Aerosol-Cloud Closure Study using Remotely Piloted Aircraft Measurements during the BACCHUS field campaign in Cyprus
Abstract
During a field campaign in Cyprus within the framework of the EU-FP7 BACCHUS project (Biogenic versus Anthropogenic emissions on Clouds and Climate: towards a Holistic UnderStanding), Remotely Piloted Aircraft System (RPAS), ground-based instruments, and remote-sensing observations were operating simultaneously to provide an integrated atmospheric characterization of aerosol-cloud interactions. A closure study on cloud optical properties is conducted to compare in situ measurements of RPA to simulation results from an Aerosol-Cloud Parcel Model (ACPM). The RPA was equipped with a 5-hole probe, pyranometers, pressure, temperature and humidity sensors, and measured updrafts at cloud base and cloud optical properties of a stratocumulus layer. Ground-based measurements of aerosol size distributions and cloud condensation nuclei, and RPA observations of vertical velocity and meteorological state parameters are used here to initialize the ACPM. Two different simulation cases are studied, including an adiabatic case and an entrainment case in which the in-cloud temperature profile from RPA is taken into account. The profile through the cloud layer of the downwelling pyranometer mounted on the RPA is then compared to simulations from the ACPM, which shows a better agreement with an extinction profile associated with entrainment compared to that of an adiabatic case. Sensitivities of the albedo from the ACPM S=∂ln(albedo)/∂ln(Nd) (Nd is the cloud droplet number) with variation of initial updraft, particle number and profile type (adiabatic or with entrainment) showed a higher value of sensitivity for entrainment ( 0.1) rather than for input parameters ( 0.01). These results highlight the importance of accounting for entrainment in deriving cloud optical properties, as well as the ability of RPAs to leverage ground-based observations for studying aerosol-cloud interactions.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.A43J..04C
- Keywords:
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- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSESDE: 3307 Boundary layer processes;
- ATMOSPHERIC PROCESSESDE: 3311 Clouds and aerosols;
- ATMOSPHERIC PROCESSES