(April - May 1998)
|1. Astronauts Document Smoke Affecting the United States||6. Smoke and US Air Qulity|
|2. More Astronaut Photos of Smoke Event||7. Other Possible Impacts of Burning|
|3. Smoke Knows No Boundaries||8. Sources of Information on Global Biomass Fires|
|4. Smoke, El-Nino, and Weather||9. Credits and Image Information|
|5. The Burning Issue|
The smoke that entered the southern states of the US originated from thousands of wildfires in Mexico and Central America. This is a continuation of seasonal burning practices that have accelerated since the early 1980's. Astronauts have been photographing fires in this region for more than 20 years. Figure 1 provides the distribution of these photos over the course of a year. The chart indicates that the periods of maximum burning occur in the seasonal dry periods of April - May and September - October. These months together account for 46% and 33% of the burning photos respectively. Figure 2 is a map of the regions where most of the burning is occurring. The tan areas indicate the extent ofloss of the rain forests as of 1990. Mexico has lost over 50% of its rain forests and El Salvador retains less than 2% of its forests (THE LAST RAIN FOREST, Mark Collins, Oxford, 1990).
Smoke from fires in Mexico and Central America during the 1998 burning season were evident from the Shuttle Mission STS-90 (April 17 to May 3). An astronaut photo from this mission, STS-90-710-087, shows many individual fires burning in Western Mexico. The view here is toward the northwest out across the Pacific Ocean with the Baja Peninsula in the background. The photo was taken on April 25. Another Astronaut photo, STS-90-710-090, was taken looking directly downward over the southern Mexico. The region is covered with a continuous veil of smoke. Fires are more numerous and the smoke is more intense in the following video clip taken by American Astronaut Andrew Thomas from aboard the MIR Space Station. Andrew is the last American Astronaut to visit the Mir Station. Andrew's bio-page can be found at http://www.jsc.nasa.gov/Bios/htmlbios/thomas-a.html. The video, NASA-MIR Video, May 18, was transmitted back from the MIR Space Station in order to provide a visual perspective of the smoke. This video shows the smoke from the fire zones in Central America moving westward into the Pacific. Some of this smoke eventually turned back toward the United States. The most intense smoke episode in the United States had already occurred starting around May 8.
Andrew Thomas of MIR - NASA 7 and the crew of STS-091 took the following revealing photos of smoke from burning spanning the period of April 9 through June 11.
(Click on any above picture or see the Image List below)
Not only are smoke episodes within countries becoming common, but visible transport of smoke across international boundaries has become a global issue as well. By way of illustration, an image from TOMS satellite May 9, 1998 (Total Ozone Mapping Spectrometer) reveals that, while smoke has traveled 800 miles from fires in Mexico, more smoke is entering the Great Lakes region from forest fires in Canada. On the same image, dust, traveling several thousand miles from Asia, is approaching the west coast of the United States. The dust appears as a blue area in the Pacific Ocean in the image from May 9. Another image from TOMS and two other remote sensing platforms shows the intrusion of smoke into the U.S. at the height of the event. This material was put together by Goddar Space Flight Center for a poster presentation to Vice President Al Gore.
A famous Astronaut Photo STS026-43-080, taken in 1988 over the Amazon Basin in Brazil, has served as a wake up call to the fact that smoke from burning was beginning to cause continental scale smoke palls. The photo shows Cumulus thunderstorm clouds protruding above a thick, continuous smoke veil covering thousands of square miles. At the time the photo was taken, Brazil was paralyzed by smoke from ten's of thousands of fires set by humans to clear vegetation and forests for agriculture.
El Nino is indirectly related to this particular smoke episode because it is responsible for the extremely dry conditions that favored wildfires. The meteorological setting responsible for the northward transport can not be specifically attributed to the El Nino event. The clockwise motions associated high pressure centered in the Gulf of Mexico were responsible for the northward transport of smoke along the gulf coast, as seen in the May 8 GOES (Geosynchronous Orbital Environmental Satellite) image. Another meteorological factor which contributed to the northward transport, was a deep trough in the western US and low pressure on the great plains that eventually brought smoke as far north as central Nebraska, according to ground based observations.
The causes of the Central American fires, as in other tropical regions undergoing rapid deforestation, are varied but virtually all are related to human activities and as such are manageable and preventable. Historically the use of fire has been the tool of choice for reshaping the landscape, not only in the tropics but in the savanna and middle latitude forested lands as well.
These fires are the result of both small and large land owners clearing vegetation and waste materials, and from land being cleared of forests. In the dry conditions of this El Nino year, fires have escaped into forested areas which do not normally burn spontaneously on their own.
The GOES May 07 image is gridded with the political boundaries including the one between Guatemala and Belize which runs from top to bottom in the picture below center on the left side of the image. The white pixels contain active fires and indicate a high incidence of burning on the Guatemala (left) side of the boundary and only scattered burning in Belize on the right side. A ground photo of the Guatemala - Belize boarder shows an extremely visible example of the difference in management practices between countries. Belize is a country which is attempting to conserve its forests through a program of sustainable harvesting of forest products.
