Quantification of structural uncertainty in climate data records from GPS radio occultation

Steiner, Andrea; Hunt, Douglas; Ho, Shu‐Peng; Kirchengast, Gottfried; Mannucci, A. J.; Scherllin‐Pirscher, Barbara; Gleisner, Hans; Engeln, Axel von; Schmidt, T.; Ao, C. O.; Leroy, S. S.; Kursinski, E. R.; Foelsche, Ulrich; Горбунов, М. Е.; Heise, S.; Kuo, Ying‐Hwa; Lauritsen, K. B.; Marquardt, Christian; Rocken, Christian; Schreiner, William S.; Sokolovskiy, Sergey; Syndergaard, Stig; Wickert, Jens

doi:10.5194/acp-13-1469-2013

Cited by 129 publications

(131 citation statements)

References 48 publications

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“…Foelsche et al (2009) showed that the monthly means of CHAMP, GRACE-A and COSMIC global-average climatology agreed well, with a < 0.05 % discrepancy in refractivity and < 0.05 % in dry temperature for almost all months in the UTLS (Foelsche et al, 2011). Ho et al (2012) and Steiner et al (2013) demonstrate the very low structural uncertainty of the data.…”

Section: Introductionmentioning

confidence: 78%

Quantifying residual ionospheric errors in GNSS radio occultation bending angles based on ensembles of profiles from end-to-end simulations

et al. 2015

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Abstract. The radio occultation (RO) technique using signals from the Global Navigation Satellite System (GNSS), in particular from the Global Positioning System (GPS) so far, is currently widely used to observe the atmosphere for applications such as numerical weather prediction and global climate monitoring. The ionosphere is a major error source in RO measurements at stratospheric altitudes, and a linear ionospheric correction of dual-frequency RO bending angles is commonly used to remove the first-order ionospheric effect. However, the residual ionospheric error (RIE) can still be significant so that it needs to be further mitigated for high-accuracy applications, especially above about 30 km altitude where the RIE is most relevant compared to the magnitude of the neutral atmospheric bending angle. Quantification and careful analyses for better understanding of the RIE is therefore important for enabling benchmark-quality stratospheric RO retrievals. Here we present such an analysis of bending angle RIEs covering the stratosphere and mesosphere, using quasi-realistic end-to-end simulations for a full-day ensemble of RO events. Based on the ensemble simulations we assessed the variation of bending angle RIEs, both biases and standard deviations, with solar activity, latitudinal region and with or without the assumption of ionospheric spherical symmetry and co-existing observing system errors. We find that the bending angle RIE biases in the upper stratosphere and mesosphere, and in all latitudinal zones from low to high latitudes, have a clear negative tendency and a magnitude increasing with solar activity, which is in line with recent empirical studies based on real RO data although we find smaller bias magnitudes, deserving further study in the future. The maximum RIE biases are found at low latitudes during daytime, where they amount to within −0.03 to −0.05 µrad, the smallest at high latitudes (0 to −0.01 µrad; quiet space weather and winter conditions). Ionospheric spherical symmetry or asymmetries about the RO event location have only a minor influence on RIE biases. The RIE standard deviations are markedly increased both by ionospheric asymmetries and increasing solar activity and amount to about 0.3 to 0.7 µrad in the upper stratosphere and mesosphere. Taking also into account the realistic observation errors of a modern RO receiving system, amounting globally to about 0.4 µrad (unbiased; standard deviation), shows that the random RIEs are typically comparable to the total observing system error. The results help to inform future RIE mitigation schemes that will improve upon the use of the linear ionospheric correction of bending angles and also provide explicit uncertainty estimates.

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Section: Introductionmentioning

confidence: 78%

Quantifying residual ionospheric errors in GNSS radio occultation bending angles based on ensembles of profiles from end-to-end simulations

et al. 2015

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“…The target domain for the comparative statistical analysis is from 5 km to 35 km height (upper 15 troposphere and lower stratosphere, UTLS), since commonly the data quality above 35 km and below 5 km is less good, due to the ionospheric effects and tropospheric multipath effects, respectively (e.g., Scherllin-Pirscher et al, 2011aSteiner et al, 2013). We first inspect difference statistics to ECMWF and subsequently to radiosondes.…”

