Climate intercomparison of GPS radio occultation, RS90/92 radiosondes and GRUAN from 2002 to 2013

Ladstädter, Florian; Steiner, Andrea; Schwärz, Marc; Kirchengast, Gottfried

doi:10.5194/amt-8-1819-2015

Cited by 51 publications

(61 citation statements)

References 48 publications

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“…In summary, also the comparison to this entirely independent radiosonde dataset underpins the finding that both the zero-and single-differencing do a robust job and that the GNOS BDS retrievals exhibit a high performance similar to GPS retrievals that have been established 20 earlier to compare well to quality radiosondes (Anthes, 2011;Ladstaedter et al, 2015).…”

Section: Comparison Analysis Of Refractivity With Radiosonde Datamentioning

confidence: 92%

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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Section: Comparison Analysis Of Refractivity With Radiosonde Datamentioning

confidence: 92%

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

Self Cite

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“…Ladstädter et al (2015) state that the good agreement of the RO and GRUAN RS data sets strongly encourages further development and advancement of both systems for the benefit of future climate monitoring and research. Vergados et al (2015) compared relative humidity of JPL RO, ECMWF Reanalysis • latitude range between 700 hPa and 400 hPa.…”

Section: Introductionmentioning

confidence: 99%

“…Ladstädter et al (2015) compared WEGC RO profiles from multiple missions to a five year record of GRUAN RS profiles (both of which have the 5 potential to serve as reference observations in the GCOS) and to a standard 11 year record of RS profiles (Vaisala RS90/92).…”

Section: Introductionmentioning

confidence: 99%

Evaluating tropospheric humidity from GPS radio occultation, radiosonde, and AIRS from high-resolution time series

Rieckh¹,

Anthes²,

Randel³

et al. 2018

Preprint

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Abstract. While water vapor is the most important tropospheric greenhouse gas, it is also highly variable in both space and time, and water vapor concentrations range over three orders of magnitude in the troposphere. These properties challenge all observing systems to accurately measure and resolve the vertical structure and variability of tropospheric humidity. In this study we characterize the humidity measurements of various observing techniques, including four separate Global Positioning System (GPS) Radio Occultation (RO) humidity retrievals (UCAR direct, UCAR 1D-Var, WEGC 1D-Var, Jet Propulsion 5 Laboratory (JPL) direct), radiosonde, and Atmospheric Infrared Sounder (AIRS) data. Furthermore, we evaluate how well the ERA-Interim reanalysis and National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS) model perform in analyzing water vapor at different levels. To investigate detailed vertical structure, we used time-height cross sections over specific locations (radiosonde stations in the tropical and subtropical western Pacific) for the year 2007. We found that RO humidity has comparable or better accuracy than both radiosonde and AIRS humidity over 800 hPa to 400 hPa, 10 as well as below 800 hPa if super-refraction is absent. The various RO retrievals of specific humidity agree within 20 % in the 1000 hPa to 400 hPa layer, and differences are most pronounced above 600 hPa.

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“…The accuracy of humidity profiles is estimated to about 0.3 g kg -1 to 0.1 g kg -1 in the lower to middle troposphere (Kursinski and Gebhardt, 2014) and to 0.03 g kg -1 for climatological averages, which are also useful in the upper troposphere (Rieckh et al, 2016) where specific humidity is small. Excessive validation of RO atmospheric profiles with independent observations, including radiosondes (e.g., Ladstädter et al, 2015) and satellite limb sounder data (e.g., 5…”

mentioning

confidence: 99%

“…Available RO data products include individual profiles as well as gridded climatologies (e.g., Ho et al, 2012;Steiner et al, 2013).…”

mentioning

confidence: 99%

Tropical convection regimes in climate models: evaluation with satellite observations

Steiner¹,

Lackner²,

Ringer³

2017

Preprint

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Abstract. High quality observations are powerful tools for the evaluation of climate models towards improvement and 10 reduction of uncertainty. Particularly at low latitudes, the most uncertain aspect lies in the representation of moist convection and interaction with dynamics, where rising motion is tied to deep convection and sinking motion to dry regimes. Since humidity is closely coupled with temperature feedbacks in the tropical troposphere a proper representation of this region is essential. Here we demonstrate the evaluation of atmospheric climate models with satellite-based observations from Global Positioning System (GPS) radio occultation (RO), which feature high vertical resolution and accuracy in the troposphere to 15 lower stratosphere. We focus on the representation of the vertical atmospheric structure in tropical convection regimes, defined by high updraft velocity over warm surfaces, and investigate atmospheric temperature and humidity profiles. Results reveal that some models do not fully capture convection regions, particularly over land, and only partly represent high updraft or downdraft velocities. Models show large biases in tropical mean temperature of more than 4 K in the tropopause region and the lower stratosphere. Reasonable agreement with observations is given in mean specific humidity in the lower 20 to mid-troposphere. In moist convection regions, models tend to underestimate moisture by 10% to 30% over oceans whereas in dry downdraft regions they overestimate moisture by 100%. Our findings provide evidence that RO observations are a unique source of information, with a range of further atmospheric variables to be exploited, for the evaluation and advancement of next generation climate models.

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Climate intercomparison of GPS radio occultation, RS90/92 radiosondes and GRUAN from 2002 to 2013

Cited by 51 publications

References 48 publications

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

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

Evaluating tropospheric humidity from GPS radio occultation, radiosonde, and AIRS from high-resolution time series

Tropical convection regimes in climate models: evaluation with satellite observations

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