Horizontal gradients in the wet path delay derived from four years of microwave radiometer data

We have analyzed four years of inferred wet path delay data from a microwave radiometer operating at 21.0 and 31.4 GHz. We have applied a four parameter gradient model to the wet delays, using different lengths of the time series for the gradient estimation. The mean gradient, averaged over 15 to 1440 minutes, varies between 0.9 and 0.4 mm End has a preferred direction towards the north-east. Increasing the averaging time causes the estimated gradient to decrease. The 15 minutes mean gradient is 1.3 mm for the summer months and 0.7 mm for the winter months. Structure function results are also presented

Microwave Measurements for Metal Vessels

We present two different measurement techniques intended for closed metal vessels, where the objective is to measure the permittivity inside the metal vessel. This problem is relevant for many applications found in e.g. process industry. The first approach exploits the measurement of resonance frequencies, where the metal vessel is used as a microwave resonator. In the second approach, we let the boundary of the metal vessel be equipped with aperture antennas, where the aperture antennas are implemented in terms of rectangular waveguides. The waveguide apertures loads the cavity significantly and we exploit the scattering matrix parameters for the solution of the inverse problem

Global monitoring of fluidized-bed processes by means of microwave cavity resonances

We present an electromagnetic measurement system for monitoring of the effective permittivity in closed metal vessels, which are commonly used in the process industry. The measurement system exploits the process vessel as a microwave cavity resonator and the relative change in its complex resonance frequencies is related to the complex effective permittivity inside the vessel. Also, thermal expansion of the process vessel is taken into account and we compensate for its influence on the resonance frequencies by means of a priori information derived from a set of temperature measurements. The sensitivities, that relate the process state to the measured resonance frequencies, are computed by means of a detailed finite element model. The usefulness of the proposed measurement system is successfully demonstrated for a pharmaceutical fluidized-bed process, where the water and solid contents inside the process vessel is of interest

Sensing Atmospheric Water Vapor Using Radio Waves: Studies of the 2, 3 and 4-D Structure of the Atmospheric Water Vapor Using Ground-based Radio Techniques Comprising the Global Positioning System, Microwave Radiometry and Very Long Baseline Interferometry

The radio wave propagation time, the primary observable in the geodetic techniques Global Positioning System (GPS) and Very Long Baseline Interferometry (VLBI) is affected by the presence of the atmospheric gases. By using appropriate modeling in the post-processing of the recorded phase measurements, together with local meteorological information, it is possible to estimate the total amount of atmospheric water vapor. Another technique able to independently provide water vapor estimates through sensing the atmospheric emission is microwave radiometry (MR). Due to the capabilities of GPS to estimate the integrated amounts of water vapor - a major greenhouse gas - it is potentially valuable for meteorology and climate studies, while VLBI and MR could be seen as independent validation techniques. Knowledge of the water vapor behaviour is of importance for: a) improved wet delay modeling in the precise geodetic techniques, b) the real-time GPS navigation, and c) weather forecasting and climate studies. In this thesis we present techniques, methods and results of measurements of the temporal variability of integrated amounts of atmospheric water vapor (2-D), its spatial horizontal gradients (3-D) as well as its 3-D spatial structure (4-D). We study the local structures of water vapor from spatial scales of a few kilometers on temporal scales of some minutes, presenting studies of the local horizontal gradients using data from GPS, VLBI and MR, to spatial scales of some thousands of kilometers, studying the integrated water vapor trends over 9 years in Scandinavia using time series from GPS. Verification of the estimated structures using intercomparisons between the techniques is included. We also present results on the studies of the 4-D structure using a small-scale GPS network where we first use the different sensitivity to gradients of a single GPS receiver compared to a network of receivers to probe the vertical structure of the atmosphere. Then we present the tomog raphic technique and suggest methods for derivation of the 4-D water vapor structure applied to different permanent as well as temporary established GPS networks. We study the quality of the input slant delay estimates and the GPS tomography capabilities and limitations, using simulated and real data. We also suggest methods to improve the technique

Sensing Atmospheric Water Vapor Using Radio Waves: Studies of the 2, 3 and 4-D Structure of the Atmospheric Water Vapor Using Ground-based Radio Techniques Comprising the Global Positioning System, Microwave Radiometry and Very Long Baseline Interferometry

The radio wave propagation time, the primary observable in the geodetic techniques Global Positioning System (GPS) and Very Long Baseline Interferometry (VLBI) is affected by the presence of the atmospheric gases. By using appropriate modeling in the post-processing of the recorded phase measurements, together with local meteorological information, it is possible to estimate the total amount of atmospheric water vapor. Another technique able to independently provide water vapor estimates through sensing the atmospheric emission is microwave radiometry (MR). Due to the capabilities of GPS to estimate the integrated amounts of water vapor - a major greenhouse gas - it is potentially valuable for meteorology and climate studies, while VLBI and MR could be seen as independent validation techniques. Knowledge of the water vapor behaviour is of importance for: a) improved wet delay modeling in the precise geodetic techniques, b) the real-time GPS navigation, and c) weather forecasting and climate studies. In this thesis we present techniques, methods and results of measurements of the temporal variability of integrated amounts of atmospheric water vapor (2-D), its spatial horizontal gradients (3-D) as well as its 3-D spatial structure (4-D). We study the local structures of water vapor from spatial scales of a few kilometers on temporal scales of some minutes, presenting studies of the local horizontal gradients using data from GPS, VLBI and MR, to spatial scales of some thousands of kilometers, studying the integrated water vapor trends over 9 years in Scandinavia using time series from GPS. Verification of the estimated structures using intercomparisons between the techniques is included. We also present results on the studies of the 4-D structure using a small-scale GPS network where we first use the different sensitivity to gradients of a single GPS receiver compared to a network of receivers to probe the vertical structure of the atmosphere. Then we present the tomog raphic technique and suggest methods for derivation of the 4-D water vapor structure applied to different permanent as well as temporary established GPS networks. We study the quality of the input slant delay estimates and the GPS tomography capabilities and limitations, using simulated and real data. We also suggest methods to improve the technique