Sharon K. Leduc

Precipitation Patterns in West Africa

Abstract A regional precipitation analysis from a total of 813 recording stations in 11 West African countries for the drought period 1968–75 is presented. Results illustrate the severity and extent of meteorological drought which prevailed throughout the region and reached greatest magnitude in 1973. In that year, the critical 300–400 mm zone of annual rainfall was at least 200 km south of its normal position resulting in major crop failures in several sub-Saharan countries. In Nigeria, 50-year records of rainfall from 28 stations were examined to study both temporal and spatial distributions. In the northern Sahelian zone of Nigeria, two prolonged drought periods were observed (i.e., 1940’s and 1968–76). This detailed analysis further demonstrated the strong relationship between rainfall in the Sahelian region and the position of the Intertropical Convergence Zone (ITCZ). However, there were years during which widespread below-normal rainfall occur-red throughout most of Nigeria which supports previous ...

Impact of Climate on Energy Sector in Economic Analysis

Abstract Assessments of economic conditions by region or sector attempt to include relevant climatic variability through residual adjustment techniques. There is no direct consideration of climatic fluctuations. Three recent severe winters combined with the increasing price of energy have intensified the need to quantify the interaction of climate with the energy sector of the economy. This paper presents examples of the uses of climatic data by utilities, public service commissions and the NOAA Center for Environmental Assessment Services to determine econoclimatic energy relationships at the local, state, regional and national levels. A technique based on the linear relationship between heating degree days and natural gas consumption for space heating is used to quantify the interaction of climate and prices on gas consumption. This provides regional estimates of the response of gas consumption to degree days and price. Climate alone does not explain all of the variations in energy consumption. Price an...

General Circulation Model Output for Forest Climate Change Research and Applications

The report reviews technical aspects of and summarizes output from four climate models. Recommendations concerning the use of these outputs in forest impact assessments are made.

LACIE - An application of meteorology for United States and foreign wheat assessment

Abstract The development of a critical world food situation during the early 1970s was the background leading to the Large Area Crop Inventory Experiment (LACIE). The need was to develop a capability for timely monitoring of crops on a global scale. Three U.S. Government agencies, NASA, NOAA and USDA, undertook the task of developing technology to extract the crop-related information available from the global weather-reporting network and the Landsat satellite. This paper describes the overall LACIE technical approach to make a quasi-operational application of existing research results and the accomplishments of this cooperative experiment in utilizing the weather information. Using available agrometeorological data, techniques were implemented to estimate crop development, assess relative crop vigor and estimate yield for wheat, the crop of principal interest to the experiment. Global weather data were utilized in preparing timely yield estimates for selected areas of the U.S. Great Plains, the U.S.S.R....

Atmospheric pressure and wheat yield modeling

Abstract Principal components of monthly sea level pressure representing large scale general circulation features such as persistent upper level troughs and ridges, blocking highs, semipermanent pressure cells, standing eddies, etc., are the predictors in a linear regression on yield for large wheat production regions in the United States, Canada, and the Soviet Union. The purpose of this modeling is to estimate national level of production and to demonstrate a link between crop forecasting and extended atmospheric outlooks. Long term, reliable records of pressure data are used. The models also benefit from the quality, reliability, and availability of foreign crop data for large areas. The monthly pressure field exhibits significant spatial collinearity which determines the time orthogonal principal components. The use of these principal components in the regression leads to a fewer number of required predictors, more stable signs on regression coefficients, minimal variance inflation of regression coefficients, and the ability to objectively partition the principal components into “real” and “noise” relationships to yield. Correlation fields are determined by correlation of pressure data to area weighted temperature or precipitation. These are used to evaluate the physical interpretation of space orthogonal eigenvector fields. The correlation fields and eigenvectors are used together to ensure that the signs on regression coefficients for principal components in the final yield equation make agronomic sense. The statistical structure of the models is discussed. Generally, the models have an explained variance of approximately 0.90 and a standard error of 1.5 quintals per hectare. For 1975 and 1976 these wheat yield models provided operational estimates which are generally within two quintals per hectare of official estimates.

