Spatial and temporal variation of MOPITT CO in Africa and South America: A comparison with SHADOZ ozone and MODIS aerosol

Abstract

Carbon monoxide (CO) measurements from the Measurements of Pollution in the Troposphere (MOPITT) experiment are used to explore the correlation between biomass burning and ozone profiles at six tropical stations namely Reunion, Irene, Natal, Ascension, San Cristobal, and Paramaribo. Distinct seasonal patterns of CO at each station indicate the strong influence of African and South American biomass burning. All stations show enhanced CO columns during September–November (SON) corresponding to austral burning. Furthermore, the effects of Sahelian burning can be seen at Natal and Ascension. Similarly, the signature of northern Amazonian fires can be observed at San Cristobal. The CO variations are generally similar to the variations of aerosol optical depth (AOD) retrieved contemporaneously from Moderate Resolution Imaging Spectroradiometer (MODIS) at most stations, with notable differences at Irene, San Cristobal, and Paramaribo. Tropospheric ozone from Southern Hemisphere Additional Ozonesonde (SHADOZ) ozonesonde measurements at all stations show elevated levels, corresponding to the CO enhancements in SON months. However, there are several instances of ozone enhancements unaccompanied by any CO increase. This might indicate that sources other than biomass burning such as stratospheric tropospheric exchange (STE) or lightning related NOx may be operative. At San Cristobal, strong CO enhancements during March–April are not accompanied by any significant change in ozone.

Three years of global carbon monoxide from SCIAMACHY: comparison with MOPITT and first results related to the detection of enhanced CO over cities

“…The large scale pattern (seasonality of CO originating from biomass burning in Africa and South America; reduction of the interhemispheric gradient towards autumn, etc.) is consistent with what is known from previous measurements, e.g., from MO-PITT (see, e.g., Bremer et al, 2004). In addition to these large scale features the maps also show considerable fine structure.…”

Variations in Subpixel Fire Properties with Season and Land Cover in Southern Africa

“…For example, Bremer et al (Bremer et al 2004) found pronounced increases in measured CO over southern Africa during the late burning season, which is consistent with the decreasing fire temperatures in Figure 8a, because CO emission increases as fire temperatures decrease below the threshold of approximately 850 K that separates flaming from smoldering combustion (e.g., Palacios-Orueta et al 2005). Although the 95% confidence intervals for the mean temperatures in Figure 8a extend below this 850-K threshold for all three scenes and the threshold temperature is approximate and depends on a variety of factors, the overall trend indicates that fires later in the burning season are more likely to be smoldering than fires early in the season.…”

“…Although the 95% confidence intervals for the mean temperatures in Figure 8a extend below this 850-K threshold for all three scenes and the threshold temperature is approximate and depends on a variety of factors, the overall trend indicates that fires later in the burning season are more likely to be smoldering than fires early in the season. Many studies have suggested biomass burning as a major determinant of the seasonal, interannual, and geographical distributions of CO (e.g., Bremer et al 2004;McMillan et al 2005;Edwards et al 2006), and the MESMA estimates in Figure 8a suggest that variations in fire temperatures likely influence these distributions and potentially the distributions of other products of incomplete combustion. The observed differences in seasonal fire temperature changes between different land-cover classes are also consistent with previously published findings.…”

MIPAS measurements of upper tropospheric C<sub>2</sub>H<sub>6</sub> and O<sub>3</sub> during the southern hemispheric biomass burning season in 2003

“…The ozone signal at this altitude can be contaminated by stratospheric ozone by two mechanisms of entirely different nature: Either stratospheric air could have been mixed or transported into the upper troposphere (c.f. Bremer et al, 2004); or, in the case of a low tropopause, due to the limited altitude resolution of the MIPAS ozone retrievals, stratospheric ozone could be misinterpreted as upper tropospheric ozone. In the given context, however, it is not necessary to distinguish between either of these causes of stratospheric signal, since the effect would be the same: Stratospheric ozone would erroneously be attributed to a biomass burning plume.…”