Integrated Studies (LIAISE – GEWEX-dET)

  Oral Presentations                     Study Study Study
No. Name Affiliation Co-authors Abstract L-WG1 L-WG2 L-WG3 OBS RS MOD PROCESS Meso-scale LSM
29 Aguirre Correa, Francisca Pontificia Universidad Católica de Chile –
Vilà-Guerau de Arellano, Jordi – Wageningen University
Ronda, Reinder – Wageningen University, the Netherlands;
Lobos Roco, Felipe – Wageningen University, the Netherlands;
Suárez, Francisco, Pontificia Universidad Católica de Chile, Chile;
Hartogensis, Oscar – Wageningen University, the Netherlands;
Evaporation and atmospheric boundary layer dynamics over a shallow salt-water lagoon in the Altiplano Desert

The Chilean Altiplano is a region in the Atacama Desert composed by multiple arid basins immersed in a complex topography. These arid basins are characterized by a dominant desert surface (> 100 km) in which small-scale heterogeneities can be found (< 10 km) in the form of salt flats with shallow, salt-water lagoons and wetlands. Controlled by the strong seasonality of precipitation and groundwater, these environments lose most of the water to the atmosphere through evaporation (E). In addition to the local lake and desert conditions, also the atmospheric boundary layer (ABL) dynamics and its interaction with large-scale forcing driven by a steep topography and a strong thermal contrast with the Pacific Ocean, play a key role in regulating E.
To understand E in such a complex system, we have selected a representative site that encompasses the main characteristics of the lake-desert interaction with the surrounding atmosphere. Our study area is a shallow lagoon defined by a surface 4 km x 800 m in the Salar del Huasco, for which, due to its limited size, detailed observations and fine-scale resolution models are required. Previous research showed that in the morning E is virtually zero over the water, with turbulence as a limiting factor due to the absence of wind. Under these conditions, a shallow internal boundary layer is formed over the lagoon. In the afternoon E is triggered by the entrance of a thermally driven and topographically enhanced regional flow characterized by strong winds, that makes E reach maximum values of ~450 W m-2. The enhanced mechanical turbulence and instability due to advection of cold air have been defined as the main drivers of E. Simultaneously, the internal boundary layer turns into a mixed layer similar to the one observed over the surrounding desert.
In this research, we use the Weather and Research Forecasting (WRF) model to understand the interaction of the regional transport with E and the ABL over the lagoon. A 100 x 100 m horizontal resolution and 79 levels vertical resolution are required to represent the local processes and the small-scale heterogeneity. Due to this high resolution, the land use, the initial conditions and the boundary conditions had to be adapted to include the presence and characteristics of the water and salt surfaces. Results were compared to observations from meteorological stations, eddy-covariance systems and radiosonde launchings gathered during a comprehensive field campaign in the Salar del Huasco during November 2018 (E-DATA). Our results confirmed that evaporation and the transition of the internal boundary layer into a mixed layer are controlled by: (1) an enhanced mixing during the afternoon due to mechanical turbulence, (2) the mass advection of a deeper ABL coming from the desert and (3) by a cold air advection that alters the land-atmosphere temperature gradient.
0 0.5 0.5 0 0.5 0 0.5 1 0.5 0.25
39 Barella-Ortiz, Anaïs Observatori de l’Ebre –
Quintana-Seguí, Pere – Observatori de l’Ebre, Spain;
Clavera-Gispert, Roger – Observatori de l’Ebre, Spain;
Munier, Simon – CNRM Météo-France, Un de Toulouse, France;
Merlin, Olivier – CESBIO, Un de Toulouse, CNES, CNRS, France;
Olivera-Guerra – Luis-E. – CESBIO, Un de Toulouse, CNES, France;
Altés-Gaspar, Víctor – University of Lleida, Spain;
Villar, Josep M. – University of Lleida, Spain;
Brocca, Luca – National Research Council, Italy;
Dari, Jacopo – University of Perugia, National Res Council, Italy;
Modanesi, Sara – National Research Council, Italy;
Zapa, Luca – Technische Universitaet Wien, Austria;
Brombacher, Joost – eLEAF, The Netherlands;
Simulating irrigation over the Ebro basin using the LIAISE-Ebro-Irrig-Sim (LE-IS) dataset at 1 km resolution

