Temporal and spatial variability of Environmental Lapse Rate distribution over Greenland and the central Arctic from 1980 to 2020

In this study, we derived the environmental lapse rate (ELR) with the new European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis data ERA5 that could cover the central Arctic area and an extended period from 1980 to this day. We focus on the Greenland region, where the melting of the Greenland ice sheet plays a vital role in global sea level rise. The temporal and spatial variability of ELR distribution over the Greenland Ice sheet is fully explored in our research and the ELR values distribution over the other central Arctic land area including the Canadian archipelago, high latitude area of North America, and Eurasian are also studied. Our results indicate that ELR values differ dramatically in different seasons and areas, and the commonly used constant ELR −6.5 K/km is not suitable for the Arctic region. The monthly averaged ELR in Greenland shows an annual seasonal cycle with the lowest value is −2.5 K/km in winter. Near-zero ELR occurs in the northeastern marginal part of Greenland for the entire year except summer months. We talked about factors that might cause the near-zero ELR values that occurred over the research area in different seasons and hence research the inversion phenomenon in detail. 

The freshwater forcing that is equivalent to ice loss from Greenland in the real world is too small to affect the AMOC in climate model experiments. The freshwater flux (FWF) is comprised of runoff(liquid) and discharge(solid). To get a real and complete FWF as a freshwater forcing to activate the hosing experiment, the first step is to downscale near-surface temperature to get a higher-resolution runoff. ELR displays how the temperature near the surface varies with altitude and has been used for downscaling the near-surface temperature which will be further used for obtaining runoff. 

Our results could not only provide a reference for future near-surface temperature research and studies about inversion phenomena in different regions, but also depict the temperature vertical changes over the Arctic land area with ELR distribution. This research could provide a useful perspective on the changes in the Arctic cryosphere in recent years and should be helpful for a better understanding of mechanisms and feedback that drive the Arctic and subarctic climate changes.