Improved groundwater table and L-band brightness temperature estimates for Northern Hemisphere peatlands using new model physics and SMOS observations in a global data assimilation framework

Bechtold, Michel; Lannoy, Gabriëlle J. M. De; Reichle, Rolf H.; Roose, Dirk; Balliston, Nicole; Burdun, Iuliia; Devito, K. J.; Kurbatova, Juliya; Strack, Maria; Zarov, Evgeny A.

doi:10.1016/j.rse.2020.111805

Cited by 22 publications

(19 citation statements)

References 49 publications

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“…Limitations to simulating the fate of peatland carbon First, our results are drawn from only five peatland models, and only four of those models can explicitly simulate permafrost processes. To reduce uncertainty in model projections, a better understanding of the differences among models (i.e., the five models used in this study and models with a specific representation for peatland hydrology [46][47][48][49] ) is needed, and our intercomparison of the five state-of-the-art peatland models represents the first step. Further work involving site-level simulations and comparison with manipulative experiments in the field are also needed.…”

Section: Permafrost Peatlands Versus Non-permafrost Peatlandsmentioning

confidence: 99%

A strong mitigation scenario maintains climate neutrality of northern peatlands

et al. 2022

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Section: Permafrost Peatlands Versus Non-permafrost Peatlandsmentioning

confidence: 99%

A strong mitigation scenario maintains climate neutrality of northern peatlands

et al. 2022

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“…Our spatially and temporally continuous 9-km simulations were evaluated against water level and not against θ 5cm , because in situ soil moisture data were not sufficiently available. However, remote sensing allows estimation of θ 5cm , which can be linked to the water level in systems with high water levels like peatlands, where the θ 5cm and water level are strongly coupled (Bechtold et al, 2020;Dadap et al, 2019). Bechtold et al (2020) recently showed that correlation between measured and estimated water level increased after data assimilation of Soil Moisture and Ocean Salinity (SMOS) brightness temperature (Tb) over northern peatlands using PEATCLSM North,Nat .…”

Section: Discussionmentioning

confidence: 99%

“…The TOPMODEL approach used in CLSM is not optimal for peatlands because most of them are virtually flat on a macrotopographic scale of kilometers, and bogs (and to a lesser extent fens) appear hydraulically decoupled from the groundwater hydrology of the rest of the catchment (Bechtold et al, 2019(Bechtold et al, , 2020. This decoupling is either due to impermeable sediments at the peat base or due to accumulated peat that lifted the peat surface (and water level) above the range of the groundwater fluctuations in the underlying aquifer.…”

Section: Original Peatclsm Modulementioning

confidence: 99%

Tropical Peatland Hydrology Simulated With a Global Land Surface Model

Apers

Lannoy

Baird

et al. 2022

J Adv Model Earth Syst

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Tropical peatlands are among the most carbon-dense ecosystems on Earth, and their water storage dynamics strongly control these carbon stocks. The hydrological functioning of tropical peatlands differs from that of northern peatlands, which has not yet been accounted for in global land surface models (LSMs). Here, we integrated tropical peat-specific hydrology modules into a global LSM for the first time, by utilizing the peatland-specific model structure adaptation (PEATCLSM) of the NASA Catchment Land Surface Model (CLSM). We developed literature-based parameter sets for natural (PEATCLSM Trop,Nat ) and drained (PEATCLSM Trop,Drain ) tropical peatlands. Simulations with PEATCLSM Trop,Nat were compared against those with the default CLSM version and the northern version of PEATCLSM (PEATCLSM North,Nat ) with tropical vegetation input. All simulations were forced with global meteorological reanalysis input data for the major tropical peatland regions in Central and South America, the Congo Basin, and Southeast Asia. The evaluation against a unique and extensive data set of in situ water level and eddy covariance-derived evapotranspiration showed an overall improvement in bias and correlation compared to the default CLSM version. Over Southeast Asia, an additional simulation with PEATCLSM Trop,Drain was run to address the large fraction of drained tropical peatlands in this region. PEATCLSM Trop,Drain outperformed CLSM, PEATCLSM North,Nat , and PEATCLSM Trop,Nat over drained sites. Despite the overall improvements of PEATCLSM Trop,Nat over CLSM, there are strong differences in performance between the three study regions. We attribute these performance differences to regional differences in accuracy of meteorological forcing data, and differences in peatland hydrologic response that are not yet captured by our model. Plain Language SummaryTropical peatlands are wetlands in which plant material accumulates under waterlogged conditions and develops into a dense organic soil layer. Disturbance of their selfregulating hydrology by external factors such as artificial drainage, land use change, and climate change can quickly convert these immense carbon stocks into strong sources of greenhouse gases. Including the hydrology of tropical peatlands into global Earth system models allows us to understand the impact of such external disturbances. We developed the first hydrology modules for natural and drained tropical peatlands to plug into the NASA Goddard Earth Observing System modeling framework. Our results display strong regional differences, and indicate that the accuracy of our model is limited by rainfall data quality and by our understanding of how peatland hydrology differs across the three regions that contain the major tropical peatland areas (Central and South America, the Congo Basin, and Southeast Asia). Nonetheless, simulations

