Mapping isoprene emissions over North America using formaldehyde column observations from space

Abstract

[1] We present a methodology for deriving emissions of volatile organic compounds (VOC) using space-based column observations of formaldehyde (HCHO) and apply it to data from the Global Ozone Monitoring Experiment (GOME) satellite instrument over North America during July 1996. The HCHO column is related to local VOC emissions, with a spatial smearing that increases with the VOC lifetime. Isoprene is the dominant HCHO precursor over North America in summer, and its lifetime ('1 hour) is sufficiently short that the smearing can be neglected. We use the Goddard Earth Observing System global 3-D model of tropospheric chemistry (GEOS-CHEM) to derive the relationship between isoprene emissions and HCHO columns over North America and use these relationships to convert the GOME HCHO columns to isoprene emissions. We also use the GEOS-CHEM model as an intermediary to validate the GOME HCHO column measurements by comparison with in situ observations. The GEOS-CHEM model including the Global Emissions Inventory Activity (GEIA) isoprene emission inventory provides a good simulation of both the GOME data (r 2 = 0.69, n = 756, bias = +11%) and the in situ summertime HCHO measurements over North America (r 2 = 0.47, n = 10, bias = À3%). The GOME observations show high values over regions of known high isoprene emissions and a day-to-day variability that is consistent with the temperature dependence of isoprene emission. Isoprene emissions inferred from the GOME data are 20% less than GEIA on average over North America and twice those from the U.S. EPA Biogenic Emissions Inventory System (BEIS2) inventory. The GOME isoprene inventory when implemented in the GEOS-CHEM model provides a better simulation of the HCHO in situ measurements than either GEIA or BEIS2 (r 2 = 0.71, n = 10, bias = À10%).

Climate-driven ground-level ozone extreme in the fall over the Southeast United States

“…S8). In addition, the increase in isoprene emissions also brings the model simulated column density of formaldehyde (CH 2 O), a high-yield product from isoprene chemistry that is often used for validating the isoprene emission inventory (33,34), to a better agreement with Global Ozone Monitoring Experiment-2 (GOME-2) satellite observations (SI Appendix, Fig. S9).…”

The impact of local surface changes in Borneo on atmospheric composition at wider spatial scales: coastal processes, land-use change and air quality

“…Global background concentrations of HCHO are determined by the balance between the source (from the oxidation of methane) and the OH and photolysis sinks. Concentrations are typically much larger over continents owing to additional sources from the oxidation of biogenic and anthropogenic VOCs, and from biomass burning (either directly released or from the oxidation of co-emitted VOCs) [21,22]. Figure 1 shows HCHO column distributions over Borneo during May-October 2008, quantified using UV spectroscopic measurements (327.5 -356.5 nm) from the Ozone Monitoring Instrument (OMI) [23].…”

Evaluation of GOME satellite measurements of tropospheric NO2 and HCHO using regional data from aircraft campaigns in the southeastern United States

“…Enhancements of HCHO reflect oxidation of VOC emissions from biogenic [Lee et al, 1998;Palmer et al, 2003] and anthropogenic [Wert et al, 2003a] sources. We use GOME observations of HCHO columns to examine the regional scale and temporal variation of VOC emissions over eastern Texas.…”