Irrigation consumes about 70% of the world’s freshwater and is one of the most significant anthropic processes affecting the land surface water cycle. Thus, it is necessary to take into account this process to better represent the real water cycle in regions where irrigation is present. This study focuses on the Ebro basin, which is a characteristic Mediterranean basin, with unevenly distributed precipitation and a variety of landscapes. To manage water resources there is a large net of dams and canals. As a result, the basin is highly influenced by human processes: 92% of the basin’s total water consumption is dedicated to irrigated agriculture and farming. This makes the Ebro an interesting site to perform case studies and improve our understanding of anthropized processes. Furthermore, the Ebro basin has the advantage of having a large range of meteorological and hydrological data available.
This work presents the LIAISE-Ebro-Irrig-Sim (LE-IS) data, which has been prepared to simulate irrigation over the Ebro basin, at a spatial resolution of 1 km, using a Land Surface Model. It provides meteorological and physiographical data. The former corresponds to a new version of the SAFRAN forcing, while the latter is composed of a vegetation classes map, an actual irrigated areas map, and an irrigation methods per area map. Taking ECOCLIMAP-SG as the base physiography, these maps were improved by using mainly information provided by farmers to the Spanish administration, about crops grown per plot and their readiness to be irrigated.
First, the sensitivity of the new datasets was evaluated comparing two simulations done with the SURFEX v9 land surface model, which has an irrigation scheme implemented. These were performed using i) the default physiography and ii) LE-IS. Second, LE-IS is used to perform SURFEX simulations considering different irrigation scenarios defined in the model. Third, these simulations are compared to remote sensing irrigation estimations from the IRRIGATION+ project, funded by the ESA. These product periods are within the 2015 to 2021 range and are estimated using different techniques (data assimilation, SM-based DELTA algorithm, SM-based inversion algorithm, and the Hydrological Similar Pixels (HSP) algorithm). Finally, the hydrological cycle is evaluated using the previous model estimations and remote sensing products, together with hydrological observations and LIAISE campaign data.
This work is a contribution to the LIAISE campaign, through the IDEWA project (PCI2020-112043), as well as to the IRRIGATION+ (4000129870/20/I-NB) project.
1 0 0 1 0 0 1 0 0 1
33 Best, Martin UK Met Office –
United Kingdom
Lock, Adrian – Met Office, UK; Comparison of modelled and observed boundary layer structure for temperature and humidity

Profiles of sonde ascents from the irrigated La Cendrosa site of the LIAISE field campaign show a gradient of humidity close to the surface within a boundary layer with a well-mixed temperature profile. This does not follow our expected theory for boundary layer mixing that assumes that temperature and humidity are both scalars. The same behaviour is not so obvious at the natural rainfed Els Plans site. So it is possible that three were issues with the sonde ascents, or that this gradient results from the additional irrigated water source. However similar behaviour is also found in some sonde assents at Cardington, in the UK, that is a natural rainfed observational site.
In this presentation we will show how this gradient in humidity from the Cardington observations varies during growth of the morning boundary layer and contrast this to cases where no gradient is observed. We will then also present results from mesoscale model simulations to demonstrate if the model is capable of capturing the differing characteristics of the two cases.
The results presented here will form the initial basis for the scientific motivation of an international model comparison experiment, utilising observations from the LIAISE field campaign. The aim of the experiment will be to establish which boundary layer schemes are able to capture the humidity gradient and to identify the physical processes that lead to the differing behaviour between temperature and humidity.
1 0 1 0.5 1 0 0.5 0 1 0.5
38 Calvet, Jean-Christophe CNRM – Météo-France –
Albergel, C. – CNRM – Météo-France, Un de Toulouse, CNRS, France;
Druel, A. – CNRM – Météo-France, Un de Toulouse, CNRS, France;
Mucia, A. – CNRM – Météo-France, Un de Toulouse, CNRS, France;
Munier, S. – CNRM – Météo-France, Un de Toulouse, CNRS, France;
Representing irrigation in the ISBA model

