Showing papers in "Bulletin of the American Meteorological Society in 1986"

An Evaluation of Summer Discomfort in the United State Using a Relative Climatological Index

Abstract: A relative climatological index is developed to evaluate interregional variations in human discomfort and the impacts of weather on a variety of socioeconomic parameters. The “weather stress index” is designed to assess the frequency and magnitude of the most uncomfortable weather conditions, and data inputs are limited to air temperature, dewpoint, and wind speed. The index is constructed by calculating the apparent temperature using a simple algorithm and comparing how a particular day's apparent temperature varies from the mean for that day at that locale. The index ranges from 0 percent to 100 percent, with the most uncomfortable apparent temperatures exhibiting the highest values. A geographical distribution of July apparent temperatures at the 95 percent and 99 percent weather-stress-index level indicates that the central and south central United States experience the highest apparent temperatures in the nation. These conditions occur when the surface flow permits maritime air to intrude wh...

HAPEX—MOBLIHY: A Hydrologic Atmospheric Experiment for the Study of Water Budget and Evaporation Flux at the Climatic Scale

Abstract: The HAPEX-MOBILHY program is aimed at studying the hydrological budget and evaporation flux at the scale of a GCM (general circulation model) grid square, i.e., 104 km2. Different surface and subsurface networks will be operated during the year 1986, to measure and monitor soil moisture, surface-energy budget and surface hydrology, as well as atmospheric properties. A two-and-a-half-month special observing period will allow for detailed measurements of atmospheric fluxes and for intensive remote sensing of surface properties using well-instrumented aircraft. The main objective of the program, for which guest investigations are strongly encouraged, is to provide a data base against which parameterization schemes for the land-surface water budget will be tested and developed.

Observing-Systems Simulation Experiments: Past, Present, and Future

Abstract: A summary of the history of observing-systems simulation experiments (OSSEs) is presented together with a description of current methodology, its capabilities and limitations, and considerations for the design of future experiments. These experiments are defined as a type of sensitivity study and are contrasted with real-data experiments otherwise known as observing-systems experiments (OSEs), data-impact, or data-denial experiments, which form a related type of sensitivity study. Simulation is presented as a means by which an a priori evaluation of proposed remote-sensing systems ran be made.

Some comments on passive microwave measurement of rain

Abstract: It is argued that because microwave radiation interacts much more strongly with hydrometeors than with cloud particles, microwave measurements from space offer a significant chance of making global precipitation estimates. Over oceans, passive microwave measurements are essentially attenuation measurements that can be very closely related to the rain rate independently of the details of the drop-size distribution. Over land, scattering of microwave radiation by the hydrometeors, especially in the ice phase, can be used to estimate rainfall. In scattering, the details of the drop-size distribution are very important and it is therefore more difficult to achieve a high degree of accuracy. The SSM/I (Special Sensor Microwave Imager), a passive microwave imaging sensor that will be launched soon, will have dual-polarized channels at 85.5 GHz that will be very sensitive to scattering by frozen hydrometeors. Other sensors being considered for the future space missions would extend the ability to estimate rain rates from space. The ideal spaceborne precipitation-measurement system would use the complementary strengths of passive microwave, radar, and visible/infrared measurements.

Scale Invariance, Symmetries, Fractals, and Stochastic Simulations of Atmospheric Phenomena

Abstract: Advances in remote sensing and in situ measurement techniques have revealed the full continuum of atmospheric motions and have underlined the importance of mesoscale processes. This paper examines the implications of three observed characteristics of mesoscale circulations: 1) the energy spectrum of the horizontal wind in the horizontal is of the form k−βh with βh ~ 5/3, (k is a wave-number); 2) the corresponding spectrum in the vertical direction is of the same scaling form, but with a very different slope (βv ~ 11/5); and 3) the variability is extreme. Some recent work in turbulence, physics, and meteorology, that is relevant to systems with extreme variability over a wide range of scales is reviewed. The concepts of scaling, intermittency, and fractals, are briefly introduced to show how they can be used to understand the physics of both homogeneous and intermittent energy cascades in isotropic atmospheres. These concepts may be generalizable (with a formalism called generalized scale invariance), to a...

