WE PROPOSE TO COLLABORATIVELY UPDATE THE AEROSOL OBSERVING CAPABILITY OF HIGH-ALTITUDE NASA AIRCRAFT BY BUILDING CALIBRATING AND FLIGHT-TESTING A UTLS AEROSOL MEASUREMENT PACKAGE (UTLS-AMP). THE INSTRUMENTS THAT COMPRISE THE UTLS-AMP ARE AS FOLLOWS: 1. NMASS (BROCK ET AL. 2000) 2. ULTRA-HIGH SENSITIVITY AEROSOL SPECTROMETER (UHSAS; CAI ET AL. 2008)3. PRINTED OPTICAL PARTICLE SPECTROMETER (POPS; GAO ET AL. 2016)4. PASSIVE NEAR-ISOKINETIC INLET (PNII; JONSSON ET AL. 1996). AS PART OF THIS PROPOSED WORK EACH OF THESE INSTRUMENTS WILL BE UPDATED WITH MODERN COMPONENTS MODIFIED TO OPERATE ON AIRCRAFT IN THE UTLS AND FLIGHT-TESTED ON APPROPRIATE AIRCRAFT. THE UHSAS WILL REPLACE THE FCAS INSTRUMENT WHILE A NEWLY-DEVELOPED POPS INSTRUMENT WILL EXTEND THE SIZING RANGE OF THE PACKAGE. THIS WILL ALLOW CHARACTERIZATION OF UTLS PARTICLES FROM 4 TO 3000 NM DIAMETER SPECIFICATIONS THAT DIRECTLY APPLY TO OBSERVATIONS OF NEWLY FORMED PARTICLES TO CONVECTIVELY TRANSPORTED DUST. THE PACKAGE WILL BE FULLY CALIBRATED WITH UPDATED HARDWARE READY TO FACILITATE RAPID RESPONSE TO EVENTS LIKE A VOLCANIC ERUPTION. MOST IMPORTANTLY PROJECT SUCCESS RELIES HEAVILY ON A DIRECT COLLABORATION BETWEEN DR. CHUCK WILSON FROM THE UNIVERSITY OF DENVER AEROSOL GROUP AND THE NASA LANGLEY RESEARCH GROUP (LARGE). THIS INCLUDES SHARING OF DATA REDUCTION ALGORITHMS LABORATORY-CALIBRATION TECHNIQUES UNIQUE TO THE LOW-PRESSURE ENVIRONMENT OF THE UTLS AND THE USE OF A SPECIALIZED AEROSOL INLET (PNII) DESIGNED FOR NASA HIGH-ALTITUDE AIRCRAFT. THE LARGE GROUP HAS A LONG-HISTORY OF AEROSOL MICROPHYSICAL CHEMICAL AND OPTICAL OBSERVATIONS AND WILL CONTINUE THE LEGACY OF UTLS AEROSOL MICROPHYSICAL MEASUREMENTS AFTER PROJECT COMPLETION.