Direct Observations of Aerosol Effects on Carbon and Water Cycles Over Different Landscapes

Direct Observations of Aerosol Direct Observations of Aerosol Effects on Carbon and Water Effects on Carbon and Water

Cycles Over Different Cycles Over Different LandscapesLandscapes

Hsin-I ChangHsin-I ChangPh D studentPh D student

Department of Atmospheric SciencesDepartment of Atmospheric SciencesEmail: Email: hchang05@[email protected]

Advisor: Dr. Dev NiyogiAdvisor: Dr. Dev NiyogiDepartment of Atmospheric Sciences/AgronomyDepartment of Atmospheric Sciences/Agronomy

Email: [email protected]: [email protected] UniversityPurdue University

Kiran AlapatyKiran Alapaty, UNC Chapel Hill, currently with National Science Foundation, UNC Chapel Hill, currently with National Science FoundationFitz BookerFitz Booker, USDA/ ARS, Air Quality-Plant Growth and Development Unit, NC, USDA/ ARS, Air Quality-Plant Growth and Development Unit, NCFei ChenFei Chen, National Center for Atmospheric Research, Boulder, National Center for Atmospheric Research, BoulderKen DavisKen Davis, Department of Meteorology, Penn State University, University Park, PA, Department of Meteorology, Penn State University, University Park, PALianhong GuLianhong Gu, Oak Ridge National Laboratory, TN, Oak Ridge National Laboratory, TNBrent HolbenBrent Holben, GSFC, NASA, Greenbelt, MD, GSFC, NASA, Greenbelt, MDTeddy HoltTeddy Holt, N. C. State Univ and Naval Research Laboratory, Monterey, CA, N. C. State Univ and Naval Research Laboratory, Monterey, CATilden MeyersTilden Meyers, ATDD/NOAA, Oak Ridge, TN, ATDD/NOAA, Oak Ridge, TN Walter C. OechelWalter C. Oechel, San Diego State University, San Diego State UniversityRoger A. Pielke Sr.Roger A. Pielke Sr. and and Toshi MatsuiToshi Matsui Colorado State University Colorado State UniversityRandy WellsRandy Wells, Department of Crop Science, N. C. State University, Raleigh, NC , Department of Crop Science, N. C. State University, Raleigh, NC Kell WilsonKell Wilson, ATDD/NOAA, Oak Ridge, TN , ATDD/NOAA, Oak Ridge, TN Yongkang XueYongkang Xue, Department of Geography, UCLA, Los Angeles, CA, Department of Geography, UCLA, Los Angeles, CA

Collaborators:

Outline:Outline:

IntroductionIntroduction

Importance and HypothesisImportance and Hypothesis

Data and MethodologyData and Methodology

Results and Discussion Results and Discussion

Summary Summary

Future WorkFuture Work

Clouds

fG

Surface Absorption-Reflection

fS

fA

fG

Ozone Layer(absorption <320nm)

fS

AerosolsfS

AirPollution

fA

Troposphere

Stratosphere

Incident Radiation Incident Radiation

FATE OF SOLAR RADIATION

- AEROSOLS AFFECT THE RADIATIVE FEEDBACK OF THE ENVIRONMENT

-Majority of the studies have focused on the ‘temperature effects’ =>whether aerosols cause cooling or warming effect in the regional climate.-In this study we propose that:

Aerosols also have a significant biogeochemical feedback on the regional landscapes, and should be considered in both carbon and water cycle studies

Why would aerosols affect biogeochemical pathways?Total solar radiation = (Diffuse + Direct) solar radiation

For increased Cloud Cover or Increased Aerosol Loading,Diffuse Component Increases => changes the DDR (Diffuse to Direct Radiation Ratio)

Hypothesis: Increase in DDR will impact the Terrestrial Carbon and Water Cycles through Transpiration and Photosynthesis changes (Transpiration is the most efficient means of water loss from land surface;Photosynthesis is the dominant mechanism for terrestrial carbon cycle)

Data Data ::Need simultaneous observations of carbon and Need simultaneous observations of carbon and water vapor fluxes, radiation (including DDR), and water vapor fluxes, radiation (including DDR), and aerosol loading. aerosol loading.

Carbon, Water vapor flux and plant information – Carbon, Water vapor flux and plant information – AmerifluxAmeriflux

Radiation (including DDR) information from Ameriflux or Radiation (including DDR) information from Ameriflux or NOAA Surface Radiation (SURFRAD) sites NOAA Surface Radiation (SURFRAD) sites

Aerosol loading information from NASA Aerosol Robotic Aerosol loading information from NASA Aerosol Robotic Network (AERONET) Network (AERONET)

Study sitesStudy sitesSix sites available across the U.S. that have Six sites available across the U.S. that have information on the required variables for our study information on the required variables for our study (AOD,diffuse radiation and latent heat flux).(AOD,diffuse radiation and latent heat flux).