Global land surface models are able to simulate more and more vegetation-related processes. This includes agricultural practices such as irrigation. A simple representation of irrigation and crop phenology was recently upgraded in the ISBA land surface model within the SURFEX modeling platform (Druel et al. 2022). Irrigation can now be represented over any region of the Earth, for a large variety of vegetation types. An evaluation of the irrigation scheme is made over southwestern France, and over Nebraska (USA). The model is able to produce realistic yearly irrigation water amounts but the simulation quality markedly depends on the quality of the atmospheric forcing, precipitation in particular. Simulations with and without the new scheme are compared to different satellite-based observations. The irrigation scheme improves the simulated leaf area index, gross primary productivity, evapotranspiration, and land surface temperature. However, it is found that simulated bare soil evaporation is probably too large over Nebraska, especially during the non-growing season (winter, spring) in relation to the large wind speed values observed over this region. This can trigger the underestimation of the soil water content available for plant growth at the start of the growing season. More research is needed to improve the representation in ISBA of bare soil evaporation over agricultural areas, in relation to crop residues and soil preparation prior to seeding.
0 0 0 1 0 0 1 0 0 1
32 Castellnou Ribau, Marc Catalan Fire Service, Universitat de Lleida, Wageningen University –
Bachfischer, Mercedes – Catalan Fire Service Bombers GRAF, Spain;
Miralles, Marta – Catalan Fire Service Bombers GRAF, Spain;
Ruiz, Borja; Catalan Fire Service. Bombers GRAF;
Stoof, Cathelijne – Wageningen University, the Netherlands;
Vilà, Jordi – Wageningen University, the Netherlands;
ABL and Pyroconvection: 2021 Fire Season Case Study in NE Ibèria Peninsula

Pyrocumulus (pyroCu) formation during convective fire-atmosphere interaction is a driving factor causing extreme wildfires. Here, by investigating several cases of pyroCu occurrence, we have monitored fire-induced changes in the Atmospheric Boundary Layer (ABL) vertical profiles of state variables (temperature, humidity, and wind) and related them to observed versus modeled fire spread biases. To this end, during the 2021 LIAISE campaign, we conducted a pyroconvection monitoring campaign on the fires of NE Iberian Peninsula. We gathered data on hourly fire spread, plume surface, deepening and penetration stages, and in-situ radio soundings within wildfire plumes. Radiosounding data from the LIAISE campaign was used as an environment reference to validate fire radiosounding accuracy and vertical profile differences. ECMWF ERA5 weather data completed the analysis as reference modeling information to characterize the meso and synoptic scales on the thermodynamic profiles. We propose a novel classification of pyroconvection-type events based on (1) differences in ABL thermodynamic stability, (2) regions characterized by high turbulence in the sub or pyroCu-layers, and (3) the reinforced entrainment of free-tropospheric air on top of every convective plume. This classification defines four types: 1) convective plumes, 2) overshooting pyroCu, 3) resilient pyroCu, and 4) deep pyroCu/pyroCb. Those prototypes change ABL conditions (temperature, humidity, height) differently. Using this distinct behavior, we find correlations between observed ABL thermodynamic changes after fire-atmosphere interaction and fire spread biases. Our findings can facilitate safer and more physically sound decisions when analyzing extreme fires.
1 0.5 0.75 0 1 0 0 1 1 0
41 Collignan, Julie Laboratoire de Météorologie Dynamique, IPSL, Ecole Polytechnique, CNRS –
Polcher, Jan – LMD, IPSL, Ecole Polytechnique, CNRS, France;
Bastin, Sophie – Observations Spatiales/IPSL, CNRS, France;
Pere, Quintana-Segui – Observatori de l’Ebre, Spain;
Identifying and quantifying the effect of climatic and non-climatic drivers on river discharge in Europe

