Isoprene emissions in Africa inferred from OMI HCHO

Isoprene emissions in Africa inferred from OMI HCHO

Eloïse Marais (emarais@fas.harvard.edu)D. Jacob, T. Kurosu, K. Chance, J. Murphy, C. Reeves, G. Mills, S. Casadio, D. Millet, M. Barkley, F. Paulot, J. Mao

AMS Conference, Boston29 May – 1 June 2012

Introduction

C5H8 ISOPOOOH HCHO

YHCHO

Original OMI slant column HCHO GLC 2000 Landcover

Steps One-Three:Filter for Biomass Burning and Anthropogenic Influences

Original OMI slant column HCHO

1

MODIS fire counts OMI AAOD thresholds

1

Original OMI slant column HCHO

OMI HCHO (no biomass burning)

1 2

Original OMI slant column HCHO

OMI HCHO (no biomass burning)

AATSR Algorithm 3 hotspots (2005)

1 2

Original OMI slant column HCHO

OMI HCHO (no biomass burning)

OMI HCHO (biogenic component)

1

3

2

Original OMI slant column HCHO

OMI HCHO (no biomass burning)

OMI HCHO (biogenic component)

Air mass factor (AMF) (2005-2009)

1

3

2

Original OMI slant column HCHO

OMI HCHO (no biomass burning)

OMI HCHO (biogenic component)

OMI vertical column HCHO (biogenic)

Step Four:Remove the influence of smearing

100s of kilometers

OHAdvectionISOPOOH HO2OH or h

~200-300 km smearing to the west in central Africa

(high isoprene emissions and dominance of low-NOx reaction pathway)

Smearing < 100 km in AMMA domain

(low isoprene emissions; high NOx)

Quantify HCHO smearing in Africa:

1

4

3

2

Original OMI slant column HCHO

OMI HCHO (no biomass burning)

OMI HCHO (biogenic component)

OMI vertical column HCHO (biogenic)

OMI VC HCHO (no smearing)

Step Five:Estimate isoprene emissions

HCHO yield (S = HCHO/EISOP) vs column NO2 (NO2) from GEOS-Chem

OMI NO2

HCHO yields[103 s]

1

4

3

2

5

Original OMI slant column HCHO

OMI HCHO (no biomass burning)

OMI HCHO (biogenic component)

OMI vertical column HCHO (biogenic)

OMI VC HCHO (no smearing)

OMI-derived isoprene emissions

Future DirectionsUse the OMI-derived isoprene emissions to understand seasonal and spatial variability of isoprene in Africa

Also assess the role of meteorological variables (such as temperature, soil moisture, LAI) on isoprene emissions in Africa

OMI-derived EISOP MEGAN EISOP OMI– MEGAN

60 Tg C y-1 77 Tg C y-1