Randolph Ware

• Principal Investigator at Radiometrics

1] A case study relative to the observation of unexpected liquid water in an apparently cloudless atmosphere is presented. Microwave radiometer profiler observations on 14 April 2008 at Boulder, Colorado, USA, showed an increase in the liquid water path with values higher than 0.05 mm and corresponding relative humidity saturation from 4.75 to 6.75...

A microwave radiometer is described that provides continuous thermodynamic (temperature, water vapor, and moisture) soundings during clear and cloudy conditions. The radiometric profiler observes radiation intensity at 12 microwave frequencies, along with zenith infrared and surface meteorological measurements. Historical radiosonde and neural netw...

Thermodynamic profiling provides continuous temperature, humidity and cloud liquid profiles during clear and cloudy conditions. The thermodynamic profiler radiometrically observes microwave radiation intensity at multiple frequencies, along with infrared and surface meteorological measurements. Historical radiosonde and neural network or regression...

Radiometric profiling provides accurate and reliable temperature and humidity profiles up to 10 km height, and low resolution cloud liquid profiles. Retrieval algorithms are derived for specific locations using historical radiosonde data and neural network or regression analysis. Radiometric profiler measurements can be used for high resolution mes...

Diurnal variations in atmospheric water vapor are studied by analyzing 30-min-averaged data of atmospheric precipitable water (PW) for 1996-2000 derived from Global Position System (GPS) observations from 54 North America stations. Vertical structures in the diurnal cycle of atmospheric water vapor are examined using 3-hourly radiosonde data from L...

In recent years techniques have been developed to obtain integrated water vapor along slant paths between ground-based Global Positioning System (GPS) receivers and the GPS satellites. Results are presented of an observing system simulation (OSS) to determine whether three-dimensional water vapor fields could be recovered from a high-resolution net...

We present a direct comparison of nonisotropic, integrated water vapor measurements between a ground-based Global Positioning System (GPS) receiver and a water vapor radiometer (WVR). These line-of-sight water vapor observations are made in the straight line path between a ground station and a GPS satellite. GPS double-difference observations are p...

We describe a passive microwave radiometer that provides continuous unattended atmospheric temperature and humidity profiles up to 10 km in height, and low resolution liquid water profiles. Profile accuracies in cloudy and clear conditions up to 7 km height are better than 2.5 K (temperature) and 1.1 g/m3 (humidity) as determined by statistical com...

We describe a method for obtaining single-path phase delays from GPS double differences. The resulting ``zero differences'' (ZDs) can be used for remote sensing of atmospheric water vapor. The method is demonstrated by simulating and observing atmospheric delay gradients, and by comparing ZDs with pointed radiometer observations of integrated water...

Using temperature profiles obtained by the GPS/MET (GPS Meteorology) experiment from April 1995 to February 1997, we have extracted mesoscale temperature perturbations with vertical wavelengths ranging from 2 to 10 km and background Brunt-Väisälä frequency squared, N2. For each occultation event, we can evaluate a potential energy Ep which is assum...

Phase delays induced in GPS signals by the ionosphere and neutral atmosphere can be measured with high precision simultaneously along a dozen or so GPS ray paths in the field of view. These delays can be converted into total electron content (TEC) and integrated water vapor (if surface pressure data or estimates are available) along each GPS ray pa...

Dry air, water vapor, hydrometeors, and other particulates (sand, dust, aerosols, and volcanic ash) in the atmosphere introduce microwave propagation delays. These delays must be properly characterized to achieve the highest accuracy in surveying and atmospheric sensing using Global Positioning System (GPS) signals. In this paper we review the theo...

The goal is to develop GPS remote sensing techniques to determine atmospheric refractivity profiles and to aid in the detection of oceanic boundary layers from a ship. The primary scientific objective of this research is to develop GPS sounding techniques for ground based atmospheric profiling. Atmospheric profiling with GPS from space has been dem...

We have developed a tunable temperature profiler based on a highly stable synthe-sizer that can observe at multiple frequencies on the shoulder of the 60 GHz atmospheric oxygen feature. We are developing a similar radiometer to obtain the vertical distribution of water vapor by making observations on the pressure broadened water vapor line from 22...

We describe sensing of atmospheric column water va-por in near real-time using the Global Positioning System (GPS). We use predicted GPS orbits for automated computation of vertical column water vapor within 30 minutes of GPS data collection. Based on a 4 month comparison, near real-time GPS column water vapor agrees with radiosondes and radiometer...

