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Title: Aerosol and cloud microphysics covariability in the northeast Pacific boundary layer estimated with ship-based and satellite remote sensing observations

We utilized ship measurements collected over the northeast Pacific along transects between the port of Los Angeles (33.7°N, 118.2°W) and Honolulu (21.3°N, 157.8°W) during May to August 2013 in order to investigate the covariability between marine low cloud microphysical and aerosol properties. Ship-based retrievals of cloud optical depth (τ) from a Sun photometer and liquid water path (LWP) from a microwave radiometer were combined to derive cloud droplet number concentration N d and compute a cloud-aerosol interaction (ACI) metric defined as ACI CCN=∂ ln(N d)/∂ ln(CCN), with CCN denoting the cloud condensation nuclei concentration measured at 0.4% (CCN 0.4) and 0.3% (CCN 0.3) supersaturation. Analysis of CCN 0.4, accumulation mode aerosol concentration (N a), and extinction coefficient (σ ext) indicates that N a and σ ext can be used as CCN 0.4 proxies for estimating ACI. ACI CCN derived from 10 min averaged N d and CCN 0.4 and CCN 0.3, and CCN 0.4 regressions using N a and σ ext, produce high ACI CCN: near 1.0, that is, a fractional change in aerosols is associated with an equivalent fractional change in Nd. ACI CCN computed in deep boundary layers was small (ACI CCN=0.60), indicating that surface aerosol measurements inadequatelymore » represent the aerosol variability below clouds. Satellite cloud retrievals from MODerate-resolution Imaging Spectroradiometer and GOES-15 data were compared against ship-based retrievals and further analyzed to compute a satellite-based ACI CCN. We found that the satellite data correlated well with their ship-based counterparts with linear correlation coefficients equal to or greater than 0.78. Combined satellite Nd and ship-based CCN 0.4 and Na yielded a maximum ACI CCN=0.88–0.92, a value slightly less than the ship-based ACI CCN, but still consistent with aircraft-based studies in the eastern Pacific.« less
ORCiD logo [1] ; ORCiD logo [2] ; ORCiD logo [3] ; ORCiD logo [4] ; ORCiD logo [5] ; ORCiD logo [6] ; ORCiD logo [7] ; ORCiD logo [8] ; ORCiD logo [3] ; ORCiD logo [9]
  1. Science Systems and Applications, Inc., Hampton VA (United States); NASA Langley Research Center, Hampton, VA (United States)
  2. Univ. of Reading, Reading (United Kingdom). Dept. of Meteorology
  3. NASA Langley Research Center, Hampton, VA (United States)
  4. Science Systems and Applications, Inc., Hampton VA (United States)
  5. McGill Univ., Montreal, QC (Canada). Dept of Atmospheric and Oceanic Sciences
  6. Argonne National Lab. (ANL), Argonne, IL (United States). Environmental Science Division
  7. Univ. of Wisconsin, Madison, WI (United States). Space Science and Engineering Center
  8. Brookhaven National Lab. (BNL), Upton, NY (United States)
  9. Stony Brook Univ., NY (United States). School of Marine and Atmospheric Sciences
Publication Date:
Report Number(s):
Journal ID: ISSN 2169-897X; R&D Project: 2016-BNL-EE630EECA-Budg; KP1701000
Grant/Contract Number:
SC0012704; FOA-0000885; SC0011666; AC02-06CH11357; SC0011675; SC00112704
Accepted Manuscript
Journal Name:
Journal of Geophysical Research: Atmospheres
Additional Journal Information:
Journal Volume: 122; Journal Issue: 4; Journal ID: ISSN 2169-897X
American Geophysical Union
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States); NASA Langley Research Center, Hampton, VA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES; aerosol-cloud interactions; marine boundary layer; remote sensing
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1355765; OSTI ID: 1402399