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 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 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~ Fossil fuel Aircraft Biomass burning Soils NH 3 oxidation Lightning Stratosphere< Total

8 UIUC Anthropogenic emissions by continent/regionY2000Y2100(A2p) Africa South America Southeast Asia India North America Europe East Asia Australia Other Sum NOx Emissions

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

10 UIUC Nitrous Oxide (N 2 O)

11 UIUC Nitrous Oxide (N 2 O) Budget

12 UIUC Atmospheric N2O

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 Weisenstein GSFC 2DJackman UCI 1DPrather Oslo 2DRognerud 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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