Cross-Calibration and Long-Term Monitoring of the Microwave Radiometers of ERS, TOPEX, GFO, Jason, and Envisat

Scharroo, Remko; Lillibridge, John; Smith, Walter H. F.; Schrama, Ernst

doi:10.1080/01490410490465265

Cited by 53 publications

(49 citation statements)

References 11 publications

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“…Such drifts may result from internal temperature changes induced by yaw maneuvers or when the instrument is turned off. Calibrations with external measurements are periodically performed to detect drifts on the T/P radiometer (TMR) (Scharroo et al, 2004) and Jason-1 radiometer (JMR) (Desai et al, 2004; Jason-1 GDR-B release). Though meteorological models do not represent necessarily the truth in term of stability, they provide a good estimate of the radiometer drift error through altimetry missions and model crosscalibration.…”

Section: Wet Troposphere Correctionmentioning

confidence: 99%

“…The combined atmospheric corrections (sum of high frequencies of MOG2D model (Carrere and Lyard, 2003) and low frequencies of inverse barometer correction) is applied instead of the usual inverse barometer correction in order to improved the cycle by cycle SSH variability. The wet troposphere correction is based on the TOPEX radiometer measurements, after removing a long-term drift (Scharroo et al, 2004) and correcting for the time dependent yaw state (Aviso T/P yearly report 2005). A non-parametric model is used for the sea state bias correction (SSB) with two distinct solutions for TOPEX A and TOPEX B (Gaspar, 2002).…”

Section: Altimeter Msl Calculation Over 1993-2008 Periodmentioning

confidence: 99%

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A new assessment of the error budget of global mean sea level rate estimated by satellite altimetry over 1993–2008

et al. 2009

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Abstract. A new error budget assessment of the global Mean Sea Level (MSL) determined by TOPEX/Poseidon and Jason-1 altimeter satellites between January 1993 and June 2008 is presented using last altimeter standards. We discuss all potential errors affecting the calculation of the global MSL rate. We also compare altimetry-based sea level with tide gauge measurements over the altimetric period. Applying a statistical approach, this allows us to provide a realistic error budget of the MSL rise measured by satellite altimetry. These new calculations highlight a reduction in the rate of sea level rise since 2005, by ∼2 mm/yr. This represents a 60% reduction compared to the 3.3 mm/yr sea level rise (glacial isostatic adjustment correction applied) measured between 1993 and 2005. Since November 2005, MSL is accurately measured by a single satellite, Jason-1. However the error analysis performed here indicates that the recent reduction in MSL rate is real.

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Section: Wet Troposphere Correctionmentioning

confidence: 99%

Section: Altimeter Msl Calculation Over 1993-2008 Periodmentioning

confidence: 99%

A new assessment of the error budget of global mean sea level rate estimated by satellite altimetry over 1993–2008

et al. 2009

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“…The measurements though require calibration and validation all along the lifetime of the altimeter mission to avoid the introduction of biases and drifts in the observed sea surface heights. The radiometers of ERS-1, TOPEX/Poseidon, ERS-2, Jason and ENVISAT exhibit significant drifts in at least one of the channels, resulting in yet unmodeled errors in path delay of up to 1 mm/year [Scharroo et al, 2004]. As it was pointed out by several investigators the onboard radiometer of Jason (JMR) has shown sudden steps or spikes of up to 6 mm wet path delay in October 2002 and between September and November 2003.…”

Section: Introductionmentioning

confidence: 97%

“…[3] Various instruments and techniques were deployed for intercomparisons assessing the performance of satellite radiometers, such as the Special Sensor Microwave Imager (SSM/I), the Tropical Rainfall Mapping Mission's Microwave Imager (TMI), coastal terrestrial GPS sites, radiosondes and the models of the European Centre for Medium-Range Weather Forecasting (ECMWF), and NOAA's National Centers for Environmental Prediction (NCEP) [Brown et al, 2004;Obligis and Tran, 2004;Zlotnicki and Desai, 2004;Desai and Haines, 2004;Scharroo et al, 2004].…”

