Assessment of radiosonde temperature measurements in the upper troposphere and lower stratosphere using COSMIC radio occultation data

He, Wei; Ho, Shu-peng; Chen, Hongbin; Zhou, Xinjia; Hunt, Douglas; Kuo, Ying‐Hwa

doi:10.1029/2009gl038712

Cited by 91 publications

(82 citation statements)

References 23 publications

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“…The value of GPSRO to act as a reference measurement with climate quality has been demonstrated in a range of publications, including GPSRO comparisons with (A)MSU and radiosonde data (e.g., Sun et al, 2010B.-R. Wang et al, 2013;Ladstädter et al, 2011;Ho et al, 2007Ho et al, , 2010He et al, 2009;Steiner et al, 2007;Kuo et al, 2005). These characteristics underpin its value to act as an upper-air reference observation system with global coverage.…”

Section: F Ladstädter Et Al: Climate Comparison Of Gps Radio Occultmentioning

confidence: 99%

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

et al. 2015

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Abstract.Observations from the GPS radio occultation (GP-SRO) satellite technique and from the newly established GCOS Reference Upper Air Network (GRUAN) are both candidates to serve as reference observations in the Global Climate Observing System (GCOS). Such reference observations are key to decrease existing uncertainties in upperair climate research. There are now more than 12 years of data available from GPSRO, with the recognized properties high accuracy, global coverage, high vertical resolution, and long-term stability. These properties make GPSRO a suitable choice for comparison studies with other upper-air observational systems. The GRUAN network consists of reference radiosonde ground stations (16 at present), which adhere to the GCOS climate monitoring principles. In this study, we intercompare GPSRO temperature and humidity profiles and Vaisala RS90/92 data from the "standard" global radiosonde network over the whole 2002 to 2013 time frame. Additionally, we include the first years of GRUAN data (using Vaisala RS92), available since 2009. GPSRO profiles which occur within 3 h and 300 km of radiosonde launches are used. Overall very good agreement is found between all three data sets with temperature differences usually less than 0.2 K. In the stratosphere above 30 hPa, temperature differences are larger but still within 0.5 K. Day/night comparisons with GRUAN data reveal small deviations likely related to a warm bias of the radiosonde data at high altitudes, but also residual errors from the GPSRO retrieval process might play a role. Vaisala RS90/92 specific humidity exhibits a dry bias of up to 40 % in the upper troposphere, with a smaller bias at lower altitudes within 15 %. GRUAN shows a marked improvement in the bias characteristics, with less than 5 % difference to GPSRO, up to 300 hPa. GPSRO dry temperature and physical temperature are validated using radiosonde data as reference. We find that GPSRO provides valuable long-term stable reference observations with well-defined error characteristics for climate applications and for anchoring other upperair measurements.

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Section: F Ladstädter Et Al: Climate Comparison Of Gps Radio Occultmentioning

confidence: 99%

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

et al. 2015

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“…Recent studies that compare RO retrievals to other in-situ and remote methods, and simulation studies that consider various sources of measurement error, tend to confirm the high accuracy of RO above the lower troposphere Kuo et al, 2005;Schreiner et al, 2007;Sun et al, 2010;Xu et al, 2009;He et al, 2009;Hayashi et al, 2009). The GPS RO technique achieves high accuracy by using "self-calibration": data acquired during the measurement also serves to calibrate the observations.…”

Section: Introductionmentioning

confidence: 99%

The impact of large scale ionospheric structure on radio occultation retrievals

Mannucci

et al. 2011

Atmos. Meas. Tech.

