scholarly journals Recovery and Validation of Venus Neutral Atmospheric Profiles from Pioneer Venus Orbiter Radio Occultation Observations

2020 ◽  
Vol 1 (3) ◽  
pp. 79
Author(s):  
Paul Withers ◽  
Kerry Hensley ◽  
Marissa F. Vogt ◽  
Jacob Hermann
Keyword(s):  
Radio Occultation ◽  
Atmospheric Profiles

scholarly journals The power of vertical geolocation of atmospheric profiles from GNSS radio occultation

2017 ◽  
Vol 122 (3) ◽  
pp. 1595-1616 ◽  
Author(s):  
Barbara Scherllin‐Pirscher ◽  
Andrea K. Steiner ◽  
Gottfried Kirchengast ◽  
Marc Schwärz ◽  
Stephen S. Leroy
Keyword(s):  
Radio Occultation ◽  
Atmospheric Profiles

scholarly journals The Radio Occultation Experiment aboard CHAMP: Operational Data Analysis and Validation of Vertical Atmospheric Profiles

2004 ◽  
Vol 82 (1B) ◽  
pp. 381-395 ◽  
Author(s):  
Jens WICKERT ◽  
Torsten SCHMIDT ◽  
Georg BEYERLE ◽  
Rolf KÖNIG ◽  
Christoph REIGBER ◽  
...  
Keyword(s):  
Data Analysis ◽  
Radio Occultation ◽  
Atmospheric Profiles ◽  
Operational Data

scholarly journals Sub-Fresnel-scale vertical resolution in atmospheric profiles from radio occultation

Radio Science ◽  
1997 ◽  
Vol 32 (2) ◽  
pp. 411-423 ◽  
Author(s):  
E. Tuna Karayel ◽  
David P. Hinson
Keyword(s):  
Radio Occultation ◽  
Vertical Resolution ◽  
Atmospheric Profiles

GPS Radio Occultation with CHAMP: Comparison of Atmospheric Profiles from GFZ Potsdam and IGAM Graz

2005 ◽  
pp. 525-530 ◽  
Author(s):  
Jens Wickert ◽  
Andreas Gobiet ◽  
Georg Beyerle ◽  
Andrea K. Steiner ◽  
Gottfried Kirchengast ◽  
...  
Keyword(s):  
Radio Occultation ◽  
Gps Radio Occultation ◽  
Atmospheric Profiles

scholarly journals An Evaluation of Fengyun-3C Radio Occultation Atmospheric Profiles Over 2015–2018

2020 ◽  
Vol 12 (13) ◽  
pp. 2116
Author(s):  
Jinde Wei ◽  
Ying Li ◽  
Kefei Zhang ◽  
Mi Liao ◽  
Weihua Bai ◽  
...  
Keyword(s):  
Radio Occultation ◽  
Specific Humidity ◽  
Altitude Range ◽  
Sampling Errors ◽  
Weather Forecasts ◽  
Temporal Domain ◽  
Relative Standard ◽  
Atmospheric Profiles ◽  
Standard Deviations ◽  
Global Mean

Fengyun-3C (FY-3C) is the first Chinese satellite that is capable of using the Radio Occultation (RO) technique to retrieve atmospheric profiles. This research evaluates the quality of FY-3C RO profiles including refractivity, temperature, and specific humidity by comparing with corresponding information from the European Centre for Medium-Range Weather Forecasts (ECMWF) Interim Reanalysis (ERA-Interim) data over the period of 2015–2018. The evaluation is carried out by calculating and analyzing mean systematic differences between FY-3C and ERA-Interim profiles and corresponding standard deviations over a selected spatial and temporal domain. Results show that the FY-3C RO profiles are overall with good agreements with the ERA-Interim data. Global mean refractivity systematic differences are within ±0.2% from 5 to 30 km altitude range with relative standard deviations of less than 2%. Global temperature mean systematic differences vary within ±0.2 K from a 10- to 20-km altitude range with standard deviations of less than 2 K. Global mean specific humidity differences are found to be within ±0.2 g/kg from 2 to 20 km with standard deviations of less than 1 g/kg. FY-3C profiles show visible latitudinal and altitudinal variations, while the seasonal variations are minor. Sampling errors of refractivity and temperature are also found to be larger at higher latitudinal regions due to RO events being less sampled in the polar region.

scholarly journals Errors in GNSS radio occultation data: relevance of the measurement geometry and obliquity of profiles

2011 ◽  
Vol 4 (2) ◽  
pp. 189-199 ◽  
Author(s):  
U. Foelsche ◽  
S. Syndergaard ◽  
J. Fritzer ◽  
G. Kirchengast
Keyword(s):  
Ray Tracing ◽  
Radio Occultation ◽  
Elevation Angle ◽  
Measurement Data ◽  
Azimuth Angle ◽  
Random Errors ◽  
Tangent Point ◽  
Atmospheric Profiles ◽  
Systematic And Random Errors ◽  
Measurement Geometry

