The focus of the EPCAPE 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, the Scripps Pier and the Scripps Mt. Soledad sites in La Jolla, California. The planned data record will start 15 February 2023 and continue until 14 February 2024, with two intensive operation periods (April-June; July-September). Coastal cities provide the opportunity to characterize marine clouds and the substantial effects of manmade particles on cloud properties and processes. 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. 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 at the Mt. Soledad location. The combined observations will provide an unprecedented set of constraints for the following questions:
Each of these questions reflects a topic of current controversy in the literature that cannot be addressed without the type of comprehensive data set that this project is expected to provide.
EPCAPE will locate most of the AMF1 instrumentation at the main site at Scripps Pier and a few additional instruments at the Scripps Mt. Soledad site. Below-cloud instrumentation, including cloud, precipitation, radiation, and aerosol instruments will be situated on the Scripps pier. Additional instrumentation (scanning radar) will be located at the Mt. Soledad site, located less than 2 km inland (250 m above sea level), which will allow for sampling downwind of the pier below, in, and above clouds depending on conditions. Statistics are not available on how frequently the Soledad location is below, in, and above cloud (other than the seasonally limited prior study), as that will be an important outcome of this 12-month data set.
The resources from ARM for this campaign are AMF1, including standard meteorological instrumentation, a broadband and spectral radiometer suite, and remote-sensing measurements including lidars and radars, plus the AOS system for aerosol observations. AMF1 is well suited for this deployment.
Russell will provide filter sampling for organic functional groups (FTIR) and elements (XRF) at the Scripps pier to complement the chemical analysis available from the AMF1 ACSM. This sampling will be housed in an AMF1 AOS van at the pier. Dan Lubin will contribute a shortwave spectroradiometer for measurement of shortwave spectral irradiance between 350 and 1700 nm complements the mid-infrared AERI radiance measurements, in that cloud optical properties (optical depth and effective radius) can be retrieved under thicker clouds that emit in the longwave as blackbodies (with no spectral sensitivity to microphysics). Delphine Farmer will measure particle fluxes at Scripps pier.
UCSD (Russell), UCLA (Suzanne Paulson), and NCSU (Markus Petters) will deploy instruments at Mt. Soledad for in-cloud sampling of detailed aerosol chemical composition, including offline filter analysis. The Mt. Soledad measurements will include aerosol size distributions, SP2, CCN, and aqueous OH radical measurements, as well as a high-resolution, time of flight, event-enabled Aerodyne AMS to provide aerosol composition and concentration for comparison to the AOS ACSM deployed at the pier. Rachel Chang (Dalhousie) plans to deploy the fog droplet monitor at this site to characterize the droplet size distribution in cloud. Environment and Climate Change Canada (John Liggio, Jeremy Wentzell, Michael Wheeler, Alex Lee) is providing a Brechtel ground-based CVI for deployment at the Mt. Soledad site to enable in-cloud composition sampling of droplet residuals. Liggio has support to bring a chemical ionization mass spectrometer, which has previously demonstrated at Mt. Soledad that cloud water chemistry was likely responsible for enhancements in low molecular weight polar organics such as isocyanic (HNCO) and formic acids in cloud droplets, with scavenging efficiencies beyond what can be expected from Henry's Law solubility. Smith will also be measuring ultrafine particles at Mt. Soledad.
Inlet column indicates isokinetic (aerosol), CVI, switched between inlets, or duplicated on both inlets.
|Evaporates cloud droplets and provides residual particles to other instruments||Brechtel Counterflow Virtual Impactor (CVI)||N/A||Michael Wheeler||ECCC|
|Number distribution of particles (0.02-0.9 µm)||Brechtel Differential Mobility Analyzer (DMA)||Switched||Lynn Russell||UCSD|
|CCN number concentration and supersaturation spectra of particles|
for 0.07-0.6% supersaturation
|DMT Cloud Condensation Nuclei (CCN) Counter||Switched||Markus Petters||NCSU|
|CCN number concentration and supersaturation spectra of particles|
for 0.1-1% supersaturation
|Mini Handix CCN (5)||Both||Markus Petters||NCSU|
|Aerosol number distribution (0.15-3 µm)||Printed Optical Particle Spectrometer (POPS)||Switched||Markus Petters||NCSU|
|Number distribution of particles (0.5-10 µm)||TSI Aerodynamic Particle Sizer (APS)||Isokinetic||Markus Russell||NCSU|
|NR organic, sulfate, nitrate, chloride,|
ammonium mass fragment concentrations (0.07-0.8 µm) every 5 min
|Aerodyne High-Resolution Aerosol Mass Spectrometer (HR-AMS) with Event Trigger (ET)||Switched||Lynn Russell||UCSD|
|BC mass and number distribution (0.08-1 µm)||DMT Single-Particle Soot Photometer (SP2)||Switched||Michael Wheeler||ECCC|
|Gas-phase compounds ionized by Iodide||Aerodyne Chemical Ionization Mass Spectrometer (CIMS)||Switched||John Liggio||ECCC|
|Number size distribution of fog (cloud) droplets||Fog Droplet Monitor||N/A||Rachel Chang||Dalhousie|
|BC and aerosol light scattering/absorption coefficients||DMT Photoacoustic Extinctiometer (PAX)||Switched||Alex Lee||ECCC|
|Hydroxyl radical formation by particles using direct-to-liquid sampling and fluorescence||Direct-to-Liquid Cloud Droplet OH Burst (DtL-OH)||Switched||Suzanne Paulson||UCLA|
|Soluble metals by ICPMS and OH burst||Filters for transition metals and OH burst||Switched||Suzanne Paulson||UCLA|
|Chemical composition, hygroscopicity, and volatility of ultrafine particles||TDCIMS, UHPLC-HRMS, and H/VTDMA||Isokinetic||James Smith||UCI|
|Organic functional group and element concentrations||Filters for FTIR and XRF||Both||Lynn Russell||UCSD|
|Aerosol source for sized calibration particles||TSI Atomizer with DMA for size selection||N/A||Lynn Russell||UCSD|
|CO, NO, and NOx concentration||Teledyne CO, NO, NOx||Isokinetic||Lynn Russell||UCSD|
|Temperature, relative humidity, winds, pressure||Weather Station||N/A||Lynn Russell||UCSD|
The Naval Postgraduate School (NPS, formerly CIRPAS) Twin Otter aircraft, led by Mikael Witte, will deploy to San Diego for the Southern California Interactions of Low cloud and Land Aerosol (SCILLA) experiment. Flights will span a four week intensive observational period during June 2023, the month of climatological maximum low cloud cover, and are designed to sample aerosol, microphysics, and meteorological state upwind of the Scripps Pier during the mesoscale eddy events that typically accompany "June gloom" low cloud occurrence at the coast. SCILLA science objectives are to 1) investigate dynamical controls on aerosol transport into, and distribution within, the Southern California Bight; 2) quantify the impact of aerosol-cloud interactions on PBL structure and evolution; and 3) characterize gradients in atmospheric properties across the PBL-capping inversion to constrain vertical mixing/turbulent transport hypotheses. In-cloud sampling of cloud droplet residuals will be performed with a counterflow virtual impactor inlet (Brechtel model 1204 CVI). Finally, the Twin Otter will be equipped to measure surface fluxes over the ocean that can be used to constrain Lagrangian modeling studies of air masses arriving at the ground-based measurement sites.
|Meteorology (T, RH, P, 3-D wind)||Thermistor, chilled mirror hygrometer, P transducers, radome/flow angle probe||Mikael Witte||NPS|
|Dry particle size distribution (0.02<Dp<0.5 µm)||Brechtel SEMS 2100||Andrew Metcalf||Clemson|
|Dry particle size distribution (0.1<Dp<3.0 µm)||PMS PCASP SPP200||Andrew Metcalf||Clemson|
|Dry particle concentration Dp>0.003 µm)||Aerosol Devices MAGIC CPC, TSI UFCPC 3025||Don Collins||UC Riverside|
|CCN concentration||DMT CCN-100 (x2)||Don Collins||UC Riverside|
|Non-refractory aerosol composition||Aerodyne C-ToF-mAMS||Roya Bahreini||UC Riverside|
|Refractory black carbon||DMT SP2||Andrew Metcalf||Clemson|
|Fast gas analyzer (CO2, H2O)||LI-COR 7500DS||Mikael Witte||NPS|
|Trace gases (NOx, O3, CO)||Teledyne-APi T200U, T400; Ecotech EC9830T||Don Collins / Andrew Metcalf||UC Riverside / Clemson|
|Water vapor isotopic analyzer||LGR WVIA-911||Lisa Welp||Purdue|
|Secondary aerosol formation||Oxidation flow reactor with dedicated SMPS||Don Collins||UC Riverside|
|Bulk liquid water content||Gerber PVM-100A||Mikael Witte||NPS|
|Cloud and drizzle drop size distribution (2<Dp<1000 µm)||Artium dual range PDI||Patrick Chuang||UC Santa Cruz|
|Cloud and drizzle drop size distribution (3<Dp<1550 µm)||DMT CAPS (CDP+CIP)||Mikael Witte||NPS|
|Sea surface temperature||Heitronics KT 19.85 pyrometer||Mikael Witte||NPS|
|Down-/upwelling solar irradiance||Kipp & Zonen modified CM22 pyranometer||Mikael Witte||NPS|
|Down-/upwelling infrared irradiance||Kipp & Zonen modified CG4 pyrgeometer||Mikael Witte||NPS|