Exploring Links Between Hydrologic Changes and Land Surface Phenology in Greenland

Abstract:

Over the past two decades warming temperatures over Greenland have caused many changes on land, over its ice-covered areas and in surrounding ocean waters. While previous studies have concentrated on changes to individual systems (e.g. ice cover, ocean, vegetation), fewer have focused on the interactions of multiple systems (e.g. ice-ocean interactions) and very few have focused on how changes in multiple physical systems will affect biology and the Greenlandic population. Although small, Greenland’s vegetated areas are of primary importance to its indigenous population as it supports herbivorous mammals and their importance to livelihood strategies.

This research explores the links between physical and biological systems, investigating how increased melt from the Greenland ice sheet and changes in snow covered area impact vegetation phenology. Using a fifteen-year Normalized Difference Vegetation Index (NDVI) time-series obtained by MODIS, seasonality descriptors are derived for ice sheet sub-basins in western Greenland. The start, end and duration of the growing period, timing of peak NDVI, and primary productivity are generated and used to describe the relationship between vegetation and runoff. In some basins years of high melt coincided with observable differences in the remotely sensed phenology descriptors, however, in other years the relationship is more complex.

Both inter- and intra-regional differences in phenology are characterized. Trends for individual basins are presented along with trends for the whole of western Greenland. Because the relationship between phenological descriptors and high melt years is complex across sub-basins, differences in snow-seasonality and snow accumulation patterns are assessed to better understand the dynamics of these systems.