New York City Case Study:New York City Case Study:Methods of AnalysisMethods of Analysis

David J. NowakDavid J. Nowak

USDA Forest ServiceUSDA Forest Service

Northeastern Research StationNortheastern Research Station

Syracuse, NYSyracuse, NY

New York City StudyNew York City Study

Goal: investigate the effects of increased Goal: investigate the effects of increased urban vegetation on biogenic emissions and urban vegetation on biogenic emissions and pollutant concentrations in the New York pollutant concentrations in the New York City area for potential incorporation in State City area for potential incorporation in State Implementation PlansImplementation Plans

New York City Project 2001-2002New York City Project 2001-2002

What is tree cover in NYC domain area?What is tree cover in NYC domain area? What is reasonable cover increase?What is reasonable cover increase? Could a realistic increase in tree cover Could a realistic increase in tree cover

have an impact on ozone?have an impact on ozone?

Cooperative project with NYS DEC and Davey Resource Group

New York City AnalysisNew York City Analysis Analyzed aerial photographs to determine Analyzed aerial photographs to determine

space available for new tree coverspace available for new tree cover– Used digital ortho-quad photographs in Used digital ortho-quad photographs in

conjunction with MRLC land cover mapsconjunction with MRLC land cover maps

Modeled three scenarios:Modeled three scenarios:– Base case (No change to the 975 urban land use Base case (No change to the 975 urban land use

grid cells)grid cells)– RealisticRealistic urban tree cover increase: Convert ~30% urban tree cover increase: Convert ~30%

of the urban grass cover to urban treesof the urban grass cover to urban trees– MaximumMaximum urban tree cover increase: Convert urban tree cover increase: Convert allall

of the urban grass cover to urban treesof the urban grass cover to urban trees

Tree Cover IncreaseTree Cover Increase

Realistic –Realistic – based on discussion with NYS DEC based on discussion with NYS DEC State Forester on reasonable amount of tree cover State Forester on reasonable amount of tree cover that could be increased (10% increase in tree that could be increased (10% increase in tree cover in urban areas – approximately 500 kmcover in urban areas – approximately 500 km22))

Maximum –Maximum – fill all urban grass areas with trees fill all urban grass areas with trees (32% increase in tree cover in urban areas – (32% increase in tree cover in urban areas – approximately 1,600 kmapproximately 1,600 km22))

Modeling SystemModeling System

Meteorology: Meteorology: MM5 (Version 3.4), modified to MM5 (Version 3.4), modified to accommodate 3 urban land use categoriesaccommodate 3 urban land use categories

Anthropogenic emissions: Anthropogenic emissions: EMS-95EMS-95 Biogenic emissions: Biogenic emissions: SMOKE-BEIS2SMOKE-BEIS2 Photochemistry: Photochemistry: MODELS-3/CMAQMODELS-3/CMAQ

4 km horizontal grid size4 km horizontal grid size July 12-15, 1995July 12-15, 1995

Land Surface Parameterizations (MM5)Land Surface Parameterizations (MM5)

ParameterParameterCommercial/ Commercial/

industrial/ industrial/ transportationtransportation

High-density High-density residentialresidential

Low-density Low-density residentialresidential

Shortwave albedo (%)Shortwave albedo (%) 12.912.9 11.811.8 14.514.5

Moisture availability (%)Moisture availability (%) 11.911.9 12.912.9 16.816.8

Longwave emissivity (%)Longwave emissivity (%) 9494 9494 9393

Roughness length (cm)Roughness length (cm) 200200 100100 6060

Thermal inertia (cal cmThermal inertia (cal cm-2-2 KK-1-1 s s-1/2-1/2))

0.0290.029 0.0300.030 0.0320.032

Surface heat capacity (J Surface heat capacity (J mm-3-3 s s-1 -1 ÷ 10÷ 1055))

18.718.7 18.918.9 20.620.6

Change in Urban Tree CoverChange in Urban Tree Cover

MM5 caseMM5 case

Commercial/ Commercial/ industrial/ industrial/

transportationtransportation

High-density High-density residentialresidential

Low-density Low-density residentialresidential

Base case Base case

(T% / G% / I%)(T% / G% / I%) 14 / 34 / 5214 / 34 / 52 25 / 16 / 5925 / 16 / 59 33 / 35 / 3233 / 35 / 32

Realistic case Realistic case

(T% / G% / I%)(T% / G% / I%) 24 / 24 / 5224 / 24 / 52 35 / 6 / 5935 / 6 / 59 43 / 25 / 3243 / 25 / 32

Maximum case Maximum case (T% / G% / I%)(T% / G% / I%) 48 / 0 / 5248 / 0 / 52 41 / 0 / 5941 / 0 / 59 68 / 0 / 3268 / 0 / 32

T%, G%, I% - percent tree, grass, and impervious cover, respectively

Biogenic EmissionsBiogenic Emissions

Emissions changed only a few percentEmissions changed only a few percent

SpeciesSpecies Base case Base case (moles)(moles)

