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At least 73 records · Page 4

Remote sensing of the ionospheric F layer by use of O I 6300-A and O I 1356-A observations

The possibility of using airglow techniques for estimating the electron density and height of the F layer is studied on the basis of a simple relationship between the height of the F2 peak and the column emission rates of the O I 6300 A and O I 1356 A lines. The feasibility of this approach is confirmed by a numerical calculation of F2 peak heights and electron densities from simultaneous measurements of O I 6300 A and O I 1356 A obtained with earth-facing photometers carried by the Ogo 4 satellite. Good agreement is established with the F2 peak heights estimates from top-side and bottom-side ionospheric sounding.

Chandra, S.↗

Radiative transfer theory for passive microwave remote sensing of a two-layer random medium with cylindrical structures

A model of the vegetation layer as a two-layer random medium with a small correlation length l sub rho in the horizontal direction, and a large correlation length l sub z in the vertical direction, is presented for fields with cylindrical structures. As l sub z approaches infinity, closed form solutions are derived for the brightness temperatures; the kernels in the scattering terms of the radiative transfer equations result in delta functions showing that forward scattering is dominant over all other directions. The results are compared with the Gaussian quadrature method data for numerical solution of the radiative transfer equations.

Chuang, S. L.↗

Prediction and monitoring of clear-air turbulence - An evaluation of the applicability of the rawinsonde system

The importance of sensing turbulent layers in the free atmosphere to further progress in the area of clear air turbulence (CAT) prediction is stressed. The results of an investigation of the applicability of rawinsonde (RW) profiles for the detection of CAT are discussed. It is noted that previous studies have determined that the most significant factor for the existence of turbulent layers is the magnitude of the vertical shear. Certain shear-layer criteria, which are obtained from theoretically consistent statistics of detailed vertical wind profiles, are applied to statistical comparisons of conjunctive rawinsonde and Jimsphere/Jimsonde (J/J) vertical profiles made between 1 and 15 km. It is found that a loose relationship exists between J/J and RW shears. That is, the cross-correlation coefficient that compares their respective shears at the same levels is quite small. This is seen as suggesting that no general statement can be made in consideration of critical shear criteria with respect to RW shears. The suggestion is made that reasons for such a loose empirical relationship include the mesoscale nature of the apparent CAT mechanism.

Keller, J. L.↗

Airborne Dial Remote Sensing of the Arctic Ozone Layer

A combined ozone and aerosol LIDAR was developed at the Institute of Physics of the Atmosphere at the DLR in Oberpfaffenhofen. It is an airborne version, that, based on the DIAL-principle, permits the recording of two-dimensional ozone profiles. This presentation will focus on the ozone-part; the aerosol subsection will be treated later.

Wirth, Martin↗