Weather Review Research Articles

Satellite accurate in tracking hurricanes

A National Oceanic and Atmospheric Administration (NOAA) satellite that is 22,300 miles out in space is locating Atlantic Ocean hurricanes with an average accuracy of about 17 nautical miles and is pinpointing their intensity within an average of 10 knots.The spacecraft's ability to track hurricanes with such accuracy is described in a paper by Donald C. Gaby and others in the Monthly Weather Review. Since 1971, Gaby reported, estimates of the locations and maximum sustained wind speeds have been made for all tropical and subtropical hurricanes in the Atlantic, the Caribbean, and the Gulf of Mexico. NOAA's National Hurricane Center ‘best tracks’ data—compiled from satellite reports, reconnaissance aircraft, and other information sources—reveals that the average location difference was only about 17 nautical miles, with the average maximum sustained wind speeds about 7 knots. ‘Our ability to estimate accurately the maximum sustained winds is significantly better for storms of at least hurricane intensity (65 knots); that is, for those storms potentially most damaging,’ according to the report.

New Editors and Editorial Policy of the Monthly Weather Review

New Editors and Editorial Policy of the Monthly Weather Review

Approximate Integration of Stochastic Differential Equations

Approximate Integration of Stochastic Differential Equations

Engine Exhaust Emission Levels

iDiitsch, H. U., Photochemistry of Ozone, Advances in Geophysics, Vol. 15, 1971, pp. 219-322. Grams, G. and G. Fiocco, Aerosol Layer During 1964 and 1965, Journal of Geophysical Research, Vol. 72 1967, pp. 3523-3542. Johnston, H. S., An Overview of Stratospheric Chemistry, CIAP, Vol. 1,1973, Nature Stratosphere (in preparation). London, J., The Distribution of Total Ozone in the Northern Hemisphere, Beitrdge zur Physik der Atmosphdre, Vol. 36, 1963, pp.254-263. Lovill, J. E., Characteristics of the General Circulation of the Atmosphere and the Global Distribution of Total Ozone as Determined by the Nimbus III Satellite Infrared Interferometer Spectrometer, Science Paper No. 180, 1972, Colorado State University, pp. 1-72. Mastenbrook, H. J., The Variability of Water Vapor in the Stratosphere, Journal of Science, Vol. 28, 1971, pp. 1495-1501. Reiter, E. R., Atmospheric Transport Processes; Part 1: Energy Transfers and Transformations, TID-24868, 1969, U. S. Atomic Energy Commission, Division of Technical Information, Springfield, Va., AEC Critical Review Series, pp. 1-253. Reiter, E. R., Atmospheric Transport Processes; Part 2: Chemical Tracers, TID-25314, 1971, U. S. Atomic Energy Commission, Division of Technical Information, Springfield, Va., AEC Critical Review Series, pp. 1-382. Reiter, E. R., Atmospheric Transport Processes; Part 3: Hydrodynamic Tracers, TID-25731, 1971, U. S. Atomic Energy Commission, Office of Information Services, Springfield, Va., AEC Critical Review Series, pp. 1-212. Reiter, E. R. and J. E. Lovill, The Longitudinal Movement of Stratospheric Ozone Waves as Determined by Satellite, Archiv fur Meteorologie, Geophysik und Bioklimatologie, Series A, 1974, (inprint). Sticksel, P. R., The Annual Variation of Total Ozone in the Southern Hemisphere, Monthly Weather Review, Vol. 98, 1970, pp.787-788. Viebrock, H. J..and E. L. Flowers, Comments on the Recent Decrease in Solar Radiation at the South -Pole, Tellus, Vol. 20, 1968, pp. 400-411. Wallace, J. M. and R. E. Newell, Eddy Fluxes and the Biennial Stratospheric Oscillation. Quarterly Journal of the Royal Meteorological Society, Vol. 92, 1966, pp. 481-489.