% change, % change, Realistic caseRealistic case

% change, % change, Maximum caseMaximum case

Nitric oxideNitric oxide 8.8 8.8 10 1044 -2.2%-2.2% -7.9%-7.9%

ParaffinsParaffins 6.5 6.5 10 1066 1.1%1.1% 2.1%2.1%

OlefinsOlefins 4.3 4.3 10 1055 1.1%1.1% 2.3%2.3%

AldehydesAldehydes 5.1 5.1 10 1055 1.7%1.7% 4.0%4.0%

IsopreneIsoprene 7.5 7.5 10 1066 0.005%0.005% 0.1%0.1%

Biogenic EmissionBiogenic Emission Except for isoprene, anthropogenic emissions are comparable Except for isoprene, anthropogenic emissions are comparable

to or much larger than biogenic emissionsto or much larger than biogenic emissions

SpeciesSpecies Base case biogenic Base case biogenic emissions (moles)emissions (moles)

Motor vehicle + area Motor vehicle + area emissions (moles)emissions (moles)

Nitric oxideNitric oxide 8.8 8.8 10 1044 8.6 8.6 10 1066

ParaffinsParaffins 6.5 6.5 10 1066 3.3 3.3 10 1077

OlefinsOlefins 4.3 4.3 10 1055 1.0 1.0 10 1066

AldehydesAldehydes 5.1 5.1 10 1055 6.2 6.2 10 1055

IsopreneIsoprene 7.5 7.5 10 1066 1.7 1.7 10 1044

Pollution RemovalPollution Removal

Estimated pollution removal (UFORE model) for Estimated pollution removal (UFORE model) for realistic tree cover increase 500 kmrealistic tree cover increase 500 km22 of new cover; of new cover; 1994 data1994 data

Average 1994 ConditionsAverage 1994 Conditions

Leaf-onLeaf-on Leaf-on dayLeaf-on day t/yr/km2 t/yr/km2 covercoverPollutantPollutant t/yrt/yr t/dayt/day kg/hrkg/hr

COCO 216.9216.9 1.11.1 4848 0.40.4

NONO22 910.4910.4 4.04.0 254254 1.81.8

OO33 2,070.62,070.6 10.210.2 687687 4.14.1

PM10PM10 1,323.81,323.8 5.55.5 240240 2.62.6

SOSO22 447.4447.4 1.91.9 124124 0.90.9

TotalTotal 4,969.14,969.1 22.722.7 1,352.31,352.3 9.89.8

1 hr ozone - Maximum Cover

Domain max. O3 concentration dropped 4.1 ppb

1 hr Ozone – Realistic Cover

Domain max. O3 concentration dropped 4.4 ppb

8 hr Ozone - Maximum Cover

Domain max. O3 concentration dropped 0.8 ppb

8 hr ozone – Realistic Cover

Domain max. O3 concentration dropped 1.0 ppb

New York City Area SummaryNew York City Area Summary

10% increase in urban tree cover 10% increase in urban tree cover – Reduced 1-hour maximum OReduced 1-hour maximum O33 by ~4 ppb (132 ppb to 128 ppb) by ~4 ppb (132 ppb to 128 ppb)– 8-hour maximum O8-hour maximum O33 by ~1 ppb by ~1 ppb– Some increases in OSome increases in O3 3 in the domainin the domain

Little difference in maximum reductions between 10% and Little difference in maximum reductions between 10% and 30% tree cover increase30% tree cover increase

Very significant impactVery significant impact– 3% reduction in peak ozone levels3% reduction in peak ozone levels– 37% reduction in amount needed to gain attainment37% reduction in amount needed to gain attainment

Effects of changes in biogenic emissions were minimal, but Effects of changes in biogenic emissions were minimal, but there is a potential for a slight increasethere is a potential for a slight increase

Additional tree cover will remove thousands of tons of air Additional tree cover will remove thousands of tons of air pollutants per yearpollutants per year

Tree Cover ChangeTree Cover Change

CCTT = C = CBB + C + CNN + C + CGG – C – CMM

CCTT = total canopy cover in model domain in year n = total canopy cover in model domain in year n

CCBB = existing tree cover in base year = existing tree cover in base year

CCNN = canopy increase from new tree planting = canopy increase from new tree planting

CCGG = growth of existing canopy = growth of existing canopy

CCMM = canopy mortality or loss due to natural of = canopy mortality or loss due to natural of human-induced causeshuman-induced causes

Potential Program OptionsPotential Program Options

Tree planting (Tree planting (↑C↑CNN))

Maintenance to promote growth of existing Maintenance to promote growth of existing canopies (canopies (↑C↑CGG))

Protect existing canopy (↓CProtect existing canopy (↓CMM))

– e.g., ordinancese.g., ordinances

Education programs Education programs ((↑C↑CN N ↑C↑CG G ↓C↓CMM))

Public relation campaigns Public relation campaigns ((↑C↑CN N ↑C↑CG G ↓C↓CMM))

Increasing in Tree CoverIncreasing in Tree Cover

Proposed a series of general programsProposed a series of general programs CCNN = Canopy increase from planting = Canopy increase from planting

