%0 Journal Article %J Atmospheric Science %D 1983 %T Testing of the Air Resources Laboratories Trajectory Model on Cases of Pollen Wet Deposition After Long-distance Transport from Known Source Regions %A Raynor, G. S. %A Hayes, J. V. %A Lewis, D. M. %K biology %X
Particulate dispersion from sources within a 10- to 13-m tall pine forest was studied experimentally at Brookhaven National Laboratory using stained ragweed pollen and other tracers ranging from 14 to 58 Μm in size. Forty-seven continuous point source releases lasting from 22 to 55 min were made at heights from 1.75 to 14.0 m from locations having a long fetch through the forest. In most experiments, differently colored ragweed pollen were emitted simultaneously from three locations. In other tests, several particle types were released from a single point. The sampling network consisted of 119 rotoslide samplers at heights from 0.5 to 21.0 m at 57 positions within and at the edge of the forest. Deposition to the ground was sampled by greased microscope slides at each position. Meteorological measurements were taken in and near the forest.
Data were classified by particle characteristics, source height and meteorological parameters. Concentration patterns were illustrated on scale diagrams of the sampling grid. Changes in centerline and crosswind integrated concentrations, plume width and height, mass flux, deposition and deposition velocity were studied as a function of distance, particle size and wind speed. Results were compared to those obtained from similar releases over open terrain.
In the forest, vertical predominates over lateral dispersion and considerable interchange occurs through the canopy. Flow is channelled somewhat by vegetation density differences but is generally in the direction of the mean wind above the forest. No systematic turning of the wind with height was observed. Most particles are lost to the foliage rather than to the ground and large particles are lost more rapidly than smaller ones. Rate of change in mass flux is similar to that over open terrain and is greater with light than with stronger wind speeds.
%B Boundary-Layer Meteorology %V 9 %P 257-277 %G eng %U http://link.springer.com/article/10.1007/BF00230770 %R 10.1007/BF00230770 %0 Journal Article %J Journal of Allergy and Clinical Immunology %D 1975 %T Spatial Variability in Airborne Pollen Concentrations %A Raynor, G. S. %A Ogden, E. C. %A Hayes, J. V. %K biology %XPollen transport and dispersion from generalized area sources was studied by 29 flights to distances of 100 km and heights of 3 km using an aircraft-mounted isokinetic sampler. Tree pollens and ragweed pollen served as tracers. Four types of flights were made to study various aspects of pollen transport: 1) ascents over a fixed location to investigate vertical distribution; 2) flights over a source-free area to document change of concentration with distance, 3) east-west flights along Long Island to study the influx of pollen from the mainland with westerly winds; and 4) vertical ascents and horizontal flights during sea breeze flows to determine their effect on pollen concentrations.
It was found that large quantities of pollen are transported in orderly fashion from their source regions but pollen often travels in large, discrete clouds. Pollen is transported to Long Island from the mainland in some quantity. Sea breeze flows greatly decrease low-level concentrations but pollen is carried aloft at the sea breeze front and recirculated in the return flow aloft. Vertical distribution is reasonably well related to lapse rate although secondary concentration peaks which often occur below elevated inversions cannot be explained by the data obtained.
Particulate dispersion into and within a 10- to 13-m tall pine forest was studied experimentally at Brookhaven National Laboratory using stained ragweed pollen and other tracers ranging from 14 to 54 Μm in diam. Seventy-two continuous point source releases lasting 20 to 40 min were made at various distances from within the forest edge to 60 m upwind and at heights of 1.75 to 14.0 m. In most experiments, differently colored ragweed pollen was released simultaneously from three locations. Thirty-six longer tests were made using pollen from area sources of ragweed and three with pollen from distant sources. All tests were made during the day with steady winds and unstable lapse rates outside the forest. The sampling network consisted of 119 rotoslide samplers mounted at heights from 0.5 to 21.0 m at 57 positions extending 100 m into the forest. Deposition was sampled by greased microscope slides at each sampling position. Meteorological measurements were taken in and near the forest.
Data were classified by particle characteristics; by source type, distance and height; and by meteorological parameters. Isopleths were drawn on scale diagrams of the sampling grid to illustrate concentration patterns. Changes in centerline concentration, crosswind integrated concentration, mass flux, plume width, plume height, deposition, and deposition velocity were related to distance within the forest and other variables. Results were compared to those of similar releases over open terrain and those of previous forest dispersion studies elsewhere.
The plume approaching the forest is broadened both vertically and horizontally by increased turbulence at the forest edge and flows mainly into the trunk space and above the forest. Lateral spread is slow within the forest, but vertical spreading beyond the entrance region is greater than in the open. Particles become mixed uniformly below the canopy while appreciable interchange takes place through this layer. Concentration within the forest decreases at a faster rate than in the open, but change in total mass flux within and above the forest is not significantly different. Loss of material takes place by impaction near the forest edge and in the tree tops and by deposition within the forest. Most loss takes place to the foliage rather than the ground, and larger particles are lost faster than smaller ones.
