# Accession Number:

## AD0726994

# Title:

## Synoptic and Climatological Density Profiles from Constant Pressure Surfaces for Ballistic Computations.

# Descriptive Note:

## Air Force surveys in geophysics,

# Corporate Author:

## AIR FORCE CAMBRIDGE RESEARCH LABS L G HANSCOM FIELD MASS

# Personal Author(s):

# Report Date:

## 1971-03-04

# Pagination or Media Count:

## 39.0

# Abstract:

The influence of atmospheric density on ballistic trajectories of re-entry vehicles usually attains a maximum below 20 kilometers. The most direct and accurate means of estimating this influence is from profiles of density specified at uniform intervals of altitude usually 2 km from individual soundings for the time and over the area of re-entry. Unfortunately, vertical distances between levels on constant pressure charts, normally available for obtaining density profiles, are generally greater than 2 kilometers. Unless interpolation between these pressure surfaces for obtaining densities at the 2-km intervals is based on the actual density-altitude relation, the interpolated densities will be in error. Three often-used methods of interpolation are 1 assumption of a linear decrease of density with altitude, 2 assumption of a linear decrease of the logarithm of density with altitude, and 3 assumption of a linear decrease of density multipliers with altitude, where a density multiplier at the altitude of a constant pressure surface represents the ratio of density to the Standard Atmosphere density at that altitude. The three methods with resultant errors are discussed and evaluated in this report. Author

# Descriptors:

# Subject Categories:

- Atmospheric Physics
- Armor