EPCAPE-OPC

Optical Particle Measurements during EPCAPE

12 March 2023 - 14 February 2024

Lead Scientist: Markus Petters

Observatory: AMF

We seek deployment of the DOE-ARM optical particle counter (OPC) at the AMF1 located at the Scripps Pier during EPCAPE. The addition of the OPC is requested for two reasons.

(1) Close the gap between the SMPS and APS size distribution from the AOS measurements. The overlap given by the UHSAS is too limited.

(2) PI Petters has been working with TRACER data to compute particle fluxes. Briefly, backscatter flux is obtained using the eddy-covariance technique using the Doppler vertical velocity and attenuated backscatter. Building upon prior studies, we were able to relate backscatter to particle number concentration by calibrating the lidar retrievals against optical particle counter-measured ground-based aerosol size distribution and radiosonde-interpolated relative humidity at lidar sample height. This analysis would be of great interest to EPCAPE to better understand the emissions and vertical transport of large particles into the overlying stratus clouds. However, as stated above, this analysis uses the OPC and requires an optical size distribution that covers the 0.3-30-μm-diameter size range.