%B Boundary-Layer Meteorology %V 7 %P 429-456 %G eng %U http://link.springer.com/article/10.1007/BF00568335 %R 10.1007/BF00568335 %0 Journal Article %J Agricultural Meteorology %D 1973 %T Dispersion of Pollens from Low-Level, Crosswind Line Sources %A Raynor, G. S. %A Ogden, E. C. %A Hayes, J. V. %K biology %XThe atmospheric dispersion and subsequent deposition of corn (Zea mays L.) pollen emitted from plants in two 18-m diameter plots were studied in 39 tests at Brookhaven National Laboratory to compare the spread of this large pollen to that of smaller pollens studied previously. Concentrations were measured by wind-impaction samplers mounted at four heights (0.5 to 4.6 m) and at five distances from the source on 20-degree radii. Deposition was measured by greased microscope slides on the ground.
Data were analyzed in terms of current meteorological dispersion theory. Normalized centerline concentrations, crosswind integrated concentrations, plume widths and heights, and mass flux are presented as functions of distance and compared to similar data from ragweed (Ambrosia) and timothy (Phleum pratense) sources of comparable size. Normalized centerline and crosswind integrated deposition and velocity of deposition are also presented as functions of distance and are compared to ragweed and timothy pollen data. The study shows that corn pollen is not transported as far by the wind as smaller pollens, does not disperse as widely in either the horizontal or the vertical direction and settles to earth more quickly, much of it within the source itself.
The dispersion of corn pollen is influenced by its large size and rapid settling rate. At 60 m from the source in the downwind direction, concentrations average about 1% of those at 1 m. Width of the pollen plume at 60 m is less than that of smaller pollens under similar conditions. The rate of settling opposes the rate of upward dispersion so that the height of the pollen plume does not increase continuously with downwind distance. At 60 m from the source concentrations integrated in the crosswind direction average from 3 to 6% of those at 1 m. The total amount of pollen remaining airborne at 60 m is 5% of that at 1 m.
Total deposition within the source plot is greater than that outside. Deposition per unit area at 60 m downwind is only 0.2% of that near the source. Crosswind integrated deposition at 60 m varies from 0.5 to 0.8% of that at 1 m. The velocity of deposition at 32 m from the source averages about 33 cm/sec.
%B Agronomy Journal %V 64 %P 420-427 %G eng %U https://dl.sciencesocieties.org/publications/aj/abstracts/64/4/AJ0640040420 %R 10.2134/agronj1972.00021962006400040004x %0 Journal Article %J Agricultural Meterology %D 1972 %T Dispersion and Deposition of Timothy Pollen from Experimental Sources %A Raynor, G. S. %A Ogden, E. C. %A Hayes, J. V. %K biology %XDispersion and deposition of ragweed pollen released naturally from circular area sources of four sizes (5–27 m in diameter) and artificially from point sources were studied at Brookhaven National Laboratory. Concentrations were measured by wind-impaction samplers mounted on 20° radii at four heights (0.5–4.6 in) and four or five distances from the sources to a maximum of 69 m. Deposition was measured by greased microscope slides on the ground. Differences in dispersion patterns between point and area sources are analyzed. Normalized centerline concentrations, cross-wind integrated concentrations, plume widths, plume heights and mass flux are presented as functions of distance and related to source size and meteorological variables. Deposition data are also related to distance and source size. Most deposition velocities ranged from 2–6 cm sec−1 but values close to area sources were much greater. Loss of airborne particles between sampling circles is compared to deposition over the same distances. Results are compared to those of previous dispersion and deposition studies and to theory.
%B Journal of Applied Meteorology %V 9 %P 885-895 %G eng %U http://journals.ametsoc.org/doi/abs/10.1175/1520-0450%281970%29009%3C0885:DADORP%3E2.0.CO%3B2 %R 10.1175/1520-0450(1970)009<0885:DADORP>2.0.CO;2 %0 Book %D 1970 %T Experimental Data on Dispersion of Timothy and Corn Pollen from Known Sources %A Raynor, G. S. %A Hayes, J. V. %A Ogden, E. C. %K biology %I Brookhaven National Laboratory %C New York %G eng %0 Journal Article %J Journal of Allergy %D 1968 %T Effect of a Local Source on Ragweed Pollen Concentrations from Background Sources %A Raynor, G. S. %A Ogden, E. C. %A Hayes, J. V. %K biology %XDispersion of pollen from local ragweed sources was studied to determine the effect of contributions from such sources upon the pollen concentrations originating in more distant areas. Since ragweed pollen is produced throughout a large region, concentrations measured at any given location represent contributions from many sources at various distances along the past trajectory of the air sampled. A local source may produce concentrations several orders of magnitude above this background in a small downwind region. These concentrations decrease with distance and at some point become insignificant in comparison to background concentrations. Five experimental plots of common ragweed (Ambrosia artemisiifolia) were grown at Brookhaven National Laboratory over a four-year period. Pollen concentrations were measured by arrays of samplers located in concentric rings at several distances from each source. These concentrations were studied in relation to background pollen. The maximum downwind concentration is related to source size. Distances necessary for concentrations to reach specified fractions of background and the areas covered by concentrations greater than specified multiples of background are related to source size, surrounding vegetation, and meteorological conditions. These data should provide guidance to allergists and public health officials in evaluating the importance of local sources.
%B Journal of Allergy %V 41 %P 217-225 %G eng %U http://www.jacionline.org/article/0021-8707%2868%2990044-0/abstract %R 10.1016/0021-8707(68)90044-0