Physics and Instrumentation of Atmospheric Aerosol Measurements Across Maryland July, 2011 Communicating Scientific Research Methods to High School Physics Students Acknowledgements This work was supported by the Long-term Engagement in Authentic Research with NASA (LEARN) project with funding provided through a NASA SMD EPOESS grant. Dr. Margaret Pippin for expertise, guidance, and inspiration, Dr. Ali Omar for his inside knowledge of aerosols and their physics, and Rebecca Kollmeyer for data retrieval and cleaning services Aeronet and Discover AQ Maryland EPA for sharing data And the best last minute what equation do I use website ever: http://asd- www.larc.nasa.gov/SOLAR/experiment-index.html Ellen Babcock McLean, WT Woodson High School, Fairfax, VA NASA Mentors: M. Pippin, A. Omar What Is This Thing We Call Data? The data obtained from NASA and EPA websites are not measured as simply as reading distance from a meter stick or time from a stopwatch. •The connection between measurement and data processing is the physics behind the instrumentation. Taking the time to understand that connection provides the researcher with a far greater comprehension, and appreciation, of what that data represents. •The quantities measured by remote sensing instrumentation are not the data reported by those instruments. Rather, the instrumentation has built into it mathematical models, or algorithms which translate the raw measurements into useable data. •The Aeronet sun photometer column measurement and the EPA surface particulate monitor both provide indirect measurements of aerosol data each using different applications of Beer’s Law What are aerosols? Aerosols are tiny particles of solids, liquids, or gases which become temporarily suspended in the air for varying lengths of time. Many particles, become airborne through natural means, but a significant portion of aerosols, especially the smaller ones, are anthropogenic: caused by Man. In the atmosphere, aerosols can: • Affect visibility • Form cloud condensation nuclei • React with other particles forming hazardous compounds • Scatter, or absorb and then re-emit energy from photons • Contribute to radiative forcing, an anthropogenic change in the radiation budget of the planet In the biosphere aerosols can cause: • Interference with the processes of plant respiration and photosynthesis • cardiovascular disease • Irregular heartbeat • Aggravated asthma • Decreased lung function • Irritation of the airways • Coughing • Difficulty breathing PM 10 are aerosols with diameters less than 10μm. Particles such as water, sand, pollen, soil, and sea salt are usually generated by natural events and tend to be classified as PM 10 . They fall from the atmosphere after only a few hours or even minutes, giving them less opportunity to interact with the environment. PM 2.5 are aerosols with diameters less than 2.5μm. The majority of anthropogenic aerosols are classified as PM 2.5. . Due to their small size, they can remain in the air for days, weeks or even months giving them increased opportunity to react with other substances in the atmosphere often with deleterious effect. PM 2.5 are able to travel deep into the organs and tissues, remaining there for long periods of time and causing, or exacerbating, a host of health issues. PM 2.5 ‘s longevity and potential for serious harm make it important to study and understand as, being largely anthropogenic, there are steps that can be taken towards positive change. EPA Continuous PM 2.5 BAM-1020 Continuous Particulate Monitor Beta-ray Attenuation Method •Absorption per unit area is pre-determined during calibration (F cal ) •Filter tape is exposed to radiation source • A semi-conductor detector measures the intensity of beta ray transmission through the clean filter tape, (I 0 ) •Air, at a controlled rate (V), is filtered through the tape allowing PM 2.5 to accumulate for the duration of the measurement, (t) •The semi-conductor detector measures the intensity of beta ray transmission through the dirty filter tape, (I) •The concentration of PM 2.5 is calculated using the form of Beer’s Law below C = concentration PM 2.5 F cal = calibration