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Abstract.We study the impact of large-scale ionospheric structure on the accuracy of radio occultation (RO) retrievals. We use a climatological model of the ionosphere as well as an ionospheric data assimilation model to compare quiet and geomagnetically disturbed conditions. The presence of ionospheric electron density gradients during disturbed conditions increases the physical separation of the two GPS frequencies as the GPS signal traverses the ionosphere and atmosphere. We analyze this effect in detail using ray-tracing and a full geophysical retrieval system. During quiet conditions, our results are similar to previously published studies. The impact of a major ionospheric storm is analyzed using data from the 30 October 2003 "Halloween" superstorm period. At 40 km altitude, the refractivity bias under disturbed conditions is approximately three times larger than quiet time. These results suggest the need for ionospheric monitoring as part of an RO-based climate observation strategy. We find that even during quiet conditions, the magnitude of retrieval bias depends critically on assumed ionospheric electron density structure, which may explain variations in previously published bias estimates that use a variety of assumptions regarding large scale ionospheric structure. We quantify the impact of spacecraft orbit altitude on the magnitude of bending angle and retrieval error. Satellites in higher altitude orbits (700+ km) tend to have lower residual biases due to the tendency of the residual bending to cancel between the top and bottomside ionosphere. Another factor affecting accuracy is the commonly-used assumption that refractive index is unity at the receiver. We conclude with remarks on the implications of this study for long-term climate monitoring using RO.

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“…Satellites can almost provide whole global wind fields, temperature and atmospheric compositions from the upper troposphere to the lower thermosphere. For example, the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) can measure the lower atmospheric temperature (He et al, 2009;Yang and Zou, 2012); the Upper Atmospheric Research Satellite/High Resolution Doppler Imager (UARS/HRDI) measures temperature, zonal and meridional wind, water vapor and ozone concentration in the middle and upper atmosphere (Wu et al, 1993(Wu et al, , 1996; the Thermosphere Ionosphere Mesosphere Energetics Dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry (TIMED/SABER) is used for temperature measurements in the upper atmosphere (Xu et al, 2007a, b); and the line-of-sight (LOS) winds can be surveyed by the Microwave Limb Sounder (MLS) on Aura (Tunbridge et al, 2011). Satellite observations contribute greatly to our knowledge of global morphology of QTDWs.…”

Section: Y Y Huang Et Al: Global Climatological Variability Of Quamentioning

confidence: 99%

Global climatological variability of quasi-two-day waves revealed by TIMED/SABER observations

et al. 2013

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This paper presents characteristics of quasi-two-day waves (QTDWs) in the mesosphere and lower thermosphere (MLT) between 52° S and 52° N from 2002 to 2011 using TIMED/SABER temperature data. Spectral analysis suggests that dominant QTDW components at mid-high latitudes of the Southern Hemisphere (SH) and the Northern Hemisphere (NH) are (2.13, W3) and (2.04, W4), respectively. The most remarkable QTDW is (2.13, W3), which happened in the southern summer of 2002–2003 at 32° S from 60 to 90 km in altitude. Its downward phase propagation indicates upward propagation of the wave energy and a potential source region below 60 km. Analysis of horizontal wind fields in the same period shows the westward and southward propagation of (2.13, W3) and a possible reflection region above 90 km. Fundamental parameters of QTDWs present significant interhemispheric differences and interannual variations in statistical analysis. Amplitudes in the SH are twice larger than that in the NH, and vertical wavelengths are a little longer in the SH. QTDWs may endure stronger dissipation in southern summer because of shorter durations of their attenuation stages. Impact of the equatorial quasi-biennial-oscillation (QBO) on QTDWs can extend to mid-high latitudes of both hemispheres. It seems easier for QTDWs to propagate upward in the equatorial QBO's westerly phase in the lower stratosphere and easterly phase in the middle stratosphere. Interannual variations of QTDW strength may be influenced by solar activity as well. Strengths of QTDWs appear to be stronger (weaker) in the solar maximum (minimum)

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Assessment of radiosonde temperature measurements in the upper troposphere and lower stratosphere using COSMIC radio occultation data

Cited by 91 publications

References 23 publications

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

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

The impact of large scale ionospheric structure on radio occultation retrievals

Global climatological variability of quasi-two-day waves revealed by TIMED/SABER observations

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