To predict and manage the evolution of water resources is a high stake for society in the context of climate change and largely managed rivers. A first step in this endeavour is to be able to determine in the past records which of both processes has dominated changes.
We propose an innovative way to detect and quantify the changes in river discharge due to climate processes or to non climatic factors over the past century for European catchments. We have a specific focus over Spain for which we have al large database of 363 pertinent catchments. The Land surface model (LSM) ORCHIDEE forced with a century long climate data set is used to simulate the complex hydrological response of natural catchments to changes in climatic variables. The Budyko framework is applied with a time-moving window to decompose the direct discharge response to changes in precipitation (P) and potential evapotranspiration (PET) and the indirect response due to climate induced changes in the evaporation efficiency of the watersheds. We then apply the same methodology to discharge observations from gauging stations over Europe. It enables to highlight the areas where the model misrepresents (or omits) important catchment processes and where non-natural changing factors impacting the watershed’s apparent evaporation efficiency significantly contribute to trends in the observed discharge over the century. Results over Spain and Europe show that long-term changes and variability in discharge due to climate processes are dominated by changes in P. The second main climatic driver of discharge changes is PET over most of Europe. However in Spain and over the Mediterranean area where water is more limiting, the intra-annual changes in the distribution of P outweigh the effect of PET trends on discharge changes. Over most catchments however and mostly in southern Spain, the changes due to factors not accounted for in the "natural" system dominate over the century. When the focus is on decadal periods, the effect of non-climatic factors is still significant but small compare to the high climate variability. Attempts to attribute non-climatic changes in the catchments evaporation efficiencies are presented. For instance, good correlations are found between changes in the evaporation efficiency of Spain catchment with the evolution of water stored in dams showing that it is a reliable indicator of the effect of human activities on the hydrological changes of watersheds in that area. Adding the effect of land-use and land-cover changes in the current implementation of the LSM has no significant effects on the hydrological behaviour of the watersheds at the studied scales. Many processes especially related to human factors impact the watershed’s apparent evaporation efficiency, often with complex and inter-correlated feedbacks. Further studies are needed to better attribute the non-climatic trends detected. In particular developments in LSM could allow to attribute these factors.
0.5 0 0 1 0 0 1 0 0 1
31 González Armas, Raquel Wageningen University –
Netherlands, The
Vilà, Jordi – Wageningen University, the Netherlands;
de Boer, Hugo – Utrecht University, the Netherlands;
Hartogensis, Oscar – Wageningen University, the Netherlands;
Mangan, Mary Rose – Wageningen University, the Netherlands;
Gibert, Fabien – LMD, France;
Water and carbon turbulent land-atmospheric exchange across scales: from leaf to canopy to field scale

