COLLABORATIVE RESEARCH: GreenTrACS: a Greenland Traverse for Accumulation and Climate Studies

GSTDTAP

项目编号	1417640
	COLLABORATIVE RESEARCH: GreenTrACS: a Greenland Traverse for Accumulation and Climate Studies
	Sean Birkel
主持机构	University of Maine
项目开始年	2015
	2015
项目结束日期	2017-12-31
资助机构	US-NSF
项目类别	Standard Grant
项目经费	169568(USD)
国家	美国
语种	英语
英文摘要	The stability of the Greenland Ice Sheet is of critical interest to scientists and society at large in the context of future sea-level rise. The extent to which the Greenland Ice Sheet will lose mass and contribute to rising sea level in the coming decades depends on the discharge from glaciers at its edges and on the surface mass balance, which is the balance between snow accumulation and surface melt. Estimates of Greenland surface mass balance increasingly utilize climate reanalyses and high-resolution regional climate models to determine snow accumulation, surface melt and runoff/refreeze. These models show significant, and model-dependent, biases (differences from observations) along the steep edges of the Greenland Ice Sheet where the highest and most variable (in space and time) rates of accumulation and surface melt are observed. Thus, the edges of the Greenland Ice Sheet are in critical need of updated accumulation and melt data to validate models and improve mass balance estimates. The investigators propose a traverse in the Western Greenland percolation zone over two field seasons to develop continuous in-situ snow accumulation and firn density records using ground-based radar and shallow firn cores. The research objectives include: (1) determining the patterns, in time and space, of snow accumulation in Western Greenland over the past 20-40 years; (2) evaluating surface melt refreeze and englacial meltwater storage in the Western Greenland percolation zone over the past 20-40 years; and (3) quantifying the accumulation and surface melt biases of the most recent climate reanalysis models and their regional climate model counterparts. This project will advance knowledge and understanding by providing in-situ validation observations for both the mass gain (snow accumulation) and mass loss (surface melt) components of Western Greenland surface mass balance. The western edge of the Greenland Ice Sheet has been losing mass at an accelerating rate since 2005, due mostly to decreasing surface mass balance. However, surface mass balance trends derived from regional climate models differ by a factor of ~2.5 in this region. Western Greenland firn core accumulation records, required for model validation, generally end in 1996-1998, before the most recent period of accelerated mass loss. The investigators will develop continuous records of Western Greenland snow accumulation over the last 20-40 years using ground-penetrating radar validated by frequent snow pits and firn cores (25-30 m) analyzed for chemistry. They also propose to use a multi-offset radar method to calculate continuous firn density data, providing a means to assess past surface melt, refreeze and current meltwater storage in glacier aquifers. Meltwater refreeze shows the largest variability in regional climate models among surface mass balance components, and thus validation observations are critically needed. The traverse route will crisscross the percolation zone, near-parallel to the steepest accumulation and surface melt gradients, which will increase the value of the dataset for model validation. The traverse will overlap previous traverse routes and reoccupy previously sampled sites to update firn core accumulation records by 18-20 years. In addition, the project will collect cores from new sites in data-poor regions at lower elevations, where both accumulation and surface melt increase and regional climate model validation is most needed. Surface mass balance validation of several climate reanalysis models will lead to more accurate assessments of current and future Greenland Ice Sheet mass balance trends, which is critical for accurately predicting future sea-level rise. The project will integrate research with student learning at multiple levels, with an emphasis on the participation of students from underrepresented groups. The project will fund four graduate students, and incorporate numerous undergraduate researchers recruited through successful programs like the Dartmouth Women in Science Project and the Diversity in Undergraduate Geoscience Alliance. K-12 students will be engaged in this project through inquiry-based, web-hosted climate lessons incorporating the University of Maine Climate Reanalyzer and Environmental Change Model, and through field-based programs in the Boise Mountains focused on snow science. The PIs will continue their active public outreach through established and successful programs like the monthly Upper Valley Science Pub and the biannual Snow Day at the Discovery Center of Idaho, in addition to their frequent public presentations and media interviews through their respective Public Affairs offices.
来源学科分类	Geosciences - Polar Programs
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/67412
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Sean Birkel.COLLABORATIVE RESEARCH: GreenTrACS: a Greenland Traverse for Accumulation and Climate Studies.2015.