Observations of the coherence bandwidth of interplanetary scintillatio
ns (IPS) made at the Nancay Radio Observatory between 1982 and 1992 ha
ve been used to estimate the variance of electron density delta N-e(2)
at solar distances of 5 to 15 R(s). These IPS observations are sensit
ive to scales of the order of 10 km; i.e., they measure the ''microsca
le variance,'' which is a small fraction of the total density variance
. Measurements in the equatorial region are invariant over the solar a
ctivity cycle and show the same behavior with distance as the mean den
sity, i.e., delta N-e(2) proportional to N-e(2). They do not show a st
atistically significant change in the ''transonic region'' as reported
by other observers (Lotova et al., 1985). Measurements over the polar
region show a clear variation with the solar cycle. At solar maximum,
delta N-e(2) is invariant with latitude, as is N-e (Withbroe; 1988).
However, the apparent delta N-e(2) measured by IFS is about 10 times l
ower in the polar streams which form during the declining and minimum
phases of solar activity. Compensation for the line of sight integrati
on inherent in the IPS observations indicates that the local value of
SN,2 is actually about 15 times lower in the polar streams. We cannot
estimate the latitude variation of the ''development'' of the compress
ive turbulence delta N-e/N-e between 5 and 15 R(s) because measurement
s of N-e in the polar hole are lacking.