Development and Application of a Statistically-Based Quality Control for Crowdsourced Air Temperature Data

In urban areas, dense atmospheric observational networks with high-quality data are still a challenge due to high costs for installation and maintenance over time. Citizen weather stations (CWS) could be one answer to that issue. Since more and more owners of CWS share their measurement data publicly, crowdsourcing, i.e., the automated collection of large amounts of data from an undefined crowd of citizens, opens new pathways for atmospheric research. However, the most critical issue is found to be the quality of data from such networks. In this study, a statistically-based quality control (QC) is developed to identify suspicious air temperature (T) measurements from crowdsourced data sets. The newly developed QC exploits the combined knowledge of the dense network of CWS to statistically identify implausible measurements, independent of external reference data. The evaluation of the QC is performed using data from Netatmo CWS in Toulouse, France, and Berlin, Germany, over a 1-year period (July 2016 to June 2017), comparing the quality-controlled data with data from two networks of reference stations. The new QC efficiently identifies erroneous data due to solar exposition and siting issues, which are common error sources of CWS. Estimation of T is improved when averaging data from a group of stations within a restricted area rather than relying on data of individual CWS. However, a positive deviation in CWS data compared to reference data is identified, particularly for daily minimum T. To illustrate the transferability of the newly developed QC and the applicability of CWS data, a mapping of T is performed over the city of Paris, France, where spatial density of CWS is especially high.DFG, 322579844, Hitzewellen in Berlin, Deutschland - StadtklimamodifkationenBMBF, 01LP1602A, Verbundprojekt Stadtklima: Evaluierung von Stadtklimamodellen (Modul B), 3DO Teilprojekt 1: Dreidimensionales Monitoring atmosphärischer Prozesse in Berli

Apport de paramétrisations avancées des processus liés à la végétation dans les modèles de surface pour la simulation des flux atmosphériques et hydrologiques

La version actuelle du modèle de surface continentale ISBA représente la couche de sol superficiel et la végétation comme un composite dont les propriétés physiques résultent de pondérations entre les propriétés du sol et de la végétation (albédo, rugosité par exemple). Une nouvelle version, ISBA-MEB (Multi-Energy-Balance), représente le sol et la végétation au travers de deux bilans séparés. Ce développement permet notamment une approche plus réaliste de la modélisation des flux au-dessus, dans et sous de la canopée avec un traitement propre à chacune des couches et la prise en compte de nouveaux processus (effet d'ombrage de la canopée sur le sol, transfert radiatif à travers la végétation, interception de la neige par la canopée). Le sol superficiel est lui désormais caractérisé, pour les surfaces forestières, par une couche de litière agissant sur le cycle énergétique comme sur le cycle hydrologique. Pour évaluer l'impact de ces nouveaux développements sur les forêts, quatre sites Français instrumentés sont dans un premier temps utilisés. Le large panel de données disponible permet une évaluation précise permettant de mettre en évidence certaines améliorations apportées par les développements, En particulier sur le bilan d'énergie en réduisant l'amplitude du flux de chaleur par conduction dans le sol et en réinjectant tout ou partie de cette énergie dans le flux sensible, mais aussi sur le bilan d'eau en améliorant le partitionnement de l'évapotranspiration en ses différentes composantes. Ensuite, leréseau Fluxnet, standard international, se révèle être outil idéal confirmer ces améliorations. Celui ci contient en effet des données relatives à des sites instrumentés correspondant à un large panel de climats et de types de végétation indispensable à la validation d'un modèle destiné à des simulations à échelle globale. 42 sites forestiers sont retenus pour procéder à l'évaluation des nouveaux développements sur la base d'un critère de fermeture du bilan énergétique. Lesrésultats de cette étude permettent non seulement de confirmer à grande échelle les résultats de la partie précédente mais aussi de caractériser des améliorations plus marquées sur les forêts de conifères ainsi que les sites enneigés. Enfin, l'impact sur le bilan hydrologique d'ISBA-MEB est évalué par l'utilisation de la chaîne opérationnelle hydrométéorologique SIM (SAFRAN-ISBAMODCOU).Cette chaîne permet de modéliser le débit des rivières françaises sur une longue période (jusqu'à un demi siècle) et par extension d'obtenir une estimation de la climatologie spatiallement distribuée de l'évapotranspiration. L'impact des développements, et nottament laprise en compte de la litière dans le modèle, modifient l'amplitude annuelle moyenne de l'évaporation du sol et impacte ainsi la modélisation des débits des rvières simulée. D'autre part, une augmentation significative de la sublimation de la neige est à l'origine dans les bassins de montagne d'une réduction du ruisselement total mais ceux-ci ne représente qu'une faible fraction du domaine d'étude

