During April 9-19, and September 30- October 11, 1994, the Measurement of Air Pollution from Satellites (MAPS) experiment flew on the Space Shuttle Endeavour. The MAPS experiment measured the carbon monoxide in the atmosphere, primarily in the mid-troposphere, between 57┬░ North latitude and 57┬░ South latitude. The MAPS carbon monoxide measurements are in the form of volume mixing ratios, which are the volume of carbon monoxide gas divided by the corresponding volume of air and are expressed in units of parts per billion by volume (ppbv).
These figures represent the ten-day averages of the carbon monoxide mixing ratios for each mission. High values of carbon monoxide mixing ratios are indicated by shades of red, while low values of carbon monoxide are indicated by shades of blue in each of the five degree latitude by five degree longitude areas. During April, the highest values of mid-tropospheric carbon monoxide (about 120 ppbv) were found over the high northern latitudes. This pattern is typical for the late winter-early spring distribution for the northern hemisphere. During October the carbon monoxide over high northern latitudes is about 90 ppbv, and peak values of 135-180 ppbv were found over the southern Tropics where the seasonal burning in South America, Africa, and Australia was ongoing. Together, these data show that the global distribution of tropospheric carbon monoxide undergoes very large changes during the course of the year. The changes are a consequence of the complex interaction of the source locations and strengths, the global circulation, and the presence of other trace gases.
