WE PROPOSE TO PROVIDE HIGH-PRECISION IN SITU AEROSOL AND CLOUD PARAMETER MEASUREMENTS ABOARD THE NASA DC-8 AIRCRAFT FOR THE KOREAN-U.S. AIR QUALITY (KORUS-AQ) MISSION AND TO CONDUCT POST-MISSION ANALYSES TO ADDRESS AEROSOL-RELATED MISSION OBJECTIVES. THE EFFORT WILL INCLUDE: 1) PROVIDING HIGH-QUALITY ARCHIVED AEROSOL MICROPHYSICAL AND OPTICAL PROPERTY MEASUREMENTS INCLUDING INFLIGHT REAL-TIME AEROSOL EXTINCTION AND NUMBER DENSITY DATA; 2) OPERATING A COMMON ISOKINETIC INLET PROVIDING MINIMALLY-PERTURBED AEROSOL SAMPLE TO ONBOARD INVESTIGATORS INCLUDING VALUABLE CALIBRATIONS FOR INTER-COMPARISON; 3) COLLABORATING WITH KOREAN SCIENTISTS TO INSTALL AND OPERATE INSTRUMENTS ONBOARD RESEARCH AIRCRAFT; AND 4) LEADING AND CONTRIBUTING TO SCIENTIFIC ANALYSES IN SUPPORT OF KORUS-AQ OBJECTIVES.OUR POST-MISSION DATA ANALYSES ADDRESS QUESTIONS ENUMERATED IN THE KORUS-AQ WHITE PAPER AND WILL INCLUDE: 1) THE IMPACT OF AIR MASS ORIGIN ON COLUMN-INTEGRATED AND PLUME-AVERAGED AEROSOL PARAMETERS TO ENABLE COMPARISONS WITH MODEL AND REMOTE SENSOR DATA PRODUCTS; 2) VALIDATING AEROSOL OPTICAL DEPTHS (AODS) AND AEROSOL-ABSORPTION OPTICAL DEPTHS (AAODS) DERIVED FROM IN SITU AND AERONET OBSERVATIONS TO RESOLVE MODEL DISCREPANCIES; 3) INVESTIGATING THE FACTORS DETERMINING REGIONAL AEROSOL SOLUBILITY AND CCNACTIVITY; AND 4) DOCUMENTING AEROSOL PHYSICOCHEMICAL PROPERTIES BASED ON AIR-MASS ORIGIN AGE AND ACROSS HORIZONTAL GRADIENTS. OUR MEASUREMENTS ARE TAILORED TO ADDRESS HIGH-PRIORITY PROJECT SCIENCE OBJECTIVES AND WILL BE PERFORMED USING FLIGHT-PROVEN INSTRUMENTS. THE PACKAGE INCLUDES MEASUREMENTS OF 1) TOTAL AND NONVOLATILE PARTICLE CONCENTRATIONS; 2) DRY SIZE DISTRIBUTIONS OF 0.010 TO 5 MICRON DIAMETER PARTICLES; 3)SIZE- HUMIDITY- AND WAVELENGTH-DEPENDENT SCATTERING COEFFICIENTS; 4) WAVELENGTH-DEPENDENT TOTAL AND SUBMICRON AEROSOL ABSORPTION COEFFICIENTS; 5) CLOUD CONDENSATION NUCLEI (CCN) NUMBER CONCENTRATION; AND 6) FREE-AIR DUST AEROSOLAND CLOUD PARTICLE SIZE OVER THE 0.5 TO 930 MICRON DIAMETER RANGE.ARCHIVED DATA SETS WILL INCLUDE CALCULATED PARAMETERS SUCH AS ULTRAFINE PARTICLE CONCENTRATION NONVOLATILE FRACTION AEROSOL SURFACE AREA AND VOLUME WAVELENGTH DEPENDENT EXTINCTION COEFFICIENTS SINGLE-SCATTERING ALBEDOS HYGROSCOPICITY (F(RH)) AND ANGSTROM EXPONENTS A 1-SEC RESOLUTION CLOUD FLAG AND LIQUID WATER CONTENT EXTINCTION AND EFFECTIVE RADIUS FOR CLOUD DROPLETS. UPDATES TO THE INSTRUMENT SUITE SINCE ITS DEPLOYMENT ONBOARD THE DC-8 DURING THE SUMMER 2013 SEAC4RS MISSION INCLUDE ADDITION OF A TRICOLOR ABSORPTION PHOTOMETER (TAP) AND A WINGTIP-MOUNTED CLOUD PARTICLE SPECTROMETER WITH POLARIZED DETECTION (CPSPD) THAT WILL PROVIDE COARSE-MODE DUST AND SEA SALT SIZE DISTRIBUTIONS THAT ARE NOT LIMITED BY INLET TRANSMISSION LOSSES AND ENABLE DISCRIMINATIONBASED ON DEPOLARIZATION OF SCATTERED LIGHT. HIGH PRIORITY MEASUREMENTS AND PERTINENT SCIENTIFIC ANALYSES PROPOSED HERE CONTRIBUTE SPECIFICALLY TO ASSESSING THE IMPACTS OF LONG-RANGE TRANSPORT EVALUATING AEROSOL RADIATIVE IMPACTS INVESTIGATING CLOUD-AEROSOL INTERACTIONS AND EVALUATING AEROSOL RETRIEVALS FROM GROUND-BASED AIR- AND SATELLITE-BORNE REMOTE-SENSOR OBSERVATIONS