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