2003-10-10 Measurement of free iron content in desert dust : effect on light absorption, and soil influence

Global and Local Dust over N. America Observations and Analysis Tools Rudolf Husar CAPITA , Washington University , St. Louis Presented at: Second Workshop on Mineral Dust Paris, France, September 10-12, 2003

Global Aerosol: Dominance of Dust, Smoke & Some Sulfate Note: Each satellite senses different aerosol parameter, indicates different pattern ,[object Object],[object Object],Herman et. al., 1997 TOMS POLDER MISR Polarization Small Particles Backscattering Scattering Particles Jun, Jul, Aug Duze et. al., 1997

Aerosols: Many Dimensions ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Satellite-Integral

Aerosols: Opportunity and Challenge ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Dust Particle Size and Shape ,[object Object],[object Object]

Atmospheric Residence Time of Dust ,[object Object],[object Object],PM2.5 Residence Time Increase with Height ,[object Object],[object Object],Residence Time in the Atmosphere (Jaenicke, 1978) 1  m ~ 15 days 100  m ~ 15 min 10  m ~ 1 day

Local, Sahara and Gobi Dust over N. America ,[object Object],[object Object]

Attribution of Fine Dust (<2.5  m) Local and Sahara ,[object Object],[object Object],[object Object],The two dust peeks at Big Bend have different Al/Si ratios During the year, Al/Si = 0.4 In July, Al/Si reaches 0.55, closer to the Al/Si of the Sahara dust (0.65-0.7) The spring peak is identified as as ‘Local Dust’, while the July peak is dominated by Sahara dust. Everglades, FL Big Bend, TX Upper Buffalo, AK Annual PM2.5 Mass

Seasonal Fine Aerosol Composition, E. US Upper Buffalo Smoky Mtn Everglades, FL Big Bend, TX

Seasonal and Secular Trends of Sahara Dust over the US ,[object Object],Regional Sahara Dust events occur several times each summer

Sahara and Local Dust Apportionment: Annual and July ,[object Object],[object Object],The Sahara and Local dust was apportioned based on their respective source profiles. ,[object Object],[object Object],Annual July

Supporting Evidence: Transport Analysis Satellite data (e.g. SeaWiFS) show Sahara Dust reaching Gulf of Mexico and entering the continent. The air masses arrive to Big Bend, TX form the east (July) and from the west (April)

Sahara PM10 Events over Eastern US ,[object Object],[object Object],Much previous work by Prospero, Cahill, Malm, Scanning the AIRS PM10 and IMPROVE chemical databases several regional-scale PM10 episodes over the Gulf Coast (> 80 ug/m3) that can be attributed to Sahara. June 30, 1993 July 5, 1992 June 21 1997

Sahara Dust Passage over the EUS (Poirot, 2003) Dirty dust composition based on Positive Matrix Factorization, PMF ,[object Object],‘ Dirty’ dust and salt composition

Direction of Dust Origin at 5 IMPROVE Sites Ad hoc Data Processing Value Chain High ‘dust’ concentration at 5 sites indicate the same airmass pathway from the tropical Atlantic Weather Serv. Upper Air Data NOAA ARL ATAD ATAD Traject Gebhart (2002) NPS-CIRA IMPROVEData PMF Tool Pareto (2001) PMF “Sources” Coutant (2002) CATT Tool Husar (2003) Aggregation Poirot (2003)

Global Scale Dust Transport: The April 1998 Asian Dust Event Location of the April 19 dust cloud over the Pacific Ocean based on daily SeaWiFS, GMS5/GOES9/GOES10 and TOMS satellite data. The April 1998 Asian dust event caused 2-3 times higher dust concentrations then any other event during 1988-1998

Decomposition of Spectral Reflectance: Dust, Haze, Sea Water ,[object Object],[object Object],[object Object]

Topography: Sahara Dust Near the Surface ,[object Object],3D View 3D view shows that shallow islands are submerged in dust, while high islands extrude from the ~1 km deep dust layer

In West-Central Africa, winter haze is surface- based; summer haze is elevated ,[object Object],[object Object],[object Object],[object Object],Based on AERONET Sun Photometer Network, NOAA SOD Visibility data

Challenge: Putting together the BIG PICTURE ,[object Object],[object Object],[object Object]

SUMMARY ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

SUMMARY: New Opportunities ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

2003-10-10 Measurement of free iron content in desert dust : effect on light absorption, and soil influence

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2003-10-10 Measurement of free iron content in desert dust : effect on light absorption, and soil influence