The 40-50 day oscillation and the El Niño/Southern Oscillation: a new perspective

Abstract: The tropical Ocean-atmosphere exhibits two prominent modes of low-frequency oscillations, ie, the “40-50” day oscillation and the El Nino/Southern Oscillation (ENSO) The two phenomena are viewed in the same perspective from 10 years of satellite-derived out-going-longwave-radiation data Results reveal some interesting features that may lead to new insights into the understanding of the two phenomena

On the design of national, real-time-warning systems with capability for site-specific, flash-flood forecasts

Abstract: Presented are necessary requirements of a modern-day flash-flood warning system that is capable of site-specific forecasts and that is suitable for national implementation. The requirements are identified based on the hydrometeorological character of the flash-flood phenomenon and on the real-time nature of the forecast procedure. Contemporary theories of heavy-rainfall and runoff generation and development are reviewed.

The Oklahoma-Kansas Preliminary Regional Experiment for STORM-Central

Abstract: During May and June 1985, the Oklahoma-Kansas Preliminary Regional Experiment for STORM-Central (the Oklahoma-Kansas PRE-STORM Program) was conducted to investigate the structure and dynamics of mesoscale convective systems (MCSs). As the name implies, the program was conducted over the Oklahoma and Kansas regions and emulated to some degree the β-scale network array proposed for the full-scale STORM-Central program. A number of sensing systems, including Doppler radars, digitized radars, surface mesonetwork stations, supplemental and National Weather Service (NWS) rawinsondes, wind profilers, a lightning location system, satellite products, and research aircraft were brought together to collect the data necessary to begin the investigations of MCSs. At the same time, testing and evaluation of new sensing systems, such as profilers and airborne Doppler radar, were carried out to determine how best to operate them in a coordinated observing system. Sixteen operational missions were conducted in which one o...

A Review of the Sierra Cooperative Pilot Project

Abstract: The Sierra Cooperative Pilot Project (SCPP) is an investigation of cloud seeding as a means of increasing winter precipitation on the Sierra Nevada. It is a concerted effort in the development of a physically sound cloud-seeding technology. It involves the use of remote-sensing devices, in situ observations, and the application of a numerical targeting model in randomized seeding experiments. The results have led SCPP scientists to believe that shallow but widespread orographic clouds provide the best opportunity for glaciogenic seeding in the central Sierra Nevada.

Doppler lidar measurements of winds in a narrow mountain valley

Abstract: During September and October of 1984, the Wave Propagation Laboratory of NOAA used its pulsed infrared Doppler lidar in support of the U.S. Department of Energy's Atmospheric Studies in Complex Terrain (ASCOT) program. The lidar measured winds channeled within a narrow mountain valley on seven experiment nights, between 2300 and 1100 MST. We were able to quantitatively define the structure of the nocturnal drainage winds, monitor their decay in the morning, and sense the formation of a thermally driven up-valley flow later in the day.

On the Economic Value of Seasonal-Precipitation Forecasts: The Fallowing/Planting Problem

Abstract: The so-called fallowing/planting problem is an example of a decision-making situation that is potentially sensitive to meteorological information. In this problem, wheat farmers in the drier, western portions of the northern Great Plains must decide each spring whether to plant a crop or to let their land lie fallow. Information that could be used to make this decision includes the soil moisture at planting time and a forecast of growing-season precipitation. A dynamic decision-making model is employed to investigate the economic value of such forecasts in the fallowing/planting situation. Current seasonal-precipitation forecasts issued by the National Weather Service are found to have minimal economic value in this decision-making problem. However, relatively modest improvements in the quality of the forecasts would lead to quite large increases in value, and perfect information would possess considerable value. In addition, forecast value is found to be sensitive to changes in crop price and pr...

FOG-82: a cooperative field study of radiation fog

Abstract: The Cloud Physics Section of the Atmospheric Sciences Research Center-State University of New York at Albany conducted a cooperative field study (FOG-82) during the autumn of 1982 as part of an ongoing radiation-fog research program. A computer-controlled data-acquisition system consisting of sophisticated soil, surface, and boundary-layer sensors, as well as contemporary aerosol and droplet probes was developed. These data are being used to address a variety of critical problems related to radiation-fog evolution. Scientists from 10 universities and research laboratories participated in portions of FOG-82. Research objectives included studies of fog mesoscale meteorology, radiation studies, low-level water budget, vertical fog structure, fog supersaturation, condensation nuclei, and fog-water chemistry, as well as radiation-fog life cycles. A comprehensive description of the FOG-82 program and objectives is presented.

