A5038934954- Ionosphere and magnetosphere dynamics
- GNSS positioning and interference
- Geophysics and Gravity Measurements
- Earthquake Detection and Analysis
- Meteorological Phenomena and Simulations
- Solar and Space Plasma Dynamics
- Geomagnetism and Paleomagnetism Studies
- Atmospheric Ozone and Climate
- Spacecraft Design and Technology
- Inertial Sensor and Navigation
- Methane Hydrates and Related Phenomena
- Oceanographic and Atmospheric Processes
- Precipitation Measurement and Analysis
- Particle Detector Development and Performance
- Space Satellite Systems and Control
- Atmospheric and Environmental Gas Dynamics
- Tropical and Extratropical Cyclones Research
- Satellite Communication Systems
- Planetary Science and Exploration
- Scientific Computing and Data Management
- Advanced Data Processing Techniques
- Astro and Planetary Science
- Advanced Frequency and Time Standards
- Laser-induced spectroscopy and plasma
- Astrophysics and Cosmic Phenomena
University Corporation for Atmospheric Research
2015-2024
University of Colorado Boulder
1991-2014
National Oceanic and Atmospheric Administration
2014
John Wiley & Sons (United States)
2014
National Chung Shan Institute of Science and Technology
2014
United States Naval Research Laboratory
2008
NSF National Center for Atmospheric Research
2008
NOAA Center for Satellite Applications and Research
2008
European Centre for Medium-Range Weather Forecasts
2008
Jet Propulsion Laboratory
2008
The radio occultation (RO) technique, which makes use of signals transmitted by the global positioning system (GPS) satellites, has emerged as a powerful and relatively inexpensive approach for sounding atmosphere with high precision, accuracy, vertical resolution in all weather over both land ocean. On 15 April 2006, joint Taiwan-U.S. Constellation Observing System Meteorology, Ionosphere, Climate (COSMIC)/Formosa Satellite Mission 3 (COSMIC/FORMOSAT-3, hereafter COSMIC) mission,...
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 Earth's atmosphere using radio occultation technique. demonstration system observes occulted GPS satellite signals received a low Earth orbiting LEO) satellite, MicroLab‐1, launched April 3,1995. can profile ionospheric electron density and neutral atmospheric properties. Neutral refractivity, density,...
This paper provides an overview of the methodology and describes preliminary results from experiment called GPS/MET (Global Positioning System/Meteorology), in which temperature soundings are obtained a low Earth-orbiting satellite using radio occultation technique. Launched into circular orbit about 750-km altitude 70° inclination on 3 April 1995, small research satellite, MicroLab 1, carried laptop-sized receiver. Each time this receiver rises sets relative to 24 operational GPS...
In this paper, we describe the GPS radio occultation (RO) inversion process currently used at University Corporation for Atmospheric Research (UCAR) COSMIC (Constellation Observing System Meteorology, Ionosphere and Climate) Data Analysis Archive Center (CDAAC). We then evaluate accuracy of RO refractivity soundings CHAMP (CHAllenging Minisatellite Payload) SACC (Satellite de Aplicaciones Cientificas-C) missions processed by CDAAC software, using data primarily from month December 2001. Our...
The Constellation Observing System for Meteorology Ionosphere and Climate (COSMIC)/Formosa Satellite 3 (FORMOSAT‐3) is a six‐satellite radio occultation mission that was launched in mid‐April, 2006. close proximity of the COSMIC satellites provides unique opportunity to estimate precision remote sensing technique from closely collocated occultations (<10 km separation tangent points). RMS difference refractivity between 10 20 altitude less than 0.2%, which approximately twice better...
Abstract Initial data from the Formosa Satellite‐7/Constellation Observing System for Meteorology Ionosphere and Climate (FORMOSAT‐7/COSMIC‐2, hereafter C2), a recently launched equatorial constellation of six satellites carrying advanced radio occultation receivers, exhibit high signal‐to‐noise ratio, precision, accuracy, ability to provide vertical resolution profiles bending angles refractivity, which contain information on temperature water vapor in challenging tropical atmosphere. After...
