Download - Jenny Stavrakou, Jean-François Müller, Maite Bauwens Isabelle De Smedt, Michel Van Roozendael
Isoprene emissions in Asia 1979-2012 : Isoprene emissions in Asia 1979-2012 : variability and trends, effects of changes variability and trends, effects of changes in meteorology and land use, in meteorology and land use, and comparison to top-down estimatesand comparison to top-down estimates
Jenny Stavrakou, Jean-François Müller, Maite BauwensIsabelle De Smedt, Michel Van RoozendaelBelgian Institute for Space Aeronomy, Brussels
Alex GuentherAtmospheric Chemistry Division, NCAR, Table Mesa Drive, Boulder, US
Isoprene is important because…
Most abundant VOC emitted by vegetation, global annual emissions of ~500 TgC
Highly reactive : with OH (< 1h), O3 (1-2 h) and NO3 (~1 d) but its degradation in the atmosphere is still not completely elucidated
Leads to ozone formation in polluted conditions : ISOP+OH RO2+HO2 (+NO) NO2 O3
Source of SOA Health impact, negative climate forcing
Key actor in chemistry-biosphere-climate interactions
Why focus on Asia? Two of world’s most rapidly expanding economies and almost ½ of world population
Dramatic changes in emissions : o In China NOx emissions doubled in only 10 years, PM2.5
increase by 2.7 between 1990 and 2005
Massive land use changes with huge environmental impacts, forests crops urban, urbanized Beijing area doubled in 1985-1992!
Massive deforestation oil palm plantations in Southeast Asia, Indonesia&Malaysia: 85-90% of the global oil palm production, oil palm: large isoprene emitter
Heavy aerosol loading likely impacts SR reaching the ground (dimming)
How do these effects influence the emitted isoprene?
Model outline
LAIdzdSdtFlux SMageTP
canopy
Emission rate in standard conditions
Response functions to radiation and T at leaf level
Dependence to leaf age and soil moisture stress
Leaf area index
• Latest database of MEGAN basal emission rates
• LAI : collection 5 8-day MODIS
• ERA-Interim ECMWF analyses for downward solar radiation, temperature, wind, humidity, cloudiness & soil moisture in 4 layers
• Vertical profiles inside the canopy obtained from a 8-layer canopy model (MOHYCAN, Müller et al., 2008)
Focus : 9 S-55 N, 60-150 E, 0.5°x0.5°, Focus : 9 S-55 N, 60-150 E, 0.5°x0.5°, Step = 0.5 h, Step = 0.5 h, S0 = S0 = Base runBase runFocus : 9 S-55 N, 60-150 E, 0.5°x0.5°, Focus : 9 S-55 N, 60-150 E, 0.5°x0.5°, Step = 0.5 h, Step = 0.5 h, S0 = S0 = Base runBase run
Strong interannual variability, highest isoprene flux in 1997-98, due to exceptional El Nino, lowest emission in
1984&2008
Largest emission flux in 2007, lower emissions afterwards
Main drivers are : warming rates & radiation trends
Annual % isoprene trend
Decadal T trend (oC) Strongest warming trend :
close to Shanghai (0.4-0.6oC/decade)& Northern provinces, in agreement with Liu et al.(2004) analysis
Warming rates < 0.4oC/decade in Southern China
Positive trend in radiation in Southern China, negative in Indonesia
Annual % PAR trend
Isoprene trend is stronger in NE China, Northern Borneo (3%/year)
Isoprene Flux Anomaly
Asia : negative deviations related to WLN (1984-85), SLN (1988-1989), SLN (1999), MLN (2007-2008), positive to MEN (1987), SEN (97-98), MEN (2009-2010), China : little correlation with El Niňo
Relation with Oceanic Niňo Index (ONI)
r = 0.73r = 0.73, in agreement with past studies
ONI is lagged to account for potentially complex influence of ENSO on isoprene emissions
Land use changes1979-2007 trend in cropland
fraction1979-2007 cropland fraction
evolution
Ramankutty and Foley (1999)
Rapid crop expansion in Southeast Asia, related to large-scale deforestation, Indonesia (1.5%/yr), Malaysia (2.3%/yr)
Crop abandonment in Central & South China
%/yr
Oil palm plantations
Fraction of oil palm plantations in 2010
Koh et al. (2011)Miettinen et al. (2012)http://bepi.mpob.gov.my
250-m resolution land cover map (Miettinen et al., 2012) gridded onto 0.5 deg.
