Synthesis of Arctic System Carbon Cycle Research Through Model-Data Fusion Studies Using Atmospheric Inversion and Process-Based Approaches(SASS PI Meeting 2-4 October 2007)

A. David McGuire (Project Leader)USGS - Institute of Arctic Biology - University of Alaska Fairbanks

Project Participants McGuire, Hayes, Balshi - UAF

Melillo, Kicklighter, Peterson - MBL

McClelland, Townsend-Small U. Texas

Follows, Prinn, Manizza, Tan, Li - MIT

Zhuang, Hu, Tang - Purdue

General Questions Guiding Research What are the geographic patterns of fluxes of CO2 and CH4 over the Pan-Arctic region and how is the balance changing over time? (Spatial Patterns and Temporal Variability)

What processes control the sources and sinks of CO2 and CH4 over the Pan-Arctic region and how do the controls change with time? (Processes and Interactions)

LandAtmosphereCO2CH4Arctic OceanDOC, DIC, POCPermafrostCO2PacificOceanAtlanticOceanTotal CKey Fluxes of Carbon in the Arctic SystemSea Ice

Tasks1. Conduct model-data fusion studies with process-based models of various components of high latitude terrestrial C dynamics including a. Terrestrial CO2 (McGuire lead; STM-TEM) and CH4 exchange (Zhuang lead; MCEM), and b. Transfer of C from high latitude terrestrial ecosystems to the mouth of rivers in the Pan-Arctic Drainage Basin (Melillo/Peterson/McClelland/Kicklighter lead; STM-TEM)

2. Conduct model-data fusion studies with a process-based model of marine CO2 exchange in oceans adjacent to the high latitude terrestrial regions (Follows lead; ECCO2 and MIT Biogeochemistry Model)

3. Improve atmospheric inversions of CO2 and CH4 across high latitude regions through better incorporation of data and process-understanding on CO2 and CH4 dynamics (Prinn lead; MATCH Atmospheric Inversion Framework).

4. Project synthesis (All).

Time Line of ResearchFirst Year Recruit Project Personnel

Second Year Organize data sets and finish up any necessary model development

Third Year Connect Up the System

Fourth Year (no cost extension) Project Synthesis

Progress: The Arctic Carbon Cycle AssessmentSponsored by AMAP, CliC, and IASCObjectivesEvaluate the current state of the Arctic carbon cycle. Evaluate potential sensitivities of the Arctic carbon cycle.Evaluate representation of the Arctic C cycle in climate models.Identify the key uncertainties and actions to reduce them. Writing Committee: A. D. McGuire, Leif Anderson, Torben Christensen, ScottDallimore, Laodong Guo, Dan Hayes, Martin Heimann, TomLorenson, Robie MacDonald, and Nigel RouletDraft: Sensitivity of the Carbon Cycle in the Arctic to Climate Change Workshop Review of Draft Seattle, February 2007Submit Assessment by End of 2007

Progress: Data Set Organization and Model DevelopmentTerrestrial Carbon Dioxide and Methane NHL Fire Data Sets and Analysis Balshi et al. 2007 (JGR-B)NHL Vulnerability to Fire and Methane Zhuang et al. 2006 (GRL)Arctic Tundra CO2 and CH4 Assessment Sitch et al. 2007 (EA)Alaska CO2 and CH4 Assessment Zhuang et al. 2007 (EA)Snow Cover and CO2 Euskirchen et al. 2006 (GCB)Western Arctic Linkage Experiment McGuire et al. in review (EI)NHL Feedbacks to Climate - McGuire et al. 2006 (ARER)NHL Terrestrial Feedbacks McGuire et al. 2007 (GCTE Book)

Land to Ocean Dissolved Organic CarbonDOC Export to the Arctic Ocean - Raymond et al. in press (GBC)Arctic River Simulation: 27 Tg C per yr (TEM) vs. 25 (Raymond)

Ocean Simulation of C Fluxes Organization of Simulations (see following slides)

Atmospheric Inversion of CO2 and CH41996-2001 Methane Exchange Chen and Prinn 2006 (JGR-A)Improving Data Set of CH4 Retrievals (see following slides)

Simulated mean net ecosystem carbon balance: Combination of CO2, climate, and fire: 1996-2002 (from Balshi et al. 2007)Hayes: Organizing Multiple Disturbance Data Sets g C m-2 yr-1

Net Methane Fluxes in the 1990s Net Methane Fluxes= 49 Tg CH4 yr-1 Emissions= 56 Tg CH4 yr-1 Consumption= -7 Tg CH4 yr-1(Zhuang et al., 2004GBC)New Research Improving Changes in Wetlands (Seasonal to Decadal)

0 1 2 4 8 16 32 315g C m-2 yr-1Annual DOC Leaching from Contemporary Ecosystems of Arctic Basins during the 1990sKicklighter et al. in preparation

Tracking Sources of Riverine DOC @ surface

Slope is 1.01, i.e., good agreement in spatial gradient.Large offsets (~8%), contamination by clouds, aerosols?

Opportunities for Linkages to Other ProjectGreening of the Arctic (Walker)Humans and Hydrology in High Latitudes (Lammers)

Synthesis of Arctic Marine Primary Production (Matrai)

Impact of Sea Ice on the Marine Production (Zhang)

An Arctic Snow-Impacts Synthesis (Sturm)

Model simulated CH4 column burden has very similar spatial gradient as observed by SCIAMACHY, i.e., slope is 1.01. But our modeled CH4 column is ~8% higher than observed value. This could be caused by cloud/aerosol contamination. SCIA CH4 team suggested using retrieved CO2 as a proxy of cloud height, i.e., higher the CO2 column, lower the cloud.