Vertical profiles of the structure parameter of refractive index and the structure parameter of temperature in the earth 's atmosphere

Vertical profiles of the structure parameter of temperature CT2 in the stable, nocturnal boundary layer are obtained with the models described by Neuwstadt (1984, 1985), Sorbjan (1986) and Dunkerke and Driedonks (1987). These theoretical profiles are compared with observed profiles obtained at the meteorological mast at Cabauw, The Netherlands.
From the observations it is found that CT2 is large in the surface layer and small at the top of the boundary layer. Observations during nights with moderate geostrophic winds or during the first few hours of nights With a high geostrophic wind show a continuous decrease of CT2 from surface layer to the top of the boundary layer. Observations done later at nights with a high geostrophie wind show the development of a maximum of CT2 at about three quarters of the boundary layer. From the
comparison with the models we conclude that the observed profiles are most satisfactory described by the model of Duynkerke and Driedonks.

In part II., the Influence of turbulence in the earth's atmosphere on stellar image degradation is discussed. By measuring temperature fluctuations or stellar scintillations the vertical profiles of the structure parameter of refractive index CN2 can be obtained.
Observations show that CN2 varies from position to position and from time to time. In the first 100-200 m above the ground CN2 is large.
Above the boundary layer CN2 decreases sharply. In the troposphere turbulence is layered. CN2 generally decreases with height. However, an
increase is seen in situations with winds from or towards mountains or near temperature inversions. In the stratosphere CN2 is small. We conclude that the lower troposphere is most responsible for phase fluctuations causing Image movement and image blurring, whereas the tropopause region seems to be more responsible for amplitude fluctuations causing scintillation.