Model Simulations of the 1991 Kuwait Oil Fires

Overview The Hysplit3 model was modified to compute potential exposures to smoke and combustion products from the Kuwait Oil Fires to support health assessments by the US Army. The model accounted for the radiative feedback effect of the dense smoke plume upon the meteorological dispersion environment. Ground-level measurements of SO2 were used to provide a data set for an independent validation. Although there were large daily variations in model calculations and observations, the longer term weekly averaged data, and statistical distributions of the calculations showed reasonable levels of model agreement with the observations considering the limitations of the validation data. If the measured levels of SO2 can be considered a reasonable surrogate for general "air pollution" due to the fires, then background air concentration levels several hundred kilometers downwind only increased by perhaps 50% due to the fires. Corresponding levels of other pollutants can be determined from the normalized air concentration predictions once their emission rates are determined.

Research Results

Gridded daily and seasonal normalized air concentrations due to emissions from the Kuwait oil fires were computed for the period of February through October of 1991. The computations were performed using a Lagrangian transport and dispersion model and analyzed meteorological fields modified to account for the non-linear radiative effects of the smoke plume on the vertical mixing of pollutants. Using independently derived emission rates, the model computations of Carbon soot smoke and SO2 air concentrations (below) were compared with the observations from several intensive aircraft measurement campaigns as well as longer-term ground-based measurements. The measurements and model calculations were in substantial agreement when the results were averaged over several episodes.

Measured and model calculations of SO2 air concentrations.

The last set of calculations was designed to develop factors to estimate exposures for any pollutant. For these simulations normalized concentrations were based on a unit emission from 8 separate oil field clusters, calculated independently, while the radiative smoke effects were based upon actual smoke emissions from all the clusters. The highest normalized concentrations (below) were always located near the coast between Kuwait and Quatar, with the peak values moving farther west and inland with each season; from over the Gulf in the spring to the west over the Saudi Peninsula by autumn due to the development of the Shamal winds and subsequently fewer disturbances passing through the region.

Model computations of smoke concentration.

References

Draxler, R.R., J.T. McQueen, and B.J.B. Stunder, 1994: An evaluation of air pollutant exposures due to the 1991 Kuwait oil fires using a Lagrangian model, Atmos. Environ., 28A: 2197-2210.

McQueen, J.T. and R.R. Draxler, 1994: Evaluation of model back trajectories of the Kuwait oil fires smoke plume using digital satellite data, Atm. Environ., 28A: 2159-2173.