Validation of Satellite-Retrieved CCN based on a Cruise Campaign over the Northwestern Pacific Ocean

Abstract:

A methodology for retriving CCN in shallow marine boundary layer clouds based on satellite observations has been recently proposed. This methodology is based on retrieving cloud base droplet concentrations (N_d) and updrafts (W_b), which are employed to calculate the supersaturation (S). The N_d is then defined as the CCN activated at that S. Here we validate CCN retrieval base don this method using cruise observation of CCN, which was done in a campaign on the northwest Pacific Ocean in 2014. The satellite retrieved N_d and S at cloud base is compared with the observed CCN spectrum as a function of S at sea surface. The main findings are as follows: (1) Coupled clouds have good agreement between satellite retrievals and ship measurements of CCN by using the brightest 10% of the clouds (the cores of the convective elements); (2) The accuracy of satellite retrieval is significantly improved by temperature correction and adiabatic fraction correction. The validation of satellite retrieval allows us to further quantify the relationships between CCN and cloud microphysical properties and reduce the uncertainty of radiation forcing introduced by aerosol cloud interaction (ACI).