Abstract. Atmospheric profiles retrieved from GNSS (Global Navigation Satellite System) radio occultation (RO) measurements are increasingly used to validate other measurement data. For this purpose it is important to be aware of the characteristics of RO measurements. RO data are frequently compared with vertical reference profiles, but the RO method does not provide vertical scans through the atmosphere. The average elevation angle of the tangent point trajectory (which would be 90° for a vertical scan) is about 40° at altitudes above 70 km, decreasing to about 25° at 20 km and to less than 5° below 3 km. In an atmosphere with high horizontal variability we can thus expect noticeable representativeness errors if the retrieved profiles are compared with vertical reference profiles. We have performed an end-to-end simulation study using high-resolution analysis fields (T799L91) from the European Centre for Medium-Range Weather Forecasts (ECMWF) to simulate a representative ensemble of RO profiles via high-precision 3-D ray tracing. Thereby we focused on the dependence of systematic and random errors on the measurement geometry, specifically on the incidence angle of the RO measurement rays with respect to the orbit plane of the receiving satellite, also termed azimuth angle, which determines the obliquity of RO profiles. We analyzed by how much errors are reduced if the reference profile is not taken vertical at the mean tangent point but along the retrieved tangent point trajectory (TPT) of the RO profile. The exact TPT can only be determined by performing ray tracing, but our results confirm that the retrieved TPT – calculated from observed impact parameters – is a very good approximation to the "true" one. Systematic and random errors in RO data increase with increasing azimuth angle, less if the TPT is properly taken in to account, since the increasing obliquity of the RO profiles leads to an increasing sensitivity to departures from horizontal symmetry. Up to an azimuth angle of 30°, however, this effect is small, even if the RO profiles are assumed to be vertical. For applications requiring highest accuracy and precision it is advisable to exclude RO profiles with ray incidence angles beyond an azimuth of 50°. Errors in retrieved atmospheric profiles decrease significantly, by up to a factor of 2, if the RO data are exploited along the retrieved TPT. The tangent point trajectory of RO profiles should therefore be exploited whenever this is possible.

scholarly journals Consistency and Stability of SNPP ATMS Microwave Observations and COSMIC-2 Radio Occultation over Oceans

2021 ◽  
Vol 13 (18) ◽  
pp. 3754
Author(s):  
Xi Shao ◽  
Shu-peng Ho ◽  
Bin Zhang ◽  
Changyong Cao ◽  
Yong Chen
Keyword(s):  
Radio Occultation ◽  
Weighting Function ◽  
Weather Prediction ◽  
Advanced Technology ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Atmospheric Profiles ◽  
Latitudinal Difference ◽  
The Stability

Radio occultation (RO) sensor measurements have critical roles in numerical weather prediction (NWP) by complementing microwave and infrared sounder measurements with information of the atmospheric profiles at high accuracy, precision, and vertical resolution. This study evaluates Constellation Observing System for Meteorology, Ionosphere, and Climate 2 (COSMIC-2) wet temperature and humidity data products’ consistency and stability through inter-comparison with SNPP advanced technology microwave sounder (ATMS) measurements. Through the community radiative transfer model (CRTM), brightness temperature (BT) at SNPP ATMS channels are simulated with COSMIC-2 retrieved atmospheric profiles from two versions of the University Corporation for Atmospheric Research (UCAR) wet profiles (WETprf and WETpf2) as inputs to the CRTM simulation. The analysis was focused on ATMS sounding channels CH07–14 and CH19–22 with sounding weighting function peak heights from 3.2 to 35 km. The COSMIC-2 vs. ATMS inter-comparison indicates that their BT biases are consistent, and the latitudinal difference is <0.3 K over three latitudinal regions. The differences between the two versions of UCAR COSMIC-2 wet profiles are identified and attributed to the differences in the implementation of 1DVAR retrieval algorithms. The stability between UCAR near real-time COSMIC-2 wet profile data and ATMS measurements is also well-maintained. It is demonstrated that the well-sustained quality of COSMIC-2 RO data makes itself a well-suited reference sensor to capture the calibration update of SNPP ATMS. Furthermore, the impacts of the assimilation of COSMIC-2 data into the European Centre for Medium-Range Weather Forecasts (ECMWF) model after 25 March 25, 2020, are evaluated by trending observation-minus-background (O-B) biases, which confirms the statistically significant positive impacts of COSMIC-2 on the ECMWF reanalysis. The validation of stability and consistency between COSMIC-2 and SNPP ATMS ensures the quality of RO and microwave sounder data assimilated into the NWP models.

scholarly journals Radio Occultation Retrieval of Atmospheric Profiles from the FORMOSAT-3/COSMIC Mission: Early Results

2009 ◽  
Vol 20 (1) ◽  
pp. 21 ◽  
Author(s):  
Cheng-Yung Huang ◽  
Chio-Zong Cheng ◽  
Po-Hsiung Lin ◽  
Chen-Joe Fong ◽  
Jens Wickert ◽  
...  
Keyword(s):  
Radio Occultation ◽  
Early Results ◽  
Atmospheric Profiles
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