Precipitation influence on and response to early and late Arctic sea ice melt onset during melt season

The region containing portions of the East Siberian Sea and Laptev Sea (73°–84°N, 90°–155°E) is the area of focus (AOF) for this study. The impacts of precipitation, latent heat (LH) and sensible heat (SH) fluxes on sea ice melt onset in the AOF are investigated. Four early melting years (1990, 2012, 2003, and 1991) and four late melting years (1982, 1983, 1984, and 1996) are compared to better identify the different responses to melt onset timing. A consistency check is performed between multiple Arctic precipitation products (including NASA MERRA-2, ECMWF ERA-Interim [ERA-I], and ECMWF ERA5 reanalyses as well as GPCP V2.3 observations) since there is not yet a high-quality ground-truth Arctic precipitation data product. MERRA-2 has the greatest monthly average precipitation, snowfall, evaporation, and net LH flux. ERA-I suggests that liquid precipitation starts earlier in the year than MERRA-2 and ERA5, while GPCP shows different seasonal precipitation variations from the reanalyses. MERRA-2 has the clearest and most amplified seasonal trends for the parameters used in this study, so the daily time series and anomalies of MERRA-2 variables before and after the first major melt event are investigated. ERA5 is used to check these results because ERA-I and ERA5 display similar seasonal trends. According to MERRA-2, during early melt years, surface SH flux loss and precipitation are above average in the days before and after the first major melt event. During late melt years, surface SH flux loss and precipitation are below average in the month leading up to the first major melt event.