 0 NO3- SO42- ash plume NH4+ K+ Mg2+ Ca2+ 16.04. 17.04. 18.04. 19.04. 20.04. 21.04. 0.15 0.13 0.11 0.09 0.07 0.05 0.03 0.01-0.01 Concentration [μg/m3] Thick lines: left y-axis; thin lines: right axis EC/OC Analysis: Absolute amounts of elemental (EC) and organic carbon (OC) enhanced (about 2x), relative amounts reduced Indications that EC is inorganic carbon (carbonates) 11

Volcanic ash particle characterization Optical characterization by Paul Scherrer Institute (PSI) Based on measurements with Aethalometer, Nephelometer, OPC, SMPS Real and imaginary parts of refractive index reduced during ash event absorption assumed to be negligible in coarse mode extinction dominated by fine mode, but fine mode is only about 1/3 of mass 12

Volcanic ash event in May 25 20 Magadino-Cadenazzo Lugano-Universita Rigi-Seebodenalp SO 2 SO 2 about 5x higher at JFJ than during April event SO2 (ug/m3) 15 10 5 Jungfraujoch PM10 about 2x higher SO 2 :PM10 ratio: - April 17-20: approx. 1:10 - May 18-19: approx. 1:3 PM10(ug/m3) 0 16.05.2010 17.05.2010 18.05.2010 19.05.2010 20.05.2010 80 70 Magadino-Cadenazzo PM10 Lugano-Universita 60 Chaumont Rigi-Seebodenalp 50 Jungfraujoch 40 30 20 10 0 16.05.2010 17.05.2010 18.05.2010 19.05.2010 20.05.2010 Lugano (280 m ASL) and Magadino (204 m ASL) measure the same concentrations as Jungfraujoch Nearly undiluted adiabatic transport of free tropospheric air into PBL in southern Switzerland during north Föhn event. Jungfraujoch (3650 m) and stations in Ticino (200 300 m) on same isentrope θ = 295 K 13

Conclusions Mulitple observations performed of early plume on 16 and 17 April - remote sensing by lidars and backscatter sonde - in-situ optical measurements from ground and aircraft - in-situ (direct) observations of particle mass, morphology, composition In-situ observations provide - scattering and absorption characteristics - refractive index - size distributions - relation between particle mass and extinction -> mass extinction to calibrate remote sensing observations by lidars and satellites Ash plume in May was more significant at Jungfraujoch than April plume: - larger PM and SO 2 concentrations -ratioso 2 :PM10 much higher than in April Clear signals of volcanic ash plume in boundary layer; nearly undiluted transport from free troposphere into PBL in southern Switzerland during North Föhn episode in May 14