Sets of mean monthly reference atmospheres that describe seasonal changes in the vertical distributions of temperature, density, and pressure at altitudes up to 90 km are presented for latitudes 60 deg N and 75 deg N. Also provided are specialized atmospheric models that reflect longitudinal differences in the vertical structure of temperature and density at these latitudes. Estimates of the seasonal, day-to-day, diurnal, and spatial variations are given with special emphasis placed on density. (Author)

Sets of mean monthly reference atmospheres that describe seasonal changes in the vertical distributions of temperature, density, and pressure up to 90 km are presented for 15 intervals of latitude between the equator and pole. Specialized atmospheres are included that portray longitudinal variations in monthly median values of temperature, density, and pressure during winter months. Other models illustrate the magnitude of the changes in the vertical distributions of these atmospheric properties during winter warmings and coolings of the stratosphere and mesosphere in arctic and subarctic regions. Estimates of the day-to-day variations around the monthly median values of temperature and density are provided for each set of models. (Author).

A set of 12 mean monthly reference atmospheres, which describes the seasonal changes in the distribution of the thermodynamic properties of the atmosphere, is provided for the North Pole for altitudes up to 55 km. Additional atmospheric models for arctic and subarctic regions are presented to describe the large variations that occur in the vertical distributions of atmospheric temperature, density, and pressure during typical warmings and coolings of the winter stratosphere and mesosphere.

An analysis of the time and space variability of density in the middle atmosphere has been developed in this report, affording a means to determine density changes that occur over distances out to 200 nmi and time periods of 1 to 72 hr. Spatial variations - The rms differences between densities at locations 50, 100, and 200 nmi apart are provided in Tables 4, 8 and 11 for low- and middle- latitude stations at altitudes from 20 through 60 km. These rms values are estimates of the day-to-day variability around the mean density gradients given in Table 5 for low latitudes and Tables 9 and 12 for middle latitudes. Time variations - The rms variability of density for time periods from 1 to 12 hr in tropical regions is given in Table 13 for altitudes up to 60 km. Estimates were derived using autocorrelation theory and an analysis of the diurnal variation of density, which is the dominant periodic cycle at low latitudes. Analyses of available density observations at several midlatitude locations for altitudes between 30 and 60 km provide reasonable estimates of the magnitude (and changes with season and latitude) of the variability of density with time for periods up to 72 hr. Variations of density at these latitudes are relatively small during summer and do not increase significantly with time. Rms variations remain between 1-1/2 and 4 percent for all periods up to 72 hr.

Sets of mean monthly reference atmospheres that describe seasonal changes in the vertical distributions of temperature, density, and pressure at altitudes up to 90 km are presented for latitudes 60 deg N and 75 deg N. Also provided are specialized atmospheric models that reflect longitudinal differences in the vertical structure of temperature and density at these latitudes. Estimates of the seasonal, day-to-day, diurnal, and spatial variations are given with special emphasis placed on density. (Author).

Sets of mean monthly reference atmospheres that describe seasonal changes in the vertical distributions of temperature, density, and pressure up to 90 km are presented for 15 intervals of latitude between the equator and pole. Specialized atmospheres are included that portray longitudinal variations in monthly median values of temperature, density, and pressure during winter months. Other models illustrate the magnitude of the changes in the vertical distributions of these atmospheric properties during winter warmings and coolings of the stratosphere and mesosphere in arctic and subarctic regions. Estimates of the day-to-day variations around the monthly median values of temperature and density are provided for each set of models. (Author)