NCSR Demokritos

Continuous Light Absorption Photometer (GMD_CLAP-3W_HAC)

PI: Dr. Eleftheriadis Konstantinos ( Operators: Dr. Fetfatzis Prodromos (

HAC station instrument (on loan from NOAA ESRL/GML): Continuous Light Absorption Photometer (GMD_CLAP-3W_HAC)

The Continuous Light Absorption Photometer (CLAP) installed at Helmos Mt st. in early July of 2018. This instrument measures the aerosol absorption coefficient of atmospheric PM10 aerosols in dry conditions for three visible wavelengths 461, 522 and 653nm. Data from this measurement is used in radiative forcing calculations, atmospheric heating rates, and as a prediction of the amount of equivalent black carbon in atmospheric aerosol. The CLAP belongs to the family of photometers that measure the transmission of light through a light-diffusing filter while particles are deposited on the filter, and utilizes solenoid valves to cycle through 8 sample filter spots and 2 reference filter spots.