The concentration of smoke particulates tends to decrease as the distance from the source increases unless concentrated by special meteorological conditions. Air quality in parts of the US deteriorated to levels considered to constitute a health hazzard during some stages of the Central America smoke event. To illustrate the effect of the smoke on air quality, average air pollution concentrations during the smoke event are provided in Figure 3. The data is from the Texas Natural Resource Conservation Commission (TNRCC) air quality monitor for Brownsville. One-hundred and fifty micrograms per cubic meter average for a 24 hour period is concidered a health risk. The normal background levels for air quality are evident in the first and last week of the month while the peak on the 8th of May is due to smoke transport.
Smoke fire and the fires themselves have many unintended consequences. The health and safety of residents are effected by the smoke and haze. In severe cases, smoke can result in the loss of human life. As of June 2, 1998, 60 people have lost their lives fighting 12,600 fires that have burned more than 950,000 acres in Mexico and Central America. Smoke also decreases visibility and can disrupt transportation. There are also incalculable damages to natural resources; including wildlife and vegetation, impacts on water and soil, and on timber and other forest resources. Deforestation in the highland watersheds has resulted in soil erosion, floods and drought, loss of productivity in forestry and agriculture, and resulted in an increase in rural poverty. The economic loss to Mexico alone, due to smoke and heavy haze, is estimated to be several million dollars each day due to health problems and economic slow down. The effects of smoke can extend far beyond national boundaries.
The losses occurring in Central America have major consequences because of the extinction of plant and animal species. As an example of the potential loss of biodiversity, consider the fact that a single forest reserve in northern Nicaragua contains more bird species than in all of continental Europe. The lush San Juan River area along the Nicaragua-Costa Rica boarder contains more species of trees than the United States and Canada combined.
The fires in Mexico and Central America also have potential consequences on weather and climate. The interaction of smoke with water vapor can effect cloud development. On a global scale, the increased carbon dioxide emissions are important in climate change and global warming. Smoke can act to reflect the sun's energy resulting in cooling on a regional basis.
Finally, in the colorized GOES May 8 image, the smoke signature, which is clearly tan near the source of the fires in Mexico, turns pink as it moves north across the Gulf of Mexico. This indicates that smoke particles are acting as condensation nuclei and thereby have implications on weather and precipitation. If clouds have too many nuclei competing for water vapor, the ability of clouds to produce precipitation is compromised.
SOURCES OF INFORMATION ON GLOBAL BIOMASS FIRES
Many efforts are underway on national and international levels that are directed toward the detection, evaluation and mitigation of wildfires. The following list of information sources and Web sites is by no means exhaustive, but is provided to indicate the extent of interest in the global wildfire issue.
THE LAST RAIN FORESTS, Mark Collins, Oxford University Press, 1990.
TNRCC, Texas Natural Resource Conservation Commission
National Geographic, Vol 182, No. 5, 1992, p 95 - Photo by Miguel Luis Fairbanks
|Figure 1||Distribution by Month of Astronaut photos showing smoke and fires in Mexico|
|Figure 2||Map showing the loss of rain forests - From The Last Rain Forest, by Collins|
|Figure 3||Average values of air quality in micro-grams per cubic meter - Measured at Brownsville TX by the TNRCC|
|STS026-43-080||Astronaut photo taken in 1988 of smoke over Brazil|
|STS-90-710-087||Astronaut photo of smoke over Western Mexico, taken April 1998|
|STS-90-710-090||Astronaut photo of smoke over Southern Mexico, taken April 1998|
|NASA-MIR Video, May 18, 1998||NASA Astronaut Video from MIR station of smoke from fires in Mexico and Central America|
|GOES May 07, 1998 image||Showing fires, each white pixel contains fire. AVHRR, 1 Km resolution|
|GOES May 08, 1998 image||Showing smoke moving from Central America to US Gulf Coast - Channels 1,2, & 4|
|Poster for VP Gore||TOMS and two other remote sensing platforms showing intrusion of smoke into US. Material put together for Vice President Al Gore by Goddard Space Flight Center|
|TOMS May 9, 1998||Showing some reduction in smoke and dust from the TOMS May 6 photo|
|Guatemala - Belize Boarder||Photo of Guatemala (left) and Belize (right) boarder - From National Geographic Vol 182, No. 5, Nov 1992, p95 - Photo by Miguel Luis Fairbanks|
|April 9||NASA7-713-064||17.3 N||99.2 W|
|May 16||NASA7-726-005||13 N||82 W|
|June 3||STS091-701-074||12 N||97 W|
|June 5||STS091-708-079||16.9 N||104.3 W|
|June 11||STS091||Ciudad del Carman|
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