Evapotranspiration partition using the multiple energy balance version of the ISBA-A-gs land surface model over two irrigated crops in a semi-arid Mediterranean region (Marrakech, Morocco)

The main objective of this work is to question the representation of the energy budget in soil–vegetation–atmosphere transfer (SVAT) models for the prediction of the turbulent fluxes in the case of irrigated crops with a complex structure (row) and under strong transient hydric regimes due to irrigation. To this end, the Interaction between Soil, Biosphere, and Atmosphere (ISBA-A-gs) is evaluated at a complex open olive orchard and, for the purposes of comparison, on a winter wheat field taken as an example of a homogeneous canopy. The initial version of ISBA-A-gs, based on a composite energy budget (hereafter ISBA-1P for one patch), is compared to the new multiple energy balance (MEB) version of ISBA that represents a double source arising from the vegetation located above the soil layer. In addition, a patch representation corresponding to two adjacent, uncoupled source schemes (hereafter ISBA-2P for two patches) is also considered for the olive orchard. Continuous observations of evapotranspiration (ET), with an eddy covariance system and plant transpiration (Tr) with sap flow and isotopic methods were used to evaluate the three representations. A preliminary sensitivity analyses showed a strong sensitivity to the parameters related to turbulence in the canopy introduced in the new ISBA–MEB version. For wheat, the ability of the single- and dual-source configuration to reproduce the composite soil–vegetation heat fluxes was very similar; the root mean square error (RMSE) differences between ISBA-1P, ISBA-2P and ISBA–MEB did not exceed 10 W m−2 for the latent heat flux. These results showed that a composite energy balance in homogeneous covers is sufficient to reproduce the total convective fluxes. The two configurations are also fairly close to the isotopic observations of transpiration in spite of a light underestimation (overestimation) of ISBA-1P (ISBA–MEB). At the olive orchard, contrasting results are obtained. The dual-source configurations, including both the uncoupled (ISBA-2P) and the coupled (ISBA–MEB) representations, outperformed the single-source version (ISBA-1P), with slightly better results for ISBA–MEB in predicting both total heat fluxes and evapotranspiration partition. Concerning plant transpiration in particular, the coupled approach ISBA–MEB provides better results than ISBA-1P and, to a lesser extent, ISBA-2P with RMSEs of 1.60, 0.90, and 0.70 mm d−1 and R2 of 0.43, 0.69, and 0.70 for ISBA-1P, ISBA-2P and ISBA–MEB, respectively. In addition, it is shown that the acceptable predictions of composite convective fluxes by ISBA-2P for the olive orchard are obtained for the wrong reasons as neither of the two patches is in agreement with the observations because of a bad spatial distribution of the roots and a lack of incoming radiation screening for the bare soil patch. This work shows that composite convection fluxes predicted by the SURFace EXternalisée (SURFEX) platform and the partition of evapotranspiration in a highly transient regime due to irrigation is improved for moderately open tree canopies by the new coupled dual-source ISBA–MEB model. It also points out the need for further local-scale evaluations on different crops of various geometry (more open rainfed agriculture or a denser, intensive olive orchard) to provide adequate parameterisation to global database, such as ECOCLIMAP-II, in the view of a global application of the ISBA–MEB model

Modeling improvement of process linked to vegetation into surfaces models for the simulation of atmospheric and hydrologic flows

