Long-range transport to the Arctic in HTAP models. Drew Shindell

Transcrição

1 Long-range transport to the Arctic in HTAP models Drew Shindell

2 2th Century Arctic Trends from GISS IPCC AR4 runs/data Shindell et al, JGR, 26

3 Effects of Pollutants on Arctic Climate What are relative impacts of local and remote pollutants? Where does Arctic BC, which definitely has a local forcing of climate, come from? What is happening and will happen as mid/high latitude developed nations decrease emissions while lower latitude developing nations increase?

4 Arctic versus Emissions Regions 68-9N (Greenland)

5 Model CAMCHEM EMEP FRSGCUCI Gasphase SR3, 5 Aerosol SR6 Passive TP1 Model type/ Meteorology SO4, BC X Offline/NCEP 1.9 SO4 Offline/? 1. Res X Offline/ECMWF 2.8 GEOSChem NOx SO4,BC Offline/? 2. GISS-PUCCINI Online/nudged to SO4 X ECMWF 4. GMI SO4, BC X? 2. GOCART-1 SO4, BC X Offline/GEOS-4 2. GOCART-2 SO4, BC Offline/ GEOS-4 2. LLNL-IMPACT SO4, BC Offline/ GEOS-3 2. MOZARTGFDL SO4, BC X? 1.9 MOZECH X? 2.8 OsloCTM2 NOx Offline/? 2.8 SPRINTARS SO4, BC? 2.8 STOC-HadAM3 SO4 X Online/HadAM3 5. TM5-JRC NOx SO4, BC X Offline/ECMWF 1. UM-CAM X Online/? 2.5

6 Arctic-wide Variations in SR1 (base case) varies by roughly a factor of 2-3 at all levels examined Sulfate varies by factors of 6 at the surface, 2 in the mid-troposphere, and 1 in the upper troposphere Attempt to unravel some of the reasons for this model diversity

7 Passive Tracer (TP1) Seasonal Arctic Response to Source Region Emissions ppbv/tg Surface 5 hpa.2 25 hpa Note spinup issue in TP1 for DJF, MAM

8 and O3 Arctic Response Surface 1 5 hpa hpa ppbv/tg pptm/tg ppbv/tg Surface O 3 /NO 5 x 5 hpa O 3 /NO x 25 hpa O 3 /NO x 2. 6 Surface SO 4 5 hpa SO hpa SO

9 pptm/tg Surface SO 4 5 hpa SO 4 25 hpa SO pptm/tg Surface BC 5 hpa BC 25 hpa BC

10 Active Seasonal Arctic Response to Source Region Emissions ppbv/tg Transport Surface 5 hpa 25 hpa ppbv/tg Transport+ loss Surface 5 hpa 25 hpa ppbv Transport+ loss+emissions Surface 5 hpa 25 hpa Annual averages, numbers give fractional variation

11 14 12 Black Carbon BC vs TP1 variability.1.8 Tracer with prescribed lifetime 19 1 pptm/tg ppbv/tg sfc 5 25 sfc 5 25 EU NA sfc 5 25 sfc Similar results for sulfate sfc 5 25 sfc 5 25 EU NA sfc 5 25 sfc 5 25

12 BC variability depends on residence time lifetime [days] Surface SR6 Black Carbon Annual Efficacies R-SQR EU NA (SR6BCarc-SR1BCarc)/(SR6BCemim-SR1BCemim) Arctic response to source region emissions [pptm/tg] R 2.74 EU.71 NA Similar results for higher altitudes and for sulfate (except ). poorly corr. w/lifetime (-.2)

13 Deposition of BC Efficacy of regional emissions

14 Deposition of BC Efficacy vs Total for Greenland

15 BC Dep Totals Systematic diffs: Not a single model has more dep from than EU or NA Greenland annual averages (Tg/m 2 x 1-14 ).8 ± 1. (.5 ±.3) (.6 ±.3) EU 1.6 ± 1.8 (1.2 ± 1.5) (1.4 ± 1.6) NA 1.7 ± 2. (1.2 ± 1.3) (1.3 ± 1.3).1 ±.2 (.6 ±.4) (.7 ±.4) all 9 8 7

16 Arctic Pollutants Ice-core record from Greenland McConnell et al., Science, 27

17 Conclusions Model spread large for aerosols, but substantial for gases too. Transport, chemistry and emissions all contribute. Climate/AQ projections for Arctic challenging. Uncertainties in BC and SO4 (incl. deposition to Arctic) dominated by modeling of aerosol physics (vs transport or emissions) Arctic most sensitive to European emissions (BC, sulfate,, NOx) surface and 5 hpa. Hence per unit Tg emission change, Europe most important (and winter most important). Greenland BC deposition most sensitive to North American emissions (but Europe important too). As total emissions larger in Asia, Asia and Europe typically comparable in impact of a given percent emission change.