CoE pi 
rm, 
ne 
d, 
y » 
tion 
same 
ime 
fore, 
ely." 
| 
C 
vations 
WS 
Dy, 
ta, 
ice 
Ir 
tra 
X m 
Mi naa. Hir 
  
    
  
O NW DM DAN 
T 
  
  
  
  
  
  
2 3 4 58$ 7^8 
m 
Fig. 1 Allowed wavenumber-frequency spectra for twice-daily synoptic 
sampling (dashed) and combined asynoptic sampling (solid). Shaded 
region corresportds to spectra resolvable in both types of observations. 
--o | 
The scheme can be shown (Salby, 1982b) to conserve information. 
It is also directly amenable to vectorization, i.e. parallel processing of 
data over an ensemble of latitudes and pressure levels. An additional 
advantage is that "global" spectra (involving the latitudinal transform) are 
at immediate disposal. This feature facilitates several important appli- 
cations, to be discussed later. 
4, Results 
Synoptic maps have been retrieved from asynoptic observations for 
several simple fields. Orbital parameters characteristic of Nimbus-6 
nadir data (v, * 13.4 orbits/day) were used in these calculations. Combined 
asynoptic observations are taken over a T-6 day interval on 40 latitudes (4), 
equispaced 5? between -80? and +80°. 
Consider the simple field 
y(A,0,t) = cos (m Ato t) COS (ky 0) (1.1) 
with Mo 7 3 (1.2) 
O50" 2.01 {1.3) 
“te = 2.25 (1.4) 
with |t| < 3.0. This field represents a traveling wavenumber 3, retrogressing 
with a period of approximately 3 days, whose amplitude varies as the funda- 
mental cosine in latitude. The calculated synoptic sequence of maps, shown 
in Fig. 2, faithfully retrieves the structure and evolution embodied in (1). 
As was the case for computation of space-time spectra (Salby, 1982a,c), 
the recovered values are "exact to machine precision." 
147 
EM CC A I E e