Constraining the N 2 O 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 14 N 14 N 16 O (446) 14 N 15 N 16 O (456) 15 N 14 N 16 O (546) 14 N 14 N 18 O (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
Goal: Calculate the gradient of a cost function with respect to initial control variables. The Adjoint Method 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) Examples MIT ocean model Hamburg Ocean Primitive Equation Model (HOPE) Tracer Model (TM2) 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) 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 N 2 O 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 15 N provides the most sensitive discrimination between natural and anthropogenic sources of N 2 O. B41G-02 (AGU 2007) Yung et al., Constraining the N2O budget using isotopologues and isotopomers