Accession Number : AD0250548

Title :   A METHOD OF PREDICTING THE FREQUENCY DISTRIBUTION OF WINDCHILL

Corporate Author : QUARTERMASTER RESEARCH AND ENGINEERING COMMAND NATICK MA

Personal Author(s) : WESTBROOK, JANE HOWE

Report Date : JAN 1961

Pagination or Media Count : 1

Abstract : EIGHT YEARS OF SIMULTANEOUS RECORDINGS OF JANUARY TEMPERATURE AND WINDSPEED FROM 20 NORTH AMERICAN STATIONS ARE USED IN THE DEVELOPMENT OF A METHOD FOR PREDICTING THE PERCENTAGE OF TIME WINDCHILL WILL LIE ABOVE OR BELOW A GIVEN VALUE. A WINDCHILL PREDICTION CHART IS CONSTRUCTED. IT COMBINES THE SIPLE NOMOGRAM,USED TO DERIVE THE WINDCHILL INDEX BASED ON AVERAGE TEMPERATURE AND WINDSPEED, AND THE PREDICTION MODEL BASED ON THE WINDCHILL FREQUENCIES. PREDICTION ERRORS (RANGE 0 - 240WINDCHILL UNITS,WITH AVERAGE OF 52) PRODUCE A SKEWED DISTRIBUTION WITH 64( OF THE ERRORS LESS THAN THE AVERAGE. ERRORS GREATER THAN AVERAGE ARE CONCENTRATED BETWEEN THE 5TH AND 30TH AND BEYOND THE 95TH PERCENTILES. MAGNITUDE OF ERROR INCREASES AS THE INDEX INCREASES. THE RELIABILITY OF THE PREDICTION CHART IS TESTED BY FREQUENCY RECORDS FROM 34 ADDITIONAL STATIONS. DEVIATIONS OF ACTUAL WINDCHILL VALUES FROM THE PREDICTIONS ARE, ON THE AVERAGE, 20 WINDCHILL UNITS GREATER THAN DEVIATIONS IN THE MODEL. THE SAME GENERAL PATTERN OF ERROR DEVIATION IS OBSERVED

Descriptors :   *CLIMATE, *WIND, COOLING, DISTRIBUTION, FREQUENCY, MATHEMATICAL PREDICTION, METEOROLOGY.

Distribution Statement : APPROVED FOR PUBLIC RELEASE