On the accuracy of integrated water vapor observations and the potential for mitigating electromagnetic path delay error in InSAR

Cimini, Domenico; Pierdicca, Nazzareno; Pichelli, Emanuela; Ferretti, Rossella; Mattioli, V.; Bonafoni, Stefania; Montopoli, Mario; Perissin, Daniele

doi:10.5194/amt-5-1015-2012

Cited by 29 publications

(22 citation statements)

References 44 publications

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“…7 is 0.98. Similar comparison was performed and the MERIS was validated to be the most accurate tool to map PWV at high resolution and was in principle particularly useful for InSAR tropospheric delay mitigation (Cimini et al, 2012). Thus GPS and MERIS measurements of water vapour are in good agreement and we should not expect a perfect correlation between the two data sets because we averaged the conical effect of GPS with a circle and there is noise in both data sets.…”

Section: Gps Pwv Measurementsmentioning

confidence: 63%

High-spatial-resolution mapping of precipitable water vapour using SAR interferograms, GPS observations and ERA-Interim reanalysis

et al. 2016

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Abstract. A high spatial and temporal resolution of the precipitable water vapour (PWV) in the atmosphere is a key requirement for the short-scale weather forecasting and climate research. The aim of this work is to derive temporally differenced maps of the spatial distribution of PWV by analysing the tropospheric delay "noise" in interferometric synthetic aperture radar (InSAR). Time series maps of differential PWV were obtained by processing a set of EN-VISAT ASAR (Advanced Synthetic Aperture Radar) images covering the area of southern California, USA from 6 October 2007 to 29 November 2008. To get a more accurate PWV, the component of hydrostatic delay was calculated and subtracted by using ERA-Interim reanalysis products. In addition, the ERA-Interim was used to compute the conversion factors required to convert the zenith wet delay to water vapour. The InSAR-derived differential PWV maps were calibrated by means of the GPS PWV measurements over the study area. We validated our results against the measurements of PWV derived from the Medium Resolution Imaging Spectrometer (MERIS) which was located together with the ASAR sensor on board the ENVISAT satellite. Our comparative results show strong spatial correlations between the two data sets. The difference maps have Gaussian distributions with mean values close to zero and standard deviations below 2 mm. The advantage of the InSAR technique is that it provides water vapour distribution with a spatial resolution as fine as 20 m and an accuracy of ∼ 2 mm. Such highspatial-resolution maps of PWV could lead to much greater accuracy in meteorological understanding and quantitative precipitation forecasts. With the launch of Sentinel-1A and Sentinel-1B satellites, every few days (6 days) new SAR images can be acquired with a wide swath up to 250 km, enabling a unique operational service for InSAR-based water vapour maps with unprecedented spatial and temporal resolution.

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Section: Gps Pwv Measurementsmentioning

confidence: 63%

High-spatial-resolution mapping of precipitable water vapour using SAR interferograms, GPS observations and ERA-Interim reanalysis

et al. 2016

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“…Here we adopt the formalism introduced by [8], with some extensions to account for later works. Supposing three measurements x, y and z, relatively to the systems X, Y and Z, we have adopted the following error model [9]:…”

Section: Smc Smcmentioning

confidence: 99%

ASCAT and SMOS soil moisture retrievals: A comparison over Europe and Northern Africa

Fascetti

Pierdicca

Pulvirenti

et al. 2014

2014 13th Specialist Meeting on Microwave Radiometry and Remote Sensing of the Environment (MicroRad)

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An analysis of two remotely sensed soil moisture data sets, derived from the Advanced SCATterometer (ASCAT) and from the Soil Moisture ad Ocean Salinity (SMOS) radiometer, has been performed. This analysis has been carried out within the framework of an activity aiming at validating the EUMETSAT Hydrology Satellite Application Facility (H-SAF) soil moisture products derived from ASCAT over Europe and North Africa. The data acquired from 2010 to 2012 have been used. We have also considered the soil moisture maps predicted by a Land Surface Model, namely the ERA Interim/Land data set. Results demonstrate that, after a conversion of the H-SAF saturation index into a volumetric soil moisture, SMOS and ASCAT present a fairly good degree of correlation and their consistency depends on season, geographical zone and surface land cover. Moreover, to estimate the relative amount of error affecting the different sources of soil moisture maps, the Triple Collocation technique has been implemented. Such an approach has been applied also considering different conditions in terms of season, time of the day and data filtering approaches.

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“…The atmospheric delays simulated by regional NWP forecasts are not directly subtracted from interferograms to reconstruct the subtle deformation in this study. It is because of their limited quality in reproducing the spatial pattern of atmospheric delays [ Foster et al ., ; Gong et al ., ; Cimini et al ., ; Liu , ]. Instead, NWP‐derived atmospheric statistics are integrated into the PSI processing to optimize a filter for removing the atmospheric delays.…”

Section: Introductionmentioning

confidence: 99%

Measurement and interpretation of subtle deformation signals at Unimak Island from 2003 to 2010 using weather model‐assisted time series InSAR

et al. 2015

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A 7 year time series of satellite radar images over Unimak Island, Alaska-site of Westdahl Volcano, Fisher Caldera, and Shishaldin Volcano-was processed using a model-free Persistent Scatterer Interferometry technique assisted by numerical weather prediction model. The deformation-only signals were optimally extracted from atmosphere-contaminated phase records. The reconstructed deformation time series maps are compared with campaign and continuous Global Positioning System (GPS) measurements as well as Small Baseline Subset interferometric synthetic aperture radar (InSAR) results for quality assessment and geophysical interpretation. We observed subtle surface inflation at Westdahl Volcano that can be fit by a Mogi source located at approximately 3.6 km north of Westdahl peak and at depth of about 6.9 km that is consistent with the GPS-estimated depth for the 1998 to 2001 time period. The magma chamber volume change decays during the period of 2003 to 2010. The deformation field over Fisher Caldera is steadily subsiding over time. Its best fit analytical model is a sill source that is about 7.9 km in length, 0.54 km in width, and located at about 5.5 km below sea level underneath the center of Fisher Caldera with strike angle of N52°E. Very little deformation was detected near Shishaldin peak; however, a region approximately 15 km east of Shishaldin, as well as an area at the Tugamak range at about 30 km northwest of Shishaldin, shows evidence for movement toward the satellite, with a temporal signature correlated with the 2004 Shishaldin eruption. The cause of these movements is unknown.

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On the accuracy of integrated water vapor observations and the potential for mitigating electromagnetic path delay error in InSAR

Cited by 29 publications

References 44 publications

High-spatial-resolution mapping of precipitable water vapour using SAR interferograms, GPS observations and ERA-Interim reanalysis

High-spatial-resolution mapping of precipitable water vapour using SAR interferograms, GPS observations and ERA-Interim reanalysis

ASCAT and SMOS soil moisture retrievals: A comparison over Europe and Northern Africa

Measurement and interpretation of subtle deformation signals at Unimak Island from 2003 to 2010 using weather model‐assisted time series InSAR

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