Representing the diurnal variability of state meteorological variables, including carbon dioxide, is still an open challenge as shown by the large discrepancies with observations and weather and climate models. These discrepancies translate into different diurnal exchanges of heat, water and carbon dioxide between the canopy and atmosphere. These sub-diurnal differences can propagate to larger temporal and spatial scales.
With a systematic approach, we investigate the diurnal gas exchange of both water and carbon dioxide for an irrigated crop. Our investigation is based on a comprehensive observational dataset that ranges from scales covering from the leaf level to the canopy level to the local field scale gathered at the LIAISE campaign. We focus specially on one of the “supersites” of the campaign: La Cendrosa, which is an irrigated alfalfa field surrounded by a very dry region.
Our observational approach is bottom-up in which we first analyze the leaf, second the canopy and third the interactions with the atmosphere at a local field scale. Among the observations, we analyzed leaf gas exchange measurements, turbulent surface fluxes and vertical profiles of driving environmental variables such as radiation, wind, temperature, and vapor pressure deficit. To support the observational analysis, we use a land-atmospheric interactive model (CLASS model). This model allows the representation at each of the three levels mentioned: (1) leaf, (2) canopy and (3) field. Emphasis is put at leaf level where new expressions of the tendency of the leaf gas exchange as a function of the mean meteorological drivers including radiation, temperature, atmospheric CO2 concentration, and water vapor deficit are derived.
Our observations show an asymmetry in the diurnal variability of the stomatal conductance, which indicates a larger opening of the stomata during the morning than during the afternoon. Radiation drives most of the diurnal variability of stomatal conductance during the early morning and late afternoon. At midday, vapor pressure deficit and temperature play a more important role. The asymmetry is only simulated by models once specific characteristics of the crop are considered. It is also observed that dynamics at the leaf level such as a closure of the stomata during the midday can cause a dip in the evapotranspiration and enhance the sensible heat flux. Our results open the debate on the circumstances under which it is important to constrain the leaf gas exchange.
1 0.5 0.5 0 0.5 0 0.5 1 0.5 0.25
35 Guerrero Calzas, Iciar Servei Meteorològic de Catalunya –
Jordi Mercader Carbó – Universitat de Barcelona, Spain. Sensitivity of WRF model simulations to high-resolution static fields: Leaf Area Index and Vegetation Fraction 

It is known that WRF simulations are sensitive to land description and land use characteristics (Teklay et al., 2019) but also to static fields such as albedo, leaf area index (LAI) (Li et al., 2019) or vegetation fraction (VEGFRA) (Jiménez-Gutiérrez et al., 2021). This work's aim is to study the sensitivity of the WRF model forecast to high-resolution data of LAI and VEGFRA. 
To assess the magnitude of the WRF model's sensitivity to this pair of static parameters, a preliminary test comprising three simulations was carried out for the case of the 4th of July 2022. The control simulation (CTL) used the operational configuration running at the Meteorological Service of Catalonia (SMC); the other two differed from CTL in LAI and VEGFRA fields, set to constant over the whole domain. The outcome of this experiment showed the importance of having a precise estimate of the vegetation parameters, as an evident 2-meter temperature difference (with reference to CTL) arose. 
Therefore, in this work, the operational configuration of the SMC with high-resolution and near-real-time data of LAI and VEGFRA (fetched from the Copernicus Global Land Service website) is used to obtain a hindcast for the period from July 15th to 31st of 2021 (the same as for the LIAISE field campaign). In order to quantify the sensitivity of the forecasts to employing this static data instead of WRF's default datasets, the objective verification of temperature, relative humidity, wind and precipitation forecasts in Catalonia, coming from simulations with and without this high-resolution data, will be shown in this presentation. 

Teklay, A., Dile, Y.T., Asfaw, D.H., Bayabil, H.K., Sisay, K., 2019: Impacts of land surface model and land use data on WRF model simulations of rainfall and temperature over Lake Tana Basin, Ethiopia. Heliyon, 5, Issue 9. 
Li, S., Gao, Y., Lyu, S. et al., 2019: Response of surface air temperature to the change of leaf area index in the source region of the Yellow River by the WRF model. Theor Appl Climatol 138, 1755–1765. 
Jiménez-Gutierrez, J.M.; Valero, F.; Ruiz-Martínez, J.; Montávez, J.P., 2021: Temperature Response to Changes in Vegetation Fraction Cover in a Regional Climate Model. Atmosphere, 12, 599. 
1 0.25 1 0.5 0.5 0.5 1 0 1 0.75
28 Hartogensis, Oscar Wageningen University –
Netherlands, The
Mangan, Mary-Rose – Wageningen University, the Netherlands;
Mol, Wouter – Wageningen University, the Netherlands;
Vis, Gijs, Technical University Delft, the Netherlands;
Coenders, Miriam, Technical University Delft, the Netherlands;
Moonen, Robbert – Utrecht University, the Netherlands;
Agmuas, Getachew – Utrecht University, the Netherlands;
Gonzalez Armas, Raquel – Wageningen University, the Netherlands;
De Boer, Hugo – Utrecht University, the Netherlands;
Röckmann, Thomas – Utrecht University, the Netherlands;
Vilà, Jordi – Wageningen University, the Netherlands;
LIAISE-NL: understanding evapotranspiration over complex terrain by integrating processes, scales and methodologies

