Comparison of Methane Emission Models to Methane Emission Measurements
Permafrost methane emission modeling - Potsdam Institute for … · Permafrost methane emission...
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Permafrost methane emission modeling Yanjiao Mi, Department of Hydrology and Geo-Environmental Sciences, Vrije Universiteit Kytalyk, Northeast Siberia, arc3c tundra, silt and clay deposits, icerich, 'Yedoma’, large thaw lakes and many drained lake basins, mean annual air temperature 14.3 o C, mean July temperature 9.5 o C, annual precipita3on 232 mm, con3nuous permafrost Test site P ermafrost methane CH 4 : global warming potential of 62 based on 20 years time horizon A considerable amount of organic carbon is stored in the upper permafrost layers The positive temperature trend make permafrost a large carbon source P ermafrost 24% of the northern circumpolar region Home to more than 4 million people Sensitive to climate change (environment, resources, food…) Tundra emission Methane emission modeling: Peatland-VU LPJ-WhyMe Hydrological modeling: Flood plain Ground water position Thaw lake emission Thaw lake model Max frac3on thawing grid cells thawing cells > high ice cells f thaw >f minthaw Number of thawing grid cells N thaw depends on f minthaw Randomized selec3on of N thaw highest ice content cells Number of thawing grid cells N thaw depends on f thaw Select all cells with ice content I > I minthaw Lake ini3a3on Thaw cells depending on ice content no yes July temperature anomaly T diff,t Precipita3on anomaly P diff,t fthaw = Tdiff ,t ⋅ MT + Pdiff ⋅ Mp Li, j,t = Li, j, t−1 + Lnew,i, j,t Lnew,i, j,t = LMax⋅ Ii, j,t Ini3al thaw par3al thawing no thaw Growth of ice content based on current ice content and mean annual air temperature Thaw > threshold? Cell is added to to lake cells Expansion rate: summer temperature, precipita3on, ice content Cell next to drainage cell? Cell added to drained system Ice content set to minimum Drainage cell with Ice content > frost heave limit? Cell removed from drainage system Cell next to lake cell? Dominant wind direc3on: modify thaw threshold Isolated land cell random erosion Next 3me step yes no no yes yes no yes no yes no Lake expansion Drainage and refreezing Thawed frac3on > threshold yes Tdiff ,t > a, Pdiff ,t > 0 Lmax exp,t = b(Tdiff ,t −a)+cPdiff ,t Li, j,t = Lmax exp,t ⋅ Ii, j,t +Li, j,t −1 d = cos(W + G) ⋅ L⋅ Fw Ld = (max(d) − d)/ Fw + d no Temporal dynamics Spa7al pa8ern Modelled thawed and drained area: Ini3al peak of lake area followed by rapid drainag, thereaYer oscilla3ons Thaw lake area: similar to terrain inves3ga3on More rapid lake development with high lake ini3a3on rate but unrealis3c morphology Thaw lake model test Integrated 100 years Max 100 years A2 B1 A2 B1 Lake area frac7on HadCM3 18.23±0.22 18.77±0.18 0.26±0.02 0.27±0.03 ECHAM5 17.23±0.22 18.01±0.27 0.24±0.03 0.25±0.04 NOAA GFDL2.1 16.55±0.13 15.66±0.08 0.25±0.03 0.25±0.02 CSIRO Mk3.5 16.17±0.20 16.75±0.25 0.24±0.03 0.25±0.03 NCAR 15.33±0.23 16.30±0.26 0.26±0.03 0.25±0.03 INMCM 16.40±0.23 16.26±0.23 0.24±0.03 0.24±0.02 Implica7on methane emission (gm 2 yr 1 ) HadCM3 2.09±0.01 2.30±0.01 3.76±0.10 3.97±0.15 ECHAM5 1.88±0.01 2.09±0.02 3.34±0.15 3.55±0.20 NOAA GFDL2.1 1.88±0.01 1.67±0.01 3.55±0.15 3.55±0.10 CSIRO Mk3.5 1.67±0.01 1.88±0.01 3.34±0.15 3.55±0.15 NCAR 1.46±0.01 1.67±0.02 3.76±0.15 3.55±0.15 INMCM 1.67±0.01 1.67±0.01 3.34±0.15 3.34±0.10 Thaw lake model results Sensi7vity experiments Experiments with 6 climate model predic7ons 21 th century SRES A2 and B1 scenarios Varying temperature and precipita3on output of the climate models Maximum lake area ± 25% Most models result in decrease of lake area aYer ±70 years by increased lake drainage Half of the model runs predict lower lake area by 2100 Small temperature and precipita3on increase (NOAA GFDL model): largest cumula3ve lake area Tann,t ≤ Tfreeze Iadd = (Imax − Ii, j,t )⋅ Igrow Tann,t > Tfreeze Iadd = 0
Transcript of Permafrost methane emission modeling - Potsdam Institute for … · Permafrost methane emission...