El Niño/Southern Oscillation Events and Their Associated Midlatitude Teleconnections 1531–1841

Abstract: This paper reports on an investigation into the chronology of El Nino/Southern Oscillation (ENSO) events during the period from the arrival of Europeans in Peru in 1531 until the year 1841 when conventional barometric data became available in the tropical regions. A number of probable ENSO events can be dated from anecdotal reports of significant rainfall in the coastal desert of northern Peru. In many of the years with anomalous Peruvian rainfall it is also possible to use various types of proxy data to identify aspects of the global teleconnection patterns usually associated with tropical ENSO events.

The Social Burden of Weather and Climate Hazards

Abstract: Socioeconomic vulnerabilities and impacts associated with weather and climate hazards in the United States are assessed. Trends in deaths and economic losses resulting from tornadoes, tropical storms and hurricanes, and floods (including flash floods) are presented in detail. To the extent possible, death statistics are normalized by the population at risk, and loss data are adjusted for inflation. The results suggest a significant decline in deaths attributed to tornadoes and hurricanes at the same time that property damages have increased. In contrast, both deaths and losses due to floods have increased substantially in the past few decades. A qualitative assessment is made of the effects of socioeconomic trends (e.g., the aging population) on the nation's sensitivity to atmospheric hazards and on the need for better information about these hazards. While the tally shows mixed impacts on vulnerability (i.e., some trends may reduce vulnerability while others increase it), the impact on information needs ...

The Fleet Numerical Oceanography Center Global Spectral Ocean Wave Model

Abstract: The Spectral Ocean Wave Model (SOWM) has been an operational product at Fleet Numerical Oceanography Center since the mid 1970s; the Global Spectral Ocean Wave Model (GSOWM) was developed to replace it. An operational test of GSOWM, using buoy, ocean-weather-station, and ship-reported wave-height data for verification, was conducted during the winter of 1984/85 by several components of the Naval Oceanography Command. This test indicated that GSOWM was superior to SOWM and that both models exhibited root-mean-square significant-wave-height errors on the order of 1 m. Wave-height errors deduced from the ship observations were comparable to those calculated from the buoy data. The GSOWM scatter index, determined from the buoy and ocean-weather-station data and defined as the, standard deviation of the model-predicted wave-height error divided by the mean observed wave height, averaged 0.34. As a result of the study reported here, GSOWM replaced SOWM as the U.S. Navy's operational wave model in June ...

Jet Contrails and Cirrus Cloud: A Feasibility Study Employing High-Resolution Satellite Imagery

Abstract: The results of a pilot study to assess the feasibility of documenting the occurrence of jet contrails over the United States from high-resolution Defense Meteorological Satellite Program (DMSP) imagery are presented. They are strongly positive, suggesting that 1) contrails can be distinguished from natural cirrus on the imagery; 2) contrails are consistently identifiable; 3) contrails often occur in association with the natural cirrus and frequently spread, and 4) this spreading could extend the accompanying natural cirrus shield. The analyses also indicate that contrails tend to occur relatively frequently, that they more often cluster in groups than appear singly, and that they seem to show a preference for developing in (near) upper-tropospheric cold troughs (ridgelines). It is accordingly suggested that DMSP imagery can provide a basis for research into a contrail-cirrus-climate relationship.

A Historical Review of Cumulus Entrainment Studies

Abstract: A review of the history of studies on cumulus entrainment with the emphasis on the most recent developments is presented.

The Frontal Air-Sea Interaction Experiment (FASINEX). II - Experimental plan

Abstract: The Frontal Air-Sea Interaction Experiment (FASINEX) is a study of the response of the upper ocean to atmospheric forcing in the vicinity of an oceanic front in the subtropical convergence zone southwest of Bermuda, the response of the lower atmosphere in that vicinity to the oceanic front, and the associated two-way interaction between ocean and atmosphere. FASINEX is planned for the winter and spring of 1985-1986 with an intensive period in February and March 1986 in the vicinity of 27 deg N, 70 deg W, where sea-surface temperature fronts are climatologically common. Measurements will be made from buoys, ships, aircraft, and spacecraft. A previous article gave a brief history of FASINEX and presented its scientific goals. This article describes the FASINEX experimental plan.