The most challenging, but at the same time most relevant conditions to accurately represent ET are found in semi-arid regions, specifically in complex terrains with strong thermal contrasts between dry and wet (irrigated) areas. The semi-arid conditions encountered now will be the norm in the future for much larger regions than is currently the case. Therefore it is timely that we study these systems now.
We will give an overview of the LIAISE-NL contribution to the overall LIAISE objectives, providing a red thread for the individual contributions of the LIAISE-NL team. The theme that joins all of our activities is understanding evapotranspiration over complex terrain by integrating biophysical processes, spatiotemporal scales and methodologies. The methodologies combine comprehensive observations and fine-scale modelling and theory supported by land-atmosphere conceptual modelling. In this endeavor we cover the relevant spatial (leaf to local to regional) and temporal scales (seconds to daily) involved in the processes that control evapotranspiration (ET) and confront these with the merits and limitations of various observation and modelling techniques. We make a strong case for integrated approaches to further develop our understanding of evapotranspiration.
0.75 0.5 0.5 0 0.5 0 0.5 1 0.5 0.25
34 Lohou, Fabienne Laboratoire d’Aérologie, CNRS, Université de Toulouse –
Bastin, Sophie – Université Versailles S-Quentin-Y, CNRS, France;
Brut, Aurore – CESBIO, CNRS, Un de Toulouse, France;
Canur, Guylaine – CNRM-CNRS, Météo-France, France;
Cheruy, Frederique – LMD, CNRS, IPSL, France;
Cohard, Jean-Martial – CNRS, Université de Grenoble, France;
Couvreux, Fleur – CNRM-CNRS, Météo-France, France;
Darrozes, José – CNRS, Un de Toulouse, CNES, Toulouse, France;
Dupont, Jean-Charles – LMD, CNRS, IPSL, France;
Lafont, Sébastien – INRA, France;
Roehrig, Romain – CNRM-CNRS, Météo-France, France;
Measure and simulate turbulent fluxes over heterogeneous land surfaces: the MOSAI project

The land surface, through its topography, soil moisture, temperature or vegetation activity, impacts the atmosphere from sub-daily to seasonal time scales. An accurate assessment of the Land-Atmosphere (L-A) exchanges and their appropriate representation are therefore essential for weather and climate modelling. However, Earth System Models (ESM) and Numerical Weather Prediction (NWP) models often exhibit large biases in their representation of surface-atmosphere flux when compared to observations. The detailed quantification and reduction of these biases are still on-going efforts in many modelling centres. The Models and Observations for Surface-Atmosphere Interactions (MOSAI) project aims at contributing to this effort, with a focus on the impact of surface heterogeneities.
The first step to achieve this objective is to conduct a fair and correct evaluation of the L-A interactions simulated by ESM and NWP. This is based on (i) reliable references against which the simulated L-A exchanges can be evaluated and (ii) relevant comparison methods able to point out the ESM and NWP weaknesses. These points define the two first scientific objectives of MOSAI project, namely (1) investigate and determine the uncertainty and representativeness of L-A exchanges measured over heterogeneous landscapes and (2) propose and test new methods to evaluate the L-A exchanges in ESM using long-term measurements.
The second step of the project tackles the improvement of the L-A exchanges as simulated by the ESMs and NWP models. The coupling between land surface models and atmospheric models is based on several simplifications which are different when considering large-eddy, weather or climate simulations. The third scientific objective (3) addresses some of these underlying simplifications in the coupling between land surface and atmospheric models, and their impacts on the simulated L-A exchanges.
From an observational perspective, MOSAI is based on long-term reference surface observations performed by research infrastructures (ACTRIS and ICOS) and on enhanced observing periods (2021-2023) on three different ACTRIS-Fr sites. From the modelling perspective, a wide range of state-of-the-art ESMs, NWP models and large-eddy models are involved.
In this presentation, we will detail the objectives and strategy of MOSAI and illustrate them with preliminary results. The latter will notably address (1) the representativity of reference long-term measurements in a heterogeneous landscape, (2) the use of Neural Networks for the evaluation of models, (3) the impact of the heterogeneity on the boundary-layer structure.
0 0.5 0.5 0.5 0.5 0 0.5 0.5 0.5 0.5
37 LUNEL, Tanguy CNRM – Météo-France, CNRS –
Boone, Aaron, CNRM – Météo-France/CNRS, France;
Le Moigne, Patrick, CNRM – Météo-France/CNRS, France;
Importance of irrigation representation in atmospheric files used for offline surface modeling

