Volcanic Ash and Saharan Dust Loads derived from Airborne Observations

Transcription

1 Volcanic Ash and Saharan Dust Loads derived from Airborne Observations Ulrich Schumann with contributions by Bernadett Weinzierl, Andreas Petzold, Hans Schlager, Andreas Minikin, Oliver Reitebuch and many others Institut für Physik der Atmosphäre in cooperation with Ludwig-Maximilians University Munich

2 Desert dust and volcanic ash Eyjafjallajökull ash April 15, 2010 Desert dust, Libyan 31 May 2009 MODIS on NASA Terra Satellite at GMT Thursday April 15, 2010 Quelle: NASA Earth Observatory DLR Institute of Atmospheric Physics 3

3 Comparison Saharan dust Volcanic ash (preliminary) Parameter Desert Dust Volcanic Ash Altitude 0-6 km 3-15 km Depth 3-5 km km width km km Critical ages < 3 days < 6 days Max concentration 100 mg/m3 1 g/m3 Concentration after one day < 5 mg/m3 < 10 mg/m3 Annual mean at airports 0.2 mg/m3 Max. particle diameter in lofted layers < 50 m < 30 m Particle shape, aspect ratio aspherical, 1-2 aspherical, 2 Lidar Depolarization 532 nm Refractive index, typical, real Imaginary (550 nm) morphology crystalline glassy or crystalline Main composition like carbonates and clay quartz, silicate more variable? Melting temperature 960 to 1700 C, low for clay lower??? etc., high for quartz Optical appearance Yellow to brownish dark grey, brownish Aerosol optical depth, after one day < 1 away from source region < 2 Impact on aviation Close to airports, LTO Free troposphere, cruise DLR Institute of Atmospheric Physics 4

4 Global Aerosol Sources boreal forest fires anthropogenic pollution desert dust anthropogenic pollution biomass burning dust + biomass burning biomass burning 2006 annual average of MODIS AOT (@550) Image of the Week - February 18, 2007 DLR Institute of Atmospheric Physics 5

5 SAMUM-1 and SAMUM-2 research flights Faro mineral dust Casablanca Ouarzazate & Zagora SAMUM-1 Tenerife SAMUM-2 Praia Dakar Sahara: largest desert on Earth (9 Mio km²) % of global annual mean dust emissions (Mahowald et al., 2005) biomass burning aerosol SAharan Mineral DUst ExperiMent (SAMUM) DLR Institute of Atmospheric Physics 6

6 Airborne instrumentation during SAMUM-1 and SAMUM-2 meteorological measurements aerosol inlet DLR Falcon 20-E5 max. altitude: ft max. endurance: 4 h gas molecules 10 4 particles cloud droplets 10 3 dn / dlog D p (cm -3 ) nm µm D p (µm) High Spectral Resolution Lidar PCASP-100X FSSP-300 & FSSP-100 aerosol in-situ measurement techniques condensation (CPSA/CPC) deposition (CPC + DS) electrical mobility (DMA) light scattering (PCASP-100X, FSSP-300, FSSP-100) light transmission (3-λ-PSAP) thermo-optic (thermal denuder + CPCs and Grimm OPC) filter sampling: chemical composition & particle shape DLR Institute of Atmospheric Physics 7

7 Lidar: vertical structure: SAMUM-1 versus SAMUM-2 3 June 2006: Casablanca - Zagora mineral dust SAMUM-1 May/June January 2008: Tenerife - Cape Verde biomass burning aerosol SAMUM-2 January 2008 mineral dust DLR Institute of Atmospheric Physics 8

8 SAMUM-1: Size distributions 6 dn (dlog D p ) -1 / cm SAMUM, ground-based SAMUM, airborne envelope of airborne measurements OPAC, dust + WASO altitude / km ASL D p / µm Good agreement between airborne and ground measurements Saltation mode" at ground. in all cases, particle diameters D p > 10 µm Mostly (80%) particles smaller than 40 µm No height dependence 1 Ouarzazate: ~ 1 km ASL D p, max [N = 10-2 scm -3 ] / µm (Weinzierl et al., 2008) DLR Institute of Atmospheric Physics 10