Walker Branch, TN (mixed forest 2000) Barrow, AK

(grassland 99)

Bondville, IL (agriculture, C3 / C4, 98-02)

Willow Creek, WI

Lost Creek, WI

(mixed forest,00,01)

Ponca, OK

(wheat 98,99)

Hypothesis Hypothesis to be testedto be tested from the from the observational analysis :observational analysis :

Increase in the aerosol loading could Increase in the aerosol loading could increaseincrease CO2 and latent heat CO2 and latent heat flux at flux at field scalesfield scales

This would indicate a more vigorous terrestrial carbon cycle because of This would indicate a more vigorous terrestrial carbon cycle because of aerosol interactionsaerosol interactions

This would also indicate potential for changes in the terrestrial water cycle This would also indicate potential for changes in the terrestrial water cycle because of aerosol loadingbecause of aerosol loading

Does DDR Change Cause Changes in the CO2 Does DDR Change Cause Changes in the CO2 Flux at Field Scale?Flux at Field Scale?

Walker Branch Forest Site

-CO2 flux into the vegetation (due to photosynthesis) increases with increasing radiation

-For a given radiation, CO2 flux is larger for higher DDR

Rg-total radiation

Rd-diffuse radiation

negative values indicate CO2 sink (into the vegetation)

Effect of DDR on field scale CO2 FluxEffect of DDR on field scale CO2 Flux

Increase in DDR Increase in DDR appears to increase appears to increase the observed CO2 flux the observed CO2 flux in the field in the field measurements.measurements.

Does DDR Change Does DDR Change Cause Changes in the Cause Changes in the CO2 Flux at Field CO2 Flux at Field Scale?Scale?

Yes!Yes!

Changes in CO2 flux Normalized for changes in global Radiation versus Diffuse Fraction

Do clouds affect CO2 flux at Field Scale?Do clouds affect CO2 flux at Field Scale?

- Yes, clouds appear to affect field scale CO2 fluxes significantly.

-CO2 flux into the vegetation (due to photosynthesis) is larger for cloudy conditions

Do Aerosols affect field scale CO2 Flux?Do Aerosols affect field scale CO2 Flux?

- Increase in AOD (no cloud conditions) causes increase in DDR (diffuse fraction)

- CO2 flux into the vegetation (due to photosynthesis) is larger for higher AOD conditions

- Aerosol loading appears to cause field scale changes in the CO2 flux

ForestsForests

Are these results true for different Are these results true for different landscapes? landscapes?

CroplandsCroplands GrasslandsGrasslands

For Forests and Croplands, aerosol loading has a positive effect on CO2 flux, where there shows a CO2 flux source at Grassland sites.

Hypothesis for LHF-aerosol relation:Hypothesis for LHF-aerosol relation:

At high vegetation LAI (leaf area index): At high vegetation LAI (leaf area index): LHF is mainly due to transpiration;LHF is mainly due to transpiration;

with increasing aerosols,diffuse radiation increases and with increasing aerosols,diffuse radiation increases and air / leaf temperature decreases,air / leaf temperature decreases,

=> => increaseincrease in transpiration and thereby in transpiration and thereby increase LHFincrease LHF

At low vegetation LAI:At low vegetation LAI: LHF is mainly due to evaporationLHF is mainly due to evaporation;;with increasing aerosols,diffuse radiation with increasing aerosols,diffuse radiation increases, and air / leaf temperature decreases,increases, and air / leaf temperature decreases, =>=> reduce reduce the evaporation and therefore the evaporation and therefore LHF LHF decreasesdecreases..

Clustering AOD-LHF relation into different Clustering AOD-LHF relation into different landscapes.landscapes.

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Forest site Cropland Grassland (LHF values opposite in sign)

Latent heat flux appears to generally decrease with increasing Aerosol Optical Depths for most of the studied sites.

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LHF decrease with aerosol loading

High LAI case (LAI >3)

LHF increase with aerosol loading

Walker Branch (Forest site):

Observed data analyses:

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Bondville (soy bean site(C3)):

However, analyzed results vary for different landscapes

For higher LAI, the AOD –ve dependence seems to be decreasing

Summary for water cycle study:Summary for water cycle study:Forest: Forest: - High LAI: LHF increase with AOD - High LAI: LHF increase with AOD

- Low LAI: LHF decrease with AOD - Low LAI: LHF decrease with AOD need to consider Leaf effect for the flux change.need to consider Leaf effect for the flux change.

