I have soil moisture data from Regional Climate Models expressed in $kg/m^2$. Τhis quantity is the total soil moisture that is estimated for the land column. The depth of this column is dependent on the land surface model that was used.
How could I transform soil moisture units expressed in $kg/m^2$ to $m^3/m^3$ so that model outputs are comparable to remote sensing soil moisture data that are expressed in $m^3/m^3$? Is there a way of doing this transformation without taking into consideration the soil depth?