# Backscattering coefficient and radar reflectivity

hello：there are some questions:
What is the relationship between backscatter coefficient and radar reflectivity?
Can radar reflectivity data be used instead of backscatter coefficients when relevant research is carried out?
At the same time, does sigma _ 0 represent the backscatter coefficient?
How to calculate the reflectivity of radar?

Hi, the usual terms used for SAR imagery is radar backscatter or radar cross-section and both the treated as being the same. Radar reflectivity is not a term that is usually used.

reflectivity is used in radar (and lidar) measurements of the atmosphere, e.g. weather/rain radars and cloud radars. it is related to the backscattering coefficient (of the respective atmospheric layers), but it’s not the same. for specifics have a look into meteorology literature.

yes, sigma_0 is the backscatter coefficient which represents the radar backscatter of the reflecting surface

Perhaps I should have said ‘Radar reflectivity is not a term that is usually used for physical parameters derived from SAR imagery’.

It seems sigma_0 is not the backscattering coefficient. As documented in many papers, the backscattering coefficients of water bodies and vegetation are in negative values,e.g. -25~0 dB. But if you just use the sigma_0 product, you will find the so-called backscattering coefficients may be greater than zero. So, when you convert the sigma_0 into dB, it seems the values are consistent with the results of most of published papers.

It seems sigma_0 is not the backscattering coefficient. As documented in many papers, the backscattering coefficients of water bodies and vegetation are in negative values,e.g. -25~0 dB. But if you just use the sigma_0 product, you will find the so-called backscattering coefficients may be greater than zero. So, when you convert the sigma_0 into dB, it seems the values are consistent with the results of most of published papers.

Hi, Sigma0 can be expressed in linear units or more usually in dB with a conversion using sigma0dB = 10*log10(sigma0linear). As you say sigma0 in dB is the same as the backscattering coefficient.

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Yes,you are quite right. I just prefer the dB values used by many scholars:). Anyway, many thanks for your kind reply:)

Hello,

Could you share some of those papers, where the backscattering coefficient values of land surface types are discussed.

• Ulaby (2019) Handbook of Radar Scattering Statistics for Terrain
• Parihar et al. (2014) Analysis of L-band SAR backscatter and coherence for delineation of land-use/land-cover
• Esch et al. (2011) Characterization of land cover types in TerraSAR-X images by combined analysis of speckle statistics and intensity information
• Dobson et al. (1996) Land-cover classification and estimation of terrain attributes using synthetic aperture radar

There are more detailed studies on specific land cover types.

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Thank you