factor (mass density) V = measured mass flow rate t = measurement duration I o = beta ray intensity at pre-exposure filter I = beta ray intensity at exposed filter Aeronet DRAGON (AOT) Cimel-318 Automatic Sun Tracking Photometer Spectral extinction of direct beam radiation Aerosol optical thickness data is calculated by measuring voltage generated within a UV enhanced silicon detector of known surface area. •The azimuth of the instrument adjusts automatically to keep the sun within the field of view (FOV in diagram above), and records the solar zenith angle, (Ɵ) (Fig2) •Optical air mass, (m), is calculated, (equation1) •Solar radiation passes through the first of two lenses,L 1 (Fig1) • A disc housing 8 monochromatic filters is rotated in the path between the two lenses, L 1 and L 2 (Fig1) •The wavelength of light through each filter is recorded, (λ) • The silicon detector measures voltage generated by the incident image, (v) •Extraterrestrial voltage, (v 0 ), is a calibration term determined using data collected from reference instruments at NOAA’s Mauna Loa Observatory in Hawaii •The Aerosol Optical Thickness is calculated using Beer’s Law (equation 2) http://pages.usherbrooke.ca/cimel/images/thumb/450px-Installationb2_1.jpg http://www.hussgroup.com/group/en/infocentePM.php http://www.epa.gov/ttnamti1/files/2009conference/Hart.pdf References •Cohen, Robert A. Readings to accompany the Physics of the Atmosphere, Physics Department East Stroudsburg University January 18, 2011 Version 5.4 ©2011 by Robert A. Cohen retrieved 19 June, 2013 from http://www.esu.edu/physics/cohen/phys305/textbook/readings.5.4.pdf •Hanna, Steven R., et al. "Air Pollution." McGraw-Hill Encyclopedia of Science & Technology. 10th ed. Vol. 1. New York: McGraw-Hill, 2007. 292-309. Gale Virtual Reference Library. Web. 22 June 2013. •Document URL http://go.galegroup.com/ps/i.do?id=GALE%7CCX3057500168&v=2.1&u=fair35939e&it=r&p=GVRL&sw=w •Zawar-Reza, Peyman. "Atmospheric Particulates Across Scales." Encyclopedia of Geography. Ed. Barney Warf. Vol. 1. SAGE Reference, 2010. 149-151. Gale Virtual Reference Library. Web. 22 June 2013. •Document URL http://go.galegroup.com/ps/i.do?id=GALE%7CCX1788300073&v=2.1&u=fair35939e&it=r&p=GVRL&sw=w •Rollin, E. M. “An introduction to the use of Sun-photometry for the atmospheric •correction of airborne sensor data.” NERC EPFS Department of Geography University of Southampton •Southampton, Electronic version retrieved from http://www.ncaveo.ac.uk/site-resources/pdf/cimel.pdf •Holben, B. N., et al. AERONET—A Federated Instrument Network •Data Archive for Aerosol Characterization. REMOTE SENS. ENVIRON. 66:1-16 (1998) Retreived from http://aeronet.gsfc.nasa.gov/new_web/PDF/afi.pdf •BAM-1020 Operators Manual. From http://www.metone.com/aerosoldocs/BAM_3-sytem_training.pdf "Atmosphere." Encyclopedia of Public Health. Ed. Morton Lippmann, Lester Breslow. Vol. 1. New York: Macmillan Reference USA, 2002. 88-90. Gale Virtual Reference Library. Web. 22 June 2013. Document URL http://go.galegroup.com/ps/i.do?id=GALE%7CCX3404000078&v=2.1&u=fair35939e&it=r&p=GVRL&sw=w "Aerosols." The Gale Encyclopedia of Science. 4th ed. Vol. 1. Detroit: Gale, 2008. 62-65. Gale Virtual Reference Library. Web. 22 June 2013. •Document URL http://go.galegroup.com/ps/i.do?id=GALE%7CCX2830100048&v=2.1&u=fair35939e&it=r&p=GVRL&sw=w •NASA Discover-AQ website http://www-air.larc.nasa.gov/missions/discover-aq/discover-aq.html •"Radiative Forcing." Environmental Science: In Context. Ed. Brenda Wilmoth Lerner and K. Lee Lerner. Vol. 2. Detroit: Gale, 2009. 