Multipath and atmospheric effects can limit GPS surveying precision. We surveyed a 43 km baseline using large diameter choke ring antennas to reduce multipath and pointed radiometer and barometric data to correct for atmospheric slant delay. Based on 11 daily solutions, atmospheric slant delay corrections improved vertical precision to 1.2 mm rms a...

We demonstrate sensing of integrated slant-path water vapor (SWV) along ray paths between Global Positioning System (GPS) satellites and receivers. We use double differenc-ing to remove GPS receiver and satellite clock errors and 85-cm diameter choke ring antennas to reduce ground-reflected multi-path. We compare more than 17,000 GPS and pointed ra...

A simple approach to estimating vertically integrated atmospheric water vapor, or precipitable water, from Global Positioning System (GPS) radio signals collected by a regional network of ground-based geodetic GPS receiver is illustrated and validated. Standard space geodetic methods are used to estimate the zenith delay caused by the neutral atmos...

This paper provides an overview of applications of the Global Positioning System (GPS) for active measurement of the Earth's atmosphere. Microwave radio signals transmitted by GPS satellites are delayed (refracted) by the atmosphere as they propagate to Earth-based GPS receivers or GPS receivers carried on low Earth orbit satellites.The delay in GP...

Atmospheric water vapor was measured with six Global Positioning System (GPS) receivers for 1 month at sites in Colorado, Kansas, and Oklahoma. During the time of the experiment from 7 May to 2 June 1993, the area experienced severe weather. The experiment, called “GPS/STORM,” used GPS signals to sense water vapor and tested the accuracy of the met...

Values of Tmr obtained from current methods and this new approach are compared to those obtained from in situ soundings. Use of forecast model data relieves a WVR site of its dependency on local climatology or the necessity of a nearby sounding, allowing more accurate retrieval of observed conditions and increased flexibility in choosing site locat...

Emerging networks of Global Positioning System (GPS) receivers can be used in the remote sensing of atmospheric water vapor. The time-varying zenith wet delay observed at each GPS receiver in a network can be transformed into an estimate of the precipitable water overlying that receiver. This transformation is achieved by multiplying the zenith wet...

Delay of the Global Positioning System (GPS) signal due to atmospheric water vapor is a major source of error in GPS surveying. Improved vertical accuracy is important for sea level and polar isostasy measurements, geodesy, normal fault motion, subsidence, earthquake studies, air and ground-based gravimetry, ice dynamics, and volcanology. We conduc...

Global Positioning System (GPS) receivers, water vapor radiometers (WVRs), and surface meteorological equipment were operated at both ends of a 50-km baseline in Colorado to measure the precipitable water vapor (PWV) and wet delay in the line-of-sight to GPS satellites. Using high precision orbits, WVR-measured and GPS-inferred PWV differences betw...

Using simulated atmospheric data from the National Center for Atmospheric Research (NCAR) community climate model (CCM), we test the hypothesis that the global positioning system (GPS) can be used to detect global and regional climate change. We examine how the fundamental GPS variables (wet and total delays and vertical profiles of refractivity) a...

We present a new approach to remote sensing of water vapor based on the Global Positioning System (GPS). Geodesists and geophysicists have devised methods for estimating the extent to which signals propagating from GPS satellites to ground-based GPS receivers are delayed by atmospheric water vapor. This delay is parameterized in terms of a time-var...

THE SPACE PHOENIX PROGRAM - Executive Summary Emptied of most of its fuel and jettisoned by the Orbiter at close to orbital velocity, the Space Shuttle's external fuel tank, at the point of separation, is poised for use in space. Instead, these immense vessels, each representing more than $300 million of sunk costs at the moment of jettison, curren...

The US federal government is collaborating with a non-profit university consortium and its commercial project managers to develop the Space Shuttle fleet's expended external fuel tanks for scientific and commercial uses in space. Nearly a half dozen years in evolution, the Space Phoenix Program is a private-sector civil space programme with the lon...

Hydrogen gas can be released by chemical and mechanical changes in crustal rocks. Once released, it is highly mobile, buoyant, and almost insoluble in groundwater. A fault system may act as a conduit, allowing hydrogen to accumulate in soil gases near a surface expression. Since hydrogen is scarce in ambient air, its presence at elevated levels in...

Wind and thermodynamic sounding using radar and microwave radiometry is now mature. Typically, radar and radiometric observations are converted into temperature, humidity, cloud liquid profiles and horizontal wind profiles. These profiles can be assimilated into numerical weather models. This approach has the advantage that methods widely used for...