UAG-93: Chapters 1 to 5 - URSI

AMODE is an input parameter specifying one of ten standard types of analysis, corresponding to
different values of NT, NV, NR and NH (Section 5.2).
The nunber of frequencies used:
NV is the number of 0-ray virtual-height data points (above FA) to which the polynomial is to be
fi tted.
NF is the number of 0-ray points actually used; normally equalto NV or to the number of 0-ray
points available before a layer peak.
NX is the nurnber of X-ray data points used (in start and va11eycalculations).
This is commonly
equal to the number available in the range FA to FM + 0. 1 MHz; points corresponding
to FN > FM + 0.1 MHz are deleted.
MV - NX + NF is the total number of virtual heights fitted.
FM = FV(MF) is the highest 0-ray frequency used in the current step.
l4F = KR + MV is the index corresponding to FM in the data arrays FV, HT'
l4X = KR + NX is the index of the highest X ray used.
The number of terms used:
NT is the initial number of terms to be used in the polynomial real height expression.
l'1T is the number of polynomial terms actually used wr'th.in P0LAN. This is normally equal to
NT + (NX+1)/2, with a maximum value of MV + NR.
JM is the total number of real-height terms calculated, normally equal to MT. An additional
term q(JM) lwjth JM = MT+l] is included at a valley, or with an X-ray start calculation,
to provide a calculated shift or offset h - HA = q(JM) in the height of the origin FA.
NR is the number of known real heights above FA to be included in the polynomia'l fit (Section 5.2).
if NR is negative, fitting is to 1 real hejght below FA and to lNRl-1 heights above FA.
NH is the number of new real heights to be calculated. This is equal to the number of points the
origin is advanced for the next step. NH = 1 for Modes 1 to 6, except just before a peak
when NH = NF so that real heights are calculated at all fitted (0-ray) frequencies.
4- Start, Peak and Val'ley Calculations.
fs, hs
is the starting point for the profile calculatjon, with f5 (= fmin and hr