1 to 9 of 9 Results
Aug 1, 2008
Pi, Xiaoqing; Edwards, Charles D.; Hajj, George A.; Ao, Chi; Romans, Larry J.; Callas, John L.; Mannucci, Anthony J.; Asmar, Sami W.; Kahan, Daniel S., 2008, "A Chapman -layers ionspheric model for Mars.", https://hdl.handle.net/2014/40912, UNKNOWN, JPL Open Repository
A numerical model (CLIMM) is developed that adopts functions of two Chapman layers to compute Mars ionospheric electron densities at given local solar zenith angle and height. Electron density profiles derived from Mars Global Survey (MGS)-to-Earth radio occultation measurements... |
Sep 13, 2005
Ao, Chi O.; Hajj, George A.; Iijima, Byron A.; Mannucci, Anthony J.; Schrøder, Thomas M.; de la Torre Juárez, Manuel; Leroy, Stephen S., 2005, "Sensitivity of stratospheric retrievals from radio occultations on upper boundary conditions", https://hdl.handle.net/2014/40630, 2nd International Workshop on Occultations for Probing Atmosphere and Climate (OPAC), Graz, Austria, September 13-17, 2004., JPL Open Repository
The main uncertainty in the stratospheric retrievals from GPS radio occultation (RO) measurements comes from the lack of reliable measurements in the upper stratosphere and above where the bending due to the neutral atmosphere is weak and residual ionospheric effects are strong.... |
May 1, 2005
Pi, Xiaoqing; Hajj, George A.; Wilson, Brian D.; Mandrake, Lukas; Mannucci, Anthony J.; Wang, Chunming; Akopian, Vardan, 2005, "Assimilative modeling of low-latitude ionosphere", https://hdl.handle.net/2014/37583, Proceedings of PLANS 2004. Position Location and Navigation Symposium (IEEE Cat. No.04CH37556), The 11th International Symposium on Equatorial Aeronomy, Taipei, Taiwan, May 9-14, JPL Open Repository
In this paper we present an observation system simulation experiment for modeling low-latitude ionosphere using a 3-dimensional (3-D) global assimilative ionospheric model (GAIM). The experiment is conducted to test the effectiveness of GAIM with a 4-D variational approach (4DVAR... |
Jan 19, 2005
Wu, Dong L.; Ao, Chi O.; Hajj, George A.; de la Torre Juarez, Manuel; Mannucci, Anthony J., 2005, "Sporadic E morphology from GPS-CHAMP radio occultation", https://hdl.handle.net/2014/40042, Journal of Geophysical Research, VOL. 110, A01306, doi:10.1029/2004JA010701, 2005, JPL Open Repository
The scintillations of phase and amplitude in terms of signal-to-noise ratio (SNR) of the GPS radio occultation signal are caused by thin ionization layers. These thin irregular electron density layers in the E region ionosphere are often called sporadic E (Es). For a monthly retr... |
Nov 1, 2004
Mannucci, Anthony J.; Ao, Chi O.; Hajj, George A.; Iijima, Byron A.; de la Torre-Juarez, Manuel; Meehan, Thomas K.; Schroder, Thomas, 2004, "Towards new scientific observations from GPS occultations: advances in retrieval methods", https://hdl.handle.net/2014/37525, Remote Sensing of the Atmosphere, Ocean, Environment, and Space, Honolulu, HI, November 8-12, 2004, JPL Open Repository
We will present recent innovations in extracting scientifically useful information from the phase and amplitude of received GPS transmissions, and discuss the technical challenges that need to be overcome to achieve new scientific results. |
Apr 26, 2004
Pi, Xiaoqing; Wang, Chunining; Hajj, George A.; Rosen, I. Gary; Wilson, Brian D.; Mannucci, Anthony J., 2004, "Assimilative modeling of low latitude ionosphere", https://hdl.handle.net/2014/38380, IEEE Position Location and Navigation Symposium, Monterey, CA, April 26-29, 2004., JPL Open Repository
In this paper we present an observation system simulation experiment for modeling low-latitude ionosphere using a 3-dimensional (3-D) global assimilative ionospheric model (GAIM). The experiment is conducted to test the effectiveness of GAIM with a 4-D variational approach (4DVAR... |
Sep 1, 2003
Yunck, Thomas P.; Hajj, George A., 2003, "Atmospheric and ocean sensing with GNSS", https://hdl.handle.net/2014/38033, 2nd CHAMP Science Meeting, Potsdam, Germany, September 1-4, 2003, JPL Open Repository
The 1980s and 1990s saw the Global Positioning System (GPS) transform space geodesy from an elite national enterprise to one open to the individual researcher. By adapting the tools from that endeavor we are learning to probe the atmosphere and the ocean surface in novel ways, in... |
Jul 8, 2003
Yunck, Tom P.; Hajj, George A., 2003, "Global navigation satellite sounding of the atmosphere and GNSS altimetry : prospects for geosciences", https://hdl.handle.net/2014/39038, IUGG General Assembly, Sapporo, Japan, July 8-11, 2003., JPL Open Repository
The vast illuminating power of the Global Positioning System (GPS), which transformed space geodesy in the 199Os, is now serving to probe the earth’s fluid envelope in unique ways. Three distinct techniques have emerged: ground-based sensing of the integrated atmospheric moisture... |
May 20, 1996
Romans, Larry J.; Hajj, George A., 1996, "Ionospheric Imaging with Low-Earth Orbiters Tracking GPS", https://hdl.handle.net/2014/25236, Baltimore, Maryland, USA, JPL Open Repository
No abstract provided |
