2004-09-21 Natural Aerosol Event Detection and Characterization - Presentation Transcript
Partially Supported by Inter-RPO WG – NESCAUM
F ast A erosol S ensing T ools fo r N atura l E vent T racking FASTNET
CAPITA
September 2004
Natural Aerosol Event Detection and Characterization
Contents
Background, Objectives and and Approach
Direct Evidence of Natural Aerosol Events
Event Definition: Time Series Approach
Origin of US Dust Events
Fine Dust Concentration Pattern
FAST-CATT: EUS Dust Transport Events
Regional PM25 Time Pattern AIRNOW (2003-2004)
Background, Objectives and and Approach to the Analysis
Background, Objectives and and Approach to the Analysis
Background
There is considerable evidence that smoke from biomass fires and windblown dust constitutes a significant component of the PM25 and PM10 over the US.
There is a rich pool of research on smoke and dust but the contributions are fragmented, and uneven in spatial, temporal an compositional coverage.
Objective
Quantify the the spatio-temporal and chemical pattern of dust and smoke over the US
Identify and possibly quantify the local and origin of NAM dust and smoke
Approach
This natural aerosol analysis applies integrative analysis along several dimensions:
Access, organize and share historical and recent aerosol-relevant data for the community
Combine surface, satellite data, relevant to emissions, transport and effects
Participate in open, collaborative projects to conduct integrative analysis
Status (Sep. 2004)
The analysis of natural aerosols over the US begun at CAPITA in 2000. Since then several funded projects have supported aspects of the analysis. Current (2004) activities support the development of collaboration technologies (NSF), haze regulations (RPO) and the use of satellite data (NASA). The natural aerosol pattern/source analysis progressing well but the collaboration with the community has been marginal.
Aerosol Types and their Events: Dust, Smoke and Haze
Aerosol are composed of multiple types including urban-industrial sulfates, nitrates and organics (industrial haze), biomass smoke and windblown dust and others.
Each type may be considered a different pollutant since it has its own class of sources, aerosol properties and it is associated with different effects.
Current regulation lump the different aerosol species into two size classes PM2.5 and PM10, regardless of their composition in each size range.
In this sense dust, smoke and haze aerosols (PM25 and PM10) are equivalents to an array of gaseous pollutants, such as SO2, NOx and CO
The assessment of PM25 and PM10 aerosols can only be accomplished through a full understanding of the component species and their interaction
This analysis assesses the dynamic, event-characteristics of sulfate, organic, dust and nitrate aerosols and their statistical interaction in producing PM25 events.
Regional Haze Rule: Nomenclature and Time Scale Schematics
Temporal Components
Historical condition, pre 2000 status
Baseline condition, established in 2000-2004
Current condition, on 2000-2064 trajectory
Natural condition, absence of human aerosol
Haze Components Natural haze is due to natural windblown dust, biomass smoke and other natural processes Man-made haze is due industrial activities AND man-perturbed smoke and dust emissions A fraction of the man-perturbed smoke and dust is assigned to natural by policy decisions Regulatory Components Goal is to attain natural conditions by 2064; Establish baseline during 2000-2004 First SIP & Natural Cond. estimate in 2008; SIP & Natural Cond. revisions every 10 yrs
Natural Aerosol Analysis Goals
Natural Haze (this Project, COHA)
Spatially resolve natural (dust, smoke, other), focus on Class I areas
Temporally resolve natural haze components for each day
Current Conditions (VIEWS, RPO Projects)
Spatially resolved haze components, focus on Class I areas
Temporally resolve aerosol components for each day
Identify worst/best visibility days for total aerosol
Natural-Total Haze Apportionment (this & other RPO projects)
Estimate the natural-manmade contribution on best/worst visibility days
Thus, Current Conditions and the Natural Conditions need to be quantified simultaneously. Thus, coordination with other work is essential.
Observational Tools Establishing Aerosol Origin
Modern Methods – similar to century-old approaches but with more data
Direct Evidence. Photographic, satellite or compelling visual evidence of origin
Aerosol Composition. Chemical fingerprinting of different source types (speciation, traces)
Temporal pattern. Chemical rPhysical property analysis (satellite, ASOS, PM2.5)
Spatial Pattern. Chemical
Transport Pattern. Forward, backward trajectory, residence time analysis
Chemistry with Transport . Combining chemical fingerprinting and transport (CATT)
Dynamic modeling . Simulation model (forward, inversion) quantifying origin/transport
Direct Evidence Spatial Pattern Wind Pattern Composition Temporal Pattern Trajectory
Historical Methods
Source attribution methods have been used for the past 2 centuries
A list of methods was given my Egen, 1835. See paper and PPT
Natural Aerosol Conditions – Default Values
The Regional Haze Rule provides initial default values for the Natural Haze Conditions
The default haze for the West is 8 deciviews while for the East is 11 deciviews
Obtained by estimating the natural concentration of SO4, EC, OC, NO3, Fine, Coarse Soil
Weighing each aerosol component by corresponding extinction efficiencies. (Trijonis, 1990)
Mass West East Regulatory objective: Fortify the natural condition estimates by the 2008 SIP call.
