Spring-summer atmospheric circulation and boundary layer processes modulating aerosol and cloud characteristics over the coastal Northeast Pacific during EPCAPE

Chellappan, Seethala; Painemal, David; Thieman, Mandana; Pelayo, Christian; Smith Jr., William L.; Russell, Lynn M.

doi:10.5194/acp-26-15201-2026

Articles | Volume 26, issue 20

https://doi.org/10.5194/acp-26-15201-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/acp-26-15201-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 26, issue 20

Research article

|

29 Oct 2026

Research article |

| 29 Oct 2026

Spring-summer atmospheric circulation and boundary layer processes modulating aerosol and cloud characteristics over the coastal Northeast Pacific during EPCAPE

Seethala Chellappan, David Painemal, Mandana Thieman, Christian Pelayo, William L. Smith Jr., and Lynn M. Russell

Supplement

https://doi.org/10.5194/acp-26-15201-2026-supplement

Data sets

Ceilometer (CEIL10M), 2023-02-15 to 2024-02-14, ARM Mobile Facility (EPC) La Jolla, CA; Supplemental Facility 2 (Mt Soledad lab) (S2) D. Zhang et al. https://doi.org/10.5439/1181954

Active Remote Sensing of Clouds (ARSCL) product using Ka-band ARM Zenith Radars (ARSCLKAZRBND1KOLLIAS), 2023-02-15 to 2024-02-14, ARM Mobile Facility (EPC) La Jolla, CA; AMF1 (main site for EPCAPE on Scripps Pier) (M1) K. Johnson et al. https://doi.org/10.5439/1393437

Atmospheric Radiation Measurement (ARM) user facility: Droplet number concentration (NDROP), 2023-02-15 to 2024-02-14, ARM Mobile Facility (EPC) La Jolla, CA; AMF1 (main site for EPCAPE on Scripps Pier) (M1) D. Zhang https://doi.org/10.5439/1131339

MWR Retrievals with MWRRET Version 2 (MWRRET2TURN), 2023-02-15 to 2024-02-14, ARM Mobile Facility (EPC) La Jolla, CA; AMF1 (main site for EPCAPE on Scripps Pier) (M1) K. Gaustad and D. Zhang https://doi.org/10.5439/1566156

Cloud optical depth retrieved from multi-channel sunphotometer (SPHOTCOD2CHIU), 2023-02-15 to 2024-02-13, ARM Mobile Facility (EPC) La Jolla, CA; AMF1 (main site for EPCAPE on Scripps Pier) (M1) T. Fairless et al. https://doi.org/10.5439/1668057

Merged aerosol particle size distribution for the SMPS and APS instruments J. E. Shilling https://doi.org/10.5439/1871375

Airmass trajectories to support studies using ARM data (ARMTRAJ), 2023-03-01 to 2024-02-13, ARM Mobile Facility (EPC) La Jolla, CA; AMF1 (main site for EPCAPE on Scripps Pier) (M1) I. Silber https://doi.org/10.5439/2309848

Balloon-Borne Sounding System (SONDEWNPN), 2023-02-15 to 2024-02-14, ARM Mobile Facility (EPC) La Jolla, CA; AMF1 (main site for EPCAPE on Scripps Pier) (M1) E. Keeler et al. https://doi.org/10.5439/1595321

Aerosol quantification products at Mt. Soledad and Scripps Pier during EPCAPE 2023-24 V. Z. Berta et al. https://doi.org/10.6075/J0WM1DSC

ERA5 hourly data on single levels from 1940 to present H. Hersbach et al. https://doi.org/10.24381/cds.adbb2d47

Model code and software

MiniSom: Minimalistic and Numpy-Based Implementation of the Self Organizing Map G. Vettigli https://github.com/JustGlowing/minisom/

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Short summary

We analyzed observations from the ARM (Atmospheric Radiation Measurement) EPCAPE (Eastern Pacific Cloud Aerosol Precipitation Experiment) campaign at coastal California, and satellite cloud properties to understand how large-scale weather patterns influence marine low clouds and aerosols. Using ERA5 data and Self-Organizing Maps, we identified nine synoptic regimes linked to cloud cover, depth, and liquid water path. Satellite data show anticyclone position strongly affects cloud properties, while aerosol–cloud covariability depends on turbulence and supersaturation.