680- 682. In Context Series. Gale Virtual Reference Library. Web. 22 June 2013. •Document URL http://go.galegroup.com/ps/i.do?id=GALE%7CCX3233900193&v=2.1&u=fair35939e&it=r&p=GVRL&sw=w •http://teaching.shu.ac.uk/hwb/chemistry/tutorials/molspec/beers1.htm Conclusions •The graphed data suggests a strong correlation between the Aeronet and EPA measurements. The explanation of the importance of the data, the differences between what was actually measured, and the similarities between the data processing methods provides non or neo-scientists with more background information and so more understanding of the final product. •Providing comprehensible details of the instrumentation, physics, and math of processes of data collection and reporting can make that data more accessible to a wider range of viewers. •Making these tangible connections between science and the physical world can be used to teach the real scientific method to high school science students or even seize and hold the attention of a committed climate change skeptic. LEARN: The Second Year 1.The teacher project will focus on a more detailed analysis of the Aeronet data for these Maryland sites looking at the speciation, distribution, sources, and consequences of lofted aerosols. 2. Physics students will propose, or be assigned, science fair projects within the scope of the teacher project 3. Remote sensing data retrievals and current research methods will be included as curricular content in the physics classroom. 4. Students will learn valuable and marketable skill sets better preparing them for internships and their eventual undergraduate studies. Matched PM2.5 and AOT Collection Sites Beer’s Law The amount of radiation absorbed or transmitted by a compound in a medium is proportional to the concentration of that compound present in the medium. Site Selection The location of selected EPA and Aeronet DRAGON sites travels the width of the state of Maryland representing four distinct regions: •Wiley Ford, a rural area far to the west in the mountains •Beltsville, midway along the highly industrialized traffic corridor between DC and Baltimore oBaltimore Harbor, Downtown area around an active seaport •Worton, rural area on the eastern shore of Maryland, across the Chesapeake Bay Google Earth 50 40 30 20 10 0 PM2.5(μg/m 3 ) 7/3/2011 7/5/2011 7/7/2011 7/9/2011 7/11/2011 7/13/2011 7/15/2011 7/17/2011 7/19/2011 7/21/2011 7/23/2011 7/25/2011 7/27/2011 7/29/2011 7/31/2011 UTC PM2_5_WF EPA Continuous PM 2.5 Wiley Ford, MD West of Baltimore Elevation 770m 1.0 0.8 0.6 0.4 0.2 AOT 7/3/2011 7/5/2011 7/7/2011 7/9/2011 7/11/2011 7/13/2011 7/15/2011 7/17/2011 7/19/2011 7/21/2011 7/23/2011 7/25/2011 7/27/2011 7/29/2011 7/31/2011 UTC AOT_500_WF Aeronet DRAGON Level2 AOT Wiley Ford, MD In the Mountains, Elevation ~ 250m 1.0 0.8 0.6 0.4 0.2 AOT 7/3/2011 7/5/2011 7/7/2011 7/9/2011 7/11/2011 7/13/2011 7/15/2011 7/17/2011 7/19/2011 7/21/2011 7/23/2011 7/25/2011 7/27/2011 7/29/2011 7/31/2011 UTC BLTV_AOT_500 Aeronet DRAGON Level2 AOT Beltsville, MD DC to Baltimore Midpoint, Elevation 54m 50 40 30 20 10 PM2.5_(μg/m 3 ) 7/1/2011 7/3/2011 7/5/2011 7/7/2011 7/9/2011 7/11/2011 7/13/2011 7/15/2011 7/17/2011 7/19/2011 7/21/2011 7/23/2011 7/25/2011 7/27/2011 7/29/2011 7/31/2011 UTC EPA Continuous PM 2.5 Beltsvillle, MD DC to Baltimore Midpoint, Elevation 54m BLTV_PM2_5_July 1.0 0.8 0.6 0.4 0.2 AOT 7/1/2011 7/3/2011 7/5/2011 7/7/2011 7/9/2011 7/11/2011 7/13/2011 7/15/2011 7/17/2011 7/19/2011 7/21/2011 7/23/2011 7/25/2011 7/27/2011 7/29/2011 7/31/2011 UTC AOT_500_WRT Aeronet DRAGON Level2 AOT Worton, MD East of Chesapeake Bay 50 40 30 20 10 PM2.5 (μg/m 3 ) 7/1/2011 7/3/2011 7/5/2011 7/7/2011 7/9/2011 7/11/2011 7/13/2011 7/15/2011 7/17/2011 7/19/2011 7/21/2011 7/23/2011 7/25/2011 7/27/2011 7/29/2011 7/31/2011 UTC EPA Continuous PM 2.5 Worton, MD East of Chesapeake Bay WRT_PM2_5 50 40 30 20 10 PM2.5_(μg/m 3 ) 7/1/2011 7/3/2011 7/5/2011 7/7/2011 7/9/2011 7/11/2011 7/13/2011 7/15/2011 7/17/2011 7/19/2011 7/21/2011 7/23/2011 7/25/2011 7/27/2011 7/29/2011 7/31/2011 UTC EPA Continuous PM 2.5 Baltimore, MD Downtown, Near Inner Harbor, Elevation ~ 8m 'BH_PM2.5_July' 1.0 0.8 0.6 0.4 0.2 AOT 7/3/2011 7/5/2011 7/7/2011 7/9/2011 7/11/2011 7/13/2011 7/15/2011 7/17/2011 7/19/2011 7/21/2011 7/23/2011 7/25/2011 7/27/2011 7/29/2011 7/31/2011 UTC AOT_500_BH Aeronet DRAGON Level2 AOT Baltimore, MD Downtown, Near Inner Harbor, Elevation 16m τ λ = optical depth λ v = digital voltage v 0 = extraterrestrial voltage m = optical air mass λ = wavelength Ɵ = solar zenith angle (eq1) (eq2) http://www.pages.drexel.edu/~brooksdr/DRB_web_page/papers/UsingTheSun/using.htm Fig 1 Fig 2 The size of aerosols can indicate their source and potential behaviors in the atmosphere, and their affects human health.
