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Analysis and validation of GPS/MET data in the neutral atmosphere

TLDR
The Global Positioning System/Meteorology ( GPS/MET) Program was established in 1993 by the University Corporation for Atmospheric Research (UCAR) to demonstrate active limb sounding of the Earth's atmosphere using the radio occultation technique.
Abstract
The Global Positioning System/Meteorology ( GPS/MET) Program was established in 1993 by the University Corporation for Atmospheric Research ( UCAR) to demonstrate active limb sounding of the Earth's atmosphere using the radio occultation technique. The demonstration system observes occulted GPS satellite signals received by a low Earth orbiting ( LEO) satellite, MicroLab-1, launched April 3,1995. The system can profile ionospheric electron density and neutral atmospheric properties. Neutral atmospheric refractivity, density, pressure, and temperature are derived at altitudes where the amount of water vapor is low. At lower altitudes, vertical profiles of density, pressure, and water vapor pressure can be derived from the GPS/MET refractivity profiles if temperature data from an independent source are available. This paper describes the GPS/MET data analysis procedures and validates GPS/MET data with statistics and illustrative case studies. We compare more than 1200 GPS/MET neutral atmosphere soundings to correlative data from operational global weather analyses, radiosondes, and the GOES, TOVS, UARS/MLS and HALOE orbiting atmospheric sensors. Even though many GPS/MET soundings currently fail to penetrate the lowest 5 km of the troposphere in the presence of significant water vapor, our results demonstrate 1°C mean temperature agreement with the best correlative data sets between 1 and 40 km. This and the fact that GPS/MET observations are all-weather and self-calibrating suggests that radio occultation technology has the potential to make a strong contribution to a global observing system supporting weather prediction and weather and climate research.

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Journal ArticleDOI

Gravity wave dynamics and effects in the middle atmosphere

TL;DR: In this article, a review of gravity wave sources and characteristics, the evolution of the gravity wave spectrum with altitude and with variations of wind and stability, the character and implications of observed climatologies, and the wave interaction and instability processes that constrain wave amplitudes and spectral shape are discussed.
Journal ArticleDOI

A Sequential Ensemble Kalman Filter for Atmospheric Data Assimilation

TL;DR: In this article, an ensemble Kalman filter is proposed for the 4D assimilation of atmospheric data, which employs a Schur (elementwise) product of the covariances of the background error calculated from the ensemble and a correlation function having local support to filter the small (and noisy) background-error covariance associated with remote observations.
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The COSMIC/FORMOSAT-3 Mission: Early Results

TL;DR: The radio occultation (RO) technique, which makes use of radio signals transmitted by the global positioning system (GPS) satellites, has emerged as a powerful and relatively inexpensive approach for sounding the global atmosphere with high precision, accuracy, and vertical resolution in all weather and over both land and ocean as mentioned in this paper.
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A new dynamic approach for statistical optimization of GNSS radio occultation bending angles for optimal climate monitoring utility

TL;DR: An advanced dynamic statistical optimization algorithm is introduced, which uses bending angles from multiple days of European Centre for Medium-range Weather Forecasts (ECMWF) short-range forecast and analysis fields, together with averaged-observed bending angles, to obtain background profiles and associated error covariance matrices with geographically varying background uncertainty estimates on a daily updated basis.
References
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Journal ArticleDOI

The NCEP/NCAR 40-Year Reanalysis Project

TL;DR: The NCEP/NCAR 40-yr reanalysis uses a frozen state-of-the-art global data assimilation system and a database as complete as possible, except that the horizontal resolution is T62 (about 210 km) as discussed by the authors.
Journal ArticleDOI

The Halogen Occultation Experiment

TL;DR: The Halogen Occultation Experiment (HALOE) uses solar occultation to measure vertical profiles of O3, HCl, HF, CH4, H2O, NO, NO2, aerosol extinction, and temperature versus pressure with an instantaneous vertical field of view of 1.6 km at the earth limb.
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The Constants in the Equation for Atmospheric Refractive Index at Radio Frequencies

TL;DR: In this paper, a relation 77.6 e N = ~ p + 4,810-T T where p = total pressure in millibars e=partial pressure of water vapor in millibrars T=absolute temperature=°C+273
Journal ArticleDOI

Potential Vorticity Diagnostics of Cyclogenesis

TL;DR: In this paper, a diagnostic system based on the relative smallness of the irrotational part of the horizontal wind was developed to calculate the balanced flow given the three-dimensional distribution of Ertel's potential vorticity (PV) framework.
Journal ArticleDOI

GPS Sounding of the Atmosphere from Low Earth Orbit: Preliminary Results

TL;DR: In this article, a low Earth-orbiting satellite using the radio occultation technique was used to obtain temperature soundings from a small research satellite, MicroLab 1, carried a laptop-sized radio receiver.
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