# Vertical Velocity Displacement along Ascending and Descending tracks

Vertical Velocity Displacement along Ascending and Descending tracks

Hello dear colleagues
one question
The following figures show the deformation evaluation of the 2 salt diapirs in the ascending and descending tracks.

Why are the values ​​inverted in two ascending and descending tracks ?

The following figure 2 shows Vertical Velocity Displacement along Ascending and Descending tracks

I think it would be helpful for us to undestand how you generated these maps. Different velocity patterns for ascending/descending results are possible if the displacement was measured along the line of sight. So how did you convert the displacement to absolute vertical velocities?

Hi ABraun, Dear colleague
The first images show the measurements along LOS

But 2 images below show the vertical displacement are calculated by considering the incident angle.

How in the above Figs the pattern are opposite?
thanks

now I understand, thank you. Which equation did you use to calculate the vertical velocity

There are many error sources which could be responsible, atmospheric disturbances in one of the images, unwrapping errors, changed environmental conditions.
Are the image pairs from the same time?

Hi

Yes, All images both AS%DS pairs are the same time (2014-2019, about 85 images).

so you followed a persistent scatterer approach?

I guess this equation is not precise enough for your purpose.

You can try to implement the formula suggested by @mdelgado, also for a Sentinel-1 persistent scatterer approach:

Source: https://www.mdpi.com/2072-4292/11/2/129/htm

3 Likes

Hi ABraum and Dear colleagues

The above method was used. But the results are not the same.
Pay Attention To:
The area is a salt dome and is elongated along NE-SW

So how to interpret the opposite signs (+ and _) results?
Best

can you please show the results? I don’t think they will be the same.

Hi