Irrigation is still largely neglected in numerical weather and climate prediction models. However, this omission leads to a warm and dry bias in the near-surface atmospheric variables over irrigated areas. These variables are subsequently used in surface, agricultural and hydrological modeling and add uncertainties to the corresponding results. The work presented here aims to quantify this bias using data from the special observation period of the LIAISE campaign that took place during the summer of 2021 in northeast Spain. First, the coupled surface-atmosphere model Surfex-MesoNH is used to model the period of interest with and without irrigation parameterization. The model outputs are then validated against the surface observational data. Heat fluxes and 2m variables are clearly improved by the irrigation representation. In particular, the modeled sensible and latent heat fluxes are reconciled with the observations, the temperature biases at 2m are corrected down to 5°C, and the specific humidity is increased by about 50% around noon near the surface. In a second step, the simulated atmospheric outputs with and without irrigation are used as forcing files to run the Surfex surface model offline. The difference between the generated evapotranspiration fluxes is quantified and commented. The results allow for a discussion of the importance of representing irrigation in atmospheric forcing files when it comes to offline surface modeling.
1 0 0.75 1 0.25 0 1 0 1 1
30 Mangan, Mary Rose Wageningen University –
Netherlands, The
Hartogensis, Oscar – Wageningen University, the Netherlands;
Chiel van Heerwaarden – Wageningen University, the Netherlands;
Jordi Vilà Guerau de Arellano – Wageningen University, the Netherlands;
Evapotranspiration Controls across Spatial Scales of Heterogeneity: a LIAISE Data- and Modeling Study

