Assessing the Climate Monitoring Utility of Radio Occultation Data: From CHAMP to FORMOSAT-3/COSMIC

Foelsche, Ulrich; Pirscher, B.; Borsche, Michael; Kirchengast, Gottfried; Wickert, Jens

doi:10.3319/tao.2008.01.14.01(f3c)

Cited by 57 publications

(50 citation statements)

References 36 publications

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“…However, the characteristic differences between 2005 and 2006 do not change significantly against the top-row panels, indicating that introducing an additional GPSRO mission (F3C) to the RO data set is not changing its behavior substantially. This consistency of GPSRO data from different missions has been demonstrated in several studies (Foelsche et al, 2009Steiner et al, 2011).…”

Section: Change In Temperature Difference Characteristics In 2005/06supporting

confidence: 70%

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: Change In Temperature Difference Characteristics In 2005/06supporting

confidence: 70%

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

et al. 2015

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“…The mean temperature difference between the collocated soundings of COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) and CHAMP was within 0.1 K from 200 to 20 hPa (Ho et al, 2009b;Anthes et al, 2008;Foelsche et al, 2009). At 20 hPa, the mean temperature difference between COSMIC and CHAMP was within 0.05 K (Ho et al, 2009b).…”

Section: Introductionmentioning

confidence: 93%

Characterization of the long-term radiosonde temperature biases in the upper troposphere and lower stratosphere using COSMIC and Metop-A/GRAS data from 2006 to 2014

Liang

Vömel

2017

Atmos. Chem. Phys.

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Abstract. Radiosonde observations (RAOBs) have provided the only long-term global in situ temperature measurements in the troposphere and lower stratosphere since 1958. In this study, we use consistently reprocessed Global Positioning System (GPS) radio occultation (RO) temperature data derived from the COSMIC and Metop-A/GRAS missions from 2006 to 2014 to characterize the inter-seasonal and interannual variability of temperature biases in the upper troposphere and lower stratosphere for different radiosonde sensor types. The results show that the temperature biases for different sensor types are mainly due to (i) uncorrected solarzenith-angle-dependent errors and (ii) change of radiation correction. The mean radiosonde-RO global daytime temperature difference in the layer from 200 to 20 hPa for Vaisala RS92 is equal to 0.20 K. The corresponding difference is equal to −0.06 K for Sippican, 0.71 K for VIZ-B2, 0.66 K for Russian AVK-MRZ, and 0.18 K for Shanghai. The global daytime trend of differences for Vaisala RS92 and RO temperature at 50 hPa is equal to 0.07 K/5 yr. Although there still exist uncertainties for Vaisala RS92 temperature measurement over different geographical locations, the global trend of temperature differences between Vaisala RS92 and RO from June 2006 to April 2014 is within ±0.09 K/5 yr. Compared with Vaisala RS80, Vaisala RS90, and sondes from other manufacturers, the Vaisala RS92 seems to provide the most accurate RAOB temperature measurements, and these can potentially be used to construct long-term temperature climate data records (CDRs). Results from this study also demonstrate the feasibility of using RO data to correct RAOB temperature biases for different sensor types.

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“…A number of studies confirmed the capability of RO measurements to monitor the dry atmosphere (above around 8 km; Foelsche et al, 2008Foelsche et al, , 2009) and for climate change detection (Leroy et al, 2006;Ho et al, 2009;Steiner et al, 2011;Ho et al, 2012). RO data feature inherent high accuracy and precision, high vertical resolution (100 to 200 m), all-weather capability, and long-term stability (Anthes, 2011), making them highly valuable for studying a large number of atmospheric phenomena.…”

Section: Introductionmentioning

confidence: 94%

Tropospheric dry layers in the tropical western Pacific: comparisons of GPS radio occultation with multiple data sets

et al. 2017

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Abstract. We use GPS radio occultation (RO) data to investigate the structure and temporal behavior of extremely dry, high-ozone tropospheric air in the tropical western Pacific during the 6-week period of the CONTRAST (CONvective TRansport of Active Species in the Tropics) experiment (January and February 2014). Our analyses are aimed at testing whether the RO method is capable of detecting these extremely dry layers and evaluating comparisons with in situ measurements, satellite observations, and model analyses. We use multiple data sources as comparisons, including CONTRAST research aircraft profiles, radiosonde profiles, AIRS (Atmospheric Infrared Sounder) satellite retrievals, and profiles extracted from the ERA (ERA-Interim reanalysis) and the GFS (US National Weather Service Global Forecast System) analyses, as well as MTSAT-2 satellite images. The independent and complementary radiosonde, aircraft, and RO data provide high vertical resolution observations of the dry layers. However, they all have limitations. The coverage of the radiosonde data is limited by having only a single station in this oceanic region; the aircraft data are limited in their temporal and spatial coverage; and the RO data are limited in their number and horizontal resolution over this period. However, nearby observations from the three types of data are highly consistent with each other and with the lower-vertical-resolution AIRS profiles. They are also consistent with the ERA and GFS data. We show that the RO data, used here for the first time to study this phenomenon, contribute significant information on the water vapor content and are capable of detecting layers in the tropics and subtropics with extremely low humidity (less than 10 %), independent of the retrieval used to extract moisture information. Our results also verify the quality of the ERA and GFS data sets, giving confidence to the reanalyses and their use in diagnosing the full four-dimensional structure of the dry layers.

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Assessing the Climate Monitoring Utility of Radio Occultation Data: From CHAMP to FORMOSAT-3/COSMIC

Cited by 57 publications

References 36 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

Characterization of the long-term radiosonde temperature biases in the upper troposphere and lower stratosphere using COSMIC and Metop-A/GRAS data from 2006 to 2014

Tropospheric dry layers in the tropical western Pacific: comparisons of GPS radio occultation with multiple data sets

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