Monthly Weather Review Centennial, 1872–1972

Monthly Weather Review Centennial, 1872–1972

Weather Modification, Review and Perspective

Weather Modification, Review and Perspective

Satellite infrared radiation system measures global sea surface temperatures

A number of reports have been published in recent years indicating that sea surface temperatures over rather limited areas, such as the Gulf Stream, can be obtained from satellite infrared measurements. The use of available infrared satellite data for the determination of accurate sea surface temperatures, taking into consideration the various attenuating factors, especially that of cloud cover, has awaited the development and testing of an objective method that lends itself to analysis by computer techniques. Such a simple and reliable statistical histogram model has been perfected to meet this need by W.L. Smith, P.K. Rao, R. Koffler and W.R. Curtis of the National Environmental Satellite Center (ESSA) as reported in Monthly Weather Review, Vol. 98, No. 8, August 1970. The method involves inferring the distribution of surface radiances for the clear atmosphere case from observed histograms of generally cloud‐contaminated radiances.

The Navy's Numerical Hurricane and Typhoon Forecast Scheme: Application to 1967 Atlantic Storm Data

Renard recently reported (Monthly Weather Review, July 1968) on the development of a numerical scheme for predicting the motion of tropical storms for periods up to three days. An extension of the forecast scheme, as presented here, may be described as a two-step process. First, numerical geostrophic steering of the cyclone center is accomplished using Fleet Numerical Weather Central's analyses and prognoses of smoothed isobaric height fields, called SR fields. Next, a statistical correction for vector bias in the numerical steering computation is used selectively in an attempt to enhance the accuracy of the forecast track of the storm. The bias modification is dependent solely on the peculiarities of recent history 12- and 24-hr forecasts in relation to the storm's actual trajectory. Forecasts for intervals up to 72 hr, generated from 1967 Atlantic operational storm positions, are compared to results from the previous experimental forecasts for 1965 using best-track positions of Atlantic storms.Results indicate that the numerical scheme shows skill in relation to the official forecast accuracy for both 1965 and 1967, as documented by Fleet Weather Facility, Jacksonville, Fla. In 1967, the average relative improvement over official forecasts, using 700-mb prognostic SR fields for steering, ranges from 52% for 12-hr forecasts (90 cases) to 9% for the 48-hr estimates (129 cases).The paper includes a discussion of various forecast modes and selective modification schemes as well as stratification of error statistics by geographical area, storm track and stage.