A climatology of total ozone mapping spectrometer data using rotated principal component analysis

The spatial and temporal variability of total column ozone (Ω) obtained from the total ozone mapping spectrometer (TOMS version 7.0) during the period 1980–1992 was examined through the use of a multivariate statistical technique called rotated principal component analysis. Utilization of Kaisers varimax orthogonal rotation led to the identification of 14, mostly contiguous subregions that together accounted for more than 70% of the total Ω variance. Each subregion displayed statistically unique Ω characteristics that were further examined through time series and spectral density analyses, revealing significant periodicities on semiannual, annual, quasi-biennial, and longer term time frames. This analysis facilitated identification of the probable mechanisms responsible for the variability of Ω within the 14 homogeneous subregions. The mechanisms were either dynamical in nature (i.e., advection associated with baroclinic waves, the quasi-biennial oscillation, or El Nino-Southern Oscillation) or photochemical in nature (i.e., production of odd oxygen (O or O3) associated with the annual progression of the Sun). The analysis has also revealed that the influence of a data retrieval artifact, found in equatorial latitudes of version 6.0 of the TOMS data, has been reduced in version 7.0.

Development of an Aggregation and Episode Selection Scheme to Support the Models-3 Community Multiscale Air Quality Model

Abstract The development of an episode selection and aggregation approach, designed to support distributional estimation for use with the Models-3 Community Multiscale Air Quality (CMAQ) model, is described. The approach utilized cluster analysis of the 700-hPa east–west and north–south wind field components over the time period of 1984–92 to define homogeneous meteorological clusters. Alternative schemes were compared using relative efficiencies and meteorological considerations. An optimal scheme was defined to include 20 clusters (five per season), and a stratified sample of 40 events was selected from the 20 clusters using a systematic sampling technique. The light-extinction coefficient, which provides a measure of visibility, was selected as the primary evaluative parameter for two reasons. First, this parameter can serve as a surrogate for particulate matter with diameter of less than 2.5 μm, for which few observational data exist. Second, of the air quality parameters simulated by CMAQ, this visib...

Climate and global grain yield variability

Historical grain yields from several countries were analyzed to determine the variability of grain yield. This was accomplished by assuming a linear technology trend and analyzing the deviations from this trend. The deviation was assumed to be primarily an effect of weather. Using 10 percent deviation from trend as a threshold, it was determined that for each of seven countries the probability of a poor yield year ranged from 17 in India and the United States to 33 percent in Canada and the U.S.S.R. The probability of two consecutive poor wheat yield years was highest in Canada (17 percent) and lowest in Argentina (6 percent). The probability of a poor year occurring in the same year in both the United States and the U.S.S.R. was about 7–8 percent. The highest variability in yield has occurred in Canada, but variability in India has increased substantially since the 1960s.

An Empirical Valuation of Meteorological Information

Abstract The NOAA/EDIS Center for Environmental Assessment Services conducted a benefit-cost study of its publication on assessments of crop-related weather information for foreign countries. As a background for the investigation, a review was conducted of the literature on the theory and methods related to the value and use of information in government programs and private marketing and consumption. Using guidelines suggested by the literature, a questionnaire was designed and the subscribers qualitative and quantitative responses evaluated to determine use of the publication, perceived benefits, and willingness to pay for the publication.

Forecasting Work Conditions for Road Construction Activities: An Application of Alternative Probability Models

certain activities of highway construction are particularly sensitive to such weather conditions as soil moisture, precipitation, and daily temperature. Re- gression analysis is used to obtain three alternative probability models designed to translate observed weather conditions into probabilities for carrying out construction activities. The models were developed using generalized least squares, normit analysis, and logit analysis. The generalized least squares method was the most convenient computationally, but it had severe interpretative dis- advantages. The results obtained by logit analysis gave the desired probabilistic interpretation most readily and had the best predictive ability. Comparison of sample observation and predicted work probabilities for common excavation during wet and dry months indicated that the logit analysis model could accurately translate weather conditions into probabilities that work would take place. Models for paving and asphalt work and for bridge and drainage structure are also estimated using logit analysis. These estimates indicate a strong sensitivity of the latter category of work to precipitation conditions. Such models may aid contract letting agencies in planning payment schedules, penalty clauses, and completion dates for new roads; construction firms may find such models valuable in planning effective use of men and equipment. 0