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This study explores the constraints on the N2O budget through the application of isotopologues and isotopomers, employing advanced computational techniques, such as the Adjoint Method. By utilizing isotopic analysis, the research enhances understanding of known sources of N2O and narrows the uncertainty range in budget projections. The findings indicate that the IPCC 2007 N2O budget is consistent with isotopic data, while highlighting the need for extending models to the pre-industrial period. Key methods and tools developed for this research are also discussed.
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B41G-02 (AGU 2007) Yung et al., Constraining the N2O budget using isotopologues and isotopomers Constraining the N2O budget using isotopologues and isotopomers Y. L. Yung, S. P. Kim, M. C. Liang and R. L. Shia Divisions of Geological and Planetary Sciecnes California Institute of Technology B41G-02 AGU - Dec 13, 2007 (Thur)
B41G-02 (AGU 2007) Yung et al., Constraining the N2O budget using isotopologues and isotopomers Method 14N14N16O (446) 14N15N16O (456) 15N14N16O (546) 14N14N18O (448)
B41G-02 (AGU 2007) Yung et al., Constraining the N2O budget using isotopologues and isotopomers Known Sources
B41G-02 (AGU 2007) Yung et al., Constraining the N2O budget using isotopologues and isotopomers The Adjoint Method • Goal: Calculate the gradient of a cost function with respect to initial control variables. • Steps: • 1. Linearize the model • 2. Transpose the linear model
B41G-02 (AGU 2007) Yung et al., Constraining the N2O budget using isotopologues and isotopomers Tangent linear and Adjoint Model Compiler (TAMC) • Created for Fortran 77 with some extensions for 90/95 • Automatic generation of adjoint code • Takes top-level routine and creates adjoint routines • Follows all guidelines in Giering (1998) • Examples • MIT ocean model • Hamburg Ocean Primitive Equation Model (HOPE) • Tracer Model (TM2)
B41G-02 (AGU 2007) Yung et al., Constraining the N2O budget using isotopologues and isotopomers
B41G-02 (AGU 2007) Yung et al., Constraining the N2O budget using isotopologues and isotopomers
B41G-02 (AGU 2007) Yung et al., Constraining the N2O budget using isotopologues and isotopomers
B41G-02 (AGU 2007) Yung et al., Constraining the N2O budget using isotopologues and isotopomers
B41G-02 (AGU 2007) Yung et al., Constraining the N2O budget using isotopologues and isotopomers
B41G-02 (AGU 2007) Yung et al., Constraining the N2O budget using isotopologues and isotopomers
B41G-02 (AGU 2007) Yung et al., Constraining the N2O budget using isotopologues and isotopomers
B41G-02 (AGU 2007) Yung et al., Constraining the N2O budget using isotopologues and isotopomers What is the uncertainty of this budget projection?
B41G-02 (AGU 2007) Yung et al., Constraining the N2O budget using isotopologues and isotopomers Conclusions • The IPCC 2007 N2O budget appears to be consistent with the isotopic data • Isotopic analysis narrows uncertainty range of the model budget • Extend the model to the pre-industrial revolution • Site preference data for 15N provides the most sensitive discrimination between natural and anthropogenic sources of N2O.