Improvement of Air Quality ModelingImprovement of Air Quality Modelingin Hong Kongin Hong Kongby Using MM5 Coupled with LSMby Using MM5 Coupled with LSMHuang J.P., Fung J.C.H.,Huang J.P., Fung J.C.H.,Zhang Y.,Zhang Y.,Lau A.K.H., Kwok R. and Lo J.F.L.Lau A.K.H., Kwok R. and Lo J.F.L.Hong Kong University of Science and TechnologyHong Kong University of Science and TechnologyNorth Carolina State UniversityNorth Carolina State UniversityzThe objective of this research is to betterunderstand and predict the atmospheric flow(in particular, within the Planetary BoundaryLayer ~ 1 to 2 km) and air quality over HK andthe Pearl River Delta.zDifferentdispersion models (SAQM andCMAQ)has been used in this study.ObjectiveFeatures of Pearl River Delta (PRD)Features of Pearl River Delta (PRD)From HKSAR Planning DepartmentHong KongHong KongShen ZhenShen ZhenGuang ZhouGuang ZhouMacauzLocated in Southern Chinaz41,700 km2in size,50 million in populationzMajor cities: Hong Kong, Shen Zhen, Guang Zhou and Macau, etc.zRapid economic and industrial growth;high air pollution potentialMeteorological Features of PRDMeteorological Features of PRDzComplex terrain, coastal, and land-use characteristicszSub-tropic climate–Synoptic scale: Meiyu, Typhoon, Monsoon–Local scale: Land-sea breeze, Urban heat island effectMonthly number of days with ( Visibility reporting < 8km & RH < 80% )

Days / monthVisibility Report (11/1976–6/2004)YearAerosol Optical Depth -Column sum of aerosol concentrationHigh concentrationLow concentrationNumber of nonNumber of non-compliance ofcompliance ofhourly AQO (hourly AQO (red)(from HKEPD, 2004)(from HKEPD, 2004)Yuen LongYuen LongO3problemproblemTsuenWanShamShuiPoTungChungCentral/WesternCentral/WesternShaTinTapMunO3problem in HK: episodesproblem in HK: episodesmajor contributors to air pollution episodes:major contributors to air pollution episodes:O3, NO2and RSPand RSPO3: the biggest contributor: the biggest contributorSea breeze circulationSea breeze circulationLand-sea breeze circulation cells in PRDsea breeze circulation cells in PRDMeteorological ModelCreate Physical AtmosphereSolve full set of atmosphericequations for evolution of wind,temperature, pressure and moisturecontent, etc.(MM5 v3.6)Atmospheric Chemistry ModelChemical reactions of various chemical speciesand solve the advection-diffusion equations(SAQM)Emissions ModelAnthropogenic, Natural(EMS95)PATH Model SystemPATHPollutants in theollutants in theAtmosphere and theirtmosphere and theirTransport overransport overHong Kongong Kong(HKEPD, 1997)(HKEPD, 1997)Domain cDomain configurations ofonfigurations ofMM5&SAQM26 sigma levels (mm5)15 sigma levels (SAQM)MM5 Model ConfigurationsMM5 Model Configurations40.5km, 13.5km4.5km, 1.5kmCumulusGrellNonePBLMRFMRFMoistureSimple iceSimple iceRadiationRRTMRRTM3⁄4MM5 v3.63⁄44 nested Domains:3⁄440.5 km (115x75), 13.5km (85x73) , 4.5km (85x73) and 1.5km (61x55)3⁄42-ways nesting3⁄426 full sigma levels (~10 levels below 1km)3⁄4Physical parameterization schemes(for the unresolved scales)MM5 Model Configurations(continued)3⁄4Up-to-date fine resolution land use(as fine as 30 m) is applied to Hong Kongand PRD (i.e. both D3 and D4)3⁄4Initial and Boundary ConditionsNCEP Global Final Analyses (1ox1o)(http://dss.ucar.edu/datasets/ds083.2)Rapid development over PRD during the past ten yearsRapid development over PRD during the past ten years1993200419932004Land usemap2003 Landuse1994 USGSPercentage of each land-use classification in theinnermost domain:Urban area:increase from 0.5% to 12.9%Cropland:decrease from 45.6% to 22.7%Land Surface Model (LSM)Land Surface Model (LSM)NOAH community land-surface soil hydrology module,which was jointly developed by the3⁄4National Centers for Environmental Prediction (NCEP)3⁄4Oregon State University3⁄4the U.S. Air Force3⁄4the Office of HydrologyCoupled mode; the scheme is fully interactive with MM5MM5 simulations of surface radiation, precipitation, andnear-surface winds, humidity, and temperature providethe external forcing for the land surfaceThe Noah-LSM provides surface sensible heat flux, latentheat flux and skin temperature as lower boundarycondition to MM5Heat and moisture fluxes are then process by PBLscheme and transported to the atmosphere.Refinements