We find that some crops, like cotton, can contribute up to 2-4 cm/yr of bias when inverting for displacement. This bias can be misinterpreted as subsidence, but is actually due to vegetation effects on InSAR phase.

For each field, we isolate the effects of vegetation by taking the difference between field pixels and nearby stable pixels. We track this difference, which we call phase bias, over time for the 6 most common crops in the region.

The SJV has been experiencing 30 cm/yr of subsidence for years due to groundwater extraction/. It also contains a wide variety of crops and land cover types, leading to some very noisy InSAR data.