The BMRC Australian Monsoon Experiment: AMEX

Abstract: The Bureau of Meteorology Research Centre (BMRC) willbe conducting a major research effort in the Australian tropics during 1986-1988 including a two-phase field experiment, the Australian Monsoon Experiment (AMEX). This will be done in collaboration with Monash University and with scientists and concomitant experiments from a numberof other international and national organizations. The aims of this research are to improve our understanding of the way that cumulonimbus convection and tropicalcloud clusters interact with the larger-scale circulation; ofair-sea interaction in the tropics; and of specif,c weather phenomena in the north Australian region. The scope of theexperiment is such that it also will provide a data base ofsome importance for atmospheric research into the tropicalatmosphere. This paper describes the background in which AMEX wasconceived, the experimental objectives, and the observingprogram. More-complete details may be found in McBrideand Holland (1986).

Computer-generated imagery for 4-D meteorological data

Abstract: The University of Wisconsin-Madison Space Science and Engineering Center is developing animated stereo display terminals for use with McIDAS (Man-computer Interactive Data Access System). This paper describes image-generation techniques which have been developed to take maximum advantage of these terminals, integrating large quantities of four-dimensional meteorological data from balloon and satellite soundings, satellite images, Doppler and volumetric radar, and conventional surface observations. The images have been designed to use perspective, shading, hidden-surface removal, and transparency to augment the animation and stereo-display geometry. They create an illusion of a moving three-dimensional model of the atmosphere. This paper describes the design of these images and a number of rules of thumb for generating four-dimensional meteorological displays.

The Cooperative Huntsville Meteorological Experiment (COHMEX)

Abstract: The Satellite Precipitation and Cloud Experiment, the Microburst and Severe Thunderstorm, and the FAA Lincoln Laboratories Operational Weather Studies of the COHMEX are described. The precipitation and cloud experiment focuses on the prestorm period in order to observe the physical processes leading to the formation of small convective systems. Aircraft, remote sensing and rewinsonde data are utilized to determine various storm/environment characteristics. Doppler velocity and reflectivity of microburst clouds are studied to evaluate the three-dimensional structure of microbursts from thunderstorms. The weather studies are designed to develop and test automatic algorithms for wind shear detection using Doppler weather radars. The application of satellite systems to data collection for these experiments is discussed.

On climate prediction in the tropics

Abstract: Climatic disasters are common in many tropical regions, and rainfall anomalies in particular have a severe human impact. Accordingly, both the World Climate Programme and the U.S. National Climate Program have identified climate prediction as a major objective. Approaches can be grouped into five major categories: (i) the extrapolation of empirically or theoretically deduced periodicities; (ii) the assessment of statistical relationships between rainfall and various meteorological elements; (iii) the relation between rainfall in the preseason and at the height of the rainy season; (iv) comprehensive diagnostic studies of climate and circulation anomalies combined with statistical methods; and (v) numerical modeling. Methods pertaining to (iv) indicate the feasibility of empirically based climate prediction for certain tropical regions. For the drought-prone region of northeast Brazil and Indonesia, in particular, it has been demonstrated on independent data sets that almost half of the interannua...

Subscribers to the NOAA Monthly and Seasonal Weather Outlook

Abstract: The identity and characteristics of users of existing climate predictions (monthly and seasonal) as inputs to decision making am described. Subscribers to the NOAA Climate Analysis Center's Monthly and Seasonal Weather Outlook (MSWO) are surveyed by questionnaire to identify their industry types, general levels of climate-information use, and geographic locations. Characteristics of subscribers who have indicated that they do use the predictions in decision making, as opposed to those who do not, are determined using stepwise discriminant analysis. It is found that agricultural activities represent the largest group of subscribers, whereas energy producers and distributors represent the largest group of systematic users of the climate predictions. Maps showing the distribution of the three leading categories of respondents (agriculture, energy, and government and education) are presented to show where certain types of subscribers are located and where they most often apply the predictions. The an...