Section: Gnos Bds Ro Single-difference and Zero-difference Results Anmentioning

confidence: 99%

“…The Earth's radio occultation (RO) technique (Melbourne et al, 1994;Ware et al, 1996) using signals from the global navigation satellite system (GNSS) has been widely used to observe 25 the atmospheric parameters (e.g., bending angle, refractivity, temperature, pressure, and water vapor) for applications such as numerical weather prediction (NWP) (e.g., Healy and Eyre, 2000;Kuo et al, 2000;Healy and Thepaut, 2006;Aparicio and Deblonde, 2008;Cucurull and Derber, 2008;Poli et al, 2008;Huang et al, 2010;Le Marshall et al, 2010;Harnisch et al, 2013) and global climate monitoring (GCM) (e.g., Steiner et al, 2001Steiner et al, , 2009Steiner et al, , 2011Steiner et al, , 201330 Atmos. Meas.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of atmospheric profiles derived from single- and zero-difference excess phase processing of BeiDou System radio occultation data of the FY-3C GNOS mission

Bai¹,

Liu²,

Meng³

et al. 2017

Preprint

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The Global Navigation Satellite System (GNSS) Occultation Sounder (GNOS) is one of the 20 new generation payloads onboard the Chinese FengYun 3 (FY-3) series of operational meteorological satellites for sounding the Earth's neutral atmosphere and ionosphere. GNOS was designed for acquiring setting and rising radio occultation (RO) data by using GNSS signals from both the Chinese BeiDou System (BDS) and the U.S. Global Positioning System (GPS). An ultra-stable oscillator with 1-sec stability (Allan deviation) at the level of 10 -12 was 25 installed on FY-3C GNOS, thus both zero-difference and single-difference excess phase processing methods should be feasible for FY-3C GNOS observations. In this study we focus on evaluating zero-difference processing of BDS RO data vs. single-difference processing, in satellites. We used a 3-month set of GNOS BDS RO data (October to December 2013) for the evaluation and compared atmospheric bending angle and refractivity profiles, derived from 5 single-and zero-difference excess phase data, against co-located profiles from ECMWF (European Centre for Medium-Range Weather Forecasts) analyses. We also compared against co-located refractivity profiles from radiosondes. The statistical evaluation against these reference data shows that the results from single-and zero-difference processing are consistent in both bias and standard deviation, clearly demonstrating the feasibility of zero-10 differencing for GNOS BDS RO observations. The average bias (and standard deviation) of the bending angle and refractivity profiles were found to be as small as about 0.05%-0.2% (and 0.7%-1.6%) over the upper troposphere and lower stratosphere, including for the GEO, IGSO, and MEO subsets. Zero-differencing was found to perform slightly better, as may be expected from its lower vulnerability to noise. The validation results establish that GNOS can 15 provide, on top of GPS RO profiles, accurate and precise BDS RO profiles both from singleand zero-difference processing. The GNOS observations by the series of FY-3 satellites will thus provide important contributions to numerical weather prediction and global climate change analysis.

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“…F3/C RO profiles can also be retrieved above 40 km altitude, but the data could obviously be contaminated by ionospheric residuals above that altitude (e.g., Rocken et al 1997;Syndergaard 2000). Ho et al (2012) and Steiner et al (2013) compared RO data from six different processing centers for the same time period (i.e., same ionospheric conditions) and found the largest differences at high altitudes due to different bending angle initialization approaches. Here we mainly examine the temperature and pressure observations between the 8 -20 km altitude range and the water vapor pressure below 8 km.…”

Section: Datamentioning

confidence: 99%

The Equatorial El Niño-Southern Oscillation Signatures Observed by FORMOSAT-3/COSMIC from July 2006 to January 2012

Sun

Liu

Tsai

et al. 2014

Terr. Atmos. Ocean. Sci.

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This paper uses the tropospheric pressure, temperature, and water vapor pressure observed by six micro-satellites of the FORMOSAT-3/COSMIC (F3/C) constellation to study El Niño-Southern Oscillation (ENSO) events from July 2006 to January 2012. The temperature and pressure profiles are used to derive the height, pressure, temperature, and potential temperature of the lapse rate tropopause. Following the calculation of the standard normalized Southern Oscillation Index (SOI) and the Niño 3.4 index, the corresponding indices of the four tropopause parameters are derived. Good agreements between the standard and F3/C-derived indices show that the derived indices are significant for monitoring ENSO signatures. With the uniform coverage, the global F3/C profiles are used to construct three-dimensional structures of temperature, pressure, and water vapor pressure to gain a better understanding of tropospheric structures and dynamics during the ENSO events.

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Quantification of structural uncertainty in climate data records from GPS radio occultation

Cited by 129 publications

References 48 publications

Quantifying residual ionospheric errors in GNSS radio occultation bending angles based on ensembles of profiles from end-to-end simulations

Quantifying residual ionospheric errors in GNSS radio occultation bending angles based on ensembles of profiles from end-to-end simulations

Evaluation of atmospheric profiles derived from single- and zero-difference excess phase processing of BeiDou System radio occultation data of the FY-3C GNOS mission

The Equatorial El Niño-Southern Oscillation Signatures Observed by FORMOSAT-3/COSMIC from July 2006 to January 2012

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