Retrieval of Surface Soil Moisture (SSM) over large scales at
high spatial resolution is crucial for numerous applications.
Existing solutions rely on the analysis of remote sensing plat-
forms or in situ measurements that are either too coarse in
their resolution or too localized to address the aforementioned
need. In this work, we propose a novel deep learning ap-
proach for reliably estimating SSM at a high spatial reso-
lution of 1 km over broad regions. To achieve this objec-
tive, the proposed framework employs a Convolutional Neu-
ral Network that can capture both multi-modal and spatial
correlations. Introducing a novel loss function, the proposed
scheme can leverage limited in situ observations while also
generating estimates consistent with physical models. This
is achieved through the utilization of coarse-resolution data
assimilation estimates. For training and assessing the perfor-
mance of the proposed framework, a novel dataset is gener-
ated by combining information from remote sensing, in situ
measurements, and data assimilation estimates. Experimental
analysis demonstrates that the proposed approach can provide
accurate retrieval of SSM, significantly outperforming exist-
ing products.