Global Positioning System (GPS) radio occultation signals received by a low Earth orbit (LEO) satellite provide information about the global distribution of electron density in ionosphere. We examine two inversion algorithms. The first algorithm utilizes Abel integral transform, which assumes spherical symmetry field. test this with approaches: through computation bending angles and total content (TEC) assuming straight line propagation. demonstrate that for GPS frequencies observations LEO,...
The Constellation Observing System for Meteorology Ionosphere and Climate (COSMIC) is a satellite mission the Earth sciences that will make use of recent developments in remote sensing, communications tech nology, computing to solve some most important geo-scientific issues today.COSMIC plans launch eight Low Orbit (LEO) satel lites 2003.Each these spacecraft carry three science payloads weather space research prediction, climate monitoring, geodesy: 1) GPS occultation receiver, 2) Tiny...
Abstract. This letter reports for the first time simulated error distribution of radio occultation (RO) electron density profiles (EDPs) from Abel inversion in a systematic way. Occultation events observed by COSMIC satellites are during spring equinox 2008 calculating integrated total content (TEC) along paths with "true" an empirical model. The retrieval errors computed comparing retrieved EDPs EDPs. results show that NmF2 and hmF2 generally good agreement true values, but reliability...
The radio occultation (RO) sounding technique that uses signals transmitted by the Global Positioning System (GPS) has evolved as an important global observing technology. In this paper, we compare RO refractivity profiles from CHAMP (CHAllenging Minisatellite Payload) satellite mission with those calculated radiosonde soundings over five geographical areas, each of which a different type radiosonde. occur within 2 hours and 300 km are used during period June 2001 through March 2004....
To examine the suitability of GPS radio occultation (RO) observations as a climate benchmark data set, this study aims at quantifying structural uncertainty in RO‐derived vertical profiles refractivity and measured trends obtained from atmospheric excess phase processing inversion procedures. Five years (2002–2006) monthly mean climatologies (MMC) retrieved experiment aboard German satellite CHAMP generated by four RO operational centers were compared. Results show that absolute values...
To examine the claim that Global Positioning System (GPS) radio occultation (RO) data are useful as a benchmark set for climate monitoring, structural uncertainties of retrieved profiles result from different processing methods quantified. Profile‐to‐profile comparisons CHAMP (CHAllenging Minisatellite Payload) January 2002 to August 2008 by six RO centers presented. Differences and standard deviations individual relative inter‐center mean used quantify uncertainty. Uncertainties accumulate...
Abstract. Global Positioning System (GPS) radio occultation (RO) has provided continuous observations of the Earth's atmosphere since 2001 with global coverage, all-weather capability, and high accuracy vertical resolution in upper troposphere lower stratosphere (UTLS). Precise time measurements enable long-term stability but careful processing is needed. Here we provide climate-oriented atmospheric scientists multicenter-based results on RO climatological fields for trend studies. We...
With the increased number of low Earth orbit (LEO) satellites equipped with GPS receivers, LEO based observations play a more important role in space weather research because better global coverage and higher vertical resolution. slant total electron content (TEC) is one most products. In this paper, TEC derivation method main error sources, including multipath calibration, leveling phase to pseudorange TEC, differential code bias (DCB) estimation, are described systematically. It found that...
The joint Taiwan-United States FORMOSAT-3/COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) mission, hereafter called COSMIC, is the first satellite constellation dedicated to remotely sense Earth's atmosphere ionosphere using a technique Global Positioning (GPS) radio occultation (RO). occultations yield abundant information about neutral atmospheric temperature moisture as well space weather estimates of slant total electron content, density profiles, an...
