Philip W. Suckling

On the Use of Synoptic Weather Map Typing to Define Solar Radiation Regimes

A synoptic approach to the analysis of solar radiation regimes is undertaken with the aim of developing a synoptic solar radiation climatology. Synoptic weather types for an area including British Columbia and the adjacent regions of the northeastern Pacific are defined using an objective correlation classification technique. These weather types are shown to determine statistically distinct solar radiation distributions. However, further analysis shows that the distinctiveness of the solar radiation regimes is not sufficient to be used in practical applications such as interpolation between measurement stations, estimation of solar radiation inputs in the absence of observed data or in the explanation of the interannual variability of solar radiation. As a result, attempts to base a solar radiation climatology solely on the synoptic regimes defined using the readily available data and techniques employed in this study are not justified. However, the statistical analyses do suggest that the use of more appropriate synoptic data and typing techniques may overcome many of the inadequacies in the present study.

FLUCTUATIONS OF LAST SPRING-FREEZE DATES IN THE SOUTHEASTERN UNITED STATES

Fluctuations for the date of the last spring freeze are examined for the period 1916–1985 for a portion of the southeastern United States including much of Alabama, Georgia, South Carolina, and southern North Carolina. Data from 43 meteorological sites were utilized. For a large portion of the region, mean dates of the last spring freeze were considerably later for the recent 35-year period 1951–1985 compared to the earlier 1916–1950 period. Of the 43 study sites, 19 experienced statistically significant later last spring freezes for the latter half of the study period while none experienced significantly earlier last freeze dates. Of potential agricultural importance is the fact that major peach growing areas in central Georgia and west-central South Carolina are located within the region of statistically significant later spring freezes.

TRENDS IN MONTHLY TEMPERATURE DEPARTURES FOR THE CONTINGUOUS UNITED STATES, 1940-1983

A temperature departure index is calculated for each month of the year for 10 regions within the contiguous United States utilizing a total of 193 sites for the 44-year period 1940 to 1983. Five-year moving averages of the index values are plotted on graphs for each region by month in an attempt to detect trends toward an increase or decrease in the occurrence of well above or well below normal monthly temperatures in recent years. Considerable regional differences are found with respect to the size and temporal trend of monthly temperature departures. For example, the Northwest and Southwest regions are often exceptions to the average national trend supporting the concept of considerable east-west differences in temperature variation patterns. Only April, June and December show increases in temperature departure index values in the most recent years for a majority of regions while the summer months of July and August do not exhibit a clear national trend. For a majority of months (January, February, Marc...

A CLIMATE DEPARTURE INDEX FOR THE STUDY OF CLIMATIC VARIABILITY

Three versions of a Climate Departure Index (CDI) are presented for studying how “normal” or “unusual” a particular year or event is compared to the long-term average for the region under consideration. Comparisons of a Simple CDI, Absolute Value CDI and Least-Squares CDI are made through the use of hypothetical examples and two case studies involving seasonal snowfall variations in northern New England and last spring-freeze date variations in the southeastern United States. Results clearly show that the Simple CDI is the inferior formulation owing to a compensation problem whereby above and below average sites within a region for a particular year cancel each other when computing the index value. Little difference in identifying extreme years was found between use of the Absolute Value CDI and Least-Squares CDI in the case studies examined. Nevertheless, a hypothetical example suggests that the least-squares approach for closeness of fit is the more appropriate method, thus making the Least-Squares CDI ...

AN ASSESSMENT OF THE ADEQUACY OF THE SOLAR RADIATION DATA NETWORK FOR THE CONTIGUOUS UNITED STATES

Relationships between the coefficient of variability and the logarithm of extrapolation distance are established by an assessment of the spatial coherence of solar radiation. Equations for different confidence levels and daily and monthly time intervals are presented. These relationships are utilized in an assessment of the adequacy of the solar radiation data network in the contiguous United States. Results indicate that the present network maintained by the federal government provides adequate coverage on a monthly basis for all but 5% of the area for an error tolerance of ±10% at a 90% confidence level. However, on a daily basis, very inadequate spatial coverage is provided.

Impact of climatic variability on residential electrical energy consumption in the Eastern United States

SummaryThe influence of interannual climatic variability upon variations in residential electrical energy consumption for 15 locations in the eastern United States is investigated. Utilizing monthly data grouped into four seasons for several years, the role of interannual climatic fluctuation is found to be important with the most influential climatic term usually being heating degree days or cooling degree days. The strongest relationships were in spring for northern sites and in fall for southern sites while the winter relationships were generally weakest.ZusammenfassungDer Einfluß interannualer Klimaschwankungen auf Veränderungen im elektrischen Energieverbrauch in Wohnhäusern wurde für 15 Örtlichkeiten in den östlichen Vereinigten Staaten untersucht. Bei Verwendung von monatlichen Daten, die für etliche Jahre in vier Jahreszeiten gruppiert wurden, erwiesen sich interannuale Klimaschwankungen als wichtiger Faktor, wobei der einflußreichste Klimaterm durch Wärmegradtage oder Kältegradtage ausgedrückt werden konnte. Die besten Korrelationen wurden im Frühling in nördlichen Lagen und für Herbst in südlichen Lagen erhalten, während die Winterkorrelationen im allgemeinen am schwächsten ausgedruckt waren.

Clear-Day Frequencies and“Indian Summer”at Athens, Georgia and Chattanooga, Tennessee

Abstract Indian summer has been defined as a period of clear weather with warm days and cool nights occurring during mid- or late autumn after the first frost or freeze of the season. Weekly clear-day frequencies (using two definitions of clear days: 0.0 cloud cover and 0.0–0.3 cloud cover) are analyzed in this study for periods of more than 30 years for the southeastern sites of Athens, Georgia and Chattanooga, Tennessee in an attempt to detect Indian summer. Results indicate that distinct periods of high clear-day frequencies occur throughout much of October as well as during the first two weeks of November and the week of 29 November– 5 December. Consideration of temperature and synoptic climatological conditions during these latter weeks eliminated their consideration as part of the Indian summer phenomenon. Therefore, Indian summer as defined by clear-day frequency occurs primarily during the October weeks of 4–10, 11–17 and 18–24. As was the case in a previous study for the north-central United Stat...

ANALYSIS OF SUMMERTIME DAILY PRECIPITATION FOR THE OKEFENOKEE SWAMP REGION

An assessment of the summertime precipitation climate for the Okefenokee Swamp region was undertaken utilizing daily precipitation data from meteorological sites near the swamp for the period 1955-1980. “Runs of dry days” were investigated in relation to total seasonal precipitation and with regard to the distribution of runs by length. Utilizing Markov chain analysis and regression techniques, relationships between the length of runs of dry days and total seasonal precipitation as well as cumulative number of runs of dry days and total seasonal precipitation were established. However, further analysis of the intensty distribution of daily precipitation suggested that the summertime precipitation climate could best be described utilizing an assessment of days with a significant amount of precipitation rather than by studying runs of dry days. An analytical definition of a “significant rain day” was attempted utilizing the correlation of the number of rain days exceeding a given daily precipitation thresho...