Space shuttle based global CO measurements during April and October 1994, MAPS instrument, data reduction, and data validation

Abstract

Abstract. The Measurement of Air Pollution From Satellites (MAPS) experiment flew as a payload aboard the space shuttle during April and October 1994. The instrument and the data reduction procedure were modified from earlier flights in 1981 and 1984. The modifications to both are described, and selected portions of the data are compared to concurrent aircraft borne direct measurements that had been carefully intercalibrated. In addition, the data acquired in 1984 were reprocessed using the new data reduction procedure, and the reprocessed data were compared to aircraft data acquired in 1984. The results of these comparisons indicate that the large bias error in the 1984 MAPS data has been reduced to about 10%. IntroductionCarbon monoxide (CO) is a key gas in the photochemistry of the global troposphere. It is the major sink for the OH radical, and as a result, increased emissions of carbon monoxide may lead to decreases in the level of tropospheric OH. Since OH is the principal oxidizer of the reduced species in the troposphere, increased CO emissions could lead to increased concentrations of gases like methane. These increases would impact both the planetary heat balance and the chemistry of ozone in the stratosphere. The major sources of CO are both natural and anthropogenic. The naturally produced CO results primarily from the oxidation of methane and other hydrocarbons. The anthropogenically produced CO usually results from the combustion of fossil fuels in the northern hemisphere and the burning of biomass in the tropics. The chemical lifetime of CO varies from about one-tenth year in the tropics to about 1 year in the wintertime polar regions. As a result, it is transported long distances from its sources, and the mixing ratio varies widely over the planet. Because of this, CO is an ideal candidate for measurement from an orbiting platform.The This paper first describes the modifications made to the MAPS instrument prior to the 1994 flights. Second, the modified data reduction process is discussed. Finally, the data acquired in 1994 and the reprocessed data acquired in 1984 are compared to concurrent aircraft measurements in order to estimate the accuracy of the data. MAPS Instrument Instrument Operating PrincipleThe MAPS instrument is a nadir viewing gas filter radiometer that operates in the region of the 4.67/•m carbon monoxide fundamental band. It operates on the principle of the selective chopper radiometer label et al., 1970]. That is, it produces its signal by forming the difference between the incoming energy as seen through a cell of fixed length that contains the gas of interest and a second cell that is either evacuated or that contains a nonabsorbing gas. As shown schematically in Figure 1

Reanalysis of tropospheric CO trends: Effects of the 1997–1998 wildfires

“…NOAA/CMDL has compared their standards with several other laboratories. In 1994, a NASA‐sponsored round robin in support of the Measurement of Air Pollution from Space experiment (MAPS) compared measurements in 11 laboratories [ Novelli et al , 1998b; Reichle et al , 1999]. Another round robin was organized in 1998 as part of a NASA‐EOS Interdisciplinary Science Team; this intercomparison focused on CO reference gases used in the US and Europe.…”

“…Samples of air, collected from the marine boundary layer (MBL) as part of a global surface sampling network for carbon dioxide and methane [ Conway et al , 1988], were also measured for CO. Beginning with 3 sites in 1988, the program expanded to include all network sites by 1994. The NOAA data set has been used to better define the global distribution of CO [ Novelli et al , 1992, 1998a], understand its budget and trends [ Novelli et al , 1994a, 1998a; Granier et al , 1996, 1999, Holloway et al , 2000]; and verify measurements of CO made from space [ Novelli et al , 1998b; Riechle et al , 1999].…”

Measurements of biomass burning influences in the troposphere over southeast Australia during the SAFARI 2000 dry season campaign

“…Analyzing both CO and tropospheric ozone (O 3 ) data from satellite‐based measurements, Watson et al [1990] and Fishman et al [1991] speculated on the significance of tropical biomass burning to southern midlatitude atmospheric composition. Subsequent MAPS experiments [ Connors et al , 1996, 1999; Reichle et al , 1999] provided a glimpse of the CO distribution in the midtroposphere, but with insufficient time resolution to clarify the speculation. There are others examining biomass burning influences on various trace species in the Southern Hemisphere using a variety of platforms.…”

Tropospheric carbon monoxide measurements from the Scanning High‐Resolution Interferometer Sounder on 7 September 2000 in southern Africa during SAFARI 2000

“…Although fossil fuel burning dominates the anthropogenic source of CO in the Northern Hemisphere, the dominant anthropogenic source in the Southern Hemisphere, particularly in southern Africa, is biomass burning [ Otter et al , 1997]. Remote sensing observations of CO from biomass burning in Africa, South America, and Indonesia were a major achievement of the first satellite‐derived global view provided by the MAPS instrument flying onboard the space shuttle [ Reichle et al , 1982, 1986, 1990, 1999; Reichle and Connors , 1999; Connors et al , 1991b, 1996, 1999; Christopher et al , 1998; Newell et al , 1999].…”