Abstract:
Ideal air blast is normally assumed in targeting and lethality exercises. It assumes that the air blast from an atmospheric
nuclear explosion interacts with a planar, reflective surface. In reality, the surface around a burst interacts
with the air blast in various ways to produce “non-ideal” environments that can
be substantially different from ideal. The
principal factors that determine these non-ideal environments can be divided into
mechanical (terrain, vegetation, urban structures), and thermal (alteration of near-surface
conditions ahead of the air blast due to exposure of the surface to intense radiation
from the fireball). Factor-of-two perturbations
due to mechanical effects can occur at all ranges. Similarly, factor-of-two perturbations to overpressure
and impulse can occur from thermal effects, but these gradually die out at ranges
beyond about 10 psi.
A relatively large base exists from atmospheric nuclear and large high explosive
events in which both mechanical and thermal non-ideal effects are evident. Air blast waveforms from approximately 3,000 records
have been digitized and are now readily accessible in a well-indexed archive in
DARE. The nuclear data base is largely confined
to dry desert surfaces (at NTS), and to sites over water or over coral and sand
islands in the Pacific. In general, these
data should not be extrapolated to other targeting surfaces of interest, but they
can provide a sound basis for calibration of models.
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