9 dn (dlog D p ) -1 / scm -3 SAMUM-1: Microphysical dust properties #060519a, L02 dust, OZT 11:23:44-11:37: m ASL RH ~ 51 % D p / µm Zone 1 Zone nm particles with nonvolatile core and volatile coating (ammoniumsulfat) m mean, 532nm = i 10 µm Nonvolatile particles with absorbing material m mean, 532nm = i n sd, 532nm = k sd, 532nm = Zone 1 Zone 2 (Weinzierl et al., 2009) DLR Institute of Atmospheric Physics 11

10 Data from SAMUM mass concentrations up to 5 mg/m3 (TSP: total suspended particulate matter; Weinzierl et al., 2009) DLR Institute of Atmospheric Physics 12

11 (Kandler et al., 2009) DLR Institute of Atmospheric Physics 13

12 Saharan dust mass concentration at ground in Morocco < 200 mg/m 3 (Kandler et al., 2009) DLR Institute of Atmospheric Physics 14

13 Dust aerosol optical depth at Quarzazate, Morocco (at Quarzazate, in 2006, Toledano et al., 2009) DLR Institute of Atmospheric Physics 15

14 Altitudes from LIDAR dust measurements Occurrence frequencies of dust layer depth above ground near to the source during SAMUM 1 Tesche et al. (2009). DLR Institute of Atmospheric Physics 16

15 Light absorbing aerosol components VIS + IR "green" Fe 2 O 3 black carbon brown carbon near IR H 2 O (NH 4 ) 2 SO 4 dust (Morocco) hematite 9 µm SiO 2 imaginary part of refractive index k dust (Burkina Faso) soot Hematite (Sokolik & Toon 1999) Kaolinite (Arakawa 1997) Soot (Shettle & Fenn, 1979) Light-absorbing properties of dust are determined by the iron oxides content. Soot mixed with dust "closes" the transparent window in the red to near IR region wavelength, µm DLR Institute of Atmospheric Physics 1737

16 Eyjafjallajökull volcano plume, May 1, noon time DLR Institute of Atmospheric Physics 18

17 Eyjafjallajökull volcano plume, May 1, noon time DLR Institute of Atmospheric Physics 19

18 Emergency Aircraft, e.g. DLR-Falcon (future: HALO) meteorological measurements DLR Falcon 20-E5 max. altitude: ft max. endurance: 4 h aerosol & trace gas instruments total & non-vol. aerosol, 3-λ B ap, particle comp. & shape (4 nm µm) CO (UV fluoresc.), O 3 (UV photom.), SO 2 (fluoresc.), H 2 O (τ-point, Ly-α) GPaC (particle collector) TU Darmstadt 2- μm-wind-lidar (heterodyne) PCASP-100X (dry accumulation mode concentration) FSSP-300 & 2-DC ( µm) DLR & LaMP DLR Institute of Atmospheric Physics 20

19 d N / d log D, cm Number and volume - size distributions nucleation mode Aitken mode accumulation mode coarse mode diameter, m d M / d log D, µg m Aitken mode nuc. mode acc. mode coarse mode diameter, m DLR Institute of Atmospheric Physics 21

20 gas molecules particles ash & dust paricles/cloud droplets Nucleation, Aitken Accumulation, coarse, super coarse mode Number size dn / dn distribution, d log (d log Dp D / cm p ) / (dn/d cm -3 logd)/cm µm CPC/CPSA µm CPC + DS CPC + Grimm OPC size resolved particle volatility µm Grimm OPC D p / µ m µm PCASP 100 -X particle samplin for chemical analyses Diameter Dp / md/ m µm FSSP -300 measurement technique condensation deposition light scattering light transmission thermo -optic µm 2D-C probe DLR Institute of Atmospheric Physics 22

21 17 DLR Falcon flights, April 19 - May 18, 2010: OP - Iceland Keflavik Eyjafjöll Stornoway Isle of Man 2-6 km altitude N km wide, km thick Oslo Koszalin De Bilt Hamburg Leipzig range-corrected backscatter 2 µm OP Keflavik: 2700 km New Quai Stuttgart Munich Oberpfaffenhofen DLR Institute of Atmospheric Physics 23

22 May 2: Plume sounded at 3.4 km altitude for 3 min Outer Hebrides 570 km range-corrected backscatter 2 µm N Iceland Eyjafjallajökull DLR Institute of Atmospheric Physics 24

23 May 2: 3 min measurements in top of ash plume at 60 N DLR Institute of Atmospheric Physics 25

24 May 17, 1 hour in ash yellow = ash retrieval red = ash + SO2 retrieval Falcon flight path within thick ash layer DLR Institute of Atmospheric Physics 26

