Comment on acp-2021-963

doi:10.5194/acp-2021-963-rc2

Abstract

Abstract. Dust particles from high latitudes have a potentially large local, regional, and global significance to climate and the environment as short-lived climate forcers, air pollutants, and nutrient sources. Identifying the locations of local dust sources and their emission, transport, and deposition processes is important for understanding the multiple impacts of high-latitude dust (HLD) on the Earth's systems. Here, we identify, describe, and quantify the source intensity (SI) values, which show the potential of soil surfaces for dust emission scaled to values 0 to 1 concerning globally best productive sources, using the Global Sand and Dust Storms Source Base Map (G-SDS-SBM). This includes 64 HLD sources in our collection for the northern (Alaska, Canada, Denmark, Greenland, Iceland, Svalbard, Sweden, and Russia) and southern (Antarctica and Patagonia) high latitudes. Activity from most of these HLD sources shows seasonal character. It is estimated that high-latitude land areas with higher (SIââ¥0.5), very high (SIââ¥0.7), and the highest potential (SIââ¥0.9) for dust emission cover >1â670â000âkm2, >560â000âkm2, and >240â000âkm2, respectively. In the Arctic HLD region (â¥60ââN), land area with SIââ¥0.5 is 5.5â% (1â035â059âkm2), area with SIââ¥0.7 is 2.3â% (440â804âkm2), and area with SIââ¥0.9 is 1.1â% (208â701âkm2). Minimum SI values in the northern HLD region are about 3 orders of magnitude smaller, indicating that the dust sources of this region greatly depend on weather conditions. Our spatial dust source distribution analysis modeling results showed evidence supporting a northern HLD belt, defined as the area north of 50ââN, with a âtransitional HLD-source areaâ extending at latitudes 50â58ââN in Eurasia and 50â55ââN in Canada and a âcold HLD-source areaâ including areas north of 60ââN in Eurasia and north of 58ââN in Canada, with currently âno dust sourceâ area between the HLD and low-latitude dust (LLD) dust belt, except for British Columbia. Using the global atmospheric transport model SILAM, we estimated that 1.0â% of the global dust emission originated from the high-latitude regions. About 57â% of the dust deposition in snow- and ice-covered Arctic regions was from HLD sources. In the southern HLD region, soil surface conditions are favorable for dust emission during the whole year. Climate change can cause a decrease in the duration of snow cover, retreat of glaciers, and an increase in drought, heatwave intensity, and frequency, leading to the increasing frequency of topsoil conditions favorable for dust emission, which increases the probability of dust storms. Our study provides a step forward to improve the representation of HLD in models and to monitor, quantify, and assess the environmental and climate significance of HLD.

Highlights

Mineral dust is often associated with hot, subtropical deserts, but importance of dust sources in the cold high latitudes (≥ 50 °N and ≥ 40 °S, including Arctic as a subregion ≥ 60 °N) has recently increased (Arnalds et al, 2016; Bachelder et al, 2020; 65 Boy et al, 2019; Bullard et al, 2016; Cosentino et al, 2020; Gasso and Torres, 2019; Groot Zwaafting et al, 2016, 2017; IPCC, 2019; Kavan et al, 2018, 2020a,b; Ranjbar et al, 2020; Sanchez-Marroqin et al, 2020; Tobo et al, 2019)
Mineral dust is transported from local high latitude dust (HLD) and low latitude dust (LLD) sources to high latitudes (Crocchianti et al, 2021; Groot Zwaafting et al, 2016, 2017; Meinander et al, 2021; Moroni et al, 2018; Varga et al, 2021), where local High Latitude Dust (HLD) dust emissions are increasingly being recognized as a driver for local climate, bio productivity and air quality
We identified 64 new HLD sources and their observations and source characteristics

Summary

Introduction

Mineral dust is often associated with hot, subtropical deserts, but importance of dust sources in the cold high latitudes (≥ 50 °N and ≥ 40 °S, including Arctic as a subregion ≥ 60 °N) has recently increased (Arnalds et al, 2016; Bachelder et al, 2020; 65 Boy et al, 2019; Bullard et al, 2016; Cosentino et al, 2020; Gasso and Torres, 2019; Groot Zwaafting et al, 2016, 2017; IPCC, 2019; Kavan et al, 2018, 2020a,b; Ranjbar et al, 2020; Sanchez-Marroqin et al, 2020; Tobo et al, 2019). Dust produced in high latitude and cold climate environments (Iceland, Greenland, Svalbard, Alaska, Canada, Antarctica, New Zealand, and Patagonia) can have regional and global significance (Bullard et al, 2016). General lack of both observational and modelling studies results in poor HLD monitoring and predicting. Bullard et al (2016) summarized natural HLD sources 85 to cover over 500 000 km and to produce particulate matter of ca. 100 Mt dust per year

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