Collaborative Research: Assessing the Impact of Arctic Sea Ice Variability on the Greenland Ice Sheet Surface Mass and Energy Balance
This project is funded by NSF
This project will diagnose the role and importance of observed and future Arctic sea ice changes on key components of the GrIS mass balance (surface ablation and accumulation). To perform this task we will use satellite, reanalysis and station data, combined with a state-of-the art regional climate model, MAR [Modèle Atmosphérique Régional, e.g. Fettweis et al., 2011]. With satellite and reanalysis data, we will update and analyze changes in Greenland melt and accumulation, sea ice characteristics, sea surface temperatures (SSTs) and corresponding changes in atmospheric circulation, temperature, sensible and latent heat fluxes, storm activity, including intensity and output during the observational data record. The regional model will be used to explore the sensitivity of the large-scale atmospheric circulation to prescribed sea ice conditions. MAR will also be used to simulate future response of GrIS melt and accumulation to sea ice and ocean conditions simulated by GCMs from the Coupled Model Intercomparison Project Phase 5 (CMIP5). Toward synthesis, we will identify processes and relationships among Greenland melt/accumulation and sea ice variability, via local environmental controls, and large-scale climate forcing. Sub-hypotheses are as follows:
- Large-scale changes and variability in atmospheric circulation, convergence of moisture fluxes, and precipitation, some of which may be associated with expanding open water areas and thinner sea ice, have a first order influence on GrIS surface climate.
- Local-scale changes in ice conditions influence SSTs and conditions in the lower atmosphere that may be advected to influence Greenland surface melt and accumulation.
- In a future climate with stronger seasonal cycle in sea ice extent, the GrIS will exhibit increased sensitivity to atmospheric conditions forced by the surrounding oceans and seas.
Julienne Stroeve (NSIDC), Asa Rennermalm (Rutgers University), and Marco Tedesco (City College of New York)
The Arctic Ocean is rapidly losing its summer sea ice cover. This ice loss has already led to anomalous warming of the overlying atmosphere in autumn. Concurrent with sea ice loss are negative trends in the Greenland ice sheet mass balance, with increased surface melt/ablation and increased glacial discharge rates. These changes are of great socioeconomic concern as continued negative trends in the floating sea ice cover and ice sheet mass loss are likely to have widespread impacts on climate and global sea levels. The simultaneous decreases in sea ice cover and increased melting of the Greenland ice sheet are probably not by chance. On the one hand, it is reasoned that both are largely responding to the same forcing to some degree, such as a generalized warming signal. On the other, it can be hypothesized that sea ice variability, through influences on mixed ocean layer temperatures, overlying air temperatures, column water vapour and atmospheric circulation, influences Greenland ice sheet surface melt and accumulation. Through a combination of data analysis, process studies and modeling, this project will seek to define the interactions between sea ice loss and Greenland ice sheet melt and accumulation. The following major research questions provide a framework for our study: Does sea ice variability influence Greenland ice sheet surface melt? And more precisely, exactly where, when and how does sea ice influence ice sheet surface melt? What is the nature of storm activity around Greenland in the context of ice and ocean conditions and how might changes in the marine environment influence Greenland surface melt and accumulation in the future?
The lack of theoretical understanding at present may largely be due to the lack of a geospatial-temporal analysis framework commensurate for extracting the patterns of covariability and revealing process linkages. Therefore, we propose a targeted geospatial investigation of the hypothesized influence of sea ice on ice sheet melt and accumulation patterns. The investigation will take advantage of up-to-date satellite-sensor data, in combination with several new atmospheric reanalysis data products, station data and a state-of-the art regional climate model, performed by a research team who are specialists in analysis of geospatial and sequential data analysis, satellite remote sensing and hydroclimatology in an Arctic setting.
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