National Data Buoy Center Programs

Abstract: The National Data Buoy Center(NDBC) operates ocean and coastal buoys and coastal land stations that report hourly through the Geostationary Operational Environmental Satellite (GOES) system. In addition, NDBC maintains drifting-buoy networks that report through the polar-orbiting TIROS-N satellites. To disseminate information on these systems that provide vital environmental reports from data-sparse marine areas, the data-acquisition systems, net-works, monitoring capabilities, data processing and distribution, data quality and availability, and future programs are discussed.

Evaluation of RADAP II Severe-Storm-Detection Algorithms

Abstract: Computer-generated volumetric radar algorithms have been available at a few operational National Weather Service sites since the mid-1970s under the Digitized Radar Experiment (D/RADEX) and Radar Data Processor (RADAP II) programs. The algorithms were first used extensively for severe-storm warnings at the Oklahoma City National Weather Service Forecast Office (WSFO OKC) in 1983. RADAP II performance in operational severe-weather forecasting was evaluated using objectively derived warnings based on computer-generated output. Statistical scores of probability of detection, false-alarm rate, and critical-success index for the objective warnings were found to be significantly higher than the average statistical scores reported for National Weather Service warnings. Even higher statistical scores were achieved by experienced forecasters using RADAP II in addition to conventional data during the 1983 severe-storm season at WSFO OKC. This investigation lends further support to the suggestion that incorporating ...

A Report on the Upper-Level Wind Conditions Preceding and During the Shuttle Challenger (STS 51L) Explosion

Abstract: The prelaunch, launch, and postlaunch synoptic-scale weather conditions on January 28, 1986 are described. Particular consideration is given to upper-level jet streams, vertical wind shear, and the possible effect of shear-induced turbulence on Cape Canaveral at the time of the Shuttle launch. General data revealing the relations between wind shear and turbulence and jet streams are discussed. The NWS operational and surface radiosonde data, visible and IR GOES imagery, and total ozone data obtained from TOMS on Nimbus-7 are analyzed. Numerical simulations of the weather conditions were conducted. The simulations and observational data are compared, and the data reveal the juxtaposition of two distinct jet-stream systems (a polar front jet and a subtropical jet) over north-central Florida the morning of the launch. Recommendations for improving the observing system at Cape Canaveral are discussed.

Transient Medium-Scale Wave Activity in the Summer Stratosphere

Abstract: Observations of medium-scale transient wave activity in the middle-latitude Southern Hemisphere summer stratosphere are interpreted using isentropic potential vorticity (IPV) distributions inferred from temperature data from the Nimbus-7 Limb Infrared Monitor of the Stratosphere (LIMS) instrument. Despite problems with errors in reference-level synoptic height information, the derived IPV distributions clearly exhibit dynamically coherent signatures of eddy mixing due to medium-scale disturbances in the lower-middle stratosphere during early January 1979. The IPV distributions are shown to be strongly correlated with those of a contemporaneous set of isentropic maps of quasi-conservative tracers such as ozone and nitric acid. The results suggest that IPV maps inferred from satellite temperature data provide a useful diagnostic for studies of large-scale dynamics and/or transport in the extratropical stratosphere. Furthermore, the comparatively high vertical resolution of the LIMS data has enabled the vertical attenuation of Southern Hemisphere wave activity to be diagnosed in greater detail than could be achieved from nadir-viewing satellite information.

The Joint Agricultural Weather Facility's Operational Assessment Program

Abstract: The Joint Agricultural Weather Facility (JAWF), a cooperative effort between the Climate Analysis Center, NMC/NWS/NOAA (National Meteorological Center/National Weather Service/National Oceanic and Atmospheric Administration) and the World Agricultural Outlook Board, U.S. Department of Agriculture (USDA), focuses on weather anomalies and their effects on the crop-yield potential in major international crop areas. The basic mission is to provide an objective procedure for translating the flow of global weather information into timely and accurate assessments of growing-season conditions which ultimately impact on global agricultural production and trade. Daily monitoring of satellite weather images and meteorological data provides the framework for agricultural weather analysis. Daily, weekly, and seasonal summaries are processed and merged with historical weather and crop data for evaluation of the crop-yield potential. Information is disseminated at routine briefings, in written summaries, and through inf...