A Late November Singularity

A Late November Singularity Jerome Namias" Asummary of CLiMATOLOGiCAL data for Washington, D. C, appears each month on the back of the U.S. Weather Bureau's printed Daily Weather Map.t Our interest is frequently aroused by graphs thereon showing the highest temperatures ever recorded on each day, such as the one for November shown in Figure 1. Despite the long period of record used in compiling these data (1871-1960), there appear to be certain periods when the highest temperature changes level abruptly. For example, in Figure 1, abrupt changes occur between November 1 and 6 and between November 21 and 25. These abrupt changes might suggest that the annual course of daily maximum temperatures is composed of step functions. Figure 1 thus raises the following questions with regard to the late November change: 1.Does the suggested sharp decline from November 21-25 also characterize the mean of a long series of mean maximum temperatures , or is this merely a chance fluctuation in an "unstable" statistic (extreme daily values from a sample of 89 years)? 2.Is this phenomenon local or is it associated with large-scale changes in the regional and general circulation, so that singularities at this time might be found elsewhere? Numerous factors to be cited point in the direction of a real singularity at this time of year, and that it is associated with largescale (regional and planetary) features. We shall not deal with the statistical reality of this singularity because of the great difficulty * Director of long-range forecasting in the U. S. Weather Bureau for many years, Mr. Namias is now Chief of the Extended Forecast Division of the National Meteorological Center, USWB-ESSA, Washington, D. C., 20233. t The U. S. Weather Bureau Daily Weather Map referred to here was discontinued in April 1968. 55 56ASSOCIATION OF PACIFIC COAST GEOGRAPHERS of dealing with time series problems, but rather stress logical synoptic aspects. The history of the study of singularities goes far back in meteorology —certainly to 1869 when the British meteorologist Alexander Buchan wrote his classical paper, "Interruptions in the Regular Rise and Fall of Temperature in the Course of the Year."1 Considerable work on this subject was later performed by A. Schmauss during the 1930's.2 In America, where the subject of singularities receives a quizzical eye particularly from statisticians, perhaps the best known singularity is the January Thaw which has been studied in some detail by Wahl3 and later by Duquet* Temperature analysis I have chosen to work with maximum rather than with minimum or mean temperatures because the former are probably more representative of the lower troposphere. This is so because nocturnal cooling of the layer of air lying near the surface increases the vertical stability and with the usually accompanying light winds a limit is not imposed on the cooling by turbulent mixing. On the other hand, the maximum temperature is limited because the instability generated by high surface temperatures frequendy leads to heat transfer aloft. The Washington, D.C., mean unsmoothed temperature maxima during the years 1872-1950 were computed for two roughly 40-year periods, as shown in Figure 2. It is quite apparent that a sharp drop in maximum temperature between November 21 and November 25 has characterized the period during 1911-1950 but not the years 1872-1910. Assuming the earlier records are as reliable as the later ones, one might seriously question the "reality" of the late November 1 Alexander Buchan, "Interruptions in the Regular Rise and Fall of Temperature in the Course of the Year," Journal of the Scottish Meteorological Society, Vol. 2 (Edinburgh, 1869), pp. 4-15. 2 A. Schmauss, "Synoptische Singularitäten," Meteorologische Zeitschiß, Vol. 55 (1938), pp. 385-403. 3E-W. Wahl, "The January Thaw in New England—An Example of A Weather Singularity," Bulletin of the American Meteorological Society, Vol. 33, (1952), pp. 380-386. * R. T. Duquet, "The January Warm Spell and Associated Large-Scale Circulation Changes," Monthly Weather Review, Vol. 91 ( 1963), pp. 47-60. VOLUME 30 YEARBOOK 1968 57 WASHINGTON. D.C RECORD HIGHEST 1871—1960 Q 65 NORMALMAXIMUM 1921 — 1950 NOVEMBER Figure 1. (Upper) Highest temperatures observed at Washington, D...

Notice of Change in Month Designation ofMonthly Weather Review

Notice of Change in Month Designation ofMonthly Weather Review

BEHAVIOR OF TWO EAST COAST STORMS, MARCH 13–24, 1958

During the period March 13-24, 1958, two major storms moved northeastward along the Atlantic coast with very similar evolution and development. Although both storms decelerated near New England, their subsequent behavior was quite different. The earlier storm weakened aa a secondary Low to its east intensified and moved into the central Atlantic Ocean. The following storm maintained its intensity after becoming stationary, and the weak secondary which formed to its east moved rapidly into the Atlantic Ocean. The weather associated with these two storms was typical of east coast developing Lows, with heavy precipitation and snow accumulations causing severe economic losses as transportation, power, and telephone services were disrupted. Other Monthly Weather Review articles [2, 5, 141 have dealt with various aspects of the formation and deepening of east coast Lows; the authors will investigate here some of the causes for the differences in the post-development behavior of these two storms. The charts shown in the illustrations are the operational ones used in the National Weather Analysis Center.

Discussion of “Comparative rain measurements and rain‐gage performances on a steep slope adjacent to a pine stand”

Hayes and Kittredge have contributed useful quantitative information to the old and possibly never‐ending problem of measuring precipitation. That the problem is old is indicated in a paper written by Abbe in July 1899, which appeared 50 in the Monthly Weather Review, where he cited articles which were about 50 years old at that time. The authors are to be commended for demonstrating a profile of rainfall catch from the edge of a clearing to a distance where the catch seems to be uninfluenced by the trees. Further, it is gratifying to see two such profiles, thus showing not only an average distribution of catch, but also indicating its variability. The validity of the profiles is based on consistent instrumentation, which in this case, was a set of gages tilted uniformly. It is regretted that details of wind force and direction were not reported. In view of the statement that much of the rain came with southeast winds, and with the map showing the pine stand to the southwest of the gages, the important question still remains: How far do the effects of a timber stand extend to gages down wind from its edge?

