30 Nov 2021
30 Nov 2021
Status: this preprint is currently under review for the journal ACP.

Assessment of NAAPS-RA performance in Maritime Southeast Asia during CAMP2Ex

Eva-Lou Edwards1, Jeffrey S. Reid2, Peng Xian2, Sharon P. Burton3, Anthony L. Cook3, Ewan C. Crosbie3,4, Marta A. Fenn3,4, Richard A. Ferrare3, Sean W. Freeman5, John W. Hair3, David B. Harper3, Chris A. Hostetler3, Claire E. Robinson3,4, Amy Jo Scarino3,4, Michael A. Shook3, G. Alexander Sokolowsky5, Susan C. van den Heever5, Edward L. Winstead3,4, Sarah Woods6, Luke D. Ziemba3, and Armin Sorooshian1,7 Eva-Lou Edwards et al.
  • 1Department of Chemical and Environmental Engineering, University of Arizona, Tucson, AZ, 85721, USA
  • 2Marine Meteorology Division, U. S. Naval Research Laboratory, Monterey, CA, 93943, USA
  • 3NASA Langley Research Center, Hampton, VA, 23681, USA
  • 4Science Systems and Applications, Inc., Hampton, VA, 23666, USA
  • 5Department of Atmospheric Science, Colorado State University, Fort Collins, CO, 80523, USA
  • 6SPEC Inc., Boulder, CO, 80301, USA
  • 7Department of Hydrology and Atmospheric Sciences, University of Arizona, Tucson, AZ, 85721, USA

Abstract. Monitoring and modeling aerosol particle lifecycle in Southeast Asia (SEA) is challenged by high cloud cover, complex meteorology, and the wide range of aerosol species, sources, and transformations found throughout the region. Satellite observations are limited, and there are few in situ observations of aerosol extinction profiles, aerosol properties, and environmental conditions. Therefore, accurate aerosol model outputs are crucial for the region. This work evaluates the Navy Aerosol Analysis and Prediction System Reanalysis (NAAPS-RA) aerosol optical thickness (AOT) and light extinction products using airborne aerosol and meteorological measurements from the Cloud, Aerosol, and Monsoon Processes Philippines Experiment (CAMP2Ex) in SEA. Modeled AOTs and extinction coefficients were compared to those retrieved with a High Spectral Resolution Lidar (HSRL-2). Correlations were highest for AOT in the mixed layer (AOTML; R2 = 0.83, bias = 0.00, root mean square error [RMSE] = 0.03) compared to total AOT (R2 = 0.68, bias = 0.01, RMSE = 0.14), although the correlations between the observations and 1° × 1° degree NAAPS-RA outputs were weaker in regions with strong gradients in aerosol properties, such as near areas of active convection. Correlations between simulated and retrieved aerosol extinction coefficients were highest from 145–500 m (R2 = 0.75, bias = 0.01 km−1, RMSE = 0.08 km−1) and decreased with increasing altitude (R2 = 0.69 and 0.26, bias = 0.00 and 0.00 km−1, RMSE = 0.09 and 0.00 km−1 for 500–1500 m and > 1500 m, respectively), which was likely a result of the use of bulk cloud mixing parameterizations. We also investigated the role of possible relative humidity (RH) errors in extinction simulations. Despite negative biases in modeled RH (−4.9, −7.7, and −2.3 % for altitudes < 500 m, 500–1500 m, and > 1500 m, respectively), AOT and extinction agreement with the HSRL-2 did not change significantly at any altitude when RHs from dropsondes were substituted into the model. Improvements may have been stunted due to errors in how NAAPS-RA modeled physics of particle hygroscopic growth, dry particle mass concentrations, and/or dry mass extinction efficiencies, especially when combined with AOT corrections from data assimilation. Specifically, the model overestimated the hygroscopicity of (i) smoke particles from biomass burning in the Maritime Continent (MC), and (ii) anthropogenic emissions transported from East Asia. This work provides insight into how certain environmental and microphysical properties influence AOT and extinction simulations, which can then be interpreted in the context of modeling global concentrations of particle mass and cloud condensation nuclei (CCN).

Eva-Lou Edwards et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-870', Anonymous Referee #1, 24 Dec 2021
  • RC2: 'Comment on acp-2021-870', Anonymous Referee #2, 17 Jan 2022

Eva-Lou Edwards et al.

Eva-Lou Edwards et al.


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Short summary
This study compares NAAPS-RA model simulations of aerosol optical thickness and extinction to those retrieved with a High Spectral Resolution Lidar near the Philippines. Correlations for AOT and extinction decreased with altitude and did not change when model errors for relative humidity were corrected. We reveal vulnerabilities in NAAPS-RA that can now be addressed. Accurately modeling future conditions in this region of the world is crucial due to its susceptibility to climate change.