The global distribution and dynamics of surface soil moisture

McColl, Kaighin A.; Alemohammad, Seyed Hamed; Akbar, Ruzbeh; Konings, Alexandra G.; Yueh, Simon; Entekhabi, Dara

doi:10.1038/ngeo2868

Cited by 375 publications

(259 citation statements)

References 41 publications

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“…In addition to the effects of global warming, loss in vegetation cover in some regions produces changes that affect the partition of energy and water fluxes at the surface. Such alterations affect the capacity to assimilate atmospheric CO 2 and the capacity to intercept and store moisture in land surface reservoirs, leading to decreases in availability of water for human and ecosystem uses (Acharya, Halihan, Zou, & Will, ; Ghannam et al, ; Kim & Jackson, ; McColl et al, ; Winter, Harvey, Franke, & Alley, ). This phenomenon can be particularly dramatic in tropical ecosystems and has been documented to occur in a variety of locations worldwide (Allen et al, ; Chazdon, Brenes, & Alvarado, ; Condit, Hubbell, & Foster, ; Khan, Rodgers, Johnsingh, & Mathur, ; Laurance et al, ; Leigh, Windsor, Rand, & Foster, ; Lwanga, ; Phillips et al, ; Rolim, Jesus, Nascimento, do Couto, & Chambers, ; Williamson et al, ).…”

Section: Introductionmentioning

confidence: 99%

On the ecohydrology of the Yucatan Peninsula: Evapotranspiration and carbon intake dynamics across an eco‐climatic gradient

Uuh-Sonda

Gutiérrez-Jurado

Figueroa-Espinoza

et al. 2018

Hydrological Processes

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The hydrology and productivity of the ecosystems of the Yucatan Peninsula (YP) are highly constrained by two factors: (a) the lack of surface drainage networks due to the existence of a highly permeable and connected karstic aquifer roughly the size of the peninsula and (b) a climatic gradient that leads to a transition from seasonally dry deciduous and sub‐deciduous tropical forests, in the north‐western and central parts of the Peninsula, to evergreen forests, in the southern and eastern parts. As a result, surface water fluxes of the YP are restricted to evapotranspiration (ET) that are tightly coupled to ecosystems health and gross primary productivity (GPP). The magnitude and seasonal variation of these fluxes are sensitive to climatic variability and perturbations caused by extreme events such as droughts and tropical storms that are frequent in the YP. In this study, we assess the spatio‐temporal dynamics of ET and GPP above average dry and wet conditions through time series analyses of 15 years of remotely sensed data from both Moderate Resolution Imaging Spectroradiometer and Tropical Rainfall Measuring Mission satellite products. Our results show that ET and GPP follow a regional moisture and temperature gradient that highly controls the distribution of ecosystems within the peninsula. We observe that ET and GPP are in phase with the rainy season in the deciduous forests, but for the evergreen forests, only the GPP is in phase. Additionally, and with the exception of droughts on deciduous ecosystems of the northern part of the YP, the productivity of these ecosystems shows a legacy effect, responding more to a defined trajectory (wetting or drying on the previous years), rather than to punctual extreme climatic events. This has implications on the resilience of these ecosystems to natural perturbations of climate. Comparisons between deciduous and evergreen forest indicate that both types of ecosystems have different plant water use strategies in response to hydrologic variability.

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Section: Introductionmentioning

confidence: 99%

On the ecohydrology of the Yucatan Peninsula: Evapotranspiration and carbon intake dynamics across an eco‐climatic gradient

Uuh-Sonda

Gutiérrez-Jurado

Figueroa-Espinoza

et al. 2018

Hydrological Processes

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“…Though the volume of water is small, surface soil moisture generates outsized effects on the global water and energy balance (McColl et al, 2017b). Climate, weather, and flood predictions depend on soil moisture Viterbo and Betts, 1999).…”

Section: Introductionmentioning

confidence: 99%

Controls on surface soil drying rates observed by SMAP and simulated by the Noah land surface model

Shellito

Small

Livneh

2018

Hydrol. Earth Syst. Sci.

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Abstract. Drydown periods that follow precipitation events provide an opportunity to assess controls on soil evaporation on a continental scale. We use SMAP (Soil Moisture Active Passive) observations and Noah simulations from drydown periods to quantify the role of soil moisture, potential evaporation, vegetation cover, and soil texture on soil drying rates. Rates are determined using finite differences over intervals of 1 to 3 days. In the Noah model, the drying rates are a good approximation of direct soil evaporation rates, and our work suggests that SMAP-observed drying is also predominantly affected by direct soil evaporation. Data cover the domain of the North American Land Data Assimilation System Phase 2 and span the first 1.8 years of SMAP's operation.Drying of surface soil moisture observed by SMAP is faster than that simulated by Noah. SMAP drying is fastest when surface soil moisture levels are high, potential evaporation is high, and when vegetation cover is low. Soil texture plays a minor role in SMAP drying rates. Noah simulations show similar responses to soil moisture and potential evaporation, but vegetation has a minimal effect and soil texture has a much larger effect compared to SMAP. When drying rates are normalized by potential evaporation, SMAP observations and Noah simulations both show that increases in vegetation cover lead to decreases in evaporative efficiency from the surface soil. However, the magnitude of this effect simulated by Noah is much weaker than that determined from SMAP observations.

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“…Soil moisture is a key variable constraining the fluxes between the land surface and atmosphere boundary, and therefore it plays a key role in regulating the feedbacks between the terrestrial water, carbon and energy cycles (Berg et al, 2014;McColl et al, 2017;. Soil moisture partitions the surface energy between latent heat and sensible heat fluxes (Entekhabi et al, 1996;Gentine et al, 2007Gentine et al, , 2011Koster et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Global Downscaling of Remotely-Sensed Soil Moisture using Neural Networks

Alemohammad¹,

Kolassa²,

Prigent³

et al. 2018

Preprint

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Abstract.Characterizing soil moisture at spatio-temporal scales relevant to land surface processes (i.e. of the order of a kilometer) is necessary in order to quantify its role in regional feedbacks between 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 days repeat time); however, their finest spatial resolution is 9km. NASA's Soil Moisture Active Passive (SMAP) satellite estimates soil moisture at two 15 different spatial scales of 36km and 9km since April 2015. In this study, we develop a neural networks-based downscaling algorithm using SMAP observations and disaggregate soil moisture to 2.25km spatial resolution. Our approach uses mean monthly Normalized Differenced Vegetation Index (NDVI) as an ancillary data to quantify sub-pixel heterogeneity of soil moisture.

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The global distribution and dynamics of surface soil moisture

Cited by 375 publications

References 41 publications

On the ecohydrology of the Yucatan Peninsula: Evapotranspiration and carbon intake dynamics across an eco‐climatic gradient

On the ecohydrology of the Yucatan Peninsula: Evapotranspiration and carbon intake dynamics across an eco‐climatic gradient

Controls on surface soil drying rates observed by SMAP and simulated by the Noah land surface model

Global Downscaling of Remotely-Sensed Soil Moisture using Neural Networks

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