Trends and spatial variation in rain-on-snow events over the Arctic Ocean during the early melt season

Tingfeng Dou,Feng Zhang,Kai Xue,Minghu Ding,Jiping Liu,Shifeng Pan,Cunde Xiao,Hajo Eicken,Jie Su,Peter A Bieniek,Xiaojun Yuan,Qiang Wang

doi:10.5194/tc-15-883-2021

Abstract

Abstract. Rain-on-snow (ROS) events can accelerate the surface ablation of sea ice, thus greatly influencing the ice–albedo feedback. However, the variability of ROS events over the Arctic Ocean is poorly understood due to limited historical station data in this region. In this study early melt season ROS events were investigated based on four widely used reanalysis products (ERA-Interim, JRA-55, MERRA, and ERA5) in conjunction with available observations at Arctic coastal stations. The performance of the reanalysis products in representing the timing of ROS events and the phase change of precipitation was assessed. Our results show that ERA-Interim better represents the onset date of ROS events in spring, and ERA5 better represents the phase change of precipitation associated with ROS events. All reanalyses indicate that ROS event timing has shifted to earlier dates in recent decades (with maximum trends up to −4 to −6 d per decade in some regions in ERA-Interim) and that sea ice melt onset in the Pacific sector and most of the Eurasian marginal seas is correlated with this shift. There has been a clear transition from solid to liquid precipitation, leading to more ROS events in spring, although large discrepancies were found between different reanalysis products. In ERA5, the shift from solid to liquid precipitation phase during the early melt season has directly contributed to a reduction in spring snow depth on sea ice by more than −0.5 cm per decade averaged over the Arctic Ocean since 1980, with the largest contribution (about −2.0 cm per decade) in the Kara–Barents seas and Canadian Arctic Archipelago.

Highlights

IntroductionChanges in the phase of precipitation (solid or liquid) can impact the freeze–thaw processes of cryospheric components (such as sea ice, snow, and permafrost), the hydrological cycle, and terrestrial and marine ecosystems
Changes in the phase of precipitation can impact the freeze–thaw processes of cryospheric components, the hydrological cycle, and terrestrial and marine ecosystems
We assessed the timing of the first ROS events in spring and the fraction of total precipitation occurring as rain over the Arctic Ocean during the initial phase of the melt season in four reanalysis products

Summary

Introduction

Changes in the phase of precipitation (solid or liquid) can impact the freeze–thaw processes of cryospheric components (such as sea ice, snow, and permafrost), the hydrological cycle, and terrestrial and marine ecosystems. With the rapid warming of the Arctic climate, precipitation will increasingly occur in liquid form (Bintanja and Andry, 2017). Liquid precipitation helps the growth and northward expansion of vegetation and promotes the ablation of snow, ice, and permafrost (e.g., Putkonen and Roe, 2003; Rennert et al, 2009; Casson et al, 2010). T. Dou et al.: Trends and spatial variation in rain-on-snow events over the Arctic Ocean in spring can accelerate the thawing of permafrost, which in turn leads to more methane release (Neumann et al, 2019). The snowmelt associated with rain-on-snow (ROS) events can directly lead to a decrease in spring snow water equivalent and have a significant influence on water storage and supply in snowmelt-controlled areas (Birsan et al, 2005; Renard et al, 2008; Jeong et al, 2016)

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