La version actuelle du modèle de surface continentale ISBA représente la couche de sol superficiel et la végétation comme un composite dont les propriétés physiques résultent de pondérations entre les propriétés du sol et de la végétation (albédo, rugosité par exemple). Une nouvelle version, ISBA-MEB (Multi-Energy-Balance), représente le sol et la végétation au travers de deux bilans séparés. Ce développement permet notamment une approche plus réaliste de la modélisation des flux au-dessus, dans et sous de la canopée avec un traitement propre à chacune des couches et la prise en compte de nouveaux processus (effet d'ombrage de la canopée sur le sol, transfert radiatif à travers la végétation, interception de la neige par la canopée). Le sol superficiel est lui désormais caractérisé, pour les surfaces forestières, par une couche de litière agissant sur le cycle énergétique comme sur le cycle hydrologique. Pour évaluer l'impact de ces nouveaux développements sur les forêts, quatre sites Français instrumentés sont dans un premier temps utilisés. Le large panel de données disponible permet une évaluation précise permettant de mettre en évidence certaines améliorations apportées par les développements, En particulier sur le bilan d'énergie en réduisant l'amplitude du flux de chaleur par conduction dans le sol et en réinjectant tout ou partie de cette énergie dans le flux sensible, mais aussi sur le bilan d'eau en améliorant le partitionnement de l'évapotranspiration en ses différentes composantes. Ensuite, leréseau Fluxnet, standard international, se révèle être outil idéal confirmer ces améliorations. Celui ci contient en effet des données relatives à des sites instrumentés correspondant à un large panel de climats et de types de végétation indispensable à la validation d'un modèle destiné à des simulations à échelle globale. 42 sites forestiers sont retenus pour procéder à l'évaluation des nouveaux développements sur la base d'un critère de fermeture du bilan énergétique. Lesrésultats de cette étude permettent non seulement de confirmer à grande échelle les résultats de la partie précédente mais aussi de caractériser des améliorations plus marquées sur les forêts de conifères ainsi que les sites enneigés. Enfin, l'impact sur le bilan hydrologique d'ISBA-MEB est évalué par l'utilisation de la chaîne opérationnelle hydrométéorologique SIM (SAFRAN-ISBAMODCOU).Cette chaîne permet de modéliser le débit des rivières françaises sur une longue période (jusqu'à un demi siècle) et par extension d'obtenir une estimation de la climatologie spatiallement distribuée de l'évapotranspiration. L'impact des développements, et nottament laprise en compte de la litière dans le modèle, modifient l'amplitude annuelle moyenne de l'évaporation du sol et impacte ainsi la modélisation des débits des rvières simulée. D'autre part, une augmentation significative de la sublimation de la neige est à l'origine dans les bassins de montagne d'une réduction du ruisselement total mais ceux-ci ne représente qu'une faible fraction du domaine d'étude.The current version of ISBA land surface model represents the superficial layer of soil and vegetation as a composite with physical properties modeled as a weighted combination between soil and vegetation properties (e.g. albedo, roughness). A new version, ISBA-MEB (Multi-Energy-Balance), represents the soil and vegetation energy budgets separately. This development consists in a more realistic modeling of the flux exchanges above, within and below the canopy with an explicit treatment of each energy budget and the associated processes (canopy shading of the forest floor, canopy radiative transfer, canopy snow interception and loading, etc.). In addition, the superficial soil layer can be characterized as being comprised of forest litter thereby modulating both thermal and hydrological processes. In order to assess the impact of these developments, first, data from four French well-instrumented sites were used. The wide range of available data permitted a thorough assessment of the impact of the improvements. In particular, the reduced amplitude of the surface ground conduction flux has a profound impact on the energy budget by transferring the resulting residual energy into the sensible heat flux. The water balance was also mainly impacted by improving the partitioning of evapotranspiration into its various components and making it depend more directly on the temporal evolution of the vegetation properties. Next, the Fluxnet network database, which is an international standard for model evaluation, proved to be ideal for confirming these improvements since it is comprised of data from instrumented sites for a wide range of climates and vegetation types. A sub-set of 42 forest sites were selected for assessing the new developments using classical energy balance closure-based criteria. The results of this study not only confirmed the results from the first part of this study for the three French sites, but it also helped characterize the biggest improvements which occurred for moderately open canopies, the pine forest class, and sites with significant snow cover. Finally, the impact of MEB on the hydrological cycle is evaluated by using the SIM operational hydrometeorological chain (SAFRAN-ISBA-MODCOU). This system is used to model and evaluate river discharge over all of France over long periods of time (up to half a century), and by extension, obtain spatially distributed climatological evapotranspiration estimates. The impact of the new developments, especially the combination of the canopy and the explicit forest litter treatment, modified the temporal evolution of bare soil evaporation which had a notable impact on river flow. Finally, significantly increased snow sublimation reduced both total runoff and evapotranspiration in mountain catchments (which comprised a relatively small part of the studied domain)