Permafrost methane emission modeling Yanjiao Mi, Department of Hydrology and Geo-Environmental Sciences, Vrije Universiteit
Kytalyk, Northeast Siberia, arc3c tundra, silt and clay deposits, ice-‐rich, 'Yedoma’, large thaw lakes and many drained lake basins, mean annual air temperature -‐ 14.3oC, mean July temperature 9.5 oC, annual precipita3on 232 mm, con3nuous permafrost
Test site Permafrost methane CH4: global warming potential of 62 based on 20 years time horizon
A considerable amount of organic carbon is stored in the upper permafrost layers
The positive temperature trend make permafrost a large carbon source
Permafrost 24% of the northern circumpolar region
Home to more than 4 million people
Sensitive to climate change (environment, resources, food…)
Tundra emission Methane emission modeling: Peatland-VU LPJ-WhyMe
Hydrological modeling: Flood plain Ground water position
Thaw lake emission Thaw lake model
Max frac3on thawing grid cells
thawing cells > high ice cells fthaw>fminthaw
Number of thawing grid cells Nthaw depends on fminthaw
Randomized selec3on of Nthaw highest ice content cells
Number of thawing grid cells Nthaw depends on fthaw
Select all cells with ice content I > Iminthaw
Lake ini3a3on
Thaw cells depending on ice content
no yes
July temperature anomaly Tdiff,t
Precipita3on anomaly Pdiff,t
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fthaw = Tdiff , t ⋅ MT + Pdiff ⋅ Mp
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Li, j , t = Li, j , t−1 + Lnew, i, j , t
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Lnew, i, j , t = LMax ⋅ Ii, j, t
Ini3al thaw par3al thawing no thaw
Growth of ice content based on current ice content and mean annual air temperature
Thaw > threshold?
Cell is added to to lake cells
Expansion rate: summer temperature, precipita3on, ice content
Cell next to drainage cell?
Cell added to drained system Ice content set to minimum
Drainage cell with Ice content > frost heave limit?
Cell removed from drainage system
Cell next to lake cell?
Dominant wind direc3on: modify thaw threshold
Isolated land cell random erosion
Next 3me step
yes no
no yes
yes
no
yes no
yes no
Lake expansion Drainage and refreezing
Thawed frac3on > threshold
yes €
Tdiff , t > a, Pdiff , t > 0
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Lmax exp, t = b(Tdiff , t −a)+cPdiff , t
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Li, j , t = Lmax exp, t ⋅ Ii, j , t +Li, j , t−1
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d = cos(W +G) ⋅ L⋅ Fw
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Ld = (max(d) − d) /Fw + d
no
Temporal dynamics Spa7al pa8ern
Modelled thawed and drained area: Ini3al peak of lake area followed by rapid drainag, thereaYer oscilla3ons Thaw lake area: similar to terrain inves3ga3on
More rapid lake development with high lake ini3a3on rate but unrealis3c morphology
Thaw lake model test
Integrated 100 years Max 100 years A2 B1 A2 B1
Lake area frac7on HadCM3 18.23±0.22 18.77±0.18 0.26±0.02 0.27±0.03 ECHAM5 17.23±0.22 18.01±0.27 0.24±0.03 0.25±0.04 NOAA GFDL2.1 16.55±0.13 15.66±0.08 0.25±0.03 0.25±0.02 CSIRO Mk3.5 16.17±0.20 16.75±0.25 0.24±0.03 0.25±0.03 NCAR 15.33±0.23 16.30±0.26 0.26±0.03 0.25±0.03 INMCM 16.40±0.23 16.26±0.23 0.24±0.03 0.24±0.02
Implica7on methane emission (gm-‐2 yr-‐1) HadCM3 2.09±0.01 2.30±0.01 3.76±0.10 3.97±0.15 ECHAM5 1.88±0.01 2.09±0.02 3.34±0.15 3.55±0.20 NOAA GFDL2.1 1.88±0.01 1.67±0.01 3.55±0.15 3.55±0.10 CSIRO Mk3.5 1.67±0.01 1.88±0.01 3.34±0.15 3.55±0.15 NCAR 1.46±0.01 1.67±0.02 3.76±0.15 3.55±0.15 INMCM 1.67±0.01 1.67±0.01 3.34±0.15 3.34±0.10
Thaw lake model results
Sensi7vity experiments
Experiments with 6 climate model predic7ons 21th century SRES A2 and B1 scenarios
Varying temperature and precipita3on output of the climate models
Maximum lake area ± 25%
Most models result in decrease of lake area aYer ±70 years by increased lake drainage
Half of the model runs predict lower lake area by 2100
Small temperature and precipita3on increase (NOAA GFDL model): largest cumula3ve lake area
€
Tann, t ≤ Tfreeze Iadd = (Imax − Ii, j, t )⋅ IgrowTann, t > Tfreeze Iadd = 0
