Is the growth rate of N 2 O increasing? Brad Hall 1 , Geoff Dutton 2 - PowerPoint PPT Presentation

Is the growth rate of N 2 O increasing? Brad Hall 1 , Geoff Dutton 2 , Ed Dlugokencky 1 , David Nance 2 , Debbie Mondeel 2 , Patricia Lang 1 , Andrew Crotwell 2 , James Elkins 2 1 NOAA/ESRL 2 University of Colorado/CIRES 2015 Global Monitoring Annual Conference, Boulder, CO

N 2 O Source Distribution 25% agricultural soils natural soils ocean 25% industry biomass burning other 40% Total source Total sink ~17 Tg-N yr -1 ~13 Tg-N yr -1

Interannual Variability Seasonal Cycle – Thompson et al, 2013 – Nevison et al, 2011 – Ishijima, et al, 2009 – Hamilton and Fan, 2000 • ENSO, QBO • STE • soil moisture • ocean exchange (thermal) • temperature Global Emissions (inverse model, ecosystem model) Thompson et al, 2014 - Saikawa et al, 2014 - Huang et al, 2008 - Tian et al, 2015 -

Global mean N 2 O AGAGE data: https://agage.mit.edu/data/agage-data

Instrumentation/Methods/Programs

N 2 O growth rate Otto CATS CCG

Focus on 2002-2013: Expanded global coverage, improved instrumentation

2 ND Order Term, least squares fit: ppb yr -2 (2002-2013) Individual programs at select measurement sites 0.025 CATS in situ Otto flask CCG flask 0.02 ppb yr -2 0.015 0.01 0.005 0 alt brw mhd mlo kum smo cgo psa spo

2 ND Order Term, least squares fit: ppb yr -2 (2002-2013) Zonal Means from CCG flask data 0.025 0.020 0.015 ppb yr -2 0.010 0.005 0.000 Arctic NH Temp. NH Tropics SH Tropics SH Temp. global

80 000 80 000 North America 70 000 70 000 West Asia 60 000 South Asia Ammonia (kilo tonnes) 60 000 Urea (kilo tonnes) 50 000 50 000 North America 40 000 East Asia 40 000 30 000 EU 30 000 20 000 20 000 10 000 10 000 0 0 2000 2005 2010 2015 2000 2005 2010 2015 International Fertilizer Industry Association

Recent Emission Trends from Modeling Studies Inversion Ecosystem South Asia, Asia N. America, Europe Tropical S. America, Africa Fig. 6 from Tian et al, 2015 {doi/10.1890/EHS14-0015.1}

Zonal means: well-resolved gradients

Compare N 2 O zonal averages

Compare to SF 6 Growth Rate

Summary • N 2 O growth rate increasing since ~2003 >> acceleration: 0.014-0.016 ppb/yr 2 • observed globally • higher growth rates in S.H. • mean growth rate in 2013: ~1 ppb/yr • inter-hemispheric difference is decreasing >> ~0.15 ppb over 10 years • influence of climate drivers on tropical S.H. emissions?

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N 2 O Growth Rate: 2002-2013 period

Calibration: Reproducibility ~0.1 ppb (1-sigma)

Monthly mean soil moisture CPC Soil Moisture data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado

N 2 O at Barrow, Alaska