Mitigating for Atmospheric Effects with SAR Image Pre-processing

Correcting Atmospheric Effects by Pre-processing SAR Images

Atmospheric effects can introduce errors into the results of interferograms. Pre-processing satellite SAR images before interferometric analysis can account for these effects.

Let’s take a closer look at this topic today.

Removing the Atmospheric Phase Screen, or APS, shows how phase delays spread out in space. These delays happen because of the atmospheric conditions and cause errors in the interferometric phase. Removing or minimizing the APS is crucial for accurately measuring ground deformations.

Persistent Scatterer Interferometry (PSI) is a method that finds and uses radar targets. These targets, called persistent scatterers, consistently reflect radar waves over time. Researchers use these targets, which include buildings and other stable structures, to estimate the atmospheric phase delays. This process begins with the identification of potential persistent scatterers based on their stability in radar scattering over multiple acquisitions.

Secondly, researchers extract the interferometric phase information over time for each persistent scatterer. To estimate the APS, model the time-dependent phase information. Then, subtract the estimated APS to get the corrected phase.

Of course, there are some challenges with mitigating the effects of atmospheric factors in interferometry. Atmospheric effects are often nonlinear and can vary spatially and temporally, posing challenges for accurate modelling and removal. Also, changes in weather over time can cause temporal decorrelation. This makes it hard to estimate the APS accurately.

Using data that covers at least one year can better show the atmospheric effects. This leads to more accurate measurements of displacement.

In summary, the Atmospheric Phase Screen removal process is important. You can use PSI, SBAS, or both methods to do it. This process helps reduce the effects of the atmosphere on interferometric phase in SAR interferometry.

These techniques help estimate and remove the changes in atmospheric delays over time and space. This leads to more accurate and reliable ground deformation measurements.