25 One hour Falcon flight in 2 km layer with >0.2 mg/m3 ash Volcanic ash layer range-corrected backscatter 2 µm DLR Institute of Atmospheric Physics 27

26 Just above volcanic ash layer Main layer topped by thin layer (also seen in in-situ measurements) Main layer very hazy Horizon not visible Ground (water) not visible to the side 17-May-2010, 15:54 UT, 6.4 km altitude, North Sea area DLR Institute of Atmospheric Physics 28

27 Inside volcanic ash layer at 5.5 km altitude looking towards sun very hazy horizon not visible ground/water not visible to the side no clouds below 17-May-2010, 16:10 UT, 5.5 km altitude, North Sea area DLR Institute of Atmospheric Physics 29

28 Below volcanic ash layer at 2.7 km altitude visibility much better than inside volcanic ash layer diffuse light horizon hardly visible ground/water visible 17-May-2010, 16:35 UT, 2.7 km altitude, North Sea area DLR Institute of Atmospheric Physics 30

29 May 17 number concentration / cm -3 RH / % GPS altitude / km GPS altitude / km x N x N NONV mass N SO 2 N >2 µm mass conc. / µg m -3 CO mixing ratio / nmol mol -1 RH O 3 DLR Institute of Atmospheric Physics 31

30 Particles collected inside the ash plume at 60 N, May m 10 m 1 m DLR Institute of Atmospheric Physics 32

31 May 2, also found: ammonium sulfate, aggregates 2 m 2 m 10 m DLR Institute of Atmospheric Physics 33

32 Particle composition for a) 2 May and b) 17 May <0.5 µm 0.5-1µm 1-2 µm >2 µm n=194 n=101 n=136 n=87 a) b) Mixtures Silicates Quartz Oxides Phosphates Carbonates Sulfates Secondary <0.5 µm 0.5-1µm 1-2 µm >2 µm n=166 n=167 n=149 n=7 Mixtures Silicates Quartz Oxides Sulfates Secondary DLR Institute of Atmospheric Physics 34

33 Particle properties derived from ESM analysis Table 4. Number of investigated particles, measured two-dimensional aspect ratio and calculated density and complex refractive index values m for different particle size classes. 2 May May 2010 Size/ m < >2 < >2 Number Aspect ratio density m (630 nm) i 0.004i 0.002i 0.001i 0.001i 0.003i 0.001i m (2 µm) i i i i i i i DLR Institute of Atmospheric Physics 35

34 Size distributions 19 April (left) 2 May (right) dn (dlogd) -1 / cm -3 ds (dlogd) -1 / µm 2 cm -3 dv (dlogd) -1 / µm 3 cm PCASP-100X OPC FSSP-300 (0i) FSSP-300 (0.004i) PCASP-100X OPC FSSP-300 (0i) FSSP-300 (0.004i) GPaC particle diameter D/µm particle diameter D/µm DLR Institute of Atmospheric Physics 36

35 Correlation between SO 2 and CO versus ash mass DLR Institute of Atmospheric Physics 37

36 Comparison Saharan dust Volcanic ash (preliminary) Parameter Desert Dust Volcanic Ash Altitude 0-6 km 3-15 km Depth 3-5 km km width km km Critical ages < 3 days < 6 days Max concentration 100 mg/m3 1 g/m3 Concentration after one day < 5 mg/m3 < 10 mg/m3 Annual mean at airports 0.2 mg/m3 Max. particle diameter in lofted layers < 50 m < 30 m Particle shape, aspect ratio aspherical, 1-2 aspherical, 2 Lidar Depolarization 532 nm Refractive index, typical, real Imaginary (550 nm) morphology crystalline glassy or crystalline Main composition like carbonates and clay quartz, silicate more variable? Melting temperature 960 to 1700 C, low for clay lower??? etc., high for quartz Optical appearance Yellow to brownish dark grey, brownish Aerosol optical depth, after one day < 1 away from source region < 2 Impact on aviation Close to airports, LTO Free troposphere, cruise DLR Institute of Atmospheric Physics 38

37 Conclusions - Mass concentration is difficult to measure - High correlation between ash concentration and SO 2 - SO 2 is a well suited volcanic plume indicator - Vulcano Ash and Saharan Dust were comparable in may respect DLR Institute of Atmospheric Physics 39