EPCAPE-PT-LANL Measurements: Humidified Cavity Attenuated Phase Shift Spectroscopy

Coastal cities offer a unique environment for studying aerosol-cloud interactions and the effects of urban emissions on cloud properties. As part of the Eastern Pacific Cloud Aerosol Precipitation Experiment (EPCAPE), the Partitioning Thrust by Los Alamos National Laboratory (EPCAPE-PT-LANL) was conducted. Our campaign focused on measuring the optical and chemical properties of aerosols and their interactions within marine stratocumulus clouds in La Jolla, California. EPCAPE-PT-LANL enhances the primary goals of EPCAPE through innovative observations of vapor-phase transitions between aerosols and cloud droplets, the impact of black carbon on aerosol-cloud dynamics, and the effects of cloud processing on aerosol optical properties. Instrument: Humidified Cavity Attenuated Phase Shift Particulate Matter Single Scattering Albedo (H-CAPS-PMSSA, Aerodyne Inc)Data Notes: The scattering truncation correction was not applied to Bsca. The Bext needs no correction.<strong>Files: data_10sec_CAPS.csv, data_10min_CAPS.csv</strong>Header:- Bext_wet_CAPS_450nm[1/Mm]: Wet aerosol extinction coefficient measured at 450 nm by the CAPS, in inverse megameters (Mm⁻¹).- Bsca_wet_CAPS_450nm[1/Mm]: Wet aerosol scattering coefficient measured at 450 nm by the CAPS, in inverse megameters (Mm⁻¹).- Temp_wet_CAPS[K]: Temperature inside the wet CAPS measurement chamber, in Kelvin.- Bext_dry_CAPS_450nm[1/Mm]: Dry aerosol extinction coefficient measured at 450 nm by the CAPS, in inverse megameters (Mm⁻¹).- Bsca_dry_CAPS_450nm[1/Mm]: Dry aerosol scattering coefficient measured at 450 nm by the CAPS, in inverse megameters (Mm⁻¹).- Temp_dry_CAPS[K]: Temperature inside the dry CAPS measurement chamber, in Kelvin.- Wet_RH_preCAPS[%]: Relative humidity before entering the wet CAPS, in percent.- Wet_RH_postCAPS[%]: Relative humidity after exiting the wet CAPS, in percent.- Humidifier_RH_CAPS[%]: Relative humidity inside the humidifier used with the CAPS, in percent.- dualCAPS_inlet_RH[%]: Relative humidity at the inlet of the dual (wet/dry) CAPS setup, in percent.- Wet_Temp_preCAPS[C]: Temperature before entering the wet CAPS, in degrees Celsius.- Wet_Temp_postCAPS[C]: Temperature after exiting the wet CAPS, in degrees Celsius.- Humidifier_Temp[C]: Temperature inside the humidifier used with the CAPS, in degrees Celsius.- dualCAPS_inlet_Temp[C]: Temperature at the inlet of the dual (wet/dry) CAPS setup, in degrees Celsius.- Zero_dry_CAPS: 1 is a calibration check for the dry CAPS to ensure zero reading under filter air conditions.- Zero_wet_CAPS: 1 is a calibration check for the wet CAPS to ensure zero reading under filter air conditions.- CVI_Flag[bool]: A boolean flag indicating whether the Counterflow Virtual Impactor (CVI) was active (true) or inactive (false) during the measurement.