EGU 2009 Liang and Yung Isotopic Constraints on

EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide Mao-Chang Liang Research Center for Environmental Changes, Academia Sinica Y. L. Yung Divisions of Geological and Planetary Sciences, California Institute of Technology European Geosciences Union General Assembly 2009, Vienna, Austria, 19 – 24 April 2009

EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide

EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide

EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide Courtesy of SJ Kao

EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide ISI 200

EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide 14 N 16 O (446) _ 14 N 15 N 16 O (456) -- N 15 N 14 N 16 O (546) -- N 14 N 18 O (448) --18 O (δ 15 N = ½ [δN + δN ]) # Source: natural -- land -- ocean anthropogenic -- agriculture, fossil fuels & industry, biomass burning, … # Sink: (stratosphere) -- photolysis and chemistry (~160 -220 nm) N 2 O continues to increase in the atmosphere. However, contribution of each source is not well-quantified.

EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide Kim and Craig 1993

EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide Liang and Yung 2007

EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide

EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide F_sink Available measurements: 1. N 2 O trend Troposphere 2. 18 O 3. 15 N ( and ) F_ocean F_land F_anthro. (1) Ocean source = prescribed isotopic composition. (2) The isotopic composition of anthropogenic source = land source (3) Solve the mean isotopic composition of land for PRE. (4) Magnitude of the natural and anthropogenic sources are deduced. (5) The strength of STE does not vary. (6) The lifetimes do not vary with time.

EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide F_sink Available measurements: 1. N 2 O trend Troposphere 2. 18 O 3. 15 N ( and ) F_ocean F_land F_anthro. (1) Ocean source = prescribed isotopic composition. (2) The isotopic composition of anthropogenic source = land source (3) Solve the mean isotopic composition of land for PRE. (4) Magnitude of the natural and anthropogenic sources are deduced. (5) The strength of STE does not vary. (6) The lifetimes do not vary with time.

EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide x: Machida et al. [1995] +: Bernard et al. [2006]

EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide Time evolution of δ 18 O(N 2 O) and δ 15 N (N 2 O) x: Rockmann and Levin [2005] x: Park et al. [2009]

EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide Sources and sinks OC -- ocean LD -- land AN -- anthropogenic Total = OC+LD+AN SK -- sink TD -- trend

150 Gt. C (Broecker 2007)

EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide Models

EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide Better measurements are needed as present data have large errors. l Use the Caltech/JPL 2 -D and MOZART/CAM-CHEM 3 -D models for better estimates.