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“…In ideal conditions this metric should be equal to unity over the entire study area. The normalized O-F residuals were obtained by normalizing each O-F residual by their simulated (expected) (forecast and observation error) standard deviation and then calculating the time-series standard deviation (Bechtold et al, 2020;Reichle et al, 2019). Third, the time-series standard deviations of the increments (analysisforecast) in SSM and LAI were investigated in order to verify whether those values are small relative to the values of the update state variables.…”

Section: Discussionmentioning

confidence: 99%

Challenges and benefits of quantifying irrigation through the assimilation of Sentinel-1 backscatter observations into Noah-MP

Modanesi

Massari

Bechtold

et al. 2022

Preprint

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Abstract. In recent years, the amount of water used for agricultural purposes has been rising due to an increase in food demand. However, anthropogenic water usage, such as for irrigation, is still not or poorly parameterized in regional and larger-scale land surface models (LSM). By contrast, satellite observations are directly affected by, and hence potentially able to detect, irrigation as they sense the entire integrated soil-vegetation system. By integrating satellite observations and fine-scale modelling it could thus be possible to improve estimation of irrigation amounts at the desired spatial-temporal scale. In this study we tested the potential information offered by Sentinel-1 backscatter observations to improve irrigation estimates, in the framework of a data assimilation (DA) system composed by the Noah-MP LSM, equipped with a sprinkler irrigation scheme, and a backscatter operator represented by a Water Cloud Model (WCM), as part of the NASA Land Information System (LIS). The calibrated WCM was used as an observation operator in the DA system to map model surface soil moisture and leaf area index (LAI) into backscatter predictions and, conversely, map observation-minus-forecast backscatter residuals back to updates in soil moisture and LAI through an ensemble Kalman filter (EnKF). The benefits of Sentinel-1 backscatter observation in two different polarizations (VV and VH) were tested in two separate DA experiments, performed over two irrigated sites, the first one located in the Po Valley (Italy) and the second one located in northern Germany. The results confirm that VV backscatter has a stronger link with soil moisture than VH backscatter, whereas VH backscatter observations introduce larger updates in the vegetation state variables. The backscatter DA introduced both improvements and degradations in soil moisture, evapotranspiration and irrigation estimates. The spatial and temporal scale had large impacts on the analysis, with more contradicting results obtained for the evaluation at the fine agriculture scale (i.e., field scale). Above all, this study sheds light on the limitations resulting from a poorly-parameterized sprinkler irrigation scheme which prevents improvements in the irrigation simulation due to DA, and points to future developments needed to improve the system.

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Improved groundwater table and L-band brightness temperature estimates for Northern Hemisphere peatlands using new model physics and SMOS observations in a global data assimilation framework

Cited by 22 publications

References 49 publications

A strong mitigation scenario maintains climate neutrality of northern peatlands

A strong mitigation scenario maintains climate neutrality of northern peatlands

Tropical Peatland Hydrology Simulated With a Global Land Surface Model

Challenges and benefits of quantifying irrigation through the assimilation of Sentinel-1 backscatter observations into Noah-MP

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