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Physics and Instrumentation of Atmospheric Aerosol Measurements Across Maryland July 2011
Communicating Scientific Research Methods to High School Physics Students
Acknowledgements This work was supported by the Long-term Engagement in Authentic Research with NASA (LEARN) project with funding provided through a NASA SMD EPOESS grant Dr Margaret Pippin for expertise guidance and inspiration Dr Ali Omar for his inside knowledge of aerosols and their physics and Rebecca Kollmeyer for data retrieval and cleaning services Aeronet and Discover AQ Maryland EPA for sharing data And the best last minute what equation do I use website ever httpasd-wwwlarcnasagovSOLARexperiment-indexhtml
Ellen Babcock McLean WT Woodson High School Fairfax VA
NASA Mentors M Pippin A Omar
What Is This Thing We Call Data The data obtained from NASA and EPA websites are not measured as simply as reading distance from a meter stick or time from a stopwatch
bullThe connection between measurement and data processing is the physics behind the instrumentation Taking the time to understand that connection provides the researcher with a far greater comprehension and appreciation of what that data represents
bullThe quantities measured by remote sensing instrumentation are not the data reported by those instruments Rather the instrumentation has built into it mathematical models or algorithms which translate the raw measurements into useable data
bullThe Aeronet sun photometer column measurement and the EPA surface particulate monitor both provide indirect measurements of aerosol data each using different applications of Beerrsquos Law
What are aerosols Aerosols are tiny particles of solids liquids or gases which become temporarily suspended in the air for varying lengths of time Many particles become airborne through natural means but a significant portion of aerosols especially the smaller ones are anthropogenic caused by Man
In the atmosphere aerosols can
bull Affect visibility bull Form cloud condensation nuclei bull React with other particles forming hazardous compounds bull Scatter or absorb and then re-emit energy from photons bull Contribute to radiative forcing an anthropogenic change in
the radiation budget of the planet
In the biosphere aerosols can cause bull Interference with the processes of plant
respiration and photosynthesis bull cardiovascular disease bull Irregular heartbeat bull Aggravated asthma bull Decreased lung function bull Irritation of the airways bull Coughing bull Difficulty breathing
PM10 are aerosols with diameters less than 10microm Particles such as water sand pollen soil and sea salt are usually generated by natural events and tend to be classified as PM10 They fall from the atmosphere after only a few hours or even minutes giving them less opportunity to interact with the environment
PM25 are aerosols with diameters less than 25microm The majority of anthropogenic aerosols are classified as PM25 Due to their small size they can remain in the air for days weeks or even months giving them increased opportunity to react with other substances in the atmosphere often with deleterious effect PM25 are able to travel deep into the organs and tissues remaining there for long periods of time and causing or exacerbating a host of health issues PM25lsquos longevity and potential for serious harm make it important to study and understand as being largely anthropogenic there are steps that can be taken towards positive change
EPA Continuous PM25 BAM-1020 Continuous Particulate Monitor Beta-ray Attenuation Method
bullAbsorption per unit area is pre-determined during calibration (Fcal)
bullFilter tape is exposed to radiation source bull A semi-conductor detector measures the intensity of beta ray transmission through the clean filter tape (I0)
bullAir at a controlled rate (V) is filtered through the tape allowing PM25 to accumulate for the duration of the measurement (t)
bullThe semi-conductor detector measures the intensity of beta ray transmission through the dirty filter tape (I)
