RTNEPH Total Cloud Cover: Validation Study

In 1983, the United States Air Force Global Weather Central (AFGWC) implemented a new model to map and store an analysis of worldwide cloud-cover derived from surface and satellite data. This model, the designated the Real- Time Nephanalysis (RTNEPH) model, contains analyses of total sky cover, clou...

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Bibliographic Details
Main Authors: Lowther, Ronald P., Surmeier, Mark T., Hartman, Richard W., Coffin, Charles R., Warren, Anthony J.
Other Authors: AIR FORCE ENVIRONMENTAL TECHNICAL APPLICATIONS CENTER SCOTT AFB IL
Format: Text
Language:English
Published: 1991
Subjects:
Meteorology
*CLOUD COVER
TEST AND EVALUATION
DATA BASES
ALGORITHMS
FREQUENCY
CLOUDS
GLOBAL
WEATHER
MODELS
REAL TIME
DISTRIBUTION
STATISTICAL TESTS
OBSERVATION
METEOROLOGICAL DATA
ARTIFICIAL SATELLITES
DATA STORAGE SYSTEMS
MAPS
LATITUDE
SEASONS
ARCTIC REGIONS
ATMOSPHERE MODELS
HEIGHT
CLIMATOLOGY
NEPHANALYSIS
Arctic
Online Access:http://www.dtic.mil/docs/citations/ADA260175
http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA260175
Description
Summary:In 1983, the United States Air Force Global Weather Central (AFGWC) implemented a new model to map and store an analysis of worldwide cloud-cover derived from surface and satellite data. This model, the designated the Real- Time Nephanalysis (RTNEPH) model, contains analyses of total sky cover, cloud bases, and cloud heights. Studies assessing the accuracy of the RTNEPH database have, up to now, been limited. In this work, the RTNEPH total sky-cover database is evaluated against independent surface observations. Since the RTNEPH algorithm heavily weights available surface observations, this was not a simple task; more than 500,000 independent surface and RTNEPH observations had to be matched and evaluated. Frequency distributions of the differences in these two sources were computed and stratified by latitude, season, time of day (day versus night), and age. Finally, statistical tests were run to obtain quantitative assessments of the results. In general, the RTNEPH total sky cover compared favorably with the surface reports, but there were differences. Certain biases in the RTNEPH were also identified, most notably the underestimation of cloud cover in arctic regions and the poor resolution of RTNEPH in regions where the airways surface observation code is used.

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