Corn: LHF decrease with AOD; Leaf area changes have more Corn: LHF decrease with AOD; Leaf area changes have more influence on LHF compare to Air Temperature and Soil Moisture.influence on LHF compare to Air Temperature and Soil Moisture.

Soybean: LHF decrease with AOD; analyses found that Soil Moisture Soybean: LHF decrease with AOD; analyses found that Soil Moisture may have influence on the decreasing trend of Latent Heat Flux- may have influence on the decreasing trend of Latent Heat Flux- without Soil Moisture effect, LHF increase with aerosol loading.without Soil Moisture effect, LHF increase with aerosol loading.

Grassland: LHF increase with AOD; not considering leaf effect. (Soil Grassland: LHF increase with AOD; not considering leaf effect. (Soil Moisture data not available)Moisture data not available)

Conclusions:Conclusions:Aerosols affect land surface processesAerosols affect land surface processes

Results confirmed for different canopy conditions (mixed forests, Results confirmed for different canopy conditions (mixed forests, corns, soybeans, winter wheat and grasslands).corns, soybeans, winter wheat and grasslands).

COCO22 sinksink increases with increasing aerosol loading over increases with increasing aerosol loading over forestsforests and and croplandscroplands (both C3 and C4) (both C3 and C4)COCO22 source source increases with increasing aerosol loading increases with increasing aerosol loading over over grasslandsgrasslands

Water Vapor Flux generally decreases with increasing Water Vapor Flux generally decreases with increasing aerosol loadingaerosol loading

Exceptions were one grassland, and high LAI forest sitesExceptions were one grassland, and high LAI forest sites

Design of experimentsDesign of experimentsDesign configuration: Need to design confounding Design configuration: Need to design confounding Environmental Confounding:Environmental Confounding:(1) crop site: (1) crop site: USDA Raleigh, Purdue AG Center USDA Raleigh, Purdue AG Center (2) forest site: ChEAS (?)(2) forest site: ChEAS (?)Radiation decreases in quantity, changing quality and spectral Radiation decreases in quantity, changing quality and spectral changes and higher DDR.changes and higher DDR.Changes in temperature will change in VPD, Changes in temperature will change in VPD, evaporation/transpiration, soil moisture, emmisivity and albedo, etc.evaporation/transpiration, soil moisture, emmisivity and albedo, etc.Experiments: Experiments: (1) for crops: use high/low diffuse radiation shed; change soil (1) for crops: use high/low diffuse radiation shed; change soil moisture stress and stress from temperature and humidity => moisture stress and stress from temperature and humidity => need need to design special chambers.to design special chambers.(2) for forest: repeat similar experiments for crops and need to (2) for forest: repeat similar experiments for crops and need to examine vertical profiles => examine vertical profiles => responses in different vertical levels responses in different vertical levels may be important. may be important.

Related work:Related work:Analysis for AOD – LHF Analysis for AOD – LHF

effects is still effects is still underway. (need to underway. (need to consider interaction consider interaction terms such as LAI, terms such as LAI, soil moisture)soil moisture)

Leaf and Canopy scale measurements of CO2 and Water Vapor Flux for plants grown under different soil moisture conditions at USDA Facility in Raleigh.

LI6400 CO2 / H2O Flux system

Related work:Related work:

Effect of Diffuse Radiation Effect of Diffuse Radiation (Clouds and Aerosols) on (Clouds and Aerosols) on Plant Scale ResponsePlant Scale Response

Modeling of the plant scale Modeling of the plant scale response for changes in response for changes in Diffuse RadiationDiffuse Radiation

(with Dr. Booker and Dr. (with Dr. Booker and Dr. Wells)Wells)

Potted plants were grown in 2 sheds with different diffuse radiation screens and CO2 / H2O Exchange Measured

Direct and diffuse radiation shedDirect and diffuse radiation shed

Ongoing and Future work:Ongoing and Future work:

Regional Analysis of DDR Changes Regional Analysis of DDR Changes on Latent Heat Fluxes using satellite on Latent Heat Fluxes using satellite (MODIS) dataset.(MODIS) dataset.

Continue on GEM-RAMS Continue on GEM-RAMS Modeling SystemModeling System for isolating the for isolating the effects of different variables in effects of different variables in understanding the aerosol understanding the aerosol feedbacks on the land surface feedbacks on the land surface response.response.

Thank youThank you

Bondville (Bondville (corn site(C4)corn site(C4)):):

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LHF increase with aerosol loading up to certain level.

