1. MONTHLY CO AND FIRE COUNTS IN THREE NORTHERN HEMISPHERE REGIONS AND IN THREE LOW LATITUDE REGIONS  With MOPITT CO data and ATSR fire count data, CO emission from biomass burning is studied at the global scale for the first year of MOPITT operation from March 2000 to February 2001. Enhanced CO in the atmosphere due to biomass burning could be detected by MOPITT in many places around the world when the fire size was big enough, which can be indicated by a hotspot count larger than 5 ~ 30, depending on vegetation type and location. CO emission from large fires in the year 2000 could generally be identified in MOPITT images including the large fires in South America and Africa during the fire seasons, in Australia in September, in North America in August and in North Asia in June.  When correlating monthly CO with fire count data, the nine study regions can be divided into three categories. The first contains the three regions in the southern hemisphere where CO concentration in the atmosphere was strongly influenced by biomass burning. In the second group, the regions in northern hemisphere, fire activities in the summer could cause an increase of CO for a short period but the predominant changes are not seen to be produced by the burning. For the third group, in low latitudes, since there was little biomass burning, little effect was seen in the MOPITT data.  Limitations in the analysis: As MOPITT’s revisit time is 2-3 days, some fires can be missed if the fire is not large enough and the burning time not closely matched with the MOPITT overpass time. Another limitation is the presence of clouds, a main cause for the missing values in Fig. 3 & 4. ATSR also suffers from limited spatial and temporal coverage and can miss fires during the day. MONTHLY CO AND FIRE COUNTS IN THREE SOUTHERN HEMISPHERE REGIONS Jane Liu, James R. Drummond, Florain Nichitiu, and Jason Zou Department of Physics, University of Toronto, 60 St. George Street, Toronto, Ontario, Canada M5S 1A7 (jliu@atmosp.physics.utoronto.ca/jim@atmosp.physics.utoronto.ca) CORRELATING MOPITT CO DATA WITH ATSR FIRE COUNT DATA INTRODUCTION Biomass burning has long been recognized as a major source of atmospheric carbon monoxide (CO). The MOPITT instrument (Measurements Of Pollution In The Troposphere) on board the Terra satellite is making global observations of CO and therefore provides a valuable dataset to assess CO emission from biomass burning at the global scale. In this study, we correlate MOPITT CO data with fire count data from the Along-Track Scanning Radiometer (ATSR) on board the ERS-2 satellite. ATSR offers a surrogate for fire data and is one of a few global fire datasets available. ATSR detects nighttime fires with the thermal channel at 3.7  m. It has a horizontal resolution of 1  1 km 2 and achieves complete global coverage every 3 days. MOPITT is a gas correlation radiometer. It has a horizontal resolution of 22  22 km 2 at nadir and takes about 3 days to attain a near-complete global coverage. This study shows that CO emission from the biomass burning could be detected in different regions with various vegetation types. Daily images show that spatial patterns of the spreading CO agree with the location and density of fire counts and wind field. The seasonal variation of CO demonstrates the combined effects of biomass burning and other sources/sinks of tropospheric CO in the different regions. STUDY REGIONS AND FIRE STATISTICS EXAMPLES OF DAILY IMAGES OF CO, FIRE COUNTS AND WIND FIELDS Fig. 3. Images of total column CO (in 10 15 mol cm -2, in night time, top panels), versus the counterpart fire images (bottom panels). The locations of relative large hotspots with some thresholds are indicated in the corresponding CO images. NCEP/NCAR reanalysis wind data at 700 mb are overlaid with the corresponding hotspot images. The image domains are shown with the latitudes and longitudes at the edges in the bottom panels. Elevated CO is clearly visible during large fire events in North America in August (Panel 1), in North Asia in June (Panel 2), in Africa and South America in December (Panel 3 & 4), and in Australia in September (Panel 5). The spatial patterns of the spreading CO qualitatively agree with the wind field data. Missing values in CO images are mainly caused by clouds. DISCUSSION AND CONCLUSIONS Fig. 4. By correlating monthly mean CO with the number of hotspots, the nine regions in Fig. 1 can be divided into 3 categories. The first, shown here, includes Africa (1 st row), South America (2 nd row), and Australia (3 rd row). Other two groups are showed in Fig. 5 and Fig. 6. Spatial distribution of CO and fire counts in March, June, September and December are also displayed. These regions are located in the southern hemisphere where biomass burning is a major source of CO. As a result, temporal variation of CO is strongly influenced by biomass burning and this can be detected by MOPITT. The locations of relative large hotspots with some thresholds are indicated in the corresponding CO images. The image domains are shown with the latitudes and longitudes at the edges in the fire images, also shown in Fig. 1. Missing values in CO images (dark blue, =0) are mainly caused by clouds. Fig. 6. With low biomass burning throughout the year, no clear correlation between CO and hotspots can be found for these three low-latitude regions. CO emission from other sources seems to dominate the situation. Fig. 1. The distribution of total hotspots from March 2000 to February 2001. Higher hotspots counts show as darker areas. The 9 study regions are also shown. Fig. 2. Hotspots by region (top panel) and seasonal variations (lower panel). See Fig. 1 for the legends. Most fires occurred in Africa, South America and Australia from July to October. American Geophysical Union Fall Meeting 8 - 12 December 2003 San Francisco, CA, USA Paper No: A22C-1080 Fig. 5. This shows some common features of combined effects of biomass burning and atmospheric oxidation in regions of the northern hemisphere. Seasonal CO follows a similar trend in the northern hemisphere with a maximum in late spring and a minimum in early fall. Although biomass burning peaks in summer, the CO tends to be a minimum at this time, although there is some sign of a temporary increase at the maximum of the burning. 9 North America, 3 August 2000 North Asia, 24 June 2000 Africa, 8 December 2000 South America, 2 December 2000 Australia, 15 September 2000 Acknowledgments The MOPITT project is funded by the Natural Sciences and Engineering Research Council (NSERC) of Canada, the Meteorological Service of Canada and the Canadian Space Agency (CSA). The US team and the Terra spacecraft are funded by NASA. 1. NA: North America 2. NAS: North Asia 3. EU: Europe 4. SEA: South East Asia 5. IN: India 6. IND: Indonesia 7. AF: Africa 8. SA: South America 9. AU: Australia