MISSION OVERVIEW AND PLATFORMS: ACTIVATE WILL DEPLOY TWO COMPLEMENTARY AIRCRAFT OVER THE WESTERN NORTH ATLANTIC OCEAN - THE NASA LARC HU-25 FALCON AND B-200 KING AIR. THE HU-25 ACQUIRES IN SITU MEASUREMENTS BELOW IN AND ABOVE CLOUDS. THE B-200 FLIES ABOVE CLOUDS TO REMOTELY MEASURE AEROSOLS AND CLOUDS USING THE HIGH SPECTRAL RESOLUTION LIDAR-2 (HSRL-2) THE RESEARCH SCANNING POLARIMETER (RSP) AND DEPLOYS DROPSONDES TO MEASURE THE ATMOSPHERIC STATE. SINCE BOTH AIRCRAFT AND THE MAJORITY OF IN SITU AND REMOTE SENSING INSTRUMENTS ARE BASED AT LARC ADJACENT TO THE WESTERN ATLANTIC STUDY REGION ACTIVATE WILL ACQUIRE A STATISTICALLY ROBUST DATASET THROUGH AN EXTENSIVE SERIES OF FLIGHTS (~50 JOINT AIRPLANE MISSIONS PER YEAR) IN EACH OF THREE YEARS (~600 HOURS AND ~150 FLIGHTS OVER THREE YEARS FOR EACH AIRPLANE). WE WILL SAMPLE A WIDE RANGE OF AEROSOL AND CLOUD CONDITIONS BY PLANNING FEBRUARY JUNE FLIGHTS. INSTRUMENTS AND MODELS: ALL INSTRUMENTS REQUIRED FOR ACTIVATE SCIENCE OBJECTIVES ARE MATURE (TRL 9); THESE ADVANCED ACTIVE AND PASSIVE REMOTE SENSING AND IN SITU INSTRUMENTS PROVIDE A LOW-RISK HIGH-IMPACT APPROACH FOR BOTH OBTAINING CRITICAL ATMOSPHERIC MEASUREMENTS TO RELATE AEROSOLS CLOUDS AND METEOROLOGY AND IMPROVING MODELS. ACTIVATE ALSO PROVIDES A UNIQUE OPPORTUNITY TO EVALUATE THE ABILITY OF A NEW COMPACT AIRBORNE RADIOMETER TO PROVIDE AN ADDITIONAL CLOUD LIQUID WATER PATH MEASUREMENT. ACTIVATE INCLUDES A SUITE OF MULTI-SCALE MODELS AND A DIVERSE SCIENCE ANALYSIS AND MODELING TEAM WITH BROAD EXPERTISE IN INTEGRATING AIRBORNE AND SATELLITE DATA TO ADVANCE OUR KNOWLEDGE OF AEROSOLCLOUD- METEOROLOGY INTERACTIONS. THE ACTIVATE TEAM BRINGS TOGETHER EXPERTS IN AIRBORNE IN SITU AND REMOTE SENSING MEASUREMENTS AND ANALYSES MODEL DEVELOPMENT SATELLITE RETRIEVALS AND FIELD CAMPAIGN LEADERSHIP.