bullThe concentration of PM25 is calculated using the form of Beerrsquos Law below
C = concentration PM25 Fcal = calibration factor (mass density) V = measured mass flow rate t = measurement duration Io = beta ray intensity at pre-exposure filter I = beta ray intensity at exposed filter
Aeronet DRAGON (AOT)
Cimel-318 Automatic Sun Tracking Photometer Spectral extinction of direct beam radiation
Aerosol optical thickness data is calculated by measuring voltage generated within a UV enhanced silicon detector of known surface area
bullThe azimuth of the instrument adjusts automatically to keep the sun within the field of view (FOV in diagram above) and records the solar zenith angle (Ɵ) (Fig2) bullOptical air mass (m) is calculated (equation1) bullSolar radiation passes through the first of two lensesL1(Fig1)
bull A disc housing 8 monochromatic filters is rotated in the path between the two lenses L1 and L2 (Fig1)
bullThe wavelength of light through each filter is recorded (λ) bull The silicon detector measures voltage generated by the incident image (v) bullExtraterrestrial voltage (v0 ) is a calibration term determined using data collected from reference instruments at NOAArsquos Mauna Loa Observatory in Hawaii bullThe Aerosol Optical Thickness is calculated using Beerrsquos Law (equation 2)
httppagesusherbrookecacimelimagesthumb450px-Installationb2_1jpg
httpwwwhussgroupcomgroupeninfocentePMphp
httpwwwepagovttnamti1files2009conferenceHartpdf
References bullCohen Robert A Readings to accompany the Physics of the Atmosphere Physics Department East Stroudsburg University January 18 2011 Version 54 copy2011 by Robert A Cohen retrieved 19 June 2013 from httpwwwesueduphysicscohenphys305textbookreadings54pdf bullHanna Steven R et al Air Pollution McGraw-Hill Encyclopedia of Science amp Technology 10th ed Vol 1 New York McGraw-Hill 2007 292-309 Gale Virtual Reference Library Web 22 June 2013 bullDocument URL httpgogalegroupcompsidoid=GALE7CCX3057500168ampv=21ampu=fair35939eampit=rampp=GVRLampsw=w bullZawar-Reza Peyman Atmospheric Particulates Across Scales Encyclopedia of Geography Ed Barney Warf Vol 1 SAGE Reference 2010 149-151 Gale Virtual Reference Library Web 22 June 2013 bullDocument URL httpgogalegroupcompsidoid=GALE7CCX1788300073ampv=21ampu=fair35939eampit=rampp=GVRLampsw=w bullRollin E M ldquoAn introduction to the use of Sun-photometry for the atmospheric bullcorrection of airborne sensor datardquo NERC EPFS Department of Geography University of Southampton bullSouthampton Electronic version retrieved from httpwwwncaveoacuksite-resourcespdfcimelpdf bullHolben B N et al AERONETmdashA Federated Instrument Network bullData Archive for Aerosol Characterization REMOTE SENS ENVIRON 661-16 (1998) Retreived from httpaeronetgsfcnasagovnew_webPDFafipdf bullBAM-1020 Operators Manual From httpwwwmetonecomaerosoldocsBAM_3-sytem_trainingpdf Atmosphere Encyclopedia of Public Health Ed Morton Lippmann Lester Breslow Vol 1 New York Macmillan Reference USA 2002 88-90 Gale Virtual Reference Library Web 22 June 2013 Document URL httpgogalegroupcompsidoid=GALE7CCX3404000078ampv=21ampu=fair35939eampit=rampp=GVRLampsw=w Aerosols The Gale Encyclopedia of Science 4th ed Vol 1 Detroit Gale 2008 62-65 Gale Virtual Reference Library Web 22 June 2013 bullDocument URL httpgogalegroupcompsidoid=GALE7CCX2830100048ampv=21ampu=fair35939eampit=rampp=GVRLampsw=w bullNASA Discover-AQ website httpwww-airlarcnasagovmissionsdiscover-aqdiscover-aqhtml bullRadiative Forcing Environmental Science In Context Ed Brenda Wilmoth Lerner and K Lee Lerner Vol 2 Detroit Gale 2009 680-682 In Context Series Gale Virtual Reference Library Web 22 June 2013 bullDocument URL httpgogalegroupcompsidoid=GALE7CCX3233900193ampv=21ampu=fair35939eampit=rampp=GVRLampsw=w bullhttpteachingshuacukhwbchemistrytutorialsmolspecbeers1htm
Conclusions bullThe graphed data suggests a strong correlation between the Aeronet and EPA measurements The explanation of the importance of the data the differences between what was actually measured and the similarities between the data processing methods provides non or neo-scientists with more background information and so more understanding of the final product
