March 25, 2023 - Fires and Smoke in Southeast Asia

Fires and Smoke
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Dozens of fires, each marked in red, speckled the landscape of
Southeast Asia on March 23, 2023, when the Moderate Resolution Imaging
Spectroradiometer (MODIS) on board NASA’s Terra satellite acquired a
true-color image of the region.

The image is centered on Laos (south) and Vietnam (north), with fires
also seen in southern China, Thailand, and Myanmar (Burma). A thick
pall of smoke obscures most of the coastal region of the South China
Sea from view, with smoke also settling into the low valleys inland.
Hanoi, Vietnam, sits under both a gray haze and a dingy-appearing
cloud.

March is the end of the dry season across Southeast Asia, and this is
the time of year when fires become widespread as people use burning to
clear and maintain agricultural fields and pastures. In permanently
cultivated (usually lowland) areas, fires are used to burn crop
residues and get the land ready for the growing season. In urban and
residential areas, people burn leaves, trash, and brush. In the
mountains, fires may indicate permanent conversion of forest to
agricultural land, or they may be associated with shifting cultivation,
also known as swidden farming. In this system, patches of forest are
cyclically cut down, burned, cultivated, and then left fallow for a
time. Secondary forest or other vegetation reclaims the clearing during
the fallow period.

While smoke is undoubtedly a primary source of the thick aerosol haze,
it is likely so thick due to a temperature inversion. Air normally
cools with altitude, but during an inversion warm air settles above a
layer of cool air near the surface. The warm air acts like a lid and
traps pollutants near the surface, especially in basins and valleys. In
addition to smoke from the widespread fires, other sources of aerosols
that may contribute to the haze include coal and wood burning for heat,
industrial activity, dust storms, and vehicle emissions.

Image Facts
Satellite: Terra
Date Acquired: 3/23/2023
Resolutions: 1km (312.4 KB), 500m (1.1 MB), 250m (3.3 MB)
Bands Used: 1,4,3
Image Credit: MODIS Land Rapid Response Team, NASA GSFC



https://modis.gsfc.nasa.gov/gallery/individual.php?db_date=2023-03-25

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