Assimilation of GPS radio occultation data for numerical weather prediction

By Ying-Hwa Kuo, Sergey Sokolovskiy, Richard Anthes, F. Vandenberghe. 2000

200 citations recorded by the source corpus.

With the availability of approximately 4,000 radio occultation soundings per day within three hours of observation, COSMIC has the potential to contribute significantly to global and regional weather analysis and prediction. However, the basic radio occultation measurements (phase delays) are very different from traditional meteorological measurements (i.e., temperature, water vapor), and to effectively assimilate them into weather prediction models is a challenging task. Over the past five years, considerable progress has been made in the development of an effective strategy for the assimilation of GPS radio occultation data. In this paper, we (1) review the measurement and data reduction procedures, (2) discuss the error characteristics of the GPS radio occultation data, (3) discuss the various strategies for data assimilation, (4) review results from recent data assimilation research, and (5) provide suggestions for future research. Results from recent studies have led to the conclusion that the best strategy to assimilate GPS radio occultation data is a mixture of bending angles below 10 km and refractivity above 10 km using a variational approach. The assimilation of GPS radio occultation data is likely to have a significant positive impact on global and regional weather prediction through improved definition of water vapor, temperature and wind fields. Although refractivity and bending angles are not directly related to the winds, the assimilation of GPS data leads to improvements in the wind analysis through internal model dynamic adjustments. In order to make optimal use of GPS radio occultation data in weather analysis and prediction, considerable research is needed in: (l) better characterization of GPS measurement errors, particularly in the lower troposphere, (2) improving the computational efficiency and optimizing the strategy of bending angle and refractivity assimilation, and (3) performing a set of observing system simulation experiments with realistic simulation of GPS radio occultation data. These research tasks should be conducted prior to the launch of the COSMIC satellites, so that we can fully realize the potential of COSMIC data in global and regional weather prediction.

Subfields: Aerospace Engineering, Astronomy and Astrophysics, Oceanography

View Paper: https://www.semanticscholar.org/paper/98837d9717f08419681db444cb5b0b1227bf7c57

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Citations in the corpus

Inversion and error estimation of GPS radio occultation Data (2004, methodology): “…meteorological variables forecast by the models, the use of advanced data assimilation techniques, such as three-dimensional or four-dimensional variational data assimilation (3DVAR/4DVAR) systems, are required to assimilate the RO data into operational NWP systems (Eyre 1994; Kuo et al. 2000).”
Assimilation of Global Positioning System radio occultation data in the ECMWF ERA–Interim reanalysis (2010, methodology): “Because the atmospheric refraction in the neutral atmosphere (below the ionosphere) depends on pressure, temperature and watervapour content, the assimilation of GPSRO measurements can be used to reduce errors in these variables in an analysis scheme (Kuo et al., 2000).”
The Radio Occultation Experiment aboard CHAMP: Operational Data Analysis and Validation of Vertical Atmospheric Profiles (2004, background): “However, the meteorological research over the past years has concentrated on the evaluation of assimilation of the ionosphere free bending angles or refractivity profiles (Kuo et al., 2000; Eyre, 1994) instead of vertical temperature and/or water vapor profiles.”
Diagnosis of an Intense Atmospheric River Impacting the Pacific Northwest: Storm Summary and Offshore Vertical Structure Observed with COSMIC Satellite Retrievals (2008, methodology): “This study adds further evidence [to the seven cases shown in Ralph et al. (2006) for flooding on California’s Russian River] that ARs are critical contributors to West Coast extreme precipitation and flooding events.”
Applications of COSMIC to Meteorology and Climate (2000, methodology): “One way to avoid the error due to horizontal inhomogeneity, as discussed by Kuo et al. (2000) elsewhere in this journal, is to avoid the Abel inversion, and to assimilate profiles of bending angles into numerical weather models (Eyre, 1994; Zou et al., 1999).”
GPS radio occultation with GRACE: Atmospheric profiling utilizing the zero difference technique (2004, background): “cent years atmospheric sounding by space-based Global Positioning System (GPS) radio occultation (RO) is considered a valuable data source for numerical weather prediction and climate change studies [Kuo et al., 2000]. From 1995 to 1997 the proof-of-concept GPS/MET mission performed aseries ofsucces”