Observed relation between evapotranspiration and soil moisture in the North American monsoon region

Abstract

[1] Soil moisture control on evapotranspiration is poorly understood in ecosystems experiencing seasonal greening. In this study, we utilize a set of multi-year observations at four eddy covariance sites along a latitudinal gradient in vegetation greening to infer the ET-q relation during the North American monsoon. Results reveal significant seasonal, interannual and ecosystem variations in the observed ET-q relation directly linked to vegetation greening. In particular, monsoon-dominated ecosystems adjust their ET-q relation, through changes in unstressed ET and plant stress threshold, to cope with differences in water availability. Comparisons of the observed relations to the North American Regional Reanalysis dataset reveal large biases that increase where vegetation greening is more significant. The analysis presented here can be used to guide improvements in land surface model parameterization in water-limited ecosystems. Citation: Vivoni, E. R., H. A.

Influence of initial soil moisture and vegetation conditions on monsoon precipitation events in northwest México

“…This suggests that the correct initialization of soil moisture and vegetation cover conditions through remote sensing or sensor networks is equally important for improving the predictability of precipitation during the NAM, and likely more important for cases with weak synoptic forcing when local interactions are more relevant (Domínguez et al, 2008). Furthermore, the sensitivity of precipitation to both soil moisture and vegetation states indicates that as the NAM progresses and the land surface becomes wetter and greener (e.g., Vivoni et al, 2008;Forzieri et al, 2011;Mascaro et al, 2015), the positive feedback loops would play an increasing more important role in sustaining local precipitation recycling. In addition, since the time scales of variability in soil moisture (1-3 days) and vegetation Fig.…”

Evaluation of soil moisture in CMIP5 simulations over the contiguous United States using in situ and satellite observations

“…Through controlling water mass transfer, soil moisture affects runoff (Penna et al, 2011;Latron and Gallart, 2008;Zhang et al, 2001) and evapotranspiration (Wetzel and Chang, 1987;Vivoni et al, 2008;Detto et al, 2006). Soil moisture also influences the surface energy balance by affecting latent heat and ground fluxes (Ek and Holtslag, 2004;Ford and Quiring, 2014a).…”

Closing the water balance with cosmic-ray soil moisture measurements and assessing their relation to evapotranspiration in two semiarid watersheds

“…Furthermore, the relation between ET and soil moisture is an important parameterization in land surface models (e.g., Laio et al, 2001;Rodríguez-Iturbe and Porporato, 2004;Vivoni et al, 2008a) and, in most cases, has been investigated using EC measurements of ET and soil moisture observations at single sites. A number of studies, however, have shown that accounting for the spatial variability of land surface states is important to properly identify the linkage with EC measurements (e.g., Detto et al, 2006;Vivoni et al, 2010;Alfieri and Blanken, 2012).…”