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the weather bureau record of war administration part 10

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Cooperation between the Weather Bureau Flight Advisory Weather Service and the Army Flight Service was maintained at a high level throughout the period. Civil Aeronautics Administration also cooperated in providing space in Air Traffic Control quarters for the Flight Advisory Weather Service units. During the early part of the period the methods of operation and the efficiency of the system were largely dependent upon arrangements worked out locally by the individuals of each unit.

The Flight Advisory Weather Service staff was recruited largely from Weather Bureau personnel with several years of experience in airway weather work. A limited number of those assigned to Flight Advisory Weather Service had previous airway forecasting experience. The emergency nature of the inauguration of this program made it necessary to draw personnel from these sources, and for the most part results were satisfactory. Ideally, however, each Flight Advisory Weather Service forecaster should come to his position with some previous experience at an airway forecast center.

Research projects directed towards the solution of local airway forecast problems and a better understanding of short range forecast techniques will be mutually helpful to Flight Advisory Weather Service and to the airway forecast program.

The amount of traffic reached such proportions by the end of the war that it was difficult to provide individual attention for each clearance and flight plan. If traffic should again approach these proportions the method of operation might well be improved by the introduction of some form of route forecasts to handle the bulk of the traffic. This procedure would free the forecaster of much of the routine load and would permit him to devote more time to the individual problems of pilots who plan flights which are out of the ordinary. Consideration should also be given to means of providing the Flight Advisory Weather Service forecaster with completed weather maps and charts in order to permit him to devote his full time to answering the questions and solving the problems brought to him. The most promising solution appears to be some form of facsimile transmission from the forecast center.

Protection for International Aviation.-United States international aviation activity prior to 1942, consisted of two flights weekly by Pan American Airways to Ireland, one flight weekly to Ireland by American Export Airlines, and service for British Overseas Airways Corporation, making two flights weekly to the United States. Pan American Airways also made flights to and from Mexico and the Carribean, but provided its own communications and weather service. As a party to the Transatlantic Air Service Safety Organization (TASSO) the United States was providing weather service at New your (La Guardia Field) for transatlantic operations. The transatlantic forecast unit at La Guardia made route and terminal forecasts, briefed pilots, and exchanged reports, analyses and forecasts with Canadian and Irish forecast offices.

The vessel weather stations that had been established in the North Atlantic supplied surface, pilot balloon and radiosonde reports on a regular schedule to New York for use in forecasting. Commercial ships also furnished surface weather reports. International exchanges of weather information were received currently from Canada, Greenland, Iceland, the British Isles, Europe and the Atlantic Islands. By teletype, the La Guardia office received United States weather reports.

Before the United States entered the war, it was difficult to obtain sufficient weather information to make reliable maps from which to furnish forecasts. Radio silence by ships at sea, to protect themselves from detection by submarines, and enciphering of weather information by the belligerents reduced very seriously the amount available.

After we entered the war all of the weather information available came to hand through arrangements with the Allied meteorological services. Since all weather information fell under security regulations, it was necessary to provide increased staff to encipher and decipher weather messages. It was also necessary to revise the TASSO arrangements as weather information supplied by radio to aircraft in fligh had to be transmitted in a secure form and yet not be subject to misinterpretation. The participation of Ireland, a neutral nation, in the TASSO service, also led to difficulties in the matter of exchanging restricted weather information, which was necessary for the protection of flights of commercial aircraft.

A meeting of representatives of the United Kingdom, Canada, Ireland, and the United States was held in Dublin in April 1942 to discuss these problems. It was called on short notice and no United States technical or military representatives attended. Accordingly, at the request of Canada, another meeting was held in Ottawa, Canada, in September of 1942. The Weather Bureau was strongly represented, and military and State Department representatives were also there. Considerable progress was made with regard to the procedures, under wartime conditions, for furbishing meteorological communications and air traffic control services to the commercial air lines which were operating wholly in furtherance of the war effort.

A further conference on the same subject followed immediately afterward in Washington, under the guidance of the Combined Meteorological Committee of the Combined Chiefs of Staff. At this conference, the necessary coordination between the military, commercial, and civil activities with regard to transatlantic flying was achieved.

During the war years, the Weather Bureau participated in arrangements for and furnishing of service for international civil aeronautics, and , in addition, furnished material assistance in the operation of Army and navy air transport. The map, Figure 17 shows the routes and places from which service was furnished.

Research in Meteorology.-A list of the research projects conducted in the fields of Short-Range and Local Forecasting, Rainfall and River Forecasting, Verification and Error Analysis, Climatology, Analysis, Observations and Instruments, Meteorological Physics, and Dynamical Meteorology as well as the field of Extended and Long-Range Forecasting is in the Archives. Only the most important of the projects will be discussed here.

Under joint support and direction by the Army, Navy, and Weather Bureau, an extensive study was made of the formation of stratus clouds along the coast of southern California. It was expected that the results of this study would be of considerable value in forecasting stratus cloud formation on the coasts of pacific Islands and at other coastal areas where stratus ceiling conditions are an important factor in planning military aircraft operations. Many observations were made in connection with this study that had been almost entirely lacking in previous work. The Army and Navy furnished personnel as well as airplanes, blimps, and captive balloons for reconnaissance, and other special observational equipment. The Weather Bureau furnished radiosondes for frequent soundings. The project was operated by the University of California at Los Angeles, and the results were published jointly by the Army, Navy and Weather Bureau.

Another joint project was carried out by the Massachusetts Institute of Technology, with the object of studying the development and movement of pressure and flow patterns at the 10,000-foot level in order to derive more reliable forecasting techniques. Study of the influence of various disturbing factors on the movement of pressure patterns led to the conclusion that thermodynamical factors are as important as dynamical factors in controlling atmospheric flow at the 10,000-foot level, and that temperature measurements aloft are as necessary as pressure measurements for forecasting.

