Forecast impact experiment with a constellation of GPS radio occultation receivers

Healy, S. B.

doi:10.1002/asl.169

Cited by 73 publications

(58 citation statements)

References 19 publications

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“…Not only do they contribute independent information that is complementary to other satellite and in-situ observations, their essential lack of bias actually improves the impact of other sensors that have biases (Healy, 2008).…”

Section: Numerical Weather Analysis and Predictionmentioning

confidence: 99%

“…Figure 27 shows that on 12 December a long-standing bias in 100-mb temperatures in the Southern Hemisphere was immediately reduced to near zero by the bias-free RO observations. Figure 28 shows the impact of COSMIC data on NCEP (Cucurull, 2010) and ECMWF (Healy, 2008) forecasts. At NCEP, the anomaly correlation for the forecast 500-mb height shows an eight-hour gain in forecast accuracy at Day 4.…”

Section: Numerical Weather Analysis and Predictionmentioning

confidence: 99%

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Exploring Earth's atmosphere with radio occultation: contributions to weather, climate and space weather

2011

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Abstract. The launch of the proof-of-concept mission GPS/MET (Global Positioning System/Meteorology) in 1995 began a revolution in profiling Earth's atmosphere through radio occultation (RO). GPS/MET; subsequent single-satellite missions CHAMP (CHAllenging Minisatellite Payload), SAC-C (Satellite de Aplicaciones Cientificas-C), GRACE (Gravity Recovery and Climate Experiment), METOP-A, and TerraSAR-X (Beyerle et al., 2010); and the six-satellite constellation, FORMOSAT-3/COSMIC (Formosa Satellite mission #3/Constellation Observing System for Meteorology, Ionosphere, and Climate) have proven the theoretical capabilities of RO to provide accurate and precise profiles of electron density in the ionosphere and refractivity, containing information on temperature and water vapor, in the stratosphere and troposphere. This paper summarizes results from these RO missions and the applications of RO observations to atmospheric research and operational weather analysis and prediction.

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Section: Numerical Weather Analysis and Predictionmentioning

confidence: 99%

Section: Numerical Weather Analysis and Predictionmentioning

confidence: 99%

Exploring Earth's atmosphere with radio occultation: contributions to weather, climate and space weather

2011

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“…During the last few years, RO measurements have been increasingly used by weather centers around the globe, and they show a surprisingly large positive impact on the quality of atmospheric analyses (Cardinali, 2009), partly due to the fact that they are the only satellite data (so far) that can be assimilated without bias correction (Healy, 2008).…”

mentioning

confidence: 99%

Refractivity and temperature climate records from multiple radio occultation satellites consistent within 0.05%

et al. 2011

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Abstract. Data consistency is an important prerequisite to build radio occultation (RO) climatologies based on a combined record of data from different satellites. The presence of multiple RO receiving satellites in orbit over the same time period allows for testing this consistency. We used RO data from CHAMP (CHAllenging Minisatellite Payload for geoscientific research), six FORMOSAT-3/COSMIC satellites (Formosa Satellite Mission 3/Constellation Observing System for Meteorology, Ionosphere and Climate, F3C), and GRACE-A (Gravity Recovery and Climate Experiment). We show latitude-altitude-resolved results for an example month (October 2007) and the temporal evolution of differences in a climate record of global and monthly means from January 2007 to December 2009. Latitude-and altitude-resolved refractivity and dry temperature climatologies clearly show the influence of different sampling characteristics; monthly mean deviations from the multi-satellite mean over the altitude domain 10 km to 30 km typically reach 0.1 % and 0.2 K, respectively. Nevertheless, the 3-yr average deviations (shorter for CHAMP) are less than 0.03 % and 0.05 K, respectively. We find no indications for instrument degradation, temporal inhomogeneities in the RO records, or temporal trends in sampling patterns. Based on analysis fields from ECMWF (European Centre for MediumRange Weather Forecasts), we can estimate -and subtract -the sampling error from each monthly climatology. After such subtraction, refractivity deviations are found reduced to <0.05 % in almost any month and dry temperature deviCorrespondence to: U. Foelsche (ulrich.foelsche@uni-graz.at) ations to <0.05 K (<0.02 % relative) for almost every satellite and month. 3-yr average deviations are even reduced to <0.01 % and <0.01 K (CHAMP: −0.05 K), respectively, establishing an amazing consistency of RO climatologies from different satellites. If applying the same processing scheme for all data, refractivity and dry temperature records from individual satellites with similar bending angle noise can be safely combined up to 30 km altitude (refractivity also up to 35 km) to a consistent single climate record of substantial value for climate monitoring in the upper troposphere and lower stratosphere.

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“…In past decades, numerous studies have demonstrated the unique strengths of GPS RO, which include high accuracy and vertical resolution, global coverage, all-weather capability, and self-calibration aptitude (e.g., Kursinski et al, 1997;Hajj et al, 2002;Wickert et al, 2004;Kuo et al, 2004). The data are accepted as an operationally reliable source of information by NWP centers worldwide (Poli et al, 2010), and have shown clear positive impacts on weather forecasting (e.g., Healy, 2008;Buontempo et al, 2008;Cucurull and Derber, 2008;Aparicio et al, 2009;Rennie, 2010) and merits in atmospheric reanalysis projects (Saha et al, 2010;Dee et al, 2011). In particular, RO data are assimilated without any bias correction.…”

Section: Introductionmentioning

confidence: 99%

A perspective on the fundamental quality of GPS radio occultation data

Wee

Kuo

2015

Atmos. Meas. Tech.

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Abstract. Radio occultation (RO) is a promising source of observation for weather and climate applications. However, the uncertainties arising from imperfect retrieval algorithms may weaken the overall confidence in the data and discourage their use. As an alternative approach of assessing the quality of RO data while avoiding the nuisance of retrieval errors, this study proposes to use minimally processed data (measurement) instead of derived RO data. This study compares measured phase paths with their model counterparts, simulated with an effective ray tracer for which the refractive indices along the complete ray path linking the transmitter and the receiver are realistically specified. The comparison of phase measurements with the European Centre for Medium-Range Weather Forecasts (ECMWF) data made in the observation space shows that the RO measurements are of sufficient accuracy to uncover regional-scale systematic errors in ECMWF's operational analysis and the 45-year reanalysis (ERA40), and to clearly depict the error growth of short-term ERA40 forecasts. In the southern hemispheric stratosphere, in particular, the RO measurements served as a robust reference against which both of the two analyses were significantly biased in opposite directions even though they were produced by the same center using virtually the same set of data. The measurement and ECMWF analyses showed a close agreement in the standard deviation except for the regions and heights that the quality of the ECMWF data is controversial. This confirms the high precision of RO measurements and also indicates that the main problem of the ECMWF analyses lies in their systematic error.

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Forecast impact experiment with a constellation of GPS radio occultation receivers

Cited by 73 publications

References 19 publications

Exploring Earth's atmosphere with radio occultation: contributions to weather, climate and space weather

Exploring Earth's atmosphere with radio occultation: contributions to weather, climate and space weather

Refractivity and temperature climate records from multiple radio occultation satellites consistent within 0.05%

A perspective on the fundamental quality of GPS radio occultation data

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