Improving MISR-retrieved Aerosol Properties Using GOCART Simulations Yang Liu, PhD June 3, 2015 St. Louis, MO

Co-authors Shenshen Li, Emory, now at CAS Ralph Kahn, GSFC and MISR Science Team Mian Chin, GSFC Michael J. Garay, MISR Science Team

Introduction Aerosol model definitions are a key factor in aerosol retrieval Operational retrievals pre- defines aerosol models globally. Better retrievals can be made with local obs, but this requires extensive ground data support CTMs can provide aerosol composition and optical properties at regional–to-global scales with complete coverage Introduction

Research Objective The operational algorithm: MISR EOF algorithm reduces the impact of surface reflectance on aerosol retrieval. Defines 74 mixtures, which are combinations of up to 3 aerosol components (out of 8). Selection of successful mixtures is not constrained by any prior information. Conflicting mixtures can pass its retrieval criteria. Goal: a post-processing technique to refine MISR- retrieved aerosol microphysical properties using GOCART aerosol simulations

Method 3. Recalculate aerosol optical properties with new mixtures 4. Compare updated results with AERONET observations 1. Calculate the ANG and AAOD differences between each successful MISR mixture and GOCART simulations 2. Rank Diffs below a combo of regional thresholds

Datasets  MISR Level 2; Version 22; 17.6x17.6km  AERONET Level 2; AOD 32 sites; AAOD 18 sites  GOCART 1x1.25 degree SO4, BC, OC, dust, sea-salt Domain & period: 2006~2009, Continental U.S. Parameters: AOD, ANG, Absorbing AOD (AAOD)

Selection of the Thresholds

Validation of MISR and GOCART data Comparison with Operational MISR Data

Spatial Patterns - ANG The adj. MISR ANG is similar to GOCART in the west and in spring and summer, and is similar to MISR in the east and in fall and winter Results

Spatial Patterns - AAOD GOCART lacks spatial contrast so our AAOD distribution is similar to MISR but has lower values Results Cont’d

Conclusions A post-processing technology was developed to refine MISR retrieved aerosol properties over land with GOCART simulations. It improved ANG and to a lesser extent AAOD without compromising the quality of AOD This is a proof-of-concept work for improving satellite aerosol retrieval algorithm from the static to dynamical look-up table approach. For details, see Li et al. (2015), Atmos. Meas. Tech. Summary