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Climatology of Air Parcel Trajectories Related to the Atmospheric Transport of Peronospora tabacina. Jerry M. Davis, Department of Marine, Earth & Atmospheric Sciences and Department of Plant Pathology, North Carolina State University, Raleigh 27695. John F. Monahan, Department of Statistics, North Carolina State University, Raleigh 27695. Plant Dis. 75:706-711. Accepted for publication 2 January 1991. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/PD-75-0706.

Five years of temperature and wind data from atmospheric soundings were used in conjunction with the U.S. National Oceanic & Atmospheric Administration (NOAA) Air Resources Laboratories Atmospheric Transport and Dispersion (ATAD) model to construct an atmospheric air parcel trajectory climatology for the transport of the sporangiospores of the fungus Peronospora tabacina. With the receptor point in the North Carolina mountains, four receptor-oriented (backward-in-time) trajectories were calculated daily for April through August, as well as for the annual period. The 12-, 24-, and 48-hr air parcel positions, before the arrival of the air parcel in the mountains, were plotted. These spatial data were used in a nonparametric density estimation routine that generated plots of probability density function contours for the 12-, 24-, and 48-hr periods. Numerical integration was used to obtain probabilities from the contours of the probability density function. These analyses should be useful in assessing the probability that the specified location in western North Carolina received air parcels from various geographical locations; however, only those air parcels that come from regions where a source of diseased tobacco plants is present would be of epidemiological significance.