ISBA-MEB (SURFEX v8.1): model snow evaluation for local-scale forest sites

International audienc

Quality control for crowdsourced data from CWS

To install the CrowdQC-package execute " install.packages(file.choose(), repos = NULL, type="source") " in your R installation. The included data is accessible with the command data("netatmoBer"). To try the developed quality control procedure, execute the routines m1 to m4 (and o1 to o3 for optional routines) with the included data. The package was build with R version 3.4.3.This package performs a quality control (QC) and filters suspicious data from citizen weather stations (CWS). It was designed for hourly air temperature data from Netatmo stations but should work with any normally-distributed data

The interactions between soil-biosphere-atmosphere land surface model with a multi-energy balance (ISBA-MEB) option in SURFEXv8-Part 1 : Model description

Land surface models (LSMs) are pushing towards improved realism owing to an increasing number of observations at the local scale, constantly improving satellite data sets and the associated methodologies to best exploit such data, improved computing resources, and in response to the user community. As a part of the trend in LSM development, there have been ongoing efforts to improve the representation of the land surface processes in the interactions between the soil–biosphere–atmosphere (ISBA) LSM within the EXternalized SURFace (SURFEX) model platform. The force–restore approach in ISBA has been replaced in recent years by multi-layer explicit physically based options for sub-surface heat transfer, soil hydrological processes, and the composite snowpack. The representation of vegetation processes in SURFEX has also become much more sophisticated in recent years, including photosynthesis and respiration and biochemical processes. It became clear that the conceptual limits of the composite soil–vegetation scheme within ISBA had been reached and there was a need to explicitly separate the canopy vegetation from the soil surface. In response to this issue, a collaboration began in 2008 between the high-resolution limited area model (HIRLAM) consortium and Météo-France with the intention to develop an explicit representation of the vegetation in ISBA under the SURFEX platform. A new parameterization has been developed called the ISBA multi-energy balance (MEB) in order to address these issues. ISBA-MEB consists in a fully implicit numerical coupling between a multi-layer physically based snowpack model, a variable-layer soil scheme, an explicit litter layer, a bulk vegetation scheme, and the atmosphere. It also includes a feature that permits a coupling transition of the snowpack from the canopy air to the free atmosphere. It shares many of the routines and physics parameterizations with the standard version of ISBA. This paper is the first of two parts; in part one, the ISBA-MEB model equations, numerical schemes, and theoretical background are presented. In part two (Napoly et al., 2016), which is a separate companion paper, a local scale evaluation of the new scheme is presented along with a detailed description of the new forest litter scheme

The effect of satellite-derived surface soil moisture and leaf area index land data assimilation on streamflow simulations over France

International audienceThis study evaluates the impact of assimilating surface soil moisture (SSM) and leaf area index (LAI) observations into a land surface model using the SAFRAN-ISBA-MODCOU (SIM) hydrological suite. SIM consists of three stages: (1) an atmospheric reanalysis (SAFRAN) over France, which forces (2) the three-layer ISBA land surface model, which then provides drainage and runoff inputs to (3) the MODCOU hydro-geological model. The drainage and runoff outputs from ISBA are validated by comparing the simulated river discharge from MODCOU with over 500 river-gauge observations over France and with a subset of stations with low-anthropogenic influence, over several years. This study makes use of the A-gs version of ISBA that allows for physiological processes. The atmospheric forcing for the ISBA-A-gs model underestimates direct shortwave and long-wave radiation by approximately 5 % averaged over France. The ISBA-A-gs model also substantially underestimates the grassland LAI compared with satellite retrievals during winter dormancy. These differences result in an underestimation (overestimation) of evapotranspira-tion (drainage and runoff). The excess runoff flowing into the rivers and aquifers contributes to an overestimation of the SIM river discharge. Two experiments attempted to resolve these problems: (i) a correction of the minimum LAI model parameter for grasslands and (ii) a bias-correction of the model radiative forcing. Two data assimilation experiments were also performed, which are designed to correct random errors in the initial conditions: (iii) the assimilation of LAI observations and (iv) the assimilation of SSM and LAI observations. The data assimilation for (iii) and (iv) was done with a simplified extended Kalman filter (SEKF), which uses finite differences in the observation operator Jacobians to relate the observations to the model variables. Experiments (i) and (ii) improved the median SIM Nash scores by about 9 % and 18 % respectively. Experiment (iii) reduced the LAI phase errors in ISBA-A-gs but had little impact on the discharge Nash efficiency of SIM. In contrast, experiment (iv) resulted in spurious increases in drainage and runoff, which degraded the median discharge Nash efficiency by about 7 %. The poor performance of the SEKF originates from the observation operator Jacobians. These Jacobians are dampened when the soil is saturated and when the vegetation is dormant, which leads to positive biases in drainage and/or runoff and to insufficient corrections during winter, respectively. Possible ways to improve the model are discussed, including a new multi-layer diffusion model and a more realistic response of photosynthesis to temperature in mountainous regions. The data assimilation should be advanced by accounting for model and forcing uncertainties

