Comparison of Contemporary In Situ, Model, and Satellite Remote Sensing Soil Moisture With a Focus on Drought Monitoring

Abstract

Soil moisture is a key drought indicator; however, current in situ soil moisture infrastructure is inadequate for large-scale drought monitoring.

Blending SMAP, Noah and In Situ Soil Moisture Using Multiple Methods

“…Specifically, the Noah and VIC models tend to overestimate soil moisture, while Mosaic and SAC models underestimate soil moisture when compared with in-situ observations (Xia et al, 2015). Ford and Quiring (2019) compared the modeled soil moisture from NLDAS-2 and CPC with in-situ measurements and that the found NLDAS-2 models consistently performed better than the CPC model. Similar to RS soil moisture, model-simulated soil moisture is difficult to validate because of the scale mismatch and the in-situ networks are not dense enough to adequately resolve soil moisture variability within each LSM pixel.…”

“…There are also challenges with retrievals in areas with complex topography, dense vegetation, near water bodies, or cities (Wagner et al, 1999;Parinussa et al, 2011). Ford and Quiring (2019) compared the RS soil moisture datasets from SMAP (SMAP L3 and SMAP L4), SMOS and ESA-CCI with in-situ measurements and found the SMAP L3 product consistently performed best among the four.…”

“…Similar to RS soil moisture, model-simulated soil moisture is difficult to validate because of the scale mismatch and the in-situ networks are not dense enough to adequately resolve soil moisture variability within each LSM pixel. In addition, the reliability of model-simulated soil moisture varies significantly from model to model, and over time and space (Ford and Quiring, 2019;Spennemann et al, 2015). Models generally perform well in representing the variations in soil moisture and soil moisture anomalies (Downer and Ogden, 2003;Meng and Quiring, 2008;Albergel et al, 2012), but they tend to have large biases in simulating the absolute volumetric water content of the soil (Xia et al, 2015;Bi et al, 2016).…”

Application of soil moisture information for operational water management

“…As the distinct advantages and limitations of the three main estimation methods partly overlap, as shown in Figure 1.8, it is possible to relate the three methods (Houser et al, 1998;Vischel et al, 2008;Rebel et al, 2012;Zhuo and Han, 2016;Brocca et al, 2017;Ford and Quiring, 2019). In situ soil moisture data are often applied in validation studies, in which the in situ data act as ground truth for remote sensing and modelling estimates (e.g.…”

“…Although not investigated in this research, several other approaches have been proposed to relate the various soil moisture estimation methods. Ford and Quiring (2019) employed various soil moisture comparison and veri cation methods to develop a comprehensive soil moisture validation framework and assess the delity of the three estimation methods. Crow and Wood (2003) applied a model-based approach to upscale in situ estimates to be representative on a satellite footprint scale.…”