Measurements and Analyses to Enable Science for the Eastern Pacific Cloud Aerosol Precipitation Experiment (EPCAPE)

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, CA, but it is often about a day directly downwind of the major pollution sources located in the ports of Los Angeles and Long Beach. The large dynamic range of aerosol

aerosols

Small particles or droplets, such as wildfire smoke, volcanic gases, or salty sea spray, that float in the air. They are emitted by both natural events and human activities.

Source: NASA Global Climate Change Source

particle concentrations combined with the multi-hour to multi-day persistence of stratocumulus cloud

stratocumulus clouds

Low clouds with irregular masses of clouds, rolling or puffy in appearance, sometimes with space between the clouds.

Source: NASA Source

layers makes the site ideal for investigating the seasonal changes in cloud and aerosol properties as well as the quantitative

quantitative

Data represented numerically, including anything that can be counted, measured, or given a numerical value.

Source: National Library of Medicine Source

relationships between cloud and aerosol properties. The Eastern Pacific Cloud Aerosol Precipitation Experiment (EPCAPE) will take advantage of the coastal location of La Jolla to characterize the extent, radiative properties, aerosol interactions, and precipitation characteristics of stratocumulus clouds in the Eastern Pacific across all four seasons at the Scripps Pier and Mt. Soledad.  The primary observational assets for EPCAPE will be supplied by the Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF1).  The focus of this project is to support and enhance the scientific investigations possible for the EPCAPE AMF1 deployment.

The support we propose to provide is to facilitate involvement of the scientific community in reviewing the results provided by ARM and to add chemical measurements of filters at the Scripps Pier, while supporting collaborative measurements and future proposed uses of EPCAPE measurements. This project supports EPCAPE objectives by compiling and reviewing measurements of cloud and aerosol properties to address the question: What are the seasonal and diurnal cycles of marine stratocumulus cloud

marine stratocumulus cloud

Marine stratocumulus clouds (MSCs) typically lie at low-altitudes below 6,000 feet, covering about 20 percent of the low-latitude oceans, or 6.5 percent of the Earth’s surface.

Source: NOAA Source

and aerosol properties on the northeastern Pacific coast? This question is an important prerequisite to understanding aerosol-cloud interactions

aerosol-cloud interaction

The interaction of airborne particles (aerosols) with clouds. Scientists study how aerosols affect clouds and how these interactions can impact the Earth's climate.

Source: DOE Source

(ACI), providing the need for such analyses to enable science. In addition, we will enhance the aerosol measurements at the Scripps Pier by providing organic and elemental filter analyses for chemical tracers to supplement the non-refractory chemical measurements provided by the AMF1 Aerosol Observing System (AOS).

The relevance of EPCAPE to the DOE 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 likely most impacted by aerosol indirect effects, but climate models do not accurately simulate the processes that control their radiative effects. The coastal orography produces 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 sources (the Los Angeles-Long Beach urban port megacity), providing a large dynamic range of aerosol conditions for investigation. This project is relevant to the DOE mission because it will enable improved and expanded scientific studies from the EPCAPE measurements.