  We present a search and characterization of ultra-diffuse galaxies (UDGs) in
the Frontier Fields cluster Abell~2744 at $z=0.308$. We use JWST/NIRISS F200W
observations, acquired as part of the GLASS-JWST Early Release Science Program,
aiming to characterize morphologies of cluster UDGs and their diffuse stellar
components. A total number of 22 UDGs are identified by our selection criteria
using morphological parameters, down to stellar mass of $\sim10^{7}M_{\odot}$.
The selected UDGs are systematically larger in effective radius in F200W than
in HST/ACS F814W images, which implies that some of them would not have been
identified as UDGs when selected at rest-frame optical wavelengths. In fact, we
find that about one third of the UDGs were not previously identified based on
the F814W data. We observe a flat distribution of the UDGs in the stellar
mass-size plane, similar to what is found for cluster quiescent galaxies at
comparable mass. Our pilot study using the new JWST F200W filter showcases the
efficiency of searching UDGs at cosmological distances, with 1/30 of the
exposure time of the previous deep observing campaign with HST. Further studies
with JWST focusing on spatially-resolved properties of individual sources will
provide insight into their origin.
