  External FUV irradiation of protoplanetary disks has an important impact on
their evolution and ability to form planets. However, nearby (<300 pc)
star-forming regions lack sufficiently massive young stars, while the Trapezium
Cluster and NGC 2024 have complicated star-formation histories and their O-type
stars' intense radiation fields ($>10^4\,G_0$) destroy disks too quickly to
study this process in detail. We study disk mass loss driven by intermediate
(10 - 1000 $G_0$) FUV radiation fields in L1641 and L1647, where it is driven
by more common A0 and B-type stars. Using the large (N=873) sample size offered
by the Survey of Orion Disks with ALMA (SODA), we search for trends in the
median disk dust mass with FUV field strength across the region as a whole and
in two separate regions containing a large number of irradiated disks. For
radiation fields between 1 - 100 $G_0$, the median disk mass in the most
irradiated disks drops by a factor $\sim 2$ over the lifetime of the region,
while the 95th percentile of disk masses drops by a factor 4 over this range.
This effect is present in multiple populations of stars, and localized in
space, to within 2 pc of ionizing stars. We fit an empirical irradiation - disk
mass relation for the first time: $M_{\rm{dust,median}} = -1.3^{+0.14}_{-0.13}
\log_{10}(F_{\rm{FUV}} / G_0) + 5.2^{+0.18}_{-0.19}$. This work demonstrates
that even intermediate FUV radiation fields have a significant impact on the
evolution of protoplanetary disks.
