Comparisons Between the RTNEPH and AFGL Cloud Layer Analysis Algorithms

Author: Robert d'Entremont, Gary Gustafson, C.B. Schaaf, J.M. Ward, J.T. Bunting, M.K. Griffin, P.L. Nowak and R.S. Hawkins
July 15, 1989
AF Geophysics Laboratory

d'Entremont, R.B., G.B. Gustafson, J.T. Bunting, M.K. Griffin, P.L. Nowak, J.M. Ward, R.S. Hawkins, 1989. Comparisons Between the RTNEPH and AFGL Cloud Layer Analysis Algorithms. AF Geophysics Laboratory Report Number GL-TR-89-0175, ERP, no. 1033, Hanscom AFB, MA.

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The Real-Time Nephanalysis (RTNEPH) is an automated cloud analysis model in operational use at the Air Force Global Weather Central (AFGWC). In the RTNEPH, polar-orbiting satellite imagery is analyzed in conjunction with conventional meteorological cloud observations to produce a global analysis of cloud attributes such as extent, height, bases, and type. In 1980, an alternative to the RTNEPH layer analysis algorithm was developed at the Air Force Geophysics Laboratory (AFGL). The AFGL algorithm performs a layer analysis using a 16 x 16 array of IR satellite pixels, four times larger than the RTNEPH array size. The AFGL cloud layer algorithm was proposed as an alternative to the current RTNEPH algorithm. This report describes the comparison study that was conducted on the AFGL and RTNEPH cloud layer algorithms and characterizes their differences in terms of the key meteorological parameters. The report contains recommendations for incorporating the AFGL algorithm into the RTNEPH and suggestions for future work in this area.