The interactions between soil-biosphere-atmosphere (ISBA) land surface model multi-energy balance (MEB) option in SURFEXv8-Part 2 : Introduction of a litter formulation and model evaluation for local-scale forest sites

Land surface models (LSMs) need to balance a complicated trade-off between computational cost and complexity in order to adequately represent the exchanges of energy, water and matter with the atmosphere and the ocean. Some current generation LSMs use a simplified or composite canopy approach that generates recurrent errors in simulated soil temperature and turbulent fluxes. In response to these issues, a new version of the interactions between soil-biosphere-atmosphere (ISBA) land surface model has recently been developed that explicitly solves the transfer of energy and water from the upper canopy and the forest floor, which is characterized as a litter layer. The multi-energy balance (MEB) version of ISBA is first evaluated for three well-instrumented contrasting local-scale sites, and sensitivity tests are performed to explore the behavior of new model parameters. Second, ISBA-MEB is benchmarked against observations from 42 forested sites from the global micrometeorological network (FLUXNET) for multiple annual cycles. It is shown that ISBA-MEB outperforms the composite version of ISBA in improving the representation of soil temperature, ground, sensible and, to a lesser extent, latent heat fluxes. Both versions of ISBA give comparable results in terms of simulated latent heat flux because of the similar formulations of the water uptake and the stomatal resistance. However, MEB produces a better agreement with the observations of sensible heat flux than the previous version of ISBA for 87.5% of the simulated years across the 42 forested FLUXNET sites. Most of this improvement arises owing to the improved simulation of the ground conduction flux, which is greatly improved using MEB, especially owing to the forest litter parameterization. It is also shown that certain processes are also modeled more realistically (such as the partitioning of evapotranspiration into transpiration and ground evaporation), even if certain statistical performances are neutral. The analyses demonstrate that the shading effect of the vegetation, the explicit treatment of turbulent transfer for the canopy and ground, and the insulating thermal and hydrological effects of the forest floor litter turn out to be essential for simulating the exchange of energy, water and matter across a large range of forest types and climates

Soil Moisture Monitoring at Kilometer Scale: Assimilation of Sentinel-1 Products in ISBA

Observed by satellites for more than a decade, surface soil moisture (SSM) is an essential component of the Earth system. Today, with the Sentinel missions, SSM can be derived at a subkilometer spatial resolution. In this work, aggregated 1 km × 1 km SSM observations combining Sentinel-1 (S1) and Sentinel-2 (S2) data are assimilated for the first time into the Interactions between Soil, Biosphere, and Atmosphere (ISBA) land surface model using the global Land Data Assimilation System (LDAS-Monde) tool of Meteo-France. The ISBA simulations are driven by atmospheric variables from the Application of Research to Operations at Mesoscale (AROME) numerical weather prediction model for the period 2017-2019 for two regions in Southern France, Toulouse and Montpellier, and for the Salamanca region in Spain. The S1 SSM shows a good agreement with in situ SSM observations. The S1 SSM is assimilated either alone or together with leaf area index (LAI) observations from the PROBA-V satellite. The assimilation of S1 SSM alone has a small impact on the simulated root zone soil moisture. On the other hand, a marked impact of the assimilation is observed over agricultural areas when LAI is assimilated, and the impact is larger when S1 SSM and LAI are assimilated together