in NoahRefinements in Noah-LSM experimentsLSM experimentsGreen vegetation fraction definition3⁄4Problems caused by interpolating the 18km AVHRR data into our innerdomains (4.5km, 1.5km)3⁄4Landuse based green vegetation is used in the inner domains3⁄4PRD located in subtropics, seasonal variation is very smallLanduse based18km AVHRRSea value = 0Refinements in NoahRefinements in Noah-LSM experimentsLSM experiments1.Up-to-date landuse map for PRD2.Better green vegetation fraction in inner domains3.Enhancements of urban landuse treatment inNoah-LSM3⁄4Simply modifying the values of physical parameters forurban landuse – albedo, roughness length, soil thermalproperties and evaporation4.Modification of MRF PBL scheme3⁄4Better methods for computation of free convectionturbulence, PBL height and surface heat flux(Liu Y., F. Chen, T. Warner, S. Swerdlin, J. Bowers, and S. Halvorson, 2004)1994 Land-use2003 Land-use2003 Land-use2003 Land-useSurface Observationbackground easterly windsea breezeRefined LSMDefault MM5Surface wind verificationvalid at 2003/10/31 2pmInitial time: 2003/10/30 8am30 hrs forecastComparison of velocityComparison of velocityTCTCTMTMMM5-STDMM5-LSMResultsResultsUrban heat islandSurface Temperature from MODIS20031031 2am (mid-night)HKGuangZhou8:00pm2:00amTemperature variant: T - mean(T)Surface Temperature from MODIS20031031 2am (mid-night)NEW8:00pm2:00amTemperature variant: T - mean(T)Surface Temperature from MODIS20031031 2am (mid-night)OLDTemperature Profiles ComparisonTemperature Profiles ComparisonSurface streamline patternSurface streamline patternSurface streamline patternSurface streamline patternSurface streamline patternSurface streamline patternDay 1, Day 2, Day 3, Day 41993 landuseDay 1, Day 2, Day 3, Day 42004 landuseMeteorological ModelCreate Physical AtmosphereSolve full set of atmosphericequations for evolution of wind,temperature, pressure and moisturecontent, etc.(MM5 v3.6)Atmospheric Chemistry ModelChemical reactions of various chemical speciesand solve the advection-diffusion equations(SAQM)Emissions ModelAnthropogenic, Natural(EMS95)PATH Model SystemIntroduction of PATH: EMSIntroduction of PATH: EMS-95EMS-95:The US Emission Modeling System (1995, version)3⁄4Point sources(power plants and industrial sources)3⁄4Mobile sources(road vehicles, railways and aircrafts)3⁄4Area sources(domestic and commercial fuel combustion)3⁄4Shipping sources(marine traffics)3⁄4Biogenic sources(vegetation)Typical ground level emission rates inPRDNOxVOCVOCVOCNOxTypical ground level emission rates inHKVOCMeteorological ModelCreate Physical AtmosphereSolve full set of atmosphericequations for evolution of wind,temperature, pressure and moisturecontent, etc.(MM5 v3.6)Atmospheric Chemistry ModelChemical reactions of various chemical speciesand solve the advection-diffusion equations(SAQM)Emissions ModelAnthropogenic, Natural(EMS95)PATH Model SystemSAQM Model Configurations3⁄4SAQM:theSARMAPAirQualityModel (Chang, 1997),modified for its application to PATH in HK;3⁄44-nested domains: 40.5, 13.5, 4.5, 1.5 km with 49x49 gridcells for each domain;3⁄4CB-IVchemical mechanismis used;diffusion:horizontal-briggs; vertical-eddies;horizontal advection: 4thorder Botts scheme;3⁄478thermal-kinetic reactions,11photolytic reactions,56reactive species,31output species (15 for gas and 16 for particle matters).An O3episode:episode:(22-24 October 2003)24 October 2003)Model resultsModel resultsSAQM simulation: standard MM5SAQM simulation: MM5-LSMCMAQ simulation: standard MM5CMAQ simulation: MM5-LSMSummary and ConclusionSummary and ConclusionThe simulations of MM5 with NOAH LSM show abetter agreement with meteorological observationssuch as surface winds and temperature profiles below850 hpa, etc., than those of MM5-STD, in comparisonwith observations;The surface ozone simulations have been improved interms of the peak ozone and spatial patterns whenMM5/NOAH LSM is used to generate meteorologicalfields for air quality models;However, the impact of MM5/NOAH LSM on PMmodeling is still under investigation.AcknowledgementsAcknowledgementsThank the Hong Kong EnvironmentProtection Department for the provisionof PATH model and air quality data, andthe Hong Kong Observatory for provisionof meteorological data.