Doctoral Dissertation Research: Effects of Sub-Grid Spatial and Temporal Variability on Modeled Evaporation Fluxes in Arctic Coastal Plain Ecosystems

San Diego State University Foundation, San Diego CA

Investigators

Abstract

Evaporation is a key link between the surface energy, carbon and water balances of Arctic tundra ecosystems. Because of the sensitivity of Arctic ecosystems to future change, understanding the links between changes in the surface energy, carbon and water balances are important for predicting the impacts of climate change on the global water, energy and carbon cycles. Given that the evaporation process is acutely non-linear, using time and space averaged inputs in evaporation models may potentially lead to significant errors. It is hypothesized that heterogeneity associated with permafrost dynamics, soil moisture, vegetation (vascular/non-vascular) and the occurrence of free water bodies (lakes) leads to large uncertainties in model estimates of evaporation where time and area averaged inputs are used. This doctoral dissertation research project will investigate the significance of sub-grid spatial and temporal heterogeneity on modeled evaporation estimates at scales ranging from landscape (1 km2) to regions (100 km2) in Arctic Coastal Plain ecosystems. The significance of these effects will be examined within the framework of the BIOME-BGC model adapted to Arctic ecosystems. BIOME-BGC is a widely used ecophysiological process model designed to compute water, carbon and nutrient fluxes at a variety of scales. Data for model inputs, calibration, and validation will be derived from a combination of eddy flux tower, eddy flux aircraft, field, and satellite remotely sensed data. A field based, high resolution, geographic information system map will be developed at each eddy flux tower locations for improving representations of vegetation and soil moisture in model estimates of evaporative fluxes. While improving our understandings of the controls over the evaporation process in Arctic coastal plain ecosystems, this research provides the foundation for adapting a regional model of the energy, carbon, and water cycles to Arctic ecosystems. Arctic ecosystems are of particular importance to global climate change studies due to their sensitivity to temperature change and potential positive feedbacks that may amplify warming across the globe. This study seeks to integrate and synthesize knowledge of evaporation (a key component of the climate system) at multiple scales in order to improve model predictions in Arctic ecosystems. Additionally, this research is expected to increase our knowledge of the complex interactions among the atmosphere, soils, biota, and permafrost in Arctic ecosystems. Finally, results from this study may be used as a basis for developing and implementing a complete carbon, water, and nitrogen model for improving our understanding of the affects of climate change in Arctic tundra regions. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.