The Statistical Analysis of the Sunspot and Lynx Cycles

The regularity and stability of the 'ten-year' lynx cycle in Canada, as revealed in the numbers trapped by the Hudson Bay Company (Elton & Nicholson, I942) naturally raised the question of it being in some way causally connected with the sunspot cycle. This question has been answered in the negative (Elton & Nicholson, I942; MacLulich, I937) and as appears from a careful examination of the figures, rightly so. However, in view of the extremely interesting nature of these two series it may be worth while to set out here the criteria by which such a question must be decided, particularly in view of the fact that the correct application of statistical theory to such a problem is not at all widely understood. In Fig. i, I have graphed Wolfer's sunspot numbers from I820 to I934 and the common logarithms of the numbers of lynx caught in the Mackenzie River district of the Northern Department of the Hudson Bay Company (or its equivalent modern area). The sunspot numbers were taken from Yule (I927) for the period I820-I924 and from the Monthly Weather Review for I925-34. The lynx numbers were taken from Elton & Nicholson (I942) and the Mackenzie River district values were chosen because they gave an uninterrupted sequence from I820 to I934, and because taking the values for a single district results in a greater regularity in the cycle. Because of the extremely large values at each peak the common logarithm was taken in order to stabilize the oscillations. The ordinary correlation coefficient between these two series,

Our changing climate

In a paper published in the Monthly Weather Review in September, 1933, the author discussed long‐time temperature trends, and presented data showing that an unusual and extended warm phase of climate had at that time developed through a more or less regular rise in temperature for a comparatively long period of years. The paper also showed that the prevailing condition was widespread, in fact apparently world‐wide, and in addition that temperature data up through 1932, the terminal of the records presented in that paper, afforded no indication of an impending trend reversal to more normal thermal conditions in the then near future.Up to the end of 1945, records for 13 subsequent years have become available, and these are here presented, supplementary to the original data, to determine tendencies since 1932. They show that the general upward temperature trend continued for several years but that the more recent records Indicate a leveling off, and even contain currently a suggestion of an impending reversal.

Regional contrasts in hot degree‐day units in the united States

At the Annual Meeting for 1945, a paper was presented on degree‐day units, especially on the regional contrasts in their range or variation. That paper was published in the Transactions for August, 1945 (v. 26, pp. 45–48).The term “degree‐day,” invented by a heating engineer and adopted by the United States Weather Bureau, has been applied hitherto to the sums below 65°F, for which the term “cold degree‐day units” is here proposed. The sums of the temperatures above 70°F, calculated in the same way as cold degree‐day units, is the subject of this paper. A day having a daily mean temperature of 71° has one hot degree‐day unit; a day with a mean of 85° has 15 units. Twenty days with means of 85° have a total of 300 units. The annual average number of hot degree‐day units in the United States has been laboriously calculated from “Daily Normal Temperatures in the United States,” Supplement 26 of the Monthly Weather Review, published in 1925.

Regionalization of the United States on a Precipitation Basis

* Helpful suggestions concerning a preliminary edition of this article were received from E. A. Ackerman, C. F. Brooks, R. M. Harper, C. D. Harris, E. E. Lackey, J. K. Rose, G. T. Trewartha, and J. R. Whitaker. Acknowledgement is also gratefully made to the National Youth Administration for the assistance of Jerome Holtel (typing) and Eldon Jann (drafting). ' N. M. Fenneman: Physiographic Divisions of the United States, Revised. These Annals, Vol. 18 (1928), 261-353. : Physiography of the Western United States, 534 pp., New York, 1931. : Physiography of the Eastern United States, 714 pp., New York, 1938. 2 C. F. Marbut: Soils of the United States. U.S.D.A. Atlas of American Agriculture, Pt. 14, Washington, 1935. H. H. Bennett: Soil Erosion in the United States. In Soil Conservation, 1009 pp., New York, 1939. 3 H. L. Shantz and R. Zon: N-atural Vegetation. Atlas of American Agriculture, loc. cit., Sec. E, 1924. B. E. Livingston and F. Shreve: Generalized Vegetation Map of the United States. Carnegie Instn. Publ. 284, 1921. 4 A. E. Parkins: Temperature Regions. These Annals, Vol. 16 (1926), 151-165. Mark Jefferson: Standard Seasons. Ibid., Vol. 28 (1938), 1-12. Richard Hartshorne: Six Standard Seasons of the Year. Ibid., 165-178. 5 W. Van Royen: Climatic Regions of North America. Monthly Weather Review, Vol. 55 (1927), 315-319. C. W. Thornthwaite: Climates of North America According to a New Classification. Geographical Review, Vol. 21 (1931), 633-655. H. M. Kendall: Notes on Climatic Boundaries in the Eastern United States. Geographical Review, Vol. 25 (1935), 117-124. G. T. Trewartha: Climates of North America. Frontispiece of Introduction to Weather and Climate, New York, 1937. E. A. Ackerman: The K6ppen Classification of Climates of North America. Geographical Review, Vol. 31 (1941), 105-111. 6 J. B. Kincer: Precipitation and Humidity. Atlas of American Agriculture, loc. cit., Sec. A of Part II, Climate, 1922. : Climate and Weather Data for the United States. U. S. Dept. of Agriculture Yearbook for 1941, Washington, D. C., 1941.

