1 research outputs found
Global downscaling of remotely sensed soil moisture using neural networks
Characterizing soil moisture at spatiotemporal scales relevant to land surface processes (i.e.,
of the order of 1 km) is necessary in order to quantify its role in regional
feedbacks between the land surface and the atmospheric boundary layer.
Moreover, several applications such as agricultural management can benefit
from soil moisture information at fine spatial scales. Soil moisture
estimates from current satellite missions have a reasonably good temporal
revisit over the globe (2–3-day repeat time); however, their finest spatial
resolution is 9 km. NASA's Soil Moisture Active Passive (SMAP) satellite has
estimated soil moisture at two different spatial scales of 36 and 9 km since
April 2015. In this study, we develop a neural-network-based downscaling
algorithm using SMAP observations and disaggregate soil moisture to 2.25 km
spatial resolution. Our approach uses the mean monthly Normalized Differenced
Vegetation Index (NDVI) as ancillary data to quantify the subpixel
heterogeneity of soil moisture. Evaluation of the downscaled soil moisture
estimates against in situ observations shows that their accuracy is better
than or equal to the SMAP 9 km soil moisture estimates.</p