Philip J. Stenger

Increasing frequencies of warm and humid air masses over the conterminous United States from 1948 to 2005

Time series of individual climate variables, such as air temperature and precipitation, have been thoroughly examined to evaluate climate change, but few studies have evaluated how air masses have varied over time. We use the Spatial Synoptic Classification air mass approach to classify multivariate meteorological surface variables into discrete groups and examine trends in air mass frequencies over the period 1948-2005 for the continental United States. We observe increases in warm, moist air masses at the expense of cold, dry air masses, consistent with expectations in an atmosphere with increasing greenhouse gas concentrations. Temporal variations in the North Atlantic Oscillation, Pacific/North American teleconnection pattern, Arctic Oscillation, and El Nino-Southern Oscillation partially explain some of these observed trends in winter.

A comparison of seasonal trends in asthma exacerbations among children from geographic regions with different climates.

BACKGROUND The fall peak in childhood asthma exacerbations is thought to be related to an increase in viral infections and allergen exposure when children return to school. Whether the seasonality of asthma attacks among children from different geographic regions follows similar trends is unclear. OBJECTIVE To compare seasonal trends in asthma exacerbations among school-age children who lived in different geographic locations, with different climates, within the United States. METHODS Hospital billing data bases were examined to determine the monthly number of school-age children who were hospitalized or treated in the emergency department (ED) for asthma exacerbations. Data from four cities within three states were compared. Climate data were obtained from archives of the National Climate Data Center, U.S. Department of Commerce. RESULTS An annual peak in asthma exacerbations was observed during the fall months (September through November) among children who lived in Charlottesville, Virginia, as well as throughout the state of Virginia. An increase in exacerbations, which peaked in November, was observed for exacerbations among children who lived in Tucson, Arizona, and Yuma, Arizona. In contrast, exacerbations among children from New Orleans, Louisiana, increased in September but remained elevated throughout the school year. Although there was annual variation in the frequency of exacerbations over time, the seasonal patterns observed remained similar within the locations from year to year. A nadir in the frequency of attacks was observed during the summer months in all the locations. CONCLUSION Seasonal peaks for asthma exacerbations varied among the children who lived in geographic locations with different climates, and were not restricted to the beginning of the school year.

Development of a Discriminant Analysis Mixed Precipitation (DAMP) Forecast Model for Mid-Atlantic Winter Storms

Abstract The frequency of “wintry mix” precipitation—freezing rain and ice pellets—is considerable in the mid-Atlantic region of the United States. Despite the fact that the general conditions necessary to support the various winter precipitation types have been known for years, in that region, the proper forecast of type and duration of winter precipitation is one of the most difficult challenges in operational meteorology, with extensive public safety and economic ramifications. The purpose of this project is to report on an improved methodology for winter precipitation forecasts. This study analyzed precipitation type and surface temperature data from NOAA’s hourly surface airway observations and temperatures and heights for all mandatory and significant levels from NOAA’s Radiosonde Data of North America from Washington Dulles International Airport, Virginia (1962–95), and Greensboro, North Carolina (1948–95). Precipitation that occurred within 2 h of a sounding for the months November through March w...

Climatic change in mixed-layer trajectories over large regions

SummaryUsing a modified version of the NOAA ARL/ATAD model, a series of over 300,000 mixed-layer back trajectories were calculated in eighteen hour time steps through the period 1948–1985 for seventeen trajectory endpoints in and around the state of Virginia. Results of these trajectory runs were aggregated both seasonally and annually to a spatial grid system covering approximately the eastern two-thirds of the United States. From this were generated plots of trajectory frequencies, residence times and transport times. A principal components analysis was performed on the spatial distribution of the gridded trajectory frequency data. The first principal component is dominated by mixed-layer-flow from the Ohio Valley and the Upper Midwest. A time-series plot of this component indicates a dramatic increase in this northwesterly flow over the study period, especially in the 1950s and early 1960s. A possible link between this observed phenomenon and anthropogenic climate alteration is discussed.

Modelling changes in the epidemic range of Southern Pine Beetle using temperature and objective moisture indicators

SummaryThis report details as statistical model that relates changes in areal coverage of the Southern Pine Beetle (Dendroctonus frontalis Zimm.) to a multivariate combination of temperature and moisture status indices. It is applicable to larger geographic areas than our previous work (Michaels 1984). Performance in a true test (predictive) mode detected the algebraic sign of major coverage changes in a highly significant fashion. The results are purely correlative, rather than causative.This report describes a test-proven tool that can be used by planners to determine whether coverage will change, based upon easily accessed climatic data. An example of its application is provided.ZusammenfassungDiese Untersuchung führt ein statistisches Modell aus, welches das flächenmäßige Auftreten vonDendroctonus frontalis Zimm. mit einer Kombination von Temperaturund Feuchteverhältnisindikatoren in Verbindung bringt. Es kann für größere Gebiete verwendet werden als ein früher vorgestelltes (Michaels 1984). Die Anwendung zur Vorhersage zeigte in einem Test gute Übereinstimmung mit der tatsächlich aufgetretenen Richtung der Veränderung in der Verbreitung des Käfers. Die Ergebnisse zeigen Korrelationen, keine Kausalitäten auf.Es wird also ein Werkzeug für den Planer vorgestellt, mit dem die Verbreitungsänderung mit Hilfe leicht zugänglicher klimatologischer Daten bestimmt werden kann. Ein Anwendungsbeispiel wird näher ausgeführt.

Climate and the eastern repository: A comparative study

We present a comparison of the climate in prospective states or sites under consideration for the eastern repository for high-level nuclear waste in the United States.We found that atmospheric conditions over several south-eastern sites rank lower than the other prospective areas in effective dispersal, as perFederal Register 10CFR 960.5-2-3 (1984). Also, damage rates in North Carolina and Virginia, and death rates in Virginia, from tropical storms and hurricanes exceed those of the other candidate states. These storms, as well as other mechanisms, subject piedmont Virginia and North Carolina to a high frequency of flash flooding. Death rates from all weather-related causes (including winter storms, tornadoes, and weather-related vehicle accidents) are also highest in Virginia and North Carolina. This finding is rather surprising in light of tornado and blizzard frequencies in northern candidate states.Based upon a 20-year study of damage and mortality figures from the US Department of Commerce publicationStorm Data for all weather-related causes, Virginia and North Carolina rank highest. If this is taken as a measure of relative compliance withFederal Register “potentially adverse condition” 960.5-2-3[c][2] pertaining to the history of severe weather phenomena in relation to repository siting, then these states are the least favorable from a climatic viewpoint.