Tracer Data
Meteorological Data
Model Evaluation






Round Hill I August 1954 – November 1955 (29 releases) (10-min sampling)
Round Hill II September 1957 – December 1957 (10 releases) (10-, 3-, and 1.5-min sampling)

LOCATION:  The experimental site was near the Round Hill Field Station of the Massachusetts Institute of Technology. This site has a roughness length that is 7 cm when the wind is off the water and 30 cm when the wind is going towards the water. During the tracer experiments the winds were going towards the water, and the upwind fetch included trees, houses, small buildings, and differences in elevation of the order of 100ft are found within a distance of 0.5 to 1km immediately upwind from the test area.

41o 32’ 34.34” degrees North Latitude and 70o 56’ 30.52” degrees West Longitude. The provided coordinates were deduced from a comparison of Figure 1.1 from Panofsky et al. (1967) and Figure 1 from Hewson et al. (1951) with images provided by Google Earth of the South Dartmouth area. These two reports were found through dilegent effort on the part of Christine Sherratt of MIT Library. I have included here two views of what I concluded was the likely test area [Expanded View (162KB pdf fileand Local View (204KB pdf file)].

TRACER: Sulfur Dioxide, SO2.

Round Hill 1: Vertical release through copper tubing 30cm above ground level.
Round Hill II: Horizontal release through plastic pipe (2 inches in diameter) 1.5 m above ground.


Round Hill I

Horizontal Sampling: 10-min average concentrations at a height of 2m above ground, along three arcs (50, 100 and 200m) downwind of the release. Each arc started with Post #1 at 25 degrees with receptors spaced at 3-degrees covering 180 degrees (moving clockwise from Post #1).

Vertical Sampling: None. On the basis of indirect evidence, the plume centerline appears to be lower than the height of the samplers during nighttimes with strong temperature inversions. At 50 m: Run Nos. 6, 7, 9, 10, and 13; at 100m: Run Nos. 9, 10, 13; at 200m: Run Nos. 9 and 10.

Round Hill II

Horizontal Sampling: 10-min, 3-min and 1.5-min average concentrations at a height of 1.5m above ground along three arcs (50, 100 and 200m) downwind of the release. Each arc started with Post #1 at 15 degrees with receptors 1-6 and 106-111 spaced at 3-degrees, and the other samplers spaced at 1.5 degrees. The 3-min and 1.5-min samples were taken at the beginning of the 10-min sampling period.

Vertical sampling array: 10-min average concentration on eleven posts spaced at intervals of 15-degrees along each horizontal sampling arc.  Samples were taken at 0.5, 1.0 and 2.5 m, along the 50m arc. Samples were taken at 0.5 and 2.5m, along the 100 and 200m arcs.


Round Hill I and Round Hill II
A 20-min observation period centered on the 10-min gas-sampling period was employed for the meteorological measurements. Cup anemometers and ventilated thermocouples, installed at four levels (1.5, 3, 6 and 12m) on a portable tower, for measuring vertical gradients of mean wind speed and air temperature. A cup anemometer and wind-direction vane, located at a height of 2m near the release point, for determining mean wind speeds and frequency distributions of azimuth wind direction. Average wind speeds and temperatures are provided for the gas-sampling periods (e.g., 10-min averages for Round Hill I; 10-min, 3-min and 0.5-min averages for Round Hill II).


Round Hill I (136KB, Excel File)

Round Hill II (126KB, Excel File)

Tracer Observations

1. Emission release rate.
2. Horizontal sampling array concentration values.
3. Vertical sampling array concentration values.
4. Correction factors for evaporative loss. The temperatures were warm enough that evaporation occurred prior to analysis of the sample concentration values.  This means the reported concentration values (listed in the tables) are slightly higher than they otherwise should be (3 to 5 percent for the nighttime experiments and 6 to 9 percent for the daytime experiments). The digitized concentration values reported at the web site are exactly as listed in the data volume, and hence have yet to be corrected for evaporative loss.

Meteorological Observations

1.2m observations.
2.Vertical profile data for wind speed and temperature.


Cramer, H.E., Record, F.A., and Vaughan, H.C., (1958): The Study of the Diffusion of Gases or Aerosols in the Lower Atmosphere.  ARCRL-TR-58-239, The Massachusetts Institute of Technology Press, 133 pages.<RoundHillDataReport.pdf(8MB)>

Cramer, H.E., and R.A. Record (1957): Field studies of atmospheric diffusion and the structure of turbulence. American Industrial Hygiene Association Quarterly, 0096-820x, Volume 18, Issue 2, 1957, Pages 126 – 131.

Cramer, H.E., (1957): A practical method for estimating the dispersal of atmospheric contaminants. Proc. First National Conference on Applied Meteorology, Section-C, Pages 33-55

Hewson, E.W., H.E. Cramer, G.C. Gill, and F.A. Record (1951): Research on Turbulence and Diffusion of Particulate Matter In the Lower Layers of the Atmosphere. Final Report. Contract No. AF 28(099)-7. November 1, 1948-November 30, 1951. Round Hill Filld Station, MIT, South Dartmouth, MA. 80 pages. [3-page extract, including Figure 1 (299KB)]

Panofsky, H.A., N. Bush, B. Prasad, S. Hanna, F. Peterson and E. Mares (1967): Properties of Wind and Temperature at Round Hill, South Darmouth, Mass. Research and Development Technical Report DCOM-0035-F, RCS-OSD-1366. US Army Electronics Command, Atmospheric Sciences Laboratory Research Division, Fort Huachuca, AR. 95 pages. [12-page exctract, including Figure 1.1 (157KB)]