– 1+ million trees per year for 10 years1+ million trees per year for 10 years Mortality rate has a dramatic effectMortality rate has a dramatic effect May take 30 years to reach cover goalsMay take 30 years to reach cover goals

Cg and CmCg and Cm– Preservation, protection, ordinances, maintenance and Preservation, protection, ordinances, maintenance and

educationeducation

Incorporating Urban Vegetation Incorporating Urban Vegetation within SIPswithin SIPs

1.1. Resource assessmentResource assessment

2.2. Modeling the effect of increasing canopy Modeling the effect of increasing canopy cover on ozonecover on ozone

3.3. Developing reasonable management Developing reasonable management programs that could be used to achieve programs that could be used to achieve modeled changes in canopy covermodeled changes in canopy cover

4.4. Incorporating the modeling results and Incorporating the modeling results and management programs within a SIPmanagement programs within a SIP

1) Resource Assessment1) Resource Assessment

Establish baselineEstablish baseline– Satellite analysesSatellite analyses– Photo interpretationPhoto interpretation– Ground assessments (leaf biomass by species)Ground assessments (leaf biomass by species)– Space available to plant treesSpace available to plant trees

2) Model Tree Effects2) Model Tree Effects

Work with local air quality modelersWork with local air quality modelers Base case vs. future case (change tree Base case vs. future case (change tree

cover)cover) 4 model analyses:4 model analyses:

– Meteorological effects (MM5)Meteorological effects (MM5)– Anthropogenic emission effects (e.g., EMS-95)Anthropogenic emission effects (e.g., EMS-95)– Biogenic emission effects (BEIS)Biogenic emission effects (BEIS)– Integrated model (CAMx), include deposition Integrated model (CAMx), include deposition

change and other model resultschange and other model results

3) Develop Tree Program3) Develop Tree Program

Work with state and local forestry personnelWork with state and local forestry personnel Determine from baseline assessment, Determine from baseline assessment,

reasonable amount that tree cover can be reasonable amount that tree cover can be increased increased

Determine programs that can be Determine programs that can be implemented to reach goalimplemented to reach goal– Tree plantingTree planting– Canopy preservationCanopy preservation– Elimination of mowing (natural regeneration)Elimination of mowing (natural regeneration)– Education and public relationsEducation and public relations

Tree Plan Enforcement and Tree Plan Enforcement and VerificationVerification

Determine how program will be verified to Determine how program will be verified to ensure and verify that it is successfulensure and verify that it is successful

Must verify that program worked, not that Must verify that program worked, not that ozone was reducedozone was reduced– Monitor trees / tree cover vs.Monitor trees / tree cover vs.– Monitor programsMonitor programs

Tree Cover Verification OptionsTree Cover Verification Options

Remote SensingRemote Sensing Program VerificationProgram Verification Ground Truth (counting trees)Ground Truth (counting trees)

4) Incorporate Results in SIP4) Incorporate Results in SIP

Work with state officials to incorporate Work with state officials to incorporate results in SIPresults in SIP

Option:Option:– ““Flexible SIP Approval Policy for Nontraditional Flexible SIP Approval Policy for Nontraditional

Measures”: currently being developed by EPAMeasures”: currently being developed by EPA actions which are voluntary in nature or which have actions which are voluntary in nature or which have

not previously been approved into SIPs because the not previously been approved into SIPs because the actions cannot be quantified as accurately as actions cannot be quantified as accurately as traditional SIP measures due to scientific or technical traditional SIP measures due to scientific or technical issues issues

allows credit to be generated up front allows credit to be generated up front

Flexible SIP Approval Flexible SIP Approval

1.1. develop a protocol, based on best develop a protocol, based on best available science, to quantify emission or available science, to quantify emission or pollutant reductions for the nontraditional pollutant reductions for the nontraditional emission reduction programemission reduction program

2.2. run the program for a period of time and run the program for a period of time and then evaluate the resultsthen evaluate the results

3.3. compare the results with the estimated compare the results with the estimated credit and make up any shortfall, if one is credit and make up any shortfall, if one is foundfound

Issues RemainingIssues Remaining Emissions reductionsEmissions reductions

– But trees emit; VOC / NOx equivalentsBut trees emit; VOC / NOx equivalents

Land Use Change (bigger issue than trees)Land Use Change (bigger issue than trees)– Models currently assume no changeModels currently assume no change– Canopy preservationCanopy preservation

Monitoring / verification / enforcementMonitoring / verification / enforcement– Programs vs. tree coverPrograms vs. tree cover

Ozone Guidance Document on Mitigation Ozone Guidance Document on Mitigation Measures (?)Measures (?)

ConclusionConclusion Increased tree cover will Increased tree cover will

likely lead to ozone likely lead to ozone reductionsreductions

There are methods There are methods available to incorporate available to incorporate results into SIPs, but issues results into SIPs, but issues remainremain

State Forestry and Air State Forestry and Air Quality personnel need to Quality personnel need to work together to address work together to address this issuesthis issues