摘要:

Microwave radiometer measurements were conducted from a railroad bridge which spans the Cape Cod Canal in Massachusetts. Data were collected as a function of viewing angle and polarization at frequencies of 1.4, 4.0, and 7.5 GHz. The results compare differences in the microwave emmissivity of a smooth vs. rough water surface. Results are also given which show the effects of roughness on the bistatic scattering of sunlight.

ISSN:0048-6604    

DOI:10.1029/RS009i007p00641

年代:1974

数据来源: WILEY

摘要:

Many recent measurements of photochemical rate constants and atmospheric ion composition have changed our understanding ofD‐region sunrise processes. In this paper several new sunrise mechanisms are suggested in the light of the recent data. It is concluded that very stable hydrated negative ions will probably be converted by chemical reaction at sunrise into less stable hydrates which can be photodetache

ISSN:0048-6604    

DOI:10.1029/RS009i007p00655

年代:1974

数据来源: WILEY

摘要:

In this paper full‐wave calculations are described to investigate the propagation of MF radio waves in the range from 255 to 950 kHz in the lower ionosphere. The method of investigation makes use of matrix multiplications with the ionosphere divided into homogeneous layers of 100‐m thickness. The model calculations provide conclusions from MF pulse sounding results on electron density and collision frequency profiles in the height interval from 50 to 100 km. The diurnal variation of electron density in the lower ionosphere is presented. Reflections observed from heights of about 75 and 87 km during the day are shown to be produced by steep gradients of electron dens

ISSN:0048-6604    

DOI:10.1029/RS009i007p00659

年代:1974

数据来源: WILEY

摘要:

Electron density profiles derived from ionograms have limited accuracy due to technical and natural reasons. In the following we show how corrections and error estimates can be obtained on the basis of the propagation theory of radio waves and the general knowledge of the ionospheric structure.

ISSN:0048-6604    

DOI:10.1029/RS009i007p00669

年代:1974

数据来源: WILEY

摘要:

Modifications were made to the global scintillation model that was developed by Fremouw (Stanford Research Institute), to better represent recent high latitude scintillation data. These modifications were made primarily in the high latitude term of the model and include a provision for variation in the position of the scintillation boundary with respect to magnetic activity. The resulting model is compared with published curves of scintillation activity with respect to latitude and is found to produce a considerably better agreement with those curves than the original model. A modification of the model is made to represent the finding that the northern and southern polar regions of the scintillation activity are not symmetrical with respect to each other.

ISSN:0048-6604    

DOI:10.1029/RS009i007p00675

年代:1974

数据来源: WILEY

摘要:

Our understanding of wave particle interactions in the magnetosphere has progressed to the point where it may be possible to stimulate wave amplification at ULF (about 0.1 to 10 Hz) by disturbing the cyclotron resonance conditions through catalytic injections of plasma clouds or particle beams. Modification of the interaction can be achieved by the introduction of localized clouds of plasma that reduce the phase velocity of the waves and cause enhanced amplification by lowering the resonance velocity. Alternatively, direct injection of hot energetic particle beams can also appreciably alter the local amplification characteristics. Different methods for injecting clouds of lithium plasma and proton beams have been modeled quantitatively to assess their relative merits. Amplifications of many tens of decibels appear to be feasible with lithium clouds of only 1 to 2 kg of material. With present technology the beam diameter from a conventional particle gun on board a satellite or rocket is too small for an effective interaction, but appreciable amplification is indicated. Such a prospect has great significance. First, it offers a direct test of the fundamental physical processes that are believed to control the state of the magnetosphere. Second, controlled injections might be used to stimulate artificial amplification of ULF emissions on command and allow them to be used as a wide‐area communication syste

ISSN:0048-6604    

DOI:10.1029/RS009i007p00683

年代:1974

数据来源: WILEY

摘要:

The radiation field patterns of an ion acoustic wave from a circular disk‐shaped antenna is controlled by applying a bias voltage to another mesh. The change of the radiation patterns is explained as a result of the in‐phase reflection of an ion acoustic wave at an electron‐rich s

ISSN:0048-6604    

DOI:10.1029/RS009i007p00697

年代:1974

数据来源: WILEY

摘要:

The wave number, the distribution of current, and the admittance of a horizontal wire antenna over a homogeneous isotropic half space are determined when the complex wave number characteristic of the half space is large in magnitude compared with the real wave number of the air. The axial electric field at the surface of the half space is described. The properties of the antenna are obtained from those of the eccentrically insulated dipole in a general medium in the limit as the radius of the insulation is increased without limit while the distance of the dipole from the boundary is kept constant. Application of the new theory to the Beverage or wave antenna is discussed.

ISSN:0048-6604    

DOI:10.1029/RS009i007p00701

年代:1974

数据来源: WILEY