U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 Soil and Water Management Research: St. Paul, MN
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                                    Software
                People

                    Staff Listing
                                    CareersSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Midwest Area St. Paul, Minnesota Soil and Water Management Research Research Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications

Title:   Author  item
                                            ZHANG, XIN - Yale Universityitem
                                            LEE, XUHUI - Yale Universityitem
                                            GRIFFIS, TIMOTHY - University Of Minnesotaitem
                                            Baker, Johnitem
                                            XIAO, WEI - Yale University
  Submitted to: Atmospheric Chemistry and Physics
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 8/27/2014
                                    Publication  Date: 9/15/2014
                                    Publication URL: http://handle.nal.usda.gov/10113/60456Citation: Zhang, X., Lee, X., Griffis, T.J., Baker, J.M., Xiao, W. 2014. Estimating regional greenhouse gas fluxes: An uncertainty analysis of planetary boundary layer techniques and bottom-up inventories. Atmospheric Chemistry and Physics. 14:10705-10719.Interpretive Summary: It is now generally accepted that changes in atmospheric composition have influenced global climate andthere is growing sentiment that this problem must be addressed. The first step in developing regional mitigation strategies is to determine what the current regional contributions of the major greenhouse gases (CO2, CH4, N2O) are. This can be done from a "top-down" approach, in which atmospheric measurements are used to infer the net exchange of gases between the surface and the atmosphere, or it can be done from the "borrom-up" standpoint, in which ground-based data are used to estimate emissions. We used three different top-down approaches and one bottom-up approach to estimate the greenhouse gas budget for the region surrounding a tall (244 m) radio tower in Minnesota on which a sensitive gas exchange system has been making measurements for a number of years. We found that all three methods produce similar seasonal patterns of greenhouse gas exchange, but that the simplest of the top-down methods substantially underestimated summer (July) exchange of CO2. For CH4 and N2O, all top-down methods produced much higher annial totals that the bottom-up, inventory-based approach. Overall, for this region the results indicate that the global warming potential of CH4 and N2O emission are roughly equal to the cooling potential of net annual CO2 uptake.
                                Technical Abstract: Quantification of regional greenhouse gas (GHG) fluxes is essential for establishing mitigation strategies and evaluating their effectiveness. Here, we used multiple top-down approaches and multiple trace gas observations at a tall tower to estimate GHG regional fluxes and evaluate the GHG fluxes derived from bottom-up approaches. We first applied the eddy covariance, equilibrium, inverse modeling (Carbon Tracker), and flux aggregation methods using three years of carbon dioxide (CO2) measurements on a 244-meter tall tower in the Upper Midwest, USA. We then applied the equilibrium method for estimating CH4 and N2O fluxes with one-month high-frequency CH4 and N2O gradient measurements on the tall tower and one-year concentration measurements on a nearby tall tower, and evaluated the uncertainties of this application. The results indicate that: 1) The flux aggregation, eddy covariance, the equilibrium method, and the Carbon Tracker product all gave similar seasonal patterns of the regional CO2 flux (105-106 km2), but that the equilibrium method underestimated the July CO2 flux by 52-69%. 2) The annual budget varied among these methods from -54 to -131 g C-CO2 m-2 yr-1, indicating a large uncertainty in the annual CO2 flux estimation. 3) The regional CH4 and N2O emissions according to a top-down method were at least six and two times higher than the emissions from a bottom-up inventory (Emission Database for Global Atmospheric Research), respectively. 4) The global warming potentials of the CH4 and N2O emissions were equal in magnitude to the cooling benefit of the regional CO2 uptake. The regional GHG budget, including both biological and anthropogenic origins, is estimated at 7 ± 160 g CO2 eq m-2 yr-1.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov