Showing papers in "Bulletin of the American Meteorological Society in 1979"
TL;DR: In this paper, the authors find that both confusion and misunderstanding exist about the inherent ability of radar to measure rainfall, about factors that contribute to errors, and about the importance of careful calibration and signal processing.
Abstract: Radar can produce detailed precipitation information for large areas from a single location in real time. Although radar has been used experimentally for nearly 30 years to measure rainfall, operational implementation has been slow. Today we find that data are underutilized and both confusion and misunderstanding exist about the inherent ability of radar to measure rainfall, about factors that contribute to errors, and about the importance of careful calibration and signal processing. Areal and point rainfall estimates are often in error by a factor of two or more. Error sources reside in measurement of radar reflectivity factor, evaporation and advection of precipitation before reaching the ground, and variations in the drop-size distribution and vertical air motions. Nevertheless, radar can be of lifesaving usefulness by alerting forecasters to the potential for flash flooding. The most successful technique for improving the radar rainfall estimates has been to “calibrate” the radar with rain g...
515 citations
TL;DR: In this article, meteorological conditions associated with more than 150 intense convective precipitation events have been examined and three basic meteorological patterns were associated with flash flooding in the central and eastern United States.
Abstract: Meteorological conditions associated with more than 150 intense convective precipitation events have been examined. These heavy rainfalls caused flash floods and affected most geographic regions of the conterminous United States. Heavy rains associated with weather systems of tropical origin were not considered. Analyses of surface and standard level upper-air data were undertaken to identify and define important synoptic and mesoscale mechanisms that act to intensify and focus precipitation events over specific regions. These analyses indicated that three basic meteorological patterns were associated with flash flooding in the central and eastern United States. Heavy convective precipitation episodes that occurred in the West were considered as a separate category event. Climatological characteristics, composite analyses, and upper-air data are presented for these four classifications of events. The large variability of associated meteorological patterns and parameters (especially winds aloft) m...
346 citations
TL;DR: In this paper, the authors report on two recently deployed NASA satellite systems (SAM II and SAGE) that are monitoring the stratospheric aerosol layer and obtain vertical aerosol and gaseous extinction profiles with 1 km vertical resolution.
Abstract: The potential climatological and environmental importance of the stratospheric aerosol layer has prompted great interest in measuring the properties of this aerosol. In this paper we report on two recently deployed NASA satellite systems (SAM II and SAGE) that are monitoring the stratospheric aerosol. The satellite orbits are such that nearly global coverage is obtained. The instruments mounted in the space-craft are sun photometers that measure solar intensity at specific wavelengths as it is moderated by atmospheric particulates and gases during each sunrise and sunset encountered by the satellites. The data obtained are “inverted” to yield vertical aerosol and gaseous (primarily ozone) extinction profiles with 1 km vertical resolution. Thus, latitudinal, longitudinal, and temporal variations in the aerosol layer can be evaluated. The satellite systems are being validated by a series of ground truth experiments using airborne and ground lidar, balloon-borne dustsondes, aircraft-mounted impactor...
276 citations
TL;DR: In this paper, the significance of Percent Correct Scores for National Weather Service (NWS) probability of precipitation (PoP) forecasts is examined, and it is shown that the areal variability of rainfall and the na...
Abstract: The significance of Percent Correct Scores for National Weather Service (NWS) probability of precipitation (PoP) forecasts is examined. It is shown that the areal variability of rainfall and the na...
83 citations
TL;DR: The first numerical weather prediction was made on the ENIAC computer in 1950 and some of the historical background is given and a partially narrative account of it is given.
Abstract: The first numerical weather prediction was made on the ENIAC computer in 1950. This lecture gives some of the historical background of that event and a partially narrative account of it.
82 citations
TL;DR: The average added cost was $93 per individual, largely to residences and vehicles, and extrapolation of this to all Illinois citizens results in an estimated statewide cost in excess of $1 billion as mentioned in this paper.
Abstract: The winter of 1977–78 was the worst, on the basis of both low temperatures and snow, on record in Illinois and many other areas of the Midwest. Representatives of 70 households in central Illinois participated in a detailed study of how the extreme cold and snow affected individuals. The average added cost was $93 per individual, largely to residences and vehicles, and extrapolation of this to all Illinois citizens results in an estimated statewide cost in excess of $1 billion. This was compounded by a wide variety of personal inconveniences, worries, extra work, and injuries. There were no deaths in the sampled group but 52 Illinoisans were killed by the 18 winter storms. For those living in rural areas beyond the city of their employment, costs and inconveniences were greater. The average individual cost was $120, and rural dwellers experienced more travel problems, move delayed services, and more absences from school and work.
44 citations
TL;DR: In this paper, two different satellite estimates of sea-surface temperature (SST) have been compared with observed temperature sections in the central tropical Pacific Ocean, and the satellite products were found to be biased with respect to the observations by approximately 1-4°C.
Abstract: Two different satellite estimates of sea-surface temperature (SST) have been compared with observed temperature sections in the central tropical Pacific Ocean. The satellite products were found to be biased with respect to the observations by approximately 1–4°C. The bias field had a strong latitudinal and longitudinal structure. The spatial structure of this field and the large magnitude of errors in estimates of SST, if a normal situation, preclude the use of the satellite products by themselves in climatological studies of the area. However, if some means can be found to remove the bias from the satellite products then they will be marginally useful in the study of interannual variations of SST in the tropical Pacific. The errors associated with the estimates of satellite SST are strongly linked to cloud cover and the amount of water vapor in the atmosphere, indicating present methods of correcting for these types of contamination are inadequate. The errors also depend on the number of observa...
33 citations
TL;DR: In the years 1694 to early 1697, cold winters and cool and wet springs and autumns led to extreme famine in northern Europe, particularly in Finland, Estonia, and Livonia as mentioned in this paper.
Abstract: In the years 1694 to early 1697, cold winters and cool and wet springs and autumns led to extreme famine in northern Europe, particularly in Finland, Estonia, and Livonia. It is estimated that in Finland about 25–33% of the population perished (Jutikkala, 1955; Muroma, 1972), and in Estonia-Livonia about 20% (Liiv, 1938). As far as is known the population disasters associated with the famines of the 1690s in France, Italy, and Scotland; 1816–17 in western Europe; 1845–46 in Ireland; and 1867–68, again in Finland; were all notably smaller than those of Finland, Estonia, and Livonia in 1695–97. A reconstruction is attempted of the coarse features of weather conditions in northern Europe in the years preceding the famine. This is based on previous work by other investigators (especially Jutikkala), and on contemporary documents and literature examined by the present authors. Records indicate that in the absence of an appropriate diet, the population consumed unwholesome and partly or fully indigesti...
30 citations
TL;DR: The Global Weather Experiment (GWE) as mentioned in this paper was the largest international scientific experiment ever attempted to analyze the Earth's atmosphere and its oceans, with the involvement of over 140 countries.
Abstract: An unprecedented analysis of the atmosphere of planet Earth is currently underway with the involvement of over 140 countries in the Global Weather Experiment—the largest international scientific experiment yet attempted. After many years of planning, the Operational Year began in December of 1978. Following the field phase and data management phase, a multi-year evaluation and research program will commence and continue until the late 1980s. During this period, scientists and technicians will examine the atmosphere, the sea surface, and the upper layer of the world's oceans in the most intense survey and study ever made. A number of successes and failures occurred in preparing for the observing phase and these are mentioned as each observing system actually deployed in the field is reviewed. The focus of the paper is on the quantity of data gathered and how it was obtained. The article concludes with some suggestions for assurances of final success of the Experiment.
27 citations
TL;DR: A short summary of the field phase of the GARP Winter Monsoon Experiment can be found in this paper, where the observing systems, type of experiments, mission objectives, components of overall data sets, and a preliminary evaluation are presented in this short survey.
Abstract: These notes provide a short summary of the field phase of the GARP Winter Monsoon Experiment. The field phase commenced on 1 December 1978, with the field operations coordinated from Kuala Lumpur. The participants included scientists and technical personnel from Malaysia, Indonesia, Thailand, the Philippines, Hong Kong, Japan, Saudi Arabia, Singapore, Australia, People's Republic of China (PRC), the U.S.S.R., and the U.S.A. The observing systems, type of experiments, mission objectives, components of overall data sets, and a preliminary evaluation are presented in this short survey.
21 citations
TL;DR: In this article, meteorological records extracted from three ancient Chinese chronicles are presented, covering a time span from 2187 B.C. to 3 A.D. Some interesting climatological variations are noted.
Abstract: Meteorological records extracted from three ancient Chinese chronicles are presented. These records cover a time span from 2187 B.C. to 3 A.D. Some interesting climatological variations are noted.
TL;DR: In this article, the case for an operational program involving the formulation and dissemination of probabilistic temperature forecasts is presented, and some suggestions are made regarding specific temperature events that should be treated on an operational basis.
Abstract: The case for an operational program involving the formulation and dissemination of probabilistic temperature forecasts is presented. First, the need for information concerning the uncertainty in temperature forecasts is discussed, and examples of formal and informal decision-making situations in which such information would be useful are described. The results of experiments in probabilistic temperature forecasting are then reviewed, and it is concluded that experienced weather forecasters can quantify the uncertainty inherent in temperature forecasts in a reliable and skillful manner. Finally, the essential components of an operational probabilistic temperature forecasting program are outlined, and some suggestions are made regarding specific temperature events that should receive probabilistic treatment on an operational basis.
TL;DR: In this paper, the possibility of tropical cyclone intensity determination through upper-tropospheric jet aircraft reconnaissance has been considered, where the cyclone's upper-level temperature anomaly and its gradient can be related to surface pressure and wind.
Abstract: It is proposed that attention be given to the possibility of tropical cyclone intensity determination through upper-tropospheric jet aircraft reconnaissance. The cyclone's upper-level temperature anomaly and its gradient can be related to surface pressure and wind. This is particularly relevant to foreign countries affected by these cyclones that do not have a dedicated low altitude aircraft reconnaissance capability, but have available jet aircraft. Only the ordinary aircraft instrumentation for measuring temperature and pressure-altitude would be required. Jet flights are faster, longer ranged, and less turbulent (if echoes are avoided) than propeller flights. Many more aircraft are available for such missions.
TL;DR: The Global Weather Experiment (GWE) as mentioned in this paper reached a peak during the Second Special Observing Period of May and June 1979, when the largest concentration of resources ever assembled was deployed to meet the challenge of observing the atmosphere and oceans to an unprecedented degree.
Abstract: During the Second Special Observing Period of May and June 1979, the Global Weather Experiment reached a peak. At this time the largest concentration of resources ever assembled was deployed to meet the challenge of observing the atmosphere and oceans to an unprecedented degree. This article outlines this effort and highlights the various observing systems involved in this effort—in particular the quantity of observations gathered from each major system.
TL;DR: The technique is shown to enhance the understanding of a) convective development, b) organization of mesoscale features as they relate to the synoptic scale, c) severe storm development, and d) precipitation mechanisms.
Abstract: A technique is developed to digitally composite satellite and radar imagery in a common coordinate reference frame. Results obtained from using Geosynchronous Operational Environmental Satellite (GOES) visible and infrared data, 5 cm radar data, and recording raingage data are presented. The composite displays are created on Colorado State University's All Digital Video Imaging System for Atmospheric Research (ADVISAR), an interactive image processing system that uses modern high fidelity digital video display technology. An efficient methodology based on analytic transforms for remapping dissimilar digital image formats into common map projections is discussed. Applications of multi-sensor composite images are demonstrated with the use of two case studies. The technique is shown to enhance our understanding of a) convective development, b) organization of mesoscale features as they relate to the synoptic scale, c) severe storm development, and d) precipitation mechanisms. Our final comments conc...
TL;DR: The concept of radiometric sounding of atmospheric temperature profiles from satellites was first demonstrated with data gathered by infrared spectrometers on the Nimbus-3 satellite in 1969 and the concept of satellite sounding over oceanic areas was introduced by the VTPR (Vertical Temperature Profile Radiometer) instrument on the NOAA 2 satellite in 1972.
Abstract: The concept of radiometric sounding of atmospheric temperature profiles from satellites was first demonstrated with data gathered by infrared spectrometers on the Nimbus-3 satellite in 1969. Operational satellite sounding over oceanic areas was introduced by the VTPR (Vertical Temperature Profile Radiometer) instrument on the NOAA 2 satellite in 1972. Early evaluations of these new observational data centered on their accuracy compared to data obtained from the conventional radiosonde system. More recent evaluations have focused on the impact of the satellite temperature soundings on numerical weather forecasts. In this paper, we review the results of such impact tests in several countries. On the average, the inclusion of satellite sounding data leads to a small improvement in the numerical forecasts.
TL;DR: The authors showed that the skill level in the consensus forecasts, relative to forecasts of the long-term mean, is slightly more than 50% for the first day and around 10% on the fourth, except for conditional quantitative precipitation forecasting.
Abstract: Forecasts of minimum temperature and precipitation amount at Boston have been made and evaluated in the Department of Meteorology, MIT, in essentially the same format since 1966. These forecasts refer to the first through fourth 24 h periods in advance and are partly categorical and partly probabilistic in form. The skill level in the consensus forecasts, relative to forecasts of the long-term mean, is slightly more than 50% for the first day and around 10% on the fourth, except for conditional quantitative precipitation forecasting, which is decidedly less skillful. Regression analysis shows, except for the first day, slight increases in the skill of these predictions, at a rate of about six-tenths of a percent per year. The skill of the guidance temperature forecasts of the National Meteorological Center has lagged the skill of the consensus forecasts by a decreasing amount from 1966 to 1972. The lag from 1972 to date has not changed significantly and varies between 10 and 30% of consensus skil...
TL;DR: In this article, a pulsed CO2 laser Doppler system was used to monitor thunderstorm gust fronts, and wind shears associated with the gust fronts were measured and tracked.
Abstract: A pulsed CO2 laser Doppler system was used to monitor thunderstorm gust fronts. Wind shears associated with the gust fronts were measured and tracked.
TL;DR: A computer program is available that produces public weather forecasts in worded form from digital forecasts of weather elements, designed to be implemented concurrently with the AFOS (Automation of Field Operations and Services) system.
Abstract: A computer program is available that produces public weather forecasts in worded form from digital forecasts of weather elements. This program was designed to be implemented concurrently with the AFOS (Automation of Field Operations and Services) system. One version of the program operates on NOAA's large computer system and will send forecasts over the National Distribution Circuit; another version can be run on the local AFOS minicomputers. This paper describes input to the program, the options available for its use, the decision processes whereby the forecast is constructed, the output of the program, and plans for its use. In addition, examples are shown of worded forecasts covering a variety of weather situations.
TL;DR: In this paper, a chronology of a major Australian flood in 1974 is presented using Nimbus 5 Passive Microwave Data (ESMR) and other conventional and satellite supporting data.
Abstract: A chronology of a major Australian flood in 1974 is presented using Nimbus 5 Passive Microwave Data (ESMR) and other conventional and satellite supporting data.
TL;DR: In this paper, a scenario in which a hurricane is approaching Galveston is developed, and the hurricane is assigned an average wind structure from which the field of wind components directed towards the radar is computed.
Abstract: Hurricanes cause sporadic devastation along the Gulf and Atlantic coasts despite intensive research and a warning system that integrates satellite surveillance, aircraft re-connaissance, and a network of coastal radars. Part of the devastation must be attributed to inadequate public preparation and response and part to the limits of weather predictability, but part must be attributed to the use of an outmoded radar system. Although there now exist Doppler radars that provide real-time colored displays of the wind structure in storms, the radars that comprise the last line of defense in the national hurricane warning service provide no wind information. To support the contention that the coastal network should consist of Doppler radars, this paper develops a scenario in which a hurricane is approaching Galveston. A Doppler radar is imagined to be located at Galveston. The hurricane is assigned an average wind structure from which the field of wind components directed towards the radar is computed....
TL;DR: AVE-SESAME '79 (Atmospheric variability experiment-Severe Environmental Storms and Mesoscale Experiment 1979) as mentioned in this paper was a large inter-agency mesoscale and severe storms experiment.
Abstract: NASA's Marshall Space Flight Center participated with its AVE (Atmospheric Variability Experiment) in a large interagency mesoscale and severe storms experiment identified herein as AVE-SESAME '79 (Atmospheric Variability Experiment-Severe Environmental Storms and Mesoscale Experiment 1979). A primary objective of NASA was to support an effort to acquire carefully edited sets of rawinsonde data during selected severe weather events for use in correlative and diagnostic studies with satellite and radar data obtained at approximately the same times. Data were acquired during six individual 24-h experiments on both the regional and storm scales over a network in the central United States that utilized approximately 20 supplemental rawinsonde sites meshed among 23 standard National Weather Service sites. Included among the six experiments are data obtained between 1200 GMT on April 10 and 1200 GMT on April 11, encompassing the formation and development period for the tornado-producing systems that devastated Wichita Falls, Texas, and other sections of Oklahoma and Texas. The other dates for which data sets are available are April 19-20 and 25-26, May 9-10 and 20-21, and June 7-8, 1979.
TL;DR: The first major state field study was the August 1978 Tennessee Plume Study conducted near the Cumberland Steam Plant in northwestern Tennessee as mentioned in this paper, where representatives from 25 governmental agencies, universities, research institutes, and private contractors participated in this joint meteorological/chemical study in an attempt to define plume transport, dispersion, transformation, and removal rates under various meteorological conditions.
Abstract: Spurred by the rising sulfate concentrations in the north-eastern United States, the Environmental Protection Agency (EPA) has established the Sulfur Transport and Transformation in the Environment (STATE) program to quantitatively determine the impact on local air quality of distant source pollutants and their transformation products. The first major STATE field study was the August 1978 Tennessee Plume Study conducted near the Cumberland Steam Plant in northwestern Tennessee. Representatives from 25 governmental agencies, universities, research institutes, and private contractors participated in this joint meteorological/chemical study in an attempt to define plume transport, dispersion, transformation, and removal rates under various meteorological conditions. A description of the field activities reveals the preplanned experimental guidelines and the flexibility with which the sampling activities were performed. The analytical priorities have since been established and various investigators a...
TL;DR: In this article, the clients of a meteorological consulting firm were studied to determine the effects of weather forecasts on their operations, and the monetary losses incurred as a result of incorrect forecasts were calculated.
Abstract: The clients of a meteorological consulting firm were studied to determine the effects of weather forecasts on their operations. We determined what weather conditions triggered certain operational decisions in three groups of clients—governmental bodies, gas utilities, and electric utilities. Then, using actual forecasts over a 2-year period, we calculated the monetary losses incurred as a result of incorrect forecasts. The results generally show losses in the thousands of dollars for each erroneous forecast. Thus, if the weather service is able to prevent even one set of poor decisions based on a forecast, the cost of the service would be returned and in many cases greatly exceeded. Other effects of the clients’ use of the forecast are discussed qualitatively. These include nonmonetary gains to the clients and their customers through increased convenience, easier planning, and fewer breakdowns in service. At least some clients fail to realize these advantages through inefficient use of the forecast.
TL;DR: In this paper, the forecaster has available high quality satellite pictures which enable high accuracy in initialization of numerical models, but their accuracy is limited by initialization errors, which is a limitation of their accuracy.
Abstract: Even though numerical models have made great strides forward in recent years, their accuracy is limited by initialization. The forecaster has available high quality satellite pictures which enable ...
TL;DR: A storm-surge model developed in 1977 for Southeast Louisiana predicts sea, lake, and overland surges from hurricanes (SLOSH) was used to profile definitive evidence for the varied impact of storm surges to future generations in Southeast Louisiana as discussed by the authors.
Abstract: A storm-surge model developed in 1977 for Southeast Louisiana predicts sea, lake, and overland surges from hurricanes (SLOSH). Primary model output is the average water level conditions over a finite geographical area. The model appears capable of profiling definitive evidence for the varied impact of storm surges to future generations in Southeast Louisiana; however, model surge forecasts are governed strongly by the accuracy in describing the movement and intensity of tropical storms. A simplified initial study was undertaken to gain a physical understanding of, and insights on, the potential surges over Southeast Louisiana. A brief synopsis of the hurricane flood potential is given.
TL;DR: The use of weather modification by farm groups, state agencies, and power companies to perform operational projects continues to expand as discussed by the authors, and a project has been launched to develop statistical-physical evaluation techniques for operational projects.
Abstract: Use of weather modification by farm groups, state agencies, and power companies to perform operational projects continues to expand. Seven percent of the United States experienced cloud seeding during 1977. The major stakeholders—those paying, those performing the seeding, and the scientific community—have all converged on the need to evaluate operational projects. Major assessments of the national situation have recommended that carefully conducted operational projects can be a source of useful scientific information if designed, operated, and evaluated properly. A project has been launched to develop statistical-physical evaluation techniques for operational projects.
TL;DR: In this paper, the authors used cloudiness data from weather satellites to refine the insolation maps and measured wind, insulation, temperature, humidity, and rainfall, aiming at improving their understanding of physical processes and at developing methods of wind and insulation forecasting.
Abstract: Hawaii, with no indigenous fossil fuel resources, is particularly susceptible to oil shortages; hence, surveys have been underway for some time to evaluate the potential of wind and insolation as alternate energy sources. Since numerical modeling of the wind field is inadequate, we have been using fixed and mobile stations to monitor the wind distribution, finding that on parts of each of the main islands average speeds are more than adequate for economic power generation. A radiometer network on Oahu and scattered measurements elsewhere reveal that over most areas sheltered from the trade winds, insulation is as high as anywhere in the continental United States. We are using cloudiness data from weather satellites to refine the insolation maps. On recent field programs, we measured wind, insulation, temperature, humidity, and rainfall, aiming at improving our understanding of physical processes and at developing methods of wind and insulation forecasting.
TL;DR: In this article, the authors analyzed the trends in forecast skill at the National Severe Storms Forecast Center and found that during significant tornado days, a much higher degree of skill is exhibited for both outlooks and watches.
Abstract: Tornado watch and severe local storm outlook verification statistics reveal the trends in forecast skill at the National Severe Storms Forecast Center. The skill level of the outlook has been steadily increasing since 1973. The percentage of watches verifying has been gradually increasing since 1970. While the probability of detection for tornadoes has decreased slightly since 1974, this appears to be highly correlated with the number of outbreak tornadoes reported in a given year. During significant tornado days, a much higher degree of skill is exhibited for both outlooks and watches. Factors influencing the results are discussed, including the impact of snoptic scale operational numerical prediction models on the severe local storm forecasting process.
TL;DR: The State of Illinois has established a climate center addressing a wide variety of climate-related activities as mentioned in this paper, which has evolved after 25 years of services, research, and data management addressing the climatology of Illinois and the Midwest.
Abstract: The State of Illinois has just established a climate center addressing a wide variety of climate-related activities. This center has evolved after 25 years of services, research, and data management addressing the climatology of Illinois and the Midwest. The products of this effort reflect state-related interests in climate information and data. The Illinois program may also help serve as a model for some states who will evolve centers as part of the federal-state cooperative effort that is to be an integral part of the National Climate Program.