bullProviding comprehensible details of the instrumentation physics and math of processes of data collection and reporting can make that data more accessible to a wider range of viewers
bullMaking these tangible connections between science and the physical world can be used to teach the real scientific method to high school science students or even seize and hold the attention of a committed climate change skeptic
LEARN The Second Year 1The teacher project will focus on a more detailed analysis of the Aeronet data for
these Maryland sites looking at the speciation distribution sources and consequences of lofted aerosols
2 Physics students will propose or be assigned science fair projects within the scope of the teacher project
3 Remote sensing data retrievals and current research methods will be included as curricular content in the physics classroom
4 Students will learn valuable and marketable skill sets better preparing them for internships and their eventual undergraduate studies
Matched PM25 and AOT Collection Sites
Beerrsquos Law The amount of radiation absorbed or transmitted by a compound in a medium is proportional to the concentration of that compound present in the medium
Site Selection The location of selected EPA and Aeronet DRAGON sites travels the width of the state of Maryland representing four distinct regions
bullWiley Ford a rural area far to the west in the mountains bullBeltsville midway along the highly industrialized traffic corridor between DC and Baltimore oBaltimore Harbor Downtown area around an active seaport bullWorton rural area on the eastern shore of Maryland across the Chesapeake Bay
Google Earth
50
40
30
20
10
0
PM
25
(microg
m3)
732011 752011 772011 792011 7112011 7132011 7152011 7172011 7192011 7212011 7232011 7252011 7272011 7292011 7312011
UTC
PM2_5_WFEPA Continuous PM25 Wiley Ford MD
West of Baltimore Elevation 770m
10
08
06
04
02
AO
T
732011 752011 772011 792011 7112011 7132011 7152011 7172011 7192011 7212011 7232011 7252011 7272011 7292011 7312011
UTC
AOT_500_WFAeronet DRAGON Level2 AOT Wiley Ford MD In the Mountains Elevation ~ 250m
10
08
06
04
02
AO
T
732011 752011 772011 792011 7112011 7132011 7152011 7172011 7192011 7212011 7232011 7252011 7272011 7292011 7312011
UTC
BLTV_AOT_500Aeronet DRAGON Level2 AOT Beltsville MD DC to Baltimore Midpoint Elevation 54m
50
40
30
20
10
PM
25
_(micro
gm
3)
712011 732011 752011 772011 792011 7112011 7132011 7152011 7172011 7192011 7212011 7232011 7252011 7272011 7292011 7312011
UTC
EPA Continuous PM25 Beltsvillle MD
DC to Baltimore Midpoint Elevation 54m BLTV_PM2_5_July
10
08
06
04
02
AO
T
712011 732011 752011 772011 792011 7112011 7132011 7152011 7172011 7192011 7212011 7232011 7252011 7272011 7292011 7312011
UTC
AOT_500_WRTAeronet DRAGON Level2 AOT Worton MD East of Chesapeake Bay
50
40
30
20
10
PM
25
(micro
gm
3)
712011 732011 752011 772011 792011 7112011 7132011 7152011 7172011 7192011 7212011 7232011 7252011 7272011 7292011 7312011
UTC
EPA Continuous PM25 Worton MD
East of Chesapeake Bay
WRT_PM2_5
50
40
30
20
10
PM
25
_(micro
gm
3)
712011 732011 752011 772011 792011 7112011 7132011 7152011 7172011 7192011 7212011 7232011 7252011 7272011 7292011 7312011
UTC
EPA Continuous PM25 Baltimore MD
Downtown Near Inner Harbor Elevation ~ 8m BH_PM25_July
10
08
06
04
02
AO
T
732011 752011 772011 792011 7112011 7132011 7152011 7172011 7192011 7212011 7232011 7252011 7272011 7292011 7312011
UTC
AOT_500_BHAeronet DRAGON Level2 AOT Baltimore MDDowntown Near Inner Harbor Elevation 16m
τλ = optical depth λ v = digital voltage v0 = extraterrestrial voltage m = optical air mass λ = wavelength Ɵ = solar zenith angle
(eq1)
(eq2)
httpwwwpagesdrexeledu~brooksdrDRB_web_pagepapersUsingTheSunusinghtm
Fig 1 Fig 2
The size of aerosols can indicate their source and potential behaviors in the atmosphere
and their affects human health
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