Second SOP0 workshop, Exeter 15 May 2007 Special issue AMMA SOP0 LISA contribution 1) Rajot et al., General overview of Banizoumbou results 2) Formenti et al., Physico-chemical characteristics of aerosols over Western Africa (I): results from the AMMA dry season campaign 3) Alfaro et al., Spectral optical properties of mineral dust and biomass burning and their mixing P. Formenti

Second SOP0 workshop, Exeter 15 May ) What are the physico-chemical and optical properties of mineral dust in the Sahel ? (source regions) 2) How to predict dust optical properties knowing their physico-chemical properties ? 3) How to account for mixing with other aerosol species ? 4) How do mineral dust aerosols modify the solar and terrestrial radiation budgets at the local and the regional scales ? Scientific questions within SOP0

Second SOP0 workshop, Exeter 15 May 2007 SOP0 operation Timing 11/0121/01 14/01 27/01 16/0212/02 DJOUGOU BANIZOUMBOU M’BOUR 03/02 DABEXDODO 24/0101/0213/01 ULM

Second SOP0 workshop, Exeter 15 May 2007 Long term ( ) + intensive observations (Jan-Fev et Jun-Jul 2006) Banizoumbou

Second SOP0 workshop, Exeter 15 May 2007 Sampling inlets Laboratory "Belgique" Banizoumbou ground-based station

Second SOP0 workshop, Exeter 15 May 2007 Ground-based measurements at Banizoumbou (1 / 2) On-line measurements (sampling interval) –Number and mass concentration, GRIMM OPC and TEOM (5-min) –Number size distribution, GRIMM OPC (5-min) –Spectral absorption coefficient, Magee Aethalometer (5-min) –Spectral scattering coefficient, TSI nephelometer (5-min) –Global, diffuse & direct radiation, MFRSR-7 shadowband radiometer (1-min) –Global and spectral downwelling radiation, ARM ancillary –Aerosol vertical profile, lidars (B. Heese and F. Cairo) –Ozone concentration (5-min) –Meteorology

Second SOP0 workshop, Exeter 15 May 2007 Filter sampling and analysis Aerosol sampling (sampling interval/frequency) Bulk –Elemental Chemical composition (12-h + events, total + PM10) –Water soluble fraction (12-h + events) –Carbon content (24-h) –Mineralogy (12-h + events) –Single-particle composition and morphology (12-h + events) Size-segregated –Chemical composition on 4- and 13-stage impactors (24-h) s

Second SOP0 workshop, Exeter 15 May 2007 Sampling strategy: schematics Lidars TEOM GRIMM NEPHELOMETRE TSI AETHALOMETRE Magee Sampling inlets (physico-chemical and optical measurements) ARM ancillary Shadow-band

Second SOP0 workshop, Exeter 15 May 2007 Ground-based, Banizoumbou To the instruments To the buried instrumented container Air in

Second SOP0 workshop, Exeter 15 May 2007 Filter collection onboard the UK BAe146 Air in Air out Quartz 0.4-µm Nuclepore 90-mm SFU1: Inorganics 47-mm SFU2: Organic and Elemental carbon Elemental Chemical composition (all) Water soluble fraction (depends on concentration) Mineralogy (depends on concentration) Single-particle composition and morphology (selected events)

Second SOP0 workshop, Exeter 15 May 2007 Collected samples About 500 bulk samples collected at the ground-based station Dust and aged BB About 120 samples collected on the aircraft SLR from ~ 170 feet to FL120 Various aerosol types (dust, fresh BB, aged BB, background, their mixing)

Second SOP0 workshop, Exeter 15 May 2007 Status of analysis Elemental Water- soluble fraction Mineralogy Iron content speciation Individual particle analysis OC/BC Bulk Ground- based DoneJulyDoneJuneJulyDone AircraftDoneJuneJulyJune June (dust) BB (TBD) Done Size- segregated Ground- based June N/A

Second SOP0 workshop, Exeter 15 May 2007 Dust aerosols are found at to the surface BB

Second SOP0 workshop, Exeter 15 May 2007 Episodes of dust and biomass burning Dust BB Banizoumbou, Jan 2006

Second SOP0 workshop, Exeter 15 May 2007 Mineral dust from different source regions

Second SOP0 workshop, Exeter 15 May 2007 Bulk composition of dust from ground-based and aircraft samples (DABEX) : Si vs Al Si vs Al

Second SOP0 workshop, Exeter 15 May 2007 Bulk composition of dust from ground-based and aircraft samples (DABEX) : Fe vs Al Ongoing analysis to quantify the proportion of iron oxydes

Second SOP0 workshop, Exeter 15 May 2007 Individual particle analysis of dust samples (B160, B161, B165) Iron oxyde Iron oxydes observed in the fine fraction (4-5% by number), results of the mass analysis are still missing "Uncontaminated" dust, soot particles less than 1% by number, although trajectories show that airmasses where dust plumes were sampled might have come in contact with pollution

Second SOP0 workshop, Exeter 15 May 2007 Dust from Mauritania is enriched in minerals such as halite (Na-rich) Confirmed by microscopy analysis

Second SOP0 workshop, Exeter 15 May 2007 Measuring the attenuation of the Al signal gives indication on particle size 20% attenuation corresponds to aerodynamic VMD of ~ 2 µm (geometric 1.2 µm) B238N3

Second SOP0 workshop, Exeter 15 May 2007 The Ca-to-Fe elemental ratio as a marker of major source region (DODO) Niger (DABEX) Local erosion

Second SOP0 workshop, Exeter 15 May 2007 Mineralogy from ground-based samples BB Clays Quartz Ca- rich

