1. 1 UIUC ATMOS 397G Biogeochemical Cycles and Global Change Lecture 19: Nitrogen Cycle (cont.) Don Wuebbles Department of Atmospheric Sciences University of Illinois, Urbana, IL March 20, 2003

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3. 3 UIUC The ammonia cycle is almost identical to that of the nitrate cycle. Both of these are elements of the larger Nitrogen Cycle.

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7. 7 UIUC NOx Budget Table 4.8: Estimates of the global tropospheric NO x budget (in TgN/yr) from different sources compared with the values adopted for this report. Reference:TAR Ehhalt (1999) Holland et al. (1999) Penner et al. (1999) Lee et al. (1997) Base year2000~1985 1992 Fossil fuel33.021.020 - 2421.022.0 Aircraft0.70.450.23 -0.60.50.85 Biomass burning 7.17.53 - 135 - 127.9 Soils5.65.54 - 214 - 67.0 NH 3 oxidation-3.00.5 - 3-0.9 Lightning5.07.03 - 133 - 55.0 Stratosphere<0.50.150.1 - 0.6-0.6 Total51.944.6 44.3

8. 8 UIUC Anthropogenic emissions by continent/regionY2000Y2100(A2p) Africa2.521.8 South America1.410.8 Southeast Asia1.26.8 India1.710.0 North America10.118.5 Europe7.314.3 East Asia5.624.1 Australia0.51.1 Other2.32.6 Sum32.6110.0 NOx Emissions

9. 9 UIUC Soil processes involved in the formation of N 2 O from agriculture

10. 10 UIUC Nitrous Oxide (N 2 O)

11. 11 UIUC Nitrous Oxide (N 2 O) Budget

12. 12 UIUC Atmospheric N2O

13. 13 UIUC Nitrous oxide lifetime feedback and residence time. ModelsContributorLifetimeSensitivity,Decay Time LT (yr)s= ln(LT)/ ln(B)of mode (yr) AER 2DKo and Weisenstein111-0.062102 GSFC 2DJackman137-0.052127 UCI 1DPrather119-0.046110 Oslo 2DRognerud97-0.061 Lifetime (LTB) is calculated at steady-state for an N2O burden (B) corresponding to a tropospheric abundance of 330 ppb. The sensitivity coefficient (s) is calculated by increasing the N2O burden approximately 10% to B+ B, calculating the new steady state atmospheric lifetime (LTB+ B), and then using a finite difference approximation for s, ln(LTB+ B/LTB) /ln(1+ B/B). The perturbation lifetime (PT), i.e., the effective duration of an N 2 O addition, can be derived as PT = LT/(1.... s) or equivalently from the simple budget-balance equation: (B+ B)/LTB+ B = B/LTB + B/PT.

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