Only a beginning was made during the war on a project to provide more detailed and specific information on the movement and development of cyclonic and anti-cyclonic pressure centers for the Northern Hemisphere. The location, direction and speed of movement and other pertinent information about Lows and Highs were tabulated from the 40 years of Historical Northern Hemisphere Sea Level Maps, and frequency summaries were prepared from part of this material for the Pacific and European theaters of war. This project had the joint support of the Army, Navy and Weather Bureau, and was carried out in part at New York University, as described hereafter.

Another group of projects was of especial importance for furnishing weather information for war purposes. A discussion appears elsewhere on the preparation of synoptics daily weather maps for use in connection with the war. This discussion refers to the preparation of normal values and frequency distributions of some of the weather elements.

A set of maps was prepared and published, showing for each month the normal isobars and isotherms for the levels of 10,000 and 20,000 feet and 10, 13, 16 and 19 kilometers above sea level. The charts covered as much of the Northern Hemisphere as could be represented by observed data or by reasonable extrapolations from observed data. Most of the work was carried on at New York University with joint support by the Army, Navy and Weather Bureau. The title of the publication is "Normal Weather maps, Northern Hemisphere Upper Level," published by the U. S. Weather Bureau in October 1944.

This project was extended to provide maps of normal values of wind speed and wind direction for the same levels and for practically the entire Northern Hemisphere, and to provide vertical cross-sections, from the surface to 19 kilometers along every 20th meridian, showing monthly normal values of temperature, density, west-east, and southnorth components of the wind velocity, and altimeter correction over the Northern Hemisphere. These charts were not published.

In addition to data on average or normal values of wind, temperature, and pressure at high altitudes, the Army and Navy found need for maps of the extreme temperatures and extreme winds that might be expected. Extreme temperature maps were prepared the basis of the highest and lowest temperatures that had been recorded at observation points over the Northern Hemisphere, plus a considerable degree of statistical smoothing and extrapolation. These maps were published under the title "Extreme Temperature Maps, Northern Hemisphere Upper Level," by the U. S. Weather Bureau in July 1945. This project also was carried on at New York University with the joint support of the Army, Navy and Weather Bureau.

Frequency distributions of winds at upper levels were computed from analyzed maps at selected points over the Atlantic and pacific Oceans, and published in two volumes, "Wind Frequency Distribution, North Atlantic Ocean, 6 and 10 Kilometers," September 1945, and "Wind Frequency Distribution, Northwest Pacific Ocean, 3, 6 and 10 Kilometers," July 1945. The Army Air Forces provided partial support for the Pacific wind project.

Historical Northern Hemisphere Weather Maps.-In October 1941, a project was undertaken under joint sponsorship of the Army, Navy and Weather Bureau to investigate the possibility of entering additional weather data on manuscript daily weather charts of the Northern Hemisphere which had been prepared currently for use by Weather Bureau forecasters. The purpose was to obtain a series of daily charts with more information than it had been possible to obtain currently, which could be analyzed in greater detail, and thus provide a series of carefully and consistently analyzed charts covering a considerable number of years which could be used in extending the range of forecasting, both in time and in area. The outbreak of war increased the need for the development of extended range forecasting on a hemisphere-wide basis and accelerated other weather research, much of which could be implemented by such a series of past weather records.

Preliminary investigations having shown that sufficient data were available to justify the preparation of a series of charts, methods of preparation were developed and a ten and a half year series was undertaken, from January 1929 through June 1939. War conditions limiting the available weather data for much of the Northern Hemisphere after June 1939 resulted in the ending of the series with that month.

The great variety found in methods of observing and recording and in units of measurement of meteorological elements employed by various meteorological services of the Northern Hemisphere necessitated conversion to standard comparable values for entering on the charts. The average number of individual weather reports on each daily charts was about 600, so that for each year of maps more than two hundred thousand entries were made, each involving five or more weather elements any or all of which might require conversion. One of the most difficult problems encountered was that of maintaining an efficient flow of work while using sources of data which varied in form of presentation from a few days observations for a large number of stations to a long period of observations for a single station. This condition was aggravated by the fact that sources of data for foreign regions were the only copies available and were frequently required for other projects.

The charts were analyzed by analysts under direction of Weather Bureau meteorologists in cooperation with university meteorological staffs. The completed charts were printed in booklet form by months for distribution to various weather research groups and were used in projects by the Army, Navy and Weather Bureau.

An additional 30-year period was planned in May 1943, for which a more rapid system of preparation was necessary in order to meet time limits set by military requirements. Accordingly, a system of using punch cards for handling the large amount of data was developed.

In the early part of 1942 plans were made and an organization set up to prepare a set of upper air charts to parallel part of the period covered by the sea-level series. This series begins with the International Polar Year, October 1932, and extends through 1940. In order to obtain values of temperature, pressure and humidity at 3000 dynamic meters, for the many sources of data for which these values had not been computed, a large amount of involved computation was necessary. Various aids were developed to simplify computation, such as graphs, tables, and slide rules. The use of such aids and the separation of the work into functions assisted in solving the problem of adapting such technical work to untrained clerical workers. The analyzed charts were used in original form and in the form of microfilm copies by many research groups during the time of preparation, and a limited number of copies have been printed in the same form as the sea-level series.

At the request of the Army, the Weather Bureau made arrangements to obtain and forward to the Tropical Research Center, Army Air Forces Weather Service at Albrook Field, Panama, complete series of weather maps issued by the United States, Mexico, Brazil, and Argentina, from 1941 on.

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