Ice nucleation by viruses and their potential for cloud glaciation

Michael P Adams,Benjamin J Murray,Nina S Atanasova,Jonathan Duplissy,Svetlana Sofieva,Dennis H Bamford,Janne Ravantti,Aino Heikkinen,Zoé Brasseur

doi:10.5194/bg-18-4431-2021

Abstract

Abstract. In order to effectively predict the formation of ice in clouds we need to know which subsets of aerosol particles are effective at nucleating ice, how they are distributed and where they are from. A large proportion of ice-nucleating particles (INPs) in many locations are likely of biological origin, and some INPs are extremely small, being just tens of nanometres in size. The identity and sources of such INPs are not well characterized. Here, we show that several different types of virus particles can nucleate ice, with up to about 1 in 20 million virus particles able to nucleate ice at −20 ∘C. In terms of the impact on cloud glaciation, the ice-nucleating ability (the fraction which are ice nucleation active as a function of temperature) taken together with typical virus particle concentrations in the atmosphere leads to the conclusion that virus particles make a minor contribution to the atmospheric ice-nucleating particle population in the terrestrial-influenced atmosphere. However, they cannot be ruled out as being important in the remote marine atmosphere. It is striking that virus particles have an ice-nucleating activity, and further work should be done to explore other types of viruses for both their ice-nucleating potential and to understand the mechanism by which viruses nucleate ice.

Highlights

The formation of ice in clouds is critically important for the planet’s radiative balance and our prediction of future changes in climate with increased greenhouse gas concentrations (Vergara-Temprado et al, 2018; Tan et al, 2016)
We examined the ice nucleation activity (INA) of 11 viruses with different particle architectures, in an effort to probe the hypothesis that virus architecture/structure influences the ice-nucleating ability of virus particles (Fig. 1)
It is important to note that we based these virus Icenucleating particles (INPs) concentrations on the INA of the specific samples which we studied, and it may be possible that other virus particles have greater INA

Summary

Introduction

The formation of ice in clouds is critically important for the planet’s radiative balance and our prediction of future changes in climate with increased greenhouse gas concentrations (Vergara-Temprado et al, 2018; Tan et al, 2016). Despite the potential importance of INPs, there is still a lack of knowledge regarding their characteristics, sources, and their temporal and spatial distribution around the globe. Our current knowledge of atmospheric INPs (under mixed-phase cloud conditions) suggests a number of potentially important aerosol types, including mineral dust, marine organics and terrestrial bioaerosols (DeMott et al, 2010; Kanji et al, 2017). The characteristics and source regions for mineral dust are relatively better understood than other potentially important INPs, and mineral dust from both high(Sanchez-Marroquin et al, 2020; Tobo et al, 2019) and lowlatitude sources is thought to be the dominant INP around much of the globe at temperatures < −20 ◦C.

Methods

Results

Conclusion