Transcript of Detection of anthropogenic formaldehyde over North America by oversampling of OMI data: Implications...
- Slide 1
- Detection of anthropogenic formaldehyde over North America by
oversampling of OMI data: Implications for TEMPO Lei Zhu and Daniel
J. Jacob
- Slide 2
- HCHO observations from space constrain emissions of highly
reactive volatile organic compounds (HRVOCs) HRVOCsHCHO h, OH
oxidation ~ 2 hours and funding from NASA ACMAP OMI HCHO columns
Jan 2006Jul 2006 T.P. Kurosu anthropogenic biogenic pyrogenic <
1 day
- Slide 3
- Nigerian air pollution revealed by satellite OMI formaldehyde
2005-2009 MISR SCIA aerosol (AOD) NO 2 HCHO glyoxal methane
Population: 170 million (+3% a -1 ) GDP: $270 billion (+7% a -1 )
oil! Most natural gas is flared >80% of domestic energy from
biofuel, waste Lagos Port Harcourt An unusual mix of very high
VOCs, low NO x What will happen as infrastructure develops? Marais
et al., 2014 gas flaring! 10 15 molecules cm -2 TES 825 hPa ozone
DJF
- Slide 4
- Detection of anthropogenic HRVOCs from HCHO over US has been
elusive: elevated HCHO is mainly from isoprene Millet et al. [2008]
OMI satellite observations of formaldehyde (HCHO) columns, Jun-Aug
2006 HCHO h, OH 2 hours oxidation isoprene 1 hour
- Slide 5
- Using non-growing season to avoid isoprene interference doesnt
work HCHO observations are then below detection limit Detection
limit (for 1-month average) HCHO detection in winter hampered by
low sun angles low PBL heights slow chemistry GOME data [Abbot et
al., 2003]
- Slide 6
- Problem is that US urban/industrial plumes are small and
localized OMI monthly detection limit of 5x10 15 molecules cm -2 1
ppb HCHO in 2 km PBL HCHO ~ 10 ppb observed in cores of
urban/industrial plumes but not on scale of OMI pixels (13x24 km 2
nadir) Day 1 Day 2 Day 3 Solve problem by oversampling: achieve
spatial resolution finer than pixel size by temporal averaging
Apply to OMI HCHO May-Aug 2005-2008 retrieval on 2x2 km 2 grid, 24
km smoothing
- Slide 7
- Oversampled OMI HCHO over eastern Texas (May-Aug 2005-2008)
Isoprene in green Large AHRVOC point sources in black vegetation
prevailing wind
- Slide 8
- Lack of temperature dependence of HCHO in Houston urban core
supports anthropogenic attribution exp[0.11T]
- Slide 9
- Using OMI HCHO to quantify Houston AHRVOC emissions HCHO source
= HCHO column o = background column = 260 110 kmol h -1 Consistent
with S = 240 90 kmol h -1 from TEXAQS [Parrish et al., 2012]
SpeciesEmission kmol h -1 HCHO source kmol h -1 ethene1627
propene6.312 HCHO9.4 CH 3 CHO1.2 TOTAL3349 Compare to EPA AHRVOC
inventory (NEI 05) EPA inventory is factor of 5.5 2.4 too low
Integrate HCHO enhancement over area of Houston plume Background
o
- Slide 10
- Implications for TEMPO TEMPO should perform much better than
OMI in detecting AHRVOC emissions Detecting AHRVOC emissions from
oil/gas fields is of particular interest; OMI is marginal, TEMPO
has promise. Staggering TEMPO pixels from day to day would allow
oversampling but that does not seem necessary Observed diurnal
variation of urban/industrial plumes will constrain primary vs.
secondary HCHO sources InstrumentPixel resolutionHCHO detection
limit (single retrieval) OMI13x24 km 2 2x10 16 molecules cm -2
TEMPO2x4.5 km 2 1x10 16 molecules cm -2