Second SOP0 workshop, Exeter 15 May 2007 Mineral dust ubiquitous even in elevated BB layer

Second SOP0 workshop, Exeter 15 May 2007 Tracers of biomass burning K vs Al BB episode in Banizoumbou

Second SOP0 workshop, Exeter 15 May 2007 Individual particle analysis of biomass burning samples B158N4 Coarse fraction dominated by mineral dust Fine and coarse fraction are externally mixed

Second SOP0 workshop, Exeter 15 May 2007 Conclusions Analysis still ongoing –won't be ready to submit in July –delaying some of your work (water-soluble fraction) Analysis is focusing on mineral dust –Biomass burning

Second SOP0 workshop, Exeter 15 May 2007

Tracers of biomass burning SAFARI2000, aged smoke K+/BC = 0.54

Second SOP0 workshop, Exeter 15 May 2007 Aerosol optical properties in Niger during the dry season Alfaro et al. Objectives: Document and explain the temporal variability of the spectral dependence of scattering and absorption measured at ground level in Banizoumbou.

Second SOP0 workshop, Exeter 15 May 2007 DATA AVAILABLE from 13 Jan. to 12 Feb. Optical properties at ground level nephelometer TSI (3 ) aethalometer (Magee scientific, 7 ) vertically averaged sunphotometer (AERONET) Particulate concentrations Bulk mass concentration (TEOM microbalance) BC estimates derived from the aethalometer Size-resolved number(Grimm optical counter)

Second SOP0 workshop, Exeter 15 May 2007 METHODOLOGY Caracterization of spectral dependence  neph = C -   abs = C -   and  are the Angström’s exponents for scattering and absorption. They are derived directly from nephelometer and aethalometer measurements. In the case of the aethalometer, difference can be made between the values of  at short (  sw ) and long (  lw ) solar wavelengths.

Second SOP0 workshop, Exeter 15 May 2007 All data is used with particular emphasis on 3 case studies Jan. 15Feb.9Jan. 18

Second SOP0 workshop, Exeter 15 May 2007 Examples of results Dependence of  to the BC mass fraction

Second SOP0 workshop, Exeter 15 May 2007 Absorption spectral dependence in the two wavelength ranges  lw is particularly stable whereas  sw is much more variable and seems to be extremely sensitive to the presence of mineral dust

Second SOP0 workshop, Exeter 15 May 2007 Sensitivity of  sw /  lw to the composition of the aerosol mixture  sw /  lw is - much larger when the proportion of dust increases - lower during BB advection than during local “pollution” events

Second SOP0 workshop, Exeter 15 May 2007 Still to be done: Assess the exact impact of aerosol size and composition (content in iron oxides) on the magnitude of  sw

Second SOP0 workshop, Exeter 15 May 2007 Radiative impact over source regions Radiatif transfert Emission model Radiative impact over transport regions Physico-mineralogical characterization Soil Optical properties Physico-chemical characterization Optical model Mineral dust aerosols Mineral dust aerosols (mixing) Transport Aerosol The mineral dust cycle

Second SOP0 workshop, Exeter 15 May 2007 The Ca-to-Fe elemental ratio as a marker of major source region Niger (DABEX)

Second SOP0 workshop, Exeter 15 May 2007 LISA contribution to field observations Dry season (Jan-Feb 2006, 6 weeks) Ground-based measurements in Banizoumbou + UK BAe146 operated in Niger and Senegal Wet season (Jun-Jul 2006, 6 weeks) Ground-based measurements in Banizoumbou + F-ATR-42 operated in Niger and Benin Wet season (Sep 2006, 2 weeks) UK BAe146 operated in Senegal

Second SOP0 workshop, Exeter 15 May 2007 Aerosol inlets, orientable to the main wind direction Banizoumbou, dry season

Second SOP0 workshop, Exeter 15 May 2007 Air masses where dust plumes where found B160N3 B165N7 Courtesy: M. Harrison

Second SOP0 workshop, Exeter 15 May 2007 FL120 FL feet FL100 FL120 B161 – 23 Janvier, nord of Niger

Second SOP0 workshop, Exeter 15 May 2007

Air in Air out 90-mm SFU1 PIXE PIGE 0.4 µm Nuclepore Bulk elemental composition (Na…Pb) IC/ICP CBD DR SEM TEM DRX Water soluble fraction Iron oxyde content and speciation Bulk mineralogy Individual particle characteristics Analysis of inorganic fraction

Second SOP0 workshop, Exeter 15 May 2007 Organic and elemental carbon Air in Air out 47-mm SFU2 DRI Quartz BC/OC

Second SOP0 workshop, Exeter 15 May 2007 This presentation Our scientific objectives for SOP0 Our contribution to field observations within SOP0 Status of data analysis: issues Some results relevant to publications in the SOP0 special issue

Second SOP0 workshop, Exeter 15 May 2007 Rajot et al., General overview of Banizoumbou results Aim of the paper 1) Description of the sampling station 2) Description of the temporal variability of the aerosol content and type as observed in Banizoumbou in Janvier-Fevrier 2006 Data Time series of 1) Number concentration 2) Mass concentration 3) Spectral scattering coefficient 4) Aerosol optical depth 5) Basic meteorology

Second SOP0 workshop, Exeter 15 May 2007 Formenti et al., Physico-chemical characteristics of aerosols over Western Africa (I): results from the AMMA dry season campaign Aim of the paper Describing the elemental and mineralogical composition and size distribution of mineral dust and biomass burning aerosols and their mixing Data Ground-based and airborne 1) Filter samples 2) OPC size distribution

Second SOP0 workshop, Exeter 15 May 2007 Bulk composition of dust from ground- based and aircraft samples (DABEX) : Ca vs Al