Disentangling The Causes of Discrepancies In Simulated Immersion-mode
Ice Nucleating Particles
Abstract
We assess the predictability of immersion-mode ice nucleating particles
(INPs) at a remote marine site in the Eastern North Atlantic (ENA) using
aerosol simulations from a global climate model as inputs to the
immersion-mode INP parameterizations. While the model- simulated INP
concentrations are lower by one to three orders of magnitudes compared
to the measurements, we achieve aerosol-INP closure at ENA using the
observed aerosol properties. We demonstrate a novel INP error
decomposition approach to quantify the portion of total INP error from
different error components. We conclude that inaccuracies in aerosols
(surface area and composition) are the dominant cause of the model INP
discrepancy at ENA. We recommend that, for future aerosol-INP closure
studies, along with the measurements for total INP concentrations,
campaigns should also collect co-located aerosol size-resolved
composition measurements (in the INP-relevant size range) to better
distinguish and quantify the error sources.