Analyzing pan-Arctic 1982–2006trends in temperature andbioclimatological indicators (productivity, phenology and vegetation indices) using remotesensing, model and field data

Remote sensing;Pan-Arctic vegetation;Net primary productivity;Phenology;Impacts of Arctic warming;Climate change;Geography

Luus, Kristina

University of Waterloo

关键词: Remote sensing;    Pan-Arctic vegetation;    Net primary productivity;    Phenology;    Impacts of Arctic warming;    Climate change;    Geography;   

Others  :  https://uwspace.uwaterloo.ca/bitstream/10012/4656/1/luusMscFINAL.pdf

瑞士|英语

来源: UWSPACE Waterloo Institutional Repository

【 摘 要 】

Warming induced changes in Arctic vegetation have to date been studied throughobservational and experimental field studies, leaving significant uncertainty aboutthe representativeness of selected field sites as well as how these field scale findingsscale up to the entire pan-Arctic. The purposes of this thesis were therefore to1) analyze remotely-sensed/modeled temperature, Normalized Difference Vegeta-tion Indices (NDVI) and plant Net Primary Productivity (NPP) to assess coarse-scale changes (1982–2006) in vegetation; and 2) compare field, remote sensing andmodel outputs to estimate limitations, challenges and disagreements between dataformats. The following data sources were used:• Advanced Very High Resolution Radiometer Polar Pathfinder Extended (APP-x, temperature & albedo)• Moderate Resolution Imaging Spectroradiometer (MODIS, Normalized Dif-ference Vegetation Index (NDVI) & Enhanced Vegetation Index (EVI) )• Landsat Enhanced Thematic Mapper (Landsat ETM, NDVI)• Global Inventory Modeling and Mapping Studies (GIMMS, NDVI)• Global Productivity Efficiency Model (GloPEM, Net Primary Productivity(NPP))Over the pan-Arctic (1982-2007), increases in temperature, total annual NPP andmaximum annual NDVI were observed. Increases in NDVI and NPP were found tobe closely related to increases in temperature according to non-parametric Sen’slope and Mann Kendall tau tests. Variations in phenology were largely non-significant but related to increases in growing season temperature.Snow melt onset and spring onset correspond closely. MODIS, Landsat andGIMMS NDVI data sets agree well, and MODIS EVI and NDVI are very similarfor spring and summer at Fosheim Peninsula. GloPEM NPP and field estimatesof NPP are poorly correlated, whereas GIMMS NDVI and GloPEM NPP are wellcorrelated, indicating a need for better calibration of model NPP to field data.In summary, increases in pan-Arctic biological productivity indicators were ob-served, and were found to be closely related to recent circumpolar warming. How-ever, these changes appear to be focused in regions from which recent field studieshave found significant ecological changes (Alaska), and coarse resolution remotesensing estimates of ecological changes have been less marked in other regions. Dis-crepancies between results from model, field data and remote sensing, as well ascentral questions remaining about the impact of increases in productivity on soil-vegetation-atmosphere feedbacks, indicate a clear need for continued research intowarming induced changes in pan-Arctic vegetation.