Regional Haze Guide on Fire and Dust
Fire
Forest and other fires can be either natural or man-induced
Many major forest fires can be inherently classified as natural
Other fires are intentional (prescribed) to reduce organic fuel accumulation
Prescribed burning will likely be increasing to reduce catastrophic wildfires
EPA considers some portion of the prescribed fire emissions as ‘natural’.
The Western Regional Air Partnership (WRAP) is conducting interesting policy discussions on defining natural and manmade smoke
Dust
Regional Haze guide document is vague on natural dust
A WRAP RPO study has concluded that windblown dust, not manmade fugitive (mechanically stirred up) dust dominated regional dust.
Pitchford suggests that a working definition of natural dust could be any dust from non-disturbed soil surfaces; dust from disturbed surfaces would be manmade.
Clearly, there is a need to begin both the scientific/technical as well as the policy discussion about natural/manmade dust.
Direct Evidence of Natural Aerosol Events
Miscellaneous Observations
Aerosol Events Catalog
Aerosol events catalog is community-based
Each cataloged event has location, time and type codes
Software tools allow event submission and browsing
Events are described in flexible user-supplied URLs
East events occur several times a year, mostly in summer
West events are lest frequent, mostly in spring
US West East
Dust
asgasgasfg
Northeast Southwest Southeast
Dust
dfjdjdfjetyj
Northwest S. California Great Plaines
Amm. Sulfate
wdthehreherh
US West East
Amm. Sulfate
stheherheyju
Northeast Southwest Southeast
Amm. Sulfate
shheherh
Northwest S. California Great Plaines
Organic Carbon
sdhdfhefheryj
US West East
Organic Carbon
sdheherh
Northeast Southwest Southeast
Organic Carbon
erheryeyj
Northwest S. California Great Plaines
Reconstructed Fine Mass
estrhertheryu
US West East
Reconstructed Fine Mass
werty3rueru
Northeast Southwest Southeast
Reconstructed Fine Mass
wthwrthwerhtr
Northwest S. California Great Plaines
Event Definition: Time Series Approach
Eastern US aggregate time series
Sulfate EUS Daily Average 50%-ile, 30 day 50%-ile smoothing Deviation from %-ile Event – Deviation > percentile value Median Seasonal Conc. Mean Seasonal Conc.
Reconstructed Fine Mass RCFM
Reconstructed Fine Mass RCFM
Organic Carbon
Eelemental Carbon
SOIL
Nitrate
Eastern US PM25 Event Composition
The largest EUS PM25 events (as RCFM) are simultaneously ‘events’ in sulfate, organics and soil!
Some EUS PM25 events are single species events
Some PM25 events are not events in any species; their reinforcing combination causes the PM25 event
Origin of US Dust Events
Origin of Fine Dust Events over the US Gobi dust in spring Sahara in summer Fine dust events over the US are mainly from intercontinental transport Fine Dust Events, 1992-2003 ug/m3
Daily Average Concentration over the US
Dust is seasonal with noise
Random short spikes added
Sulfate is seasonal with noise Noise is by synoptic weather VIEWS Aerosol Chemistry Database
Dust Event Detection
Determine concentration baseline
Use ‘spike filter’ to remove outlier
Declare remaining data as ‘baseline’
Plot of the daily avg. fine SOIL
Baseline with strong seasonality
Events superimposed on baseline
Separate event days from baseline
Identify spike (event) days
Subtract baseline to get event ‘excess’
Seasonal Pattern of Dust Baseline and Events
The dust baseline concentration is has a 5x seasonal amplitude from 0.2 to 1 ug/m3
The dust events (determined by the spike filter) occur in April/May and in July
The two April/May and the July peak in avg. dust is due to the events
Fine Dust Concentration Pattern
Annual Average Fine Dust Pattern (Derived from VIEWS 1992-2002)
Seasonal Average Fine Soil (VIEWS database, 1992-2002)
Fine soil concentration is highest in the summer over Mississippi Valley, lowest in the winter
In the spring, high concentrations also exists in the arid Southwest (Arizona and Texas)
Evidently, the summer Mississippi Valley peak is Sahara dust while the Spring peak is from local sources
Annual Average Fine Dust Concentration (VIEWS database, 1992-2002)
The highest annual fine dust concentration is in southern Arizona and Texas
Elevated dust is also evident in the Mississippi Valley
TOMS and VIEWS, July
TOMS – Dust plume from Sahara
VIEWS SOILf in July – Sahara dust plume penetrating the continent
Local Dust
VIEWS SOILf, Spring - Local dust
TOMS local dust
Local Dust
Dust Storm Damage, 19030-1940 Dust Bowl States (brown), most dust storm damage (red), less damage (yellow).
Dust frequency based on visibility obs. – Sehmel (1975?)
FAST-CATT: EUS Dust Transport Events
Sahara Dust Events over the EUS
Example high fine dust days ( See console for complete list ) Asian Dust April 16, 2001 Sahara Dust July 5, 2001 Southwestern Dust Oct. 16, 2001
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