Seismology in the United States—A retrospect

Twenty years ago the total number of seismographic stations in the United States was only a fraction of those we have today. There was not a single first‐class station in continental United States. Even the number of second‐class stations was very small. Nearly all the stations were third‐class from every point of view‐equipment, time‐service, and personnel. Even among these many were comparatively inactive; some were not even operating.The Government stations in those days were divided into three groups. To the first group belonged those stations which were under the administration of the Weather Bureau. This was the Bureau officially responsible for seismology in the United States. It published station bulletins in the Monthly Weather Review. The principal stations in this group were Washington, D.C, Northfield, Vermont, and the cooperative station at the University of Chicago. Secondly, there was the station at Balboa Heights under the Canal Zone administration. The third group was maintained by the United States Coast and Geodetic Survey as an incidental activity and was particularly helpful in the interpretation of magnetograph‐records. The stations belonging to this group were located at Cheltenham, Tucson, Sitka, Honolulu, and Vieques (near Puerto Rico). Their equipment consisted for the most part of very low‐sensitivity horizontal pendulums of the Bosch type.

The chemical absorption hygrometer as a meteorological instrument

In the Monthly Weather Review for January 1939 the author in collaboration with Benjamin Holzman [see 5 of “References” at end of paper] reported on a new method for measuring evaporation from land‐ and water‐surfaces. The method involves recent developments in aerodynamics and employs the general equationequation imagein which A is the intensity of turbulent mixing or the Austausch‐coefficient and (dq/dz) is the rate of change of concentration of atmospheric moisture with respect to height.

Our Changing Climate*

In a paper published in the Monthly Weather Review in September, 1933, the author discussed long-time temperature trends, and presented data showing that an unusual and extended warm phase of climate had at that time developed through a more or less regular rise in temperature for a comparatively long period of years. The paper also showed that the prevailing condition was widespread, in fact apparently world-wide, and in addition that temperature data up through 1932, the terminal of the records presented in that paper, afforded no indication of an impending trend reversal to more normal thermal conditions in the then near future. Up to the end of 1945, records for 13 subsequent years have become available, and these are here presented, supplementary to the original data, to determine tendencies since 1932. They show that the general upward temperature trend continued for several years but that the more recent records Indicate a leveling off, and even contain currently a suggestion of an impending reversal.

The Weather Element in the Hawaiian Climate

* The writer is greatly indebted to the staffs of the United States Weather Bureau, Honolulu, and the Fleet Air Base, Pearl Harbor, for information embodied in this paper. He wishes to thank Robert G. Stone of Blue Hill Observatory for invaluable constructive suggestions. Some of the data on which the study is based are given in metric, others in English units. For uniformity all measurements used in the paper are expressed in the metric system. 1 E. A. Beals, Free-air Winds over Honolulu and Guam, Monthly Weather Review, Vol. 55, 1927, pp. 222-225. A. Thomson, Upper-air Currents at Honolulu, Territory of Hawaii, ibid., Vol. 56, 1928, pp. 496-498.