High carbon monoxide concentrations during the rainy season in Campo Grande, in central Brazil

This work describes an event of unusually large mixing ratios of carbon monoxide, CO, observed during a typical rainy season time period in central Brazil, when concentrations are expected to be at low levels. CO measurements were performed in Campo Grande (20.02° S; 54.5° W), from July 2001 to October 2002, covering entire periods of the dry and wet seasons. From January to June, average CO was 131 parts per billion by volume (ppbv). During November/December, average CO is about 180 ppbv. On November 13, 521.9 and 565.6 ppbv were observed. It is shown that for this special event, in which there was practically no fire activity at or near the site, air parcels reaching the site were enriched with fire products from regions much further north, near the equatorial region, where the fire activity is delayed in time, compared to central Brazil.