CNT Parameterization Based on the Observed INP Concentration during Arctic Summer Campaigns in a Marine Environment

Ana Cirisan,Eric Girard,Wanmin Gong,Allan K Bertram,Vickie Irish,Setigui Aboubacar Keita,Jean-Pierre Blanchet

doi:10.3390/atmos11090916

Ana Cirisan, Eric Girard + Show 5 more

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https://doi.org/10.3390/atmos11090916

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Abstract

Aerosol–cloud interactions present a large source of uncertainties in atmospheric and climate models. One of the main challenges to simulate ice clouds is to reproduce the right ice nucleating particle concentration. In this study, we derive a parameterization for immersion freezing according to the classical nucleation theory. Our objective was to constrain this parameterization with observations taken over the Canadian Arctic during the Amundsen summer 2014 and 2016 campaigns. We found a linear dependence of contact angle and temperature. Using this approach, we were able to reproduce the scatter in ice nucleated particle concentrations within a factor 5 of observed values with a small negative bias. This parameterization would be easy to implement in climate and atmospheric models, but its representativeness has to first be validated against other datasets.

Highlights

Cloud processes are among the most difficult challenges to represent reliably in large-scale atmospheric models
In an attempt to narrow down this uncertainty, we propose to parametrize this relation in terms of direct in-situ measurements taken during extensive campaignes by the Canadian Coast Guard Services (CCGS)’s Amundsen research ship during summers 2014 and 2016
The main idea of the parameterization was to derive a representation of the observed ice nucleating particles (INPs) concentration, active in the immersion freezing mode at ambient atmospheric measured temperatures during the field experiment (−15, −20, −22.5 and −25 ◦ C)

Summary

Introduction

Cloud processes are among the most difficult challenges to represent reliably in large-scale atmospheric models. Nucleation strongly depends on aerosol physico-chemical properties which are, to a good extent, a characteristic of regional environment. This study focuses on a cloud scheme representation of ice forming nuclei in the Arctic environment during summer, a specific but poorly studied case in polar regional climate models. The Arctic is the region most affected by climate warming, leading to a decrease in sea ice and land snow cover, altering the regional aerosol composition and sources, which indirectly affect clouds and their properties [1]. Arctic mixed-phase clouds have a large impact on the surface energy budget, more knowledge on the physical and chemical characteristics of ice nucleating particles (INPs) in this region is required

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