Onboard Radio Frequency Interference as the Origin of Inter-Satellite Biases for Microwave Humidity Sounders

Hans, Imke; Burgdorf, M.; Buehler, Stefan A.

doi:10.3390/rs11070866

Cited by 4 publications

(5 citation statements)

References 10 publications

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“…A dedicated study presented in a different article [32] revealed that also AMSU-B on NOAA-16 and even MHS on NOAA-19 suffer significantly from RFI. RFI was identified as the main reason for the strong inter-satellite biases that are observed for channels 3-5 for AMSU-B on NOAA-16 and 3 and 4 for MHS on NOAA-19.…”

Section: Radio Frequency Interference (Rfi)mentioning

confidence: 99%

An Uncertainty Quantified Fundamental Climate Data Record for Microwave Humidity Sounders

et al. 2019

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To date, there is no long-term, stable, and uncertainty-quantified dataset of upper tropospheric humidity (UTH) that can be used for climate research. As intermediate step towards the overall goal of constructing such a climate data record (CDR) of UTH, we produced a new fundamental climate data record (FCDR) on the level of brightness temperature for microwave humidity sounders that will serve as basis for the CDR of UTH. Based on metrological principles, we constructed and implemented the measurement equation and the uncertainty propagation in the processing chain for the microwave humidity sounders. We reprocessed the level 1b data to obtain newly calibrated uncertainty quantified level 1c data in brightness temperature. Three aspects set apart this FCDR from previous attempts: (1) the data come in a ready-to-use NetCDF format; (2) the dataset provides extensive uncertainty information taking into account the different correlation behaviour of the underlying errors; and (3) inter-satellite biases have been understood and reduced by an improved calibration. Providing a detailed uncertainty budget on these data, this new FCDR provides valuable information for a climate scientist and also for the construction of the CDR.

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Section: Radio Frequency Interference (Rfi)mentioning

confidence: 99%

An Uncertainty Quantified Fundamental Climate Data Record for Microwave Humidity Sounders

et al. 2019

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“…Channel H3 on NOAA‐19, however, was affected by radio‐frequency interference, and the correction scheme by Hans et al. (2019) only works for Earth view counts. Therefore, we excluded these data from our calculations and decided to plot the average of channels H4 and H5 in Figure 5 as a way to reduce the scatter of points.…”

Section: Resultsmentioning

confidence: 99%

“…All sounding channels of AMSU-B and MHS provide the radiance of the Moon very close to 183.31 GHz with the exception of channel H5 on MHS, which operates at 190.31 GHz. Channel H3 on NOAA-19, however, was affected by radio-frequency interference, and the correction scheme by Hans et al (2019) only works for Earth view counts. Therefore, we excluded these data from our calculations and decided to plot the average of channels H4 and H5 in Figure 5 as a way to reduce the scatter of points.…”

Section: Brightness Temperature Of the Waxing And Waning Moonmentioning

confidence: 99%

Calibration and Characterization of Satellite‐Borne Microwave Sounders With the Moon

Burgdorf

Buehler

Prange

2021

Earth and Space Science

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“…This can explain the emerging scan-and time-dependent biases, since the effect of RFI is both scan-and time-dependent. An RFI correction was applied in the FIDUCEO FCDR to all three instruments 39 , which was shown to improve the consistency between instruments. However, for NOAA15 and NOAA17 only an early version of the correction scheme could be applied due to the lack of a reference month that is not affected by RFI.…”

Section: Comparison To the Cm-saf Uth Cdr To Validate The Fiduceo Utmentioning

confidence: 99%

“…Combined, the weaker decrease of NOAA17 UTH and the stronger decrease of NOAA16 UTH due to the near-nadir pixel selection result in a larger bias between NOAA16 and NOAA17 in UTH FID than in UTH CMSAF . The instruments onboard NOAA15, NOAA16 and NOAA17 are known to suffer from radio frequency interference (RFI) from transmitters on-board the satellite 37 – 39 . This can explain the emerging scan- and time-dependent biases, since the effect of RFI is both scan- and time-dependent.…”

Section: Technical Validationmentioning

confidence: 99%

A new climate data record of upper-tropospheric humidity from microwave observations

et al. 2020

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data record to earlier years. The new definition has the additional advantage that UTH can be calculated directly from given atmospheric profiles of humidity and temperature without a detour via radiative transfer simulations. Detailed uncertainty information in CDRs derived from satellite-based Earth observations are needed to support the application of the data in climate research 7,8. Providing such information on CDR level (level 2 or 3) has mainly been constrained by the availability of uncertainty information in the underlying FCDRs (level 1) in the past. Within the FIDUCEO project four new versions of such FCDRs were created, among them the FIDUCEO Microwave FCDR used as input for our UTH CDR. The FCDR includes information on observational uncertainty on pixel level, which is the result of rigorous uncertainty analyses based on metrological principles 9. These uncertainties are propagated to the spatially and temporally averaged quantities in the UTH CDR. Depending on the spatial and temporal correlation behaviour of the underlying error sources, uncertainties are divided into three different classes, enabling the user to propagate them to spatial and temporal averages of the data. The FIDUCEO UTH CDR is validated against an exisiting microwave UTH data record provided by the Satellite Application Facility on Climate Monitoring (CM-SAF). Differences in monthly tropical mean UTH do not exceed 2% RH and can be attributed to differences in the underlying FCDR and in the CDR processing in approximately equal parts. The structure of this paper is as follows: The Methods chapter introduces the satellite instruments, the UTH retrieval method and the new definition of UTH. Furthermore, a detailed description of the CDR processing is provided. This is followed by the Data Records chapter, which includes a description of the CDR data file format as well as the satellite missions and time periods covered. The subsequent chapter Technical Validation consists of an evaluation of the UTH retrieval performance, the comparison of our CDR with the CM-SAF UTH CDR and a description of uncertainties not estimated in the CDR.

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Onboard Radio Frequency Interference as the Origin of Inter-Satellite Biases for Microwave Humidity Sounders

Cited by 4 publications

References 10 publications

An Uncertainty Quantified Fundamental Climate Data Record for Microwave Humidity Sounders

An Uncertainty Quantified Fundamental Climate Data Record for Microwave Humidity Sounders

Calibration and Characterization of Satellite‐Borne Microwave Sounders With the Moon

A new climate data record of upper-tropospheric humidity from microwave observations

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