As our civilization becomes more dependent on space based technolo gies, we become vulnerable to conditions in weather.Accurate weather specification and forecasting require proper modeling which account for the coupling between sun, magnetosphere, thermo sphere, ionosphere mesosphere.In spite of tremendous advances that have been made understanding physics behind differ ent phenomena, ability specify or predict is limited due lack continuous extensive observations these regions.Placing a...
This paper investigates the global ionospheric response during January 2009 stratospheric sudden warming (SSW) event by using electron density profiles derived from GPS radio occultation measurements of COSMIC satellites. The peak (NmF2), height (hmF2), and total content (ITEC) increase in morning hours decrease afternoon globally for 75% cases, which SSW non‐SSW days are available around same location local time bins. NmF2, hmF2, ITEC days, on average, 19%, 12 km, 17% 23%, 19 25% afternoon,...
A new type of radio occultation (RO) data, recorded in open‐loop (OL) mode from the SAC‐C satellite, has been tested for monitoring refractivity Atmospheric Boundary Layer (ABL). Previously available RO signals, phase‐locked loop were often unusable sensing lower troposphere (LT) or resulted significant inversion errors, especially tropics. The OL signals allow LT and accurate ABL and, especially, its depth. Comparison RO‐inverted profiles to ECMWF analysis radiosondes generally shows good...
We report preliminary results of a global 3‐D ionospheric electron density reanalysis demonstration study during 2002–2011 based on multisource data assimilation. The monthly has been done by assimilating the quiet days into assimilation model constructed using International Reference Ionosphere (IRI) 2007 and Kalman filter technique. These include navigation satellite system (GNSS) observations total content (TEC) from ground‐based stations, radio occultations CHAMP, GRACE, COSMIC, SAC‐C,...
Previous studies report unexpected electron density reductions, termed “plasma caves,” located underneath the equatorial ionization anomaly (EIA) crests. A radio occultation (RO) observation simulation experiment has been built to evaluate possible biases introduced by spherical symmetry assumption in standard (Abel) RO inversion processes. The simulates profiles and reconstructs plasma structure of EIA at low latitudes, where horizontal gradient is most significant. reconstruction shows...
Transient loss of lock is one the key space weather effects on Global Navigation Satellite System (GNSS). Based Constellation Observing for Meteorology, Ionosphere, and Climate Positioning (GPS) radio occultation (RO) observations during 2007–2011, we have analyzed signal cycle slip (CS) occurrence comprehensively its correlation to ionospheric phenomena such as sporadic E (Es), equatorial F region irregularity (EFI), ionization anomaly (EIA). The high vertical resolution RO enables us...
Abstract. This study investigates the noise level and mission-to-mission stability of Global Positioning System (GPS) radio occultation (RO) neutral atmospheric bending angle data at UCAR COSMIC Data Analysis Archive Center (CDAAC). are used from two independently developed RO instruments currently flying in orbit on FORMOSAT-3/COSMIC (F3C) Metop/GRAS (GNSS Receiver for Atmospheric Sounding) missions. The F3C 50 Hz post-processed with a single-difference excess phase algorithm, closed loop...
[1] In this paper, the Kalman filter is used to retrieve electron density profile along tangent points by assimilating slant total content data observed during a radio occultation (RO) event into an empirical background model. The RO COSMIC satellites on day of year 266 in 2009 are selected do both simulation work and real retrieval test. results show that assimilation technique can improve comparison with Abel inversion. It less influenced ionospheric inhomogeneity than method. Some...
Abstract New ionosphere and electrodynamics modules have been incorporated in the thermosphere eXtension of Whole Atmosphere Community Climate Model (WACCM‐X), order to self‐consistently simulate coupled atmosphere‐ionosphere system. The first specified dynamics WACCM‐X v.2.0 results are compared with several data sets, Thermosphere‐Ionosphere‐Electrodynamics General Circulation (TIE‐GCM), during deep solar minimum year. Comparisons Thermosphere Ionosphere Mesosphere Energetics Dynamics...