AN IMPORTANT FINGERPRINT OF WILDFIRES ON THE EUROPEAN AEROSOL LOAD

Francesca Barnaba, Federico Angelini, Gabriele Curci, Gian Paolo Gobbi

CNR - Area Ricerca Tor Vergata12 January 2010

CNR - Area Ricerca Tor Vergata14 January 2010

ISAC-CNR, Rome, Italyf.barnaba@isac.cnr.it

CETEMPS - Dip. FisicaUniversità dell’Aquila, Italygabriele.curci@aquila.infn.it

[Barnaba et al., ACPD 2011]

EGU 2011, 4 April, Vienna

… but a “bimodal” cycle is observed

AOT

Data Counts

AOT anomaly

AEROSOL OPTICAL THICKNESS (AOT) IN ROME DOES NOT PERFECTLY FOLLOW A “SINUSOIDAL” YEARLY CYCLE …

http://aeronet.gsfc.nasa.gov/

ROME

[Yu et al., JGR 2003 ]

AOT is expected to have a “sinusoidal” yearly cycle

AOT “BIMODALITY” IS A MORE GENERAL FEATURE OVER EUROPE

AOT and FFAOT @ 550 nm from MISR satellite

instrument also shows significant deviation from “sinusoidal” yearly cycle.

AOT max: April & Jul-Aug

2002-2007 average

WILDFIRES IN EASTERN EUROPE ARE MOSTLY CONCENTRATED INEARLY SPRING & SUMMER

Example: MODIS Fire Counts 2006 Spring

SummerThese fires are mostly related to human activities (crops, forestry, …)

WE COMBINE SATELLITE DATA AND TRAJECTORY MODEL TO ESTIMATE THE IMPACT OF WILDFIRES ON EUROPEAN AOT

1. MISR AOT & Fine Fraction AOT (< 0.35 µm), λ = 550 nm, 0.5° x 0.5° Level 3 Monthly

2. MODIS, 0.5° x 0.5° Level 3 Monthly mean:

– Fire Counts, FC (counts/km2/day)

– Fire Radiative Power, FRP (MW)

3. HYSPLIT Lagrangian trajectory model (http://ready.arl.noaa.gov)

q

n1Tn1

n2

Tn2

FRPn2

FRPn1

Target Region

Combining 2 and 3 we derive a

Fire Weighted Trajectory Density (FWTD)

N

n thn

h

tFRPqFWTD1

)/exp()( 5 days

MONTHLY FIRE WEIGHTED TRAJECTORY DENSITY (FWTD) 2002-2007

JAN FEB MAR APR

MAY JUN JUL AUG

SEP OCT NOV DEC

FWTD YEARLY CYCLE IN PHASE WITH AOT & FFAOT

MISR AOT2002-2007 average

MISR FFAOT(~ no dust/sea salt)

FWTD

LARGER INTER-ANNUAL VARIABILITY @ MAX

IMPACT OF EASTERN EUROPE FIRES IS UBIQUITOUS.PORTUGAL FIRES LIMITED TO SOUTH-WESTERN EUROPE

Q1 Q2

Q3Q4

Eastern Europe (Q3) Fires

WMed (Q1) Fires

CONTRIBUTION OF WILDFIRES TO FINE FRACTION AOT (FFAOT):ESTIMATED FROM DIFFERENCE WITH “SINUSOIDAL” FIT

OBSERVED MISR FFAOT

FFAOT_RB (fit)

FFAOT_WF = FFAOT – FFAOT_RB

“Reconstructed” FFAOT

CONTAMINATION FROM INTERCONTINENTAL TRANSPORT FROM NORTH AMERICA SIGNIFICANT ONLY IN SOUTH-WESTERN EUROPE IN SPRING

MISR FFAOT JULY2002-2007 average

MISR FFAOT

FFAOT_RB (fit)

FFAOT – FFAOT_RB

CONCLUDING REMARKS

• A step forward toward a comprehensive long-term (2002-2007) evaluation of wildfires impact (mostly from agricultural & forestry practices) on European aerosol load: previous studies focused on episodic events.

• A combination of satellite observations and trajectory modelling show that fires (mostly from Eastern EU and European Russia) contribute to a continent-wide haze.

• In spring and summer, 10-30% of Fine Fraction AOT over Europe is related to wildfires.

• Clear target for mitigation: biomass energy production and air quality

• To be done: Evaluation of the impact on PM at the ground (air quality) – Preliminary estimate on PM10:

WF Fine Fraction AOT = 0.04Mass-to-extinction = 4 m2/g

Column Mass = 0.01 g/m2

If PBL Height = 1000 mand Uniform distribution

Monthly mean WF related PM10 = 10 µg/m3