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- Title
Vertical Profiles of Aerosol Mass, Number, and Cloud Droplet Number Concentrations: Comparisons of GEOS‐Chem‐APM Simulations With ATom Airborne Measurements and CloudSat Retrievals.
- Authors
Luo, Gan; Yu, Fangqun
- Abstract
A better understanding of vertical distributions of aerosol and cloud droplet number concentrations is important for the study of aerosol‐cloud interaction which is one of the key uncertainties in climate change projection. In this study, we compared the aerosol mass and number concentrations simulated by a size‐resolved advanced particle microphysics (APM) package coupled with a global 3‐D chemical transport model (GEOS‐Chem) with the NASA's Atmospheric Tomography Mission (ATom) measurements at the Pacific Ocean and the Atlantic Ocean during ATom‐1 and ATom‐2 campaign periods. Generally, the model captured the spatial pattern and seasonal variation of aircraft observed aerosol mass and number concentrations. The model simulated cloud droplet number concentrations (CDNC) were compared with CloudSat retrievals whose orbits were nearby ATom's flight tracks on the same days. Correlation coefficients of simulated and retrieved CDNC at ATom‐1 Pacific Ocean, ATom‐1 Atlantic Ocean, ATom‐2 Pacific Ocean, and ATom‐2 Atlantic Ocean are 0.83, 0.97, 0.87, and 0.73, respectively. Both satellite retrievals and model simulations indicated that the averaged values of CDNC at the Pacific Ocean and the Atlantic Ocean during ATom‐1 and ATom‐2 periods decreased with altitudes. The ratio of CDNC in the lower troposphere (1,000–800 hPa) to those in the middle troposphere (600–400 hPa) was 1.9 (1.6–2.3) based on CloudSat retrievals and 2.2 (1.2–3.0) based on the model simulations. Model analysis indicated that secondary particles dominate CDNC in the atmosphere and primary organic aerosols have important contributions to CDNC, especially at the Atlantic Ocean during ATom‐1. Plain Language Summary: Climatic effects of aerosol and cloud are strongly influenced by aerosol vertical distributions. In order to better understand the relationship between aerosols and cloud droplets, measurement and model simulation of vertical distributions of aerosol and cloud droplet number concentrations at the same regions are needed. Although satellite retrieval has been applied to obtain vertical distribution of cloud droplet number concentration, it is challenging to retrieve vertical distribution of aerosol number concentration. In this study, we used ATom aircraft campaign measured aerosol mass and number concentrations and CloudSat retrieved CDNC along orbits nearby ATom's flight tracks to validate the model simulations at the same places during the same periods. Our study indicated that the model can capture the major characteristics shown in aircraft measurements and CloudSat retrievals and could be a useful tool for the estimation of aerosol‐cloud interaction's impacts on climate change. Based on process analysis in the model, we found secondary particles dominate CDNC at the Pacific and Atlantic Oceans during ATom‐1 and ATom‐2 periods and primary organic aerosols, which are associated with transport of open fire, have important contributions to CDNC, especially at the Atlantic Ocean during ATom‐1. Key Points: Using ATom measurements and CloudSat retrievals nearby flight tracks to represent vertical aerosol and droplet numbers at the same placesModel captured major characteristics of vertical distribution of aerosol and droplet shown in aircraft measurements and CloudSat retrievalsSecondary particles dominate CDNC, while open fire organic aerosols contribute remarkably to CDNC over the Atlantic Ocean during ATom‐1
- Subjects
UNITED States. National Aeronautics &; Space Administration; CLOUD droplets; AEROSOLS; ARTIFICIAL satellite tracking; CHEMICAL models; ATOMS; TROPOSPHERIC aerosols; ICE clouds
- Publication
Journal of Geophysical Research. Atmospheres, 2024, Vol 129, Issue 9, p1
- ISSN
2169-897X
- Publication type
Article
- DOI
10.1029/2023JD040386