Dear Hussein,

I used for research needs some free gridded reanalysis data: NOAA NCEP-NCAR CDAS-1 DAILY datafiles

There are many meteorological fields for entire globe and for long periods of time provided. Different formats of data files are supported.

The link is attached. This web-page contains a list of meteorological data. There are soil moisture data among them (two datasets):

1) NOAA NCEP-NCAR CDAS-1 DAILY Diagnostic 0-10_cm_down soil moisture 0-10 cm down Data Files

2) NOAA NCEP-NCAR CDAS-1 DAILY Diagnostic 10-200_cm_down soil moisture 10-200 cm down Data Files

The appropriate links to these datasets are attached to the message accordingly (datasets mentioned have coverage for Iran as they are global). Their resolution is 1.875 deg. by latitude and longitude. Long period of time (since 1948 to present days) is available. These soil moisture data are unitless.

You can select time, territory and file format. You can also map these data using Data Viewer. These datasets are free.

http://iridl.ldeo.columbia.edu/SOURCES/.NOAA/.NCEP-NCAR/.CDAS-1/.DAILY/datasetdatafiles.html

http://iridl.ldeo.columbia.edu/SOURCES/.NOAA/.NCEP-NCAR/.CDAS-1/.DAILY/Diagnostic+.0-10_cm_down+.soil+.moisture/datafiles.html

http://iridl.ldeo.columbia.edu/SOURCES/.NOAA/.NCEP-NCAR/.CDAS-1/.DAILY/Diagnostic+.10-200_cm_down+.soil+.moisture/datafiles.html

Thank you Dear Oleksandr,

The suggested websites are so interesting for me. But by now, I need soil moisture data in a spatial resolution about 100 meters. Of course it seems unlikely that such data exists or is available.

Have you considered using a soil water balance model to estimate soil water, using meteorological data of the kind noted above, or even better, generated from within Iran?

Dear Peter,

I am looking for the SM data assimilated from RS images.

May be you try acquiring Radarsat or Risat data and concurrent to satellite pass measure soil moisture on ground and use them in modeling Soil Moisture

At 100 m resolution, no dataset is available from remote sensing. Not only in Iran, but everywhere!

I suggest to consider the assimilation of coarse resolution satellite soil moisture product. They have been demonstrated to provide useful information even at spatial scale much finer than the original product resolution.

Hi Dear Brocca,

Based on the assumption that SM pattern in a watershed is constant over time,  I want to use the fine resolution pattern of the SM, for downscaling the SMAP. So I need some SM map (100 m pixel size) in more than 20 dates to obtain the SM pattern.The problem is that I dont have measured SM data for the calibration of the ENVISAT or similar sensors products from the past. And I cant wait for about two years for SM measurement and use the data produced by Sentinel or Alos.

Is it feasible to downscale SMAP data at 100 m resolution? I guess no, but you can try, of course.

I might suggest to perform high resolution hydrological modelling, but usually the agreement between satellite derived and modelled soil moisture patterns is low. So, I guess that your target is really difficult to achieve.

Moreover, have you checked the availability of a soil moisture products by ASAR at 1 km resolution? You can ask to TU Wien guys.

No fine resolution data is available in 100m. SMOS (50 km) and soon SMAP (20km) are available. The solution is to write a research proposal for TerraSAR X (Germany) to justify the use and then get the data (30-100m) resolution and use Oh model to obtain volumetric water content. The model is described in the attached file, You don't need to write the equations. You can download PolSAR software or ENVI and get the soil moisture.

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Thank you Dear Jawad.

The soil moisture data is very specific as it is related with the depth of soil too, therefore you would not get any remote sensing data about it. For example, the soil moisture data from 0-5cm depth is the average representation of moisture in the soil from top to 5 cm depth, similarly 5-10cm depth and so on are average representation of the average moisture in soil for those depths. Therefore, it is difficult to get as you are wishing. 

Dear Hussein

Most of Satellite producing soil moisture data are operating in MW band (SMOS, ASCAT, AMSR-E, SMAP) and since signals in this band is too weak they have to increase the pixel size to get a stronger signal and their spatial resolution are usually between 10-60 km. However,there are many algorithms that use finer optical and thermal infrared products like NDVI, LST or surface albedo from different satellites like MODIS, ASTER or landsat to produce soil moisture data.

Recently I found this paper that used ASTER and landsat data to downscale SMOS soil moisture to 100 m resolution, for more information check the link below:

http://www.sciencedirect.com/science/article/pii/S0034425712004324