measure soil moisture in your study area at the time when the image is acquired and locate the meastrements by a GPS device, for example.
Yes sir, I have these data
But i don’t know how to import these data to SNAP
Why not try this one - https://land.copernicus.eu/global/themes/Vegetation . This is verified product.
For SHP files import just do File->Import->VectorData->ESRI Shapefile
But when I search Surface Soil Moisture, I don’t find my study area because Spatial information is only in Europe
Hi @ABraun, how to use the correlative plot?
@Andiray I didn’t know that your area is outside EU. Sorry.
Hi @hriston_bg, thanks for your response.
@Andiray You may try Vegetation Condition Index as a proxy for SM.
The global product is here - https://land.copernicus.eu/global/products/vci
First you need a shapefile with numerical values (hoehe_cm in my case)
Load it into SNAP and overlay it with your SAR data
Then open the correlative plot view
Select the point shapefile and the attribute and correlate the raster values with the point information
Hi @ABraun, how to make this shapefile? I only have ground data but I don’t know how to make it to shapefile.
I have coordinate point and value of soil moisture in ground data. I’m so sorry. I don’t have basic in SNAP
SNAP can import csv files when they are formatted correctly.
If not, load the coordinates (and moisture attribute) in a GIS and export it as a shapefile. There are lots of tutorials on this around.
Okay sir @ABraun, I will learn about it
Import of CSV files into QGIS: https://www.qgistutorials.com/en/docs/importing_spreadsheets_csv.html
Import of CSV files into SNAP: Import CSV File
I have correlative plot now.
whether this graph is true to soil moisture validation?
My step backscatter is:
- Multilooking (4:1)
- Calibration: Sigma 0
- Speckle Filter : Gamma Map
- Terrain Correction
Does it only at this step? Shouldn’t I find its polarimetric decomposition?
R²=0.17 means that you can currently only explain 17% of the variations of both variables by the each other. For statistically valid predictions you need probably more measurements and higher R² (0.5 and above).
If you have the chance for polarimetric decomposition, you can correlate the moisture with new rasters and see if their predictive value is higher. But Sentinel-1 is dual-pol only.
What kind of new raster can i use sir?
Can’t I use sentinel 1 _SLC for calculate Polarimetric Decompotion?
Apply Orbit file>>Calibrate>>Tops Deburst>>H/A dual deccomposition.
yes, this is probably the only one which works for Sentinel-1. Then you can correlate each band with the moisture. I would also try VH as well.
When I do step Apply Orbit File, why in https://qc.sentinel1.eo.esa.int/ is not provide update POEORB?
what do you mean?