Tropospheric propagation

About: Tropospheric propagation is a research topic. Over the lifetime, 273 publications have been published within this topic receiving 2456 citations.

Prediction of tropospheric radio transmission loss over irregular terrain. a computer method-1968

Abstract: This report describes a computer method for predicting long-term median transmission loss over irregular terrain. The method is applicable for radio frequencies above 20 MHz and may be used either with detailed terrain profiles for actual paths or with profiles that are representative of median terrain characteristics for a given area. Estimates of variability in time and with location, and a method for computing service probability, are included.

Recursive Two-Way Parabolic Equation Approach for Modeling Terrain Effects in Tropospheric Propagation

Abstract: The Fourier split-step method is a one-way marching-type algorithm to efficiently solve the parabolic equation for modeling electromagnetic propagation in troposphere. The main drawback of this method is that it characterizes only forward-propagating waves, and neglects backward-propagating waves, which become important especially in the presence of irregular surfaces. Although ground reflecting boundaries are inherently incorporated into the split-step algorithm, irregular surfaces (such as sharp edges) introduce a formidable challenge. In this paper, a recursive two-way split-step algorithm is presented to model both forward and backward propagation in the presence of multiple knife-edges. The algorithm starts marching in the forward direction until the wave reaches a knife-edge. The wave arriving at the knife-edge is partially-reflected by imposing the boundary conditions at the edge, and is propagated in the backward direction by reversing the paraxial direction in the parabolic equation. In other words, the wave is split into two components, and the components travel in their corresponding directions. The reflected wave is added to the forward-wave in each range step to obtain the total wave. The wave-splitting is performed each time a wave is incident on one of the knife-edges. This procedure is repeated until convergence is achieved inside the entire domain.

The TropGrid2 standard tropospheric correction model

Abstract: TropGrid2 is a new version of a tropospheric model that is based on climatology and provides tropospheric propagation delay corrections for standard positioning users without temperature, pressure and humidity measurements. Zenith hydrostatic and wet delays are modeled as special harmonic functions taking seasonal and diurnal variations into consideration. The grid-point values are height-reduced and can be interpolated horizontally to the user position. The database used to derive this model consists of more than 9 years of 3D numerical weather fields of the NOAA NCEP GDAS weather model. We validated this standard model using 10 years of GPS-derived zenith path delays at 290 International GPS service reference stations. The gridded version is accurate at a level of 3.8 cm (root mean square in zenith direction) on global average; the average long-term bias is ?0.3 cm. The standard deviations computed by the model turn out to be slightly too pessimistic for almost all stations under investigation, in contrast to the site-specific version, which is only marginally (1 mm) more accurate on global scale.

Path Delays in the Neutral Atmosphere

Abstract: This part describes the effects of the troposphere—strictly speaking the neutral atmosphere—on the propagation delay of space geodetic signals. A theoretical description of this tropospheric propagation delay is given as well as strategies for correcting for it in the data analysis of the space geodetic observations. The differences between the tropospheric effects for microwave techniques, like the Global Navigation Satellite Systems (GNSS) and Very Long Baseline Interferometry (VLBI), and those for optical techniques, like Satellite Laser Ranging (SLR), are discussed. Usually, residual tropospheric delays are estimated in the data analysis, and the parameterization needed to do so is presented. Other possibilities of correcting for the tropospheric delays are their calculation by ray-tracing through the fields of numerical weather models and by utilizing water vapor radiometer measurements. Finally, we shortly discuss how space geodetic techniques can be used in atmospheric analysis in meteorology and climatology.