VOL. 32, No. 1, JANUARY, 1951 27

The "Thunderstorm-Project" Data

Louis J. BATTAN United States Weather Bureau, Washington, D. C.

URING 1945 the Thunderstorm Project interested in knowing the location of these files was established as a joint effort by the and the procedure to be followed for obtaining D U. S. Weather Bureau, Army Air Force, particular types of data. In the following para- Navy and National Advisory Committee for graphs a brief description is given of the obser- Aeronautics for the purpose of collecting the neces- vations taken and data obtained by the Thunder- sary data to permit obtainment of a detailed de- storm Project during its observational program. scription of the thunderstorm in all its phases [ 1 ]. Dr. Horace R. Byers was appointed as project di- SURFACE DATA rector. Two field locations were selected as most FIGURES la and b present the surface networks desirable for observational purposes, both from established in Florida and Ohio. On each map, the viewpoint of high frequency of thunderstorms symbols are used to differentiate between different and of facilities available. Observational networks types of installations. TABLE 1 gives a summary were established and operated near Orlando, of the equipment used at these stataions and pe- Florida during the summer of 1946 and near riods of record. Wilmington, Ohio during the summer of 1947. Analysis of the data was carried on until June of UPPER AIR DATA 1949 at which time a final report [2] was pre- During both seasons of operations rawinsonde pared which described the operation of the project and rawin equipment was used for making upper- and the results of the analysis. The data were air observations. TABLE 1 shows the type of then shipped to the Central Office of the U. S. equipment and periods of operation. In Florida Weather Bureau and are now filed at the Climato- simultaneous releases were made by all stations logical and Hydrologic Services Division. Since whenever it was deemed advisable by a controller a great deal of very valuable data have been col- who was located at the radar site and was informed lected it is felt that other meteorologists may be by radio of cloud conditions over and near the sur-

FIG. la.

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devices on each airplane for measuring gust and draft velocities. The pertinent aircraft panel in- struments, electric field meters and a specially de- signed aircraft thermometer were continuously photographed on each mission. Normally each mission was planned with five airplanes having an altitude separation of 5,000 feet with the lowest at 5,000 m.s.l. In Florida 38 missions were flown between June 27 and Sept. 18, 1946; in Ohio a similar number were accomplished between May 13 and Sept. 15, 1947. In all, there were 1,363 cloud traverses during these periods of flying. Each airplane had a crew consisting of a pilot, weather observer and radar operator. Among the duties of the latter was the operation of the air- borne radar SCR-720, the radio altimeter SCR- 718 and the camera equipment used to photograph both. Comments pertaining to the weather were made by all crew members either in written form or on the wire recorder which was carried by each airplane.

RADAR DATA The position of the airplane and the size and movement of the thunderstorms in the area were observed by radar equipment whose 'scopes were photographed by automatic time-lapse cameras. Vertical scanning radar sets were utilized for ob- taining vertical dimensions of thunderstorms. Fig. lb. The radar equipments which served as the princi- FIG. 1. Network of surface and upper-air stations pal source of data are summarized in TABLE 2. used during the observational phases of the Thunder- storm Project in (a) Florida during the summer of 1946 and (b) Ohio during the summer of 1947. Upper-air VISUAL OBSERVATIONS stations with dashes protruding from the symbol also were equipped with surface instruments. Observations of clouds and other visual phe- nomena were made by Weather Bureau observers located at several points in the surface network face network. In Ohio the release procedure was during most periods when thunderstorms were altered somewhat. In addition to sporadic simul- occurring or threatening. In addition time-lapse taneous releases by some or all stations a procedure cloud photography was carried on from a number was established whereby releases by a number of of locations both in Florida and Ohio. Technical stations were made at two hour intervals between difficulties during the summer of 1947 seriously the hours of 0600 and 1800 EST. On some oc- reduced the quantity and quality of the time-lapse casions similar sequences of releases were made photographs during that season. for shorter periods when a front was approaching Of necessity, the above summarization of the the surface network. Thunderstorm Project Data has been brief. A much more detailed description of the instrumenta- AIRCRAFT DATA tion and of the data1 is given in the final report of the Thunderstorm Project. In addition to the surface and rawinsonde data, measurements of meteorological conditions in and around thunderstorms were made using radar AVAILABILITY OF DATA controlled F-61 airplanes. Engineers of N.A.C.A. All of the surface, rawin and rawinsonde data installed and maintained accelerometers and other have been put on microfilm and filed in the li-

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TABLE 1. TYPE OF EQUIPMENT USED IN THUNDERSTORM PROJECT NETWORKS

Station symbol Type of data Type of instrument Speed Period of record (Figs. 1 and 2)

Surface pressure M icrobarograph 2 rev. of drum Fla.: April 12-Sept. 20, 1946 type 790 per 24 hours Ohio: April 12-Sept. 22, 1947

Temperature and Hydro-thermograph 2 rev. of drum Fla.: April 12-Sept. 20, 1946 relative humidity type 594 per 24 hours Ohio: April 12-Sept. 22, 1947

Precipitation Ferguson weighing-type 4 rev. of drum Fla.: April 12-Sept. 20, 1946 + * rain gage per 24 hours Ohio: April 12-Sept. 22, 1947

Wind t Fla.—conventional with One rev. of Fla.: April 12-Sept. 20, 1946 double register drum per 6 hr Ohio: April 12-Sept. 22, 1947 Ohio—modified Lionel 6 in/hr Sangamo with Easterline Angus Recorders

Radiosonde and Rawinsonde equip. Fla.: May 29-Sept. 16, 1946 rawin SCR-658 Total release: 429 O or • — Ohio: May 13-Sept. 22, 1947 Total release: 443

Rawin Radar set Same dates as for SCR-658 A or A SCR-584 — Fla. releases: 289 Ohio releases: 214

* In Ohio, Stations B, 19 and 39 were also equipped with recording electric-field meters which were continuously operated. t Some surface stations in Florida used modified Lionel-Sangamo wind equipment with Easterline-Angus Recorders at a speed of 4 in/hr.

TABLE 2. RADAR EQUIPMENT USED BY THUNDERSTORM PROJECT IN FLORIDA AND OHIO

Location of network Radar set 'Scope presentation Type of data Period of record

AN/CPS-1 Plan-position One 'scope for thunderstorm May 21-Sept. 20, 1946 indicator (PPI) echoes, another showing plane Florida position (1946) AN/CPS-4 Range-height Thunderstorm echo height to July 11-Sept. 19, 1946 indicator (RHI) 40,000 ft

AN/CPN-18 40-mile range 'scope for indicating May 13-Sept. 21, 1947 beacon plane position and thun- derstorms Ohio AN/CPS-6 PPI 200-mile range 'scope for large July 9-Sept. 21, 1947 (1947) scale thunderstorm picture

AN/TPS-10 RHI Thunderstorm echo heights to June 6-Sept. 21, 1947 60,000 ft

brary of the U. S. Weather Bureau. The data de- REFERENCES scribed above as well as the charts and tabulations [1] Byers, H. R., Holzman, B. G., and Maynard, R. H., prepared by analysts of the Thunderstorm Project 1946: "A Project on Thunderstorm Microstruc- ture," Bull. Am. Meteo. Soc., Vol. 27, No. 4, pp. are available either on microfilm or in original 143-6. form. Requests for specific items should be for- [2] Byers, H. R. and Braham, R. R., 1949: The Thunder- storm. U. S. Weather Bureau, Washington, D. C. warded to the Chief, U. S. Weather Bureau, (Available from Supt. of Doc., Gov't. Printing Washington 25, D. C. Office, for $2.25.)

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