ABSTRACT
Fine particulate matter (PM1 diameter <1 μm)strongly affects air quality andhealth, with sulfate, nitrate, and ammonium(SNA)asmajorcomponentsacrossEastAsia.Because
NH3 isakeyprecursorofSNAformation, accurateNH3emission dataareessential forreliableSNAsimulations.Thisstudyimproves NH3emissioninventories inEastAsiabyintegratingtheWeather
ResearchandForecastingmodel coupledwithChemistry(WRF Chem) and the Cross-Track Infrared Sounder (CrIS), with extensiveevaluationagainstground-basedandaircraftobservations
fromtheKorea-UnitedStatesAirQuality(KORUS-AQ)campaign. Iterative linear inversion of NH3 emissions usingWRF-Chem markedly enhances simulations of nitrate and ammonium, in
agreementwithboththeaircraftandsurfacemeasurements.Theabsolutebiasesofnitrateandammoniumwerereducedfrom89.7and50.1%to13.6and0.6%,respectively,comparedtotheaircraftobservationsoverSeoul.However,uncertaintiesinnocturnalNH3 emissionsremainpotentialsourcesofnighttimebiasesinnitrateandammonium.Overall, theresultsindicatethatnitrateaerosol in
mostofEastAsia is sensitive toNH3 emissionchanges.ToadvanceourunderstandingofSNAformationandsupport effective
aerosolmitigationpolicies, improvedcharacterizationof thediurnalcycleofNH3emissionsthroughground-basedmonitoringand high-resolutiongeostationarysatelliteobservations isurgentlyneeded.
KEYWORDS: secondary inorganicaerosols, ammonium, nitrate,WRF-Chem,CrIS,NH3