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Purpose

 

This panel enables to set the default processing parameters, which are used in those functions related to the generation of interferometric products.

 

Technical Note

 

None.

 

Input Parameter(s)

 

Meris Conversion Factor Type        

This parameters define how is estimates the conversion factor from Meris Water Vapor layer to phase delay, the user can chose one of the following option:

•No Method, is the default Conversion Factor modeled with a fix average default value.

•Emarson, Emardson[1998], if no surface temperatures are available, conversion Factor is modeled as function of latitude and day of year (DoY). The coefficients are valid for most of the European continent.

•Bevis, Bevis et al.[1992]. An analysis of 8718 radiosondes profiles spanning approximately a two-year interval from sites in USA with a latitude range of 27deg to 65deg and a height range of 0 to 1.6km yields a linear regression Tm = 70.2 + 0.72Ts, with a RMS deviation from this regression of 4.74K, which is a relative error of less than 2%.

•Lindember, Lindenberg-2003. An analysis of one-year radiosondes profiles from Oct 2002 to Sep 2003 from Lindenberg site in Germany yields a linear regression Tm = 89.7 + 0.65Ts, with an RMS deviation from this regression of 2.4K.

•Schueler, T., A. Pósfay,  G.W. Hein,  and R. Biberger, A Global Analysis of the Mean Atmospheric Temperature for GPS Water Vapor Estimation. Proceedings of ION-GPS 2001, Salt Lake City, Utah, USA,2001.

 

Meris Cloud Mask Flag        

By setting this flag the tool uses the Meris Cloud Mask layer to mask the Meris Water Vapor layer. The mask will create voids on the estimated phase delay and consequentially on the flattened interferogram. Note that the presence of clouds do not allow a correct estimation of water vapor.

 

Meris Cloud Reflectance Flag

By setting this flag the tool uses the Meris Reflectance Mask layer to mask the Meris Water Vapor layer. The mask will create voids on the estimated phase delay and consequentially on the flattened interferogram. Note that the presence of reflectance <0 does not allow a correct estimation of water vapor.

 

Meris Pressure Difference Mask Flag

By setting this flag the tool re-projects the phase delay estimated from Meris from vertical to satellite  line of sight. This flag is a debug parameter only. It should be leaved to false.

 

Re-project Zenith Path Delay Along LOS

By setting this flag the tool estimate the residual interferometric phase component correlated to topography height (related to stratified atmosphere component in the flattened interferograms). The estimation of this component can bring to wrongly remove real phase components (mostly when the correlation windows size is small) from the flattened interferograms. For this reason, this functionality should be used carefully.

 

Atmosphere Height Correlation Flag

By setting this flag the tool estimates the residual interferometric phase component correlated to topography height (related to stratified atmosphere component in the flattened interferograms), using a the “Height Correlation Window Size [m]”. Note that the estimation of this component could remove real phase components (mostly when the correlation windows size is small) from the flattened interferograms. For this reason, this functionality should be used carefully.

Note: The HC correction is a solution fully developed and customized by sarmap. You could find papers online that refer to a similar technique, but not used by sarmap as reference. The working principle of our algorithm is the following: a window of customer-defined size (Height Correlation Window Size) is created for every pixel, a linear correlation between phase and topographic height (retrieved from the input DEM) is estimated for each window. Only the points, for which the correlation phase-height exceeds a certain customer-defined threshold value, are used to estimate the phase-height proportionality factor. The factor is then interpolated on the whole scene, after that the phase-height correlated atmosphere contribution is removed from then _upha files. Note that this operation could lead to removing the component of the phase related to the real displacement, since this estimation of the phase-height correlated atmosphere is made on the SAR measure itself and not on external and independent data.

 

Height Correlation High Pass Window Size [m]

Size  of the  high pass filter used during the Atmosphere Height Correlation process, before proceeding with the proper height correlation estimation. Phase components in the flattened interferogram, with a spatial patterns larger than this threshold, are considered as potentially atmosphere phase change distortions and removed.  Smaller values risk to remove real phase pattern related to surface deformations.

 

Height Correlation Window Size

Size of the moving window adopted for the Atmosphere Height Correlation estimation process. Larger the Window Size weaker the capability to resolve and remove local phase height correlated effects. But also, larger the Window Size lower the probability to remove phase signal correlated to other phenomena as displacement or residual topography.

 

Height Correlation STD Factor

Minimum phase standard deviation threshold, inside the moving window,  to estimate and apply the Atmosphere Height Correlation procedure. When the topography height is almost constant inside the moving window, the Atmosphere Height Correlation correction is not applied.

 

Height Correlation min correlation

Minimum correlation between height and phase inside the moving windows threshold. For windows with low correlation, the Atmosphere Height Correlation correction is not applied.

 

Height Correlation min Valid Pixels

Minimum valid pixels inside the moving windows threshold. For windows with poor coverage, the Atmosphere Height Correlation correction is not applied.

 

References

 

None.