ARM Southern Great Plains site observations of the smoke pall associated with the 1998 Central American fires

Drought-stricken areas of Central America and Mexico were victimized in 199 8 by forest and brush fires that burned out of control during much of the f irst half of the year. Wind currents at various times during the episode he lped transport smoke from these fires over the Gulf of Mexico and into port ions of the United Slates. Visibilities were greatly reduced during favorab le flow periods from New Mexico to south Florida and northward to Wisconsin as a result of this smoke and haze. In response to the reduced visibilitie s and increased pollutants, public health advisories and information statem ents were issued by various agencies in Gulf Coast states and in Oklahoma. This event was also detected by a unique array of instrumentation deployed at the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) program Southern Great Plains Cloud and Radiation Testbed and by sensors of the Oklahoma Department of Environmental Quality/Air Quality Division. Obs ervations from these measurement devices suggest elevated levels of aerosol loading and ozone concentrations during May 1998 when prevailing winds wer e favorable for the transport of the Central American smoke pall into Oklah oma and Kansas. In particular, aerosol extinction profiles derived from the ARM Raman lidar measurements revealed large variations in the vertical dis tribution of the smoke.