Planted palm area expanded extremely rapidly in1979-2010, factor of 55 in Sarawak, 20 in Indonesia and Sabah, 3 in Peninsular Malaysia
Solar radiation changes
Annual surface solar radiation anomaly data
ECMWF SR data fail to reproduce the observations, changes in aerosol loading are omitted
ECMWF overestimates by 8-20% ground observations of SR in China (Jia et al. 2013)
Measurement sites
Solar dimming in China until 1990, most pronounced in eastern China, brightening after 1990 in SE China
Significant brightening in Japan over 1990-2002
Over India strong solar dimming after 1985
SimulationSimulation DescriptionDescription
S0S0 standardstandard
S1S1as S0, account for as S0, account for
land use changesland use changes
S2S2 as S1, reduction of isoprene rate for tropical as S1, reduction of isoprene rate for tropical
forestsforests
by factor of 4.1 (Langford et al. 2010) by factor of 4.1 (Langford et al. 2010)
S3S3as S2, emissions from oil palms as S2, emissions from oil palms
in Indonesia&Malaysiain Indonesia&Malaysia
S4S4as S3, effect of solar radiation as S3, effect of solar radiation
changes and correction changes and correction
factors from Jia et al. (2013)factors from Jia et al. (2013)
Best bottom-upBest bottom-up
Isoprene emissions across S0-S4 in 2005 (mg isoprene/m2/s)
S0 (90 Tg)S0 (90 Tg) S1 (71 S1 (71 Tg)Tg)
S2 (42 S2 (42 Tg)Tg)
S4 (40 S4 (40 Tg)Tg)
Trend reinforced in S1 due to negative trend in cropland fraction in China
Consider SR changes in S4 further trend enhancement due to brightening in SE China, emissions have decreased because we have adopted decreased SR fields
Strong emission trend in S0, due to 0.2o-0.6oC/decade warming rates & positive radiation trend, warming rate exceeds by far the global 20th century warming rate (0.6oC, IPCC)
Increasing trend in cropland fraction in S1 reduces trend
x2-3 emission reduction in S2
Further trend enhancement in S3, due to the expansion of oil palm plantations
Evaluation against top-down estimates
HCHO is major intermediate product in the oxidation of isoprene in the atmosphere
Past studies demonstrated the capabilities of HCHO columns to infer isoprene emissions
GOME-2 HCHO July 2010
A priori IMAGESv2 HCHO
Optimized columns
1015 molec.cm-2
Use 2007-2012 GOME-2 HCHO, De Smedt et al., AMT, 2012, http://www.temis.nlPerform grid-based inversion with IMAGESv2 global CTM for 6 years using S4 bottom-up as a priori, x2.5 error on biogenic flux
1010 molec. cm-2 s-1
2008 a priori isoprene emission Emission change (optimized-prior)
Small changes wrt the prior, by up to 30% higher emission in SE China, by up to 30% lower emission in Borneo
Satellite data support the strong reduction of emission rate for tropical forests in Indonesia and Malaysia
Tg/yr
Conclusions Best bottom-up inventory has lower emissions by factor of
2 compared to MEGANv2 this enhances the relative importance of anthropogenic emissions to the total VOC budget !
Lower emissions o due to drastic emission rate reduction in tropical
forests Need for additional measumentso due to more extensive cropland and lower solar
radiation over China compared to ECMWF High isoprene emission rate from oil palms in combination
with rapid oil palm expansion causes higher trend over Indonesia and Malaysia
Top-down estimates confirm lower emission rate for tropical forests & corroborate the decreasing trend over China due to the cooling epidode since 2007