Section: Introductionmentioning

confidence: 99%

Tropospheric water vapor from solar spectrometry and comparison with Jason microwave radiometer measurements

et al. 2006

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[1] Atmospheric water vapor is a crucial factor in achieving highest accuracies in the field of space geodesy, particularly in the determination of height. A new instrumental approach to high-precision determination of tropospheric water vapor has been investigated and realized in the construction of a mobile solar spectrometer. The optical approach as applied to the spectrometer allows the simultaneous measurement of single vibrational-rotational absorption lines in the wide wavelength range between 728 nm and 915 nm. Dedicated field experiments have been carried out in the frame of an EU project for calibrating the Jason onboard microwave radiometer. A comparison of the spectrometer results with a conventional ground-based water vapor radiometer and radiosondes revealed a fit on the order of 10 mm for the wet path delay, which corresponds to 1.6 kg/m 2 integrated water vapor content (IWV). The comparison with the measurements from the radiometer of Jason reveals an even better agreement for the wet path delay. Long time series are foreseen for a detailed statistical analysis. The mobile solar spectrometer can be considered as a novel portable tool for determining tropospheric water vapor and as an excellent space-borne radiometer calibration and validation system.

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“…The dataset covers nearly 12 years from September 1992 to March 2005 (cycles 1 to 460) at approximately 10-days intervals (9.9156 days, corresponding to the satellite repeat period). Corrected sea surface heights are derived from the Merged Geophysical Data Records (MGDR) products (AVISO, 1996) by applying standard instrumental and geophysical corrections and editing procedures, including the Inverse Barometer (IB) correction (Dorandeu and Le Traon, 1999), the smoothing of TOPEX dual frequency ionospheric correction (Fernandes and Antunes, 2003), the cycle dependent drift effect in the wet tropospheric correction derived from the onboard TOPEX Microwave Radiometer (Scharroo et al, 2004), the sea state bias (SSB) correction (Chambers et al, 2003) and a residual SSB correction of −3 mm applied to cycles 236 and greater (Berwin, 2003). Tides are removed using the NAO99b model (Matsumoto et al, 2000).…”

Section: Datamentioning

confidence: 99%

Multivariate autoregressive modelling of sea level time series from TOPEX/Poseidon satellite altimetry

Barbosa

Silva

Fernandes

2006

Nonlin. Processes Geophys.

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Abstract. This work addresses the autoregressive modelling of sea level time series from TOPEX/Poseidon satellite altimetry mission. Datasets from remote sensing applications are typically very large and correlated both in time and space. Multivariate analysis methods are useful tools to summarise and extract information from such large space-time datasets. Multivariate autoregressive analysis is a generalisation of Principal Oscillation Pattern (POP) analysis, widely used in the geosciences for the extraction of dynamical modes by eigen-decomposition of a first order autoregressive model fitted to the multivariate dataset of observations. The extension of the POP methodology to autoregressions of higher order, although increasing the difficulties in estimation, allows one to model a larger class of complex systems. Here, sea level variability in the North Atlantic is modelled by a third order multivariate autoregressive model estimated by stepwise least squares. Eigen-decomposition of the fitted model yields physically-interpretable seasonal modes. The leading autoregressive mode is an annual oscillation and exhibits a very homogeneous spatial structure in terms of amplitude reflecting the large scale coherent behaviour of the annual pattern in the Northern hemisphere. The phase structure reflects the seesaw pattern between the western and eastern regions in the tropical North Atlantic associated with the trade winds regime. The second mode is close to a semi-annual oscillation. Multivariate autoregressive models provide a useful framework for the description of time-varying fields while enclosing a predictive potential.

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Cross-Calibration and Long-Term Monitoring of the Microwave Radiometers of ERS, TOPEX, GFO, Jason, and Envisat

Cited by 53 publications

References 11 publications

A new assessment of the error budget of global mean sea level rate estimated by satellite altimetry over 1993–2008

A new assessment of the error budget of global mean sea level rate estimated by satellite altimetry over 1993–2008

Tropospheric water vapor from solar spectrometry and comparison with Jason microwave radiometer measurements

Multivariate autoregressive modelling of sea level time series from TOPEX/Poseidon satellite altimetry

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