Quantifying Arctic Terrestrial Ecosystem Carbon Dynamics Using Mechanistically-Based Biogeochemistry Models and In Situ and Satellite Data

• Main Author: Lyu, Zhou
• Format: Text
• Language: unknown
• Published: Purdue University 2018
• Subjects: Arctic; Canada; Siberia
• Online Access: https://docs.lib.purdue.edu/open_access_dissertations/2012; https://docs.lib.purdue.edu/context/open_access_dissertations/article/3228/viewcontent/LyuZhouAcc.pdf

Terrestrial ecosystems of northern mid-to-high latitudes (45°-90°N) play a critical role in global carbon cycling and climate system feedbacks, given the massive carbon storage in the region and the amplification effects due to year-round and seasonal snow covering. This region has vast area of peatlands with a large amount of soil organic carbon. It has experienced dramatic climatic and environmental changes in recent decades, and the changes are expected to continue. This dissertation aims to quantify the Arctic carbon dynamics under these changes using mechanistically-based biogeochemistry models and in situ and remotely sensed data. In the Arctic, snow pack modifies soil and carbon dynamics in the region due to its insulation effects. This dissertation first incorporated these effects by introducing a snow model into an existing soil thermal model in a biogeochemistry modeling framework, the Terrestrial Ecosystem Model (TEM). The coupled model was then used to quantify snow insulation effects on carbon (C) and soil thermal dynamics in the 45°-90°N region for the historical period of 2003-2010 and the future period of 2017-2099 under two future climate scenarios. The revised model captured the snow insulation effects and improved the estimates of soil thermal dynamics and the land freeze-thaw as well as terrestrial ecosystem carbon dynamics. Historical mean cold-season soil temperature at 5cm depth driven with satellite-based snow data was 6.4℃ warmer in comparison with the original model simulation. Frozen area in late spring was estimated to shrink mainly over eastern Siberia, in central to eastern Europe, and along southern Canada in November. During each non-growing season in the historical period, 0.41 Pg more soil C was released due to warmer soil temperature estimated using the new model. During 2003-2010, the revised model estimated that the region accumulated 0.86 Pg less C due to weaker gross primary production, leading to a regional C loss at 0.19 PgC/yr. The revised model projected that the region ...