Atmospheric Radiation Measurement Climate Research Facility US Department of Energy

Eastern Pacific Cloud Aerosol Precipitation Experiment

15 February 2023 - 14 February 2024

Lead Scientist: Lynn Russell

Observatory: amf, epc

Coastal cities provide the opportunity to characterize marine clouds and the substantial effects of manmade particles on cloud properties and processes. La Jolla lies to the north of San Diego, California, but it is often about a day downwind of the major pollution sources located in the ports of Los Angeles and Long Beach. The large dynamic range of aerosol particle concentrations combined with the multi-hour to multi-day persistence of stratocumulus cloud layers makes the site ideal for investigating the seasonal changes in cloud and aerosol properties as well as the quantitative relationships between cloud and aerosol properties.

The focus of this project is to characterize the extent, radiative properties, aerosol interactions, and precipitation characteristics of stratocumulus clouds in the Eastern Pacific across all four seasons at a coastal location, such as the Scripps Pier and the Scripps Mt. Soledad sites in La Jolla.  An important enhancement to this study will be the collection of simultaneous in-cloud aerosol and droplet measurements to investigate the differences in these cloud properties during regional polluted and clean marine conditions. The combined observations will provide an unprecedented set of constraints for the following questions:

  1. Cloud and aerosol climatology: What are the seasonal and diurnal cycles of marine stratocumulus cloud and aerosol properties on the northeastern Pacific coast? 
  2. Cloud radiative fluxes: How do cloud properties, including the ratio of direct-to-diffuse radiation, change as coastal clouds are advected inland?
  3. Aerosol-cloud interactions: Will retrieved cloud properties reflect the regional signatures of aerosol?

Each of these questions reflects a topic of current controversy in the literature that cannot be addressed without the type of comprehensive data set proposed here.

The relevance of this campaign to the ARM mission is its strategic location in an accessible and economically important region of the world that lacks long-term observations of its frequent, persistent, and climatically important coastal stratocumulus cloud cover.

The clouds lie in one of the largest regions of upwelling-driven stratocumulus layers that are most likely impacted by aerosol indirect effects, but climate models do not accurately simulate the processes that control their radiative effects. Furthermore, the coastal orography incites significant additional uncertainties related to cloud turbulence, air motion spectrum, and drop size distributions.

Finally, the aerosol in the region ranges from a clean marine background to frequent intrusions from a large and regionally homogeneous, well-characterized, surface‑based pollution source (the Los Angeles-Long Beach urban port megacity), providing a large dynamic range of aerosol conditions for investigation.


Andrew Ackerman Edwin Eloranta Johannes Muelmenstaedt
Allison Aiken Ann Fridlind Markus Petters
Susannah Burrows Dan Lubin Israel Silber
Rachel Chang Mark Miller Die Wang


  • Child Campaign


Giangrande S, J Comstock, S Collis, J Shilling, K Gaustad, K Kehoe, S Xie, and D Zhang. 2022. Translator Plan: A Coordinated Vision for Fiscal Years 2023-2025. Ed. by Robert Stafford, ARM user facility. DOE/SC-ARM-22-003. 10.2172/1893730.

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EPC Data Sources

Name Full Name Browse Data
ACSM Aerosol Chemical Speciation Monitor Browse Data
ACSMCDCE ACSM, corrected for composition-dependent collection efficiency Browse Data
AERI Atmospheric Emitted Radiance Interferometer Browse Data
AETH Aethalometer Browse Data
AOP Aerosol Optical Properties Browse Data
AOS Aerosol Observing System Browse Data
AOSMET Meteorological Measurements associated with the Aerosol Observing System Browse Data
APS Aerodynamic Particle Sizer Browse Data
CAMSITE camera that monitors a site area Browse Data
CEIL Ceilometer Browse Data
CO-ANALYZER Carbon Monoxide Analyzer Browse Data
CPC Condensation Particle Counter Browse Data
CSPHOT Sunphotometer Browse Data
DL Doppler Lidar Browse Data
ECOR Eddy Correlation Flux Measurement System Browse Data
GNDRAD Ground Radiometers on Stand for Upwelling Radiation Browse Data
HTDMA Humidified Tandem Differential Mobility Analyzer Browse Data
INTERPSONDE Interpolated Sonde Browse Data
IRT Infrared Thermometer Browse Data
KASACR Ka-Band Scanning ARM Cloud Radar Browse Data
KAZR Ka ARM Zenith Radar Browse Data
LDIS Laser Disdrometer Browse Data
LDQUANTS Laser Disdrometer Quantities Browse Data
MAWS Automatic Weather Station Browse Data
MET Surface Meteorological Instrumentation Browse Data
MFR Multifilter Radiometer Browse Data
MFRSR Multifilter Rotating Shadowband Radiometer Browse Data
MONITORINST sensors for providing instrument system monitoring Browse Data
MPL Micropulse Lidar Browse Data
MWR Microwave Radiometer Browse Data
MWRHF Microwave Radiometer - High Frequency Browse Data
NEPHELOMETER Nephelometer Browse Data
NFOV Narrow Field of View Zenith Radiometer Browse Data
ORG Optical Rain Gauge Browse Data
OZONE Ozone Monitor Browse Data
PSAP Particle Soot Absorption Photometer Browse Data
RAIN Rain Gauge Browse Data
RWP Radar Wind Profiler Browse Data
SASHE Shortwave Array Spectroradiometer-Hemispheric Browse Data
SASZE Shortwave Array Spectroradiometer-Zenith Browse Data
SEBS Surface Energy Balance System Browse Data
SKYRAD Sky Radiometers on Stand for Downwelling Radiation Browse Data
SMPS Scanning mobility particle sizer Browse Data
SO2 Sulfur Dioxide Monitor Browse Data
SONDE Balloon-Borne Sounding System Browse Data
SONDEGRID Gridded Sonde VAP Product Browse Data
TSI Total Sky Imager Browse Data
UHSAS Ultra-High Sensitivity Aerosol Spectrometer Browse Data
VDIS Video Disdrometer Browse Data
VDISQUANTS Video Disdrometer VAP Browse Data
WB Weighing Bucket Precipitation Gauge Browse Data
WSACR W-band Scanning ARM Cloud Radar Browse Data