AOD-LHF relation after accounting for AOD-LHF relation after accounting for both leaf and air temperature effects:both leaf and air temperature effects:

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soy bean sitesoy bean sitecorn sitecorn site

Compare with previous slides, Latent heat fluxes still decrease with aerosol loading without leaf and temperature effects.

Accounting for Soil Moisture effect:Accounting for Soil Moisture effect:

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For both high and low SM conditions, LHF decreases with aerosol loading for agricultural sites (not shown).

With no Soil Moisture effect, Latent Heat Flux increases with aerosol at Soybean site.

Glazing material treatment effects on average Glazing material treatment effects on average photosynthetic photon flux density (PPDF) at upper canopy photosynthetic photon flux density (PPDF) at upper canopy height between 0800-1600 h (EST) during the experimental height between 0800-1600 h (EST) during the experimental period. The ratio of diffuse PPFD radiation to total PPDF period. The ratio of diffuse PPFD radiation to total PPDF radiation is also shown. Values are means ± SE. Values radiation is also shown. Values are means ± SE. Values followed by a different letter were statistically significantly followed by a different letter were statistically significantly different (P ≤ 0.05).different (P ≤ 0.05).

Glazing Material

Parameter Ambient Clear Diffusing

PPFD (µmol m-2 s-1) 958 ± 6 a 840 ± 6 b 755 ± 5 c

Diffuse: Total 0.389 ± 0.002 a 0.415 ± 0.002 b

Soybean biomass and yield responses to growth under Clear and Diffusing Soybean biomass and yield responses to growth under Clear and Diffusing glazing materials (mean ± SE). Plants were harvested for determination of glazing materials (mean ± SE). Plants were harvested for determination of biomass (Biomass) at 88 days after planting (DAP), and for determination of biomass (Biomass) at 88 days after planting (DAP), and for determination of seed yield (Yield) at 153 DAP. Values in parenthesis indicate percent change seed yield (Yield) at 153 DAP. Values in parenthesis indicate percent change from the Clear treatment. Statistics: P ≤ 0.1 (†).from the Clear treatment. Statistics: P ≤ 0.1 (†).

Glazing Material

Harvest Parameter Clear Diffusing

Biomass

Height (cm) 55.6 ± 1.4 56.1 ± 1.4

Branch number (plant-1) 17.3 ± 1.4 18.0 ± 1.4

Leaf dry mass (g plant-1) 45.4 ± 3.0 52.0 ± 3.0

Main stem dry mass (g plant-1) 19.2 ± 1.5 19.8 ± 1.5

Branch dry mass (g plant-1) 51.7 ± 3.9 63.0 ± 3.9 (+22%) †

Pod dry mass (g plant-1) 67.3 ± 8.0 75.4 ± 8.0

Root mass (g plant-1) 30.1 ± 2.6 28.8 ± 2.6

Total dry mass (g plant-1) 213.7 ± 15.2 239.0 ± 15.2

Main stem leaf area (m2 plant-1) 0.19 ± 0.01 0.20 ± 0.01

Branch leaf area (m2 plant-1) 1.21 ± 0.08 1.41 ± 0.08 (+16%) †

Total leaf area (m2 plant-1) 1.40 ± 0.08 1.61 ± 0.08 (+15%) †

Yield

Pod number (plant-1) 397 ± 32 394 ± 32

Seed mass (g plant-1) 173 ± 15 179 ± 15

Mass per seed (g) 0.20 ± 0.01 0.19 ± 0.01

Stem mass (g plant-1) 43 ± 4 49 ± 4

Net photosynthesis (Net photosynthesis (AA) of upper canopy leaves and whole-plants ) of upper canopy leaves and whole-plants treated with either Clear or Diffusing glazing materials (mean ± SE). treated with either Clear or Diffusing glazing materials (mean ± SE). Net photosynthesis of upper canopy leaves on four plants per Net photosynthesis of upper canopy leaves on four plants per treatment was measured weekly between 48 and 105 DAP (seven treatment was measured weekly between 48 and 105 DAP (seven occasions). In addition, whole-plant occasions). In addition, whole-plant AA of three sets of three plants was of three sets of three plants was measured on 56 DAP. Treatment effects on measured on 56 DAP. Treatment effects on AA were not statistically were not statistically significant.significant.

Glazing Material

Clear Diffusing

Upper canopy leaves(µmol m-2 s-1)

28.4 ± 3.3 26.4 ± 2.6

Whole-plant (µmol plant s-1)

14.7 ± 2.3 17.9 ± 0.7