In heterogeneous environments, evaporation is controlled not only by the land surface, but also by the interaction between the surface and the atmospheric boundary layer. The spatial scale of heterogeneity impacts the processes that drive evaporation. In this study, we combine a comprehensive observational data set across scales with a conceptual, coupled land-atmosphere model to study the drivers of evapotranspiration across spatial scales of heterogeneity for the Land Interactions with the Atmosphere in the Iberian Semi-arid Environment (LIAISE) field campaign. We aim to understand the role of spatial scales of irrigation-induced, thermal heterogeneity on the surface fluxes, and consequently, the development of the diurnal convective boundary layer. To do this, we have introduced a spatial scaling scheme based on observed surface characteristics to describe the LIAISE environment where heterogeneities range from the regional scale (~10s km) to the landscape scale (~1s km) to the local scale (~100s m). We find that the boundary layer observed in the LIAISE campaign is formed by the composite, regional land surface.
In this study, we use a latent heat tendency equation as a diagnostic tool to quantify the contributions of various surface- and boundary-layer-driven processes on surface latent heat flux . This method allows us to quantify the forcings and feedback processes of latent heat (LE). The LE equation nis validated against observations. We find that at the larger spatial scales (> 1 km), boundary-layer processes including the feedback mechanism resulting from surface warming, are relatively more important for enhancing surface evaporation compared to local spatial scales ( ~ 100 m) where surface-driven processes are most important for governing evapotranspiration. At the local scale, the time lag between latent heat and net radiation is mainly explained through boundary-layer processes. Boundary-layer warming through surface sensible heat enhances LE in the afternoons. Additionally, in heterogeneous areas, non-local drivers including advection of heat and moisture influence local evaporation in a heterogeneous environment. The role of warm air advection is more important for enhancing evaporation than dry air advection. Surface-driven processes control LE to a lesser extent at the local scale. However, energy stored in the soil enhances evapotranspiration in the late afternoon at the local scale. This could explain the observed time lag between the net radiation and latent heat flux. Our approach is not only useful to advance understanding and data interpretation but also as a diagnostic tool to evaluate the performance of land-surface models at the parameter level.
1 0.5 0.5 0 0.5 0 0.5 1 0.5 0.25
36 Udina, Mireia Universitat de Barcelona –
Udina, Mireia – University of Barcelona, Spain;
Peinó, Eric – University of Barcelona, Spain;
Bech, Joan – University of Barcelona, Spain;
Polls, Francesc – University of Barcelona, Spain;
Jordi Mercader – Servei Meteorològic de Catalunya, Spain;
Iciar Guerrero – Servei Meteorològic de Catalunya, Spain;
Exploring WRF irrigation parameterization impact on the lower atmosphere and precipitation during LIAISE-2021

This study aims to explore the impact of land irrigation in the lower atmosphere and in the precipitation field using WRF simulations. Simulations are run for July 2021 in order to analyze the special observation period (SOP) of the LIAISE field campaign (15-31 July 2021) for a control case and for the irrigated case that includes the irrigation parameterization (Valmassoi et al. 2020), which modifies the amount of water in the land-surface model. In addition, sensitivity tests are done varying the spin-up time of the irrigated land.
The comparisons between WRF and the automatic weather stations show better statistics for temperature, humidity and wind speed and direction when including the irrigation parameterization. The warm bias in maximum 2-m temperatures are highly reduced when introducing the irrigation effects, although the minimum temperatures are not improved. Errors in 2-m specific humidity and 10-m wind speed are also reduced in irrigation simulations. Using the tower measurements of sensible and latent heat fluxes at la Cendrosa it is also seen a better energy partitioning representation in simulations that include the irrigation at the site, where the latent heat flux is prevailing over the sensible heat flux. The boundary layer height is lowered in the area nearby where the irrigation is applied. These modifications lead to decreases in the lifting condensation level and the level of free convection, which also cause increases in CAPE and CIN indexes. Regarding precipitation, there are hardly any differences between control and irrigated simulations for the biggest area of study, but they become more relevant for smaller areas, close to the irrigated lands. Simulations including irrigation tend to produce lower rainfall intensities than the control ones, which seem to be related to the less enhancement of convective initiation. However, the precipitation systems that occurred during the SOP in LIAISE affecting the area around the Urgell channel did not seem to be highly influenced by the lower atmosphere processes.
This work was partly funded by the projects WISE-PreP (RTI2018-098693-B-C32), ARTEMIS (PID2021-124253OB-I00) and the Water Research Institute (IdRA) of the University of Barcelona.

Valmassoi A, Dudhia J, Sabatino SD, Pilla F (2020). Evaluation of three new surface irrigation parameterizations in the WRF-ARW v3. 8.1 model: the Po Valley (Italy) case study. Geoscientific Model Development, 13(7), 3179-3201.
1 0 0.75 1 0.25 0 1 0 1 0.75
40 Verhoef, Anne University of Reading –
United Kingdom
Cuntz, Matthias – Université de Lorraine, AgroParisTech, France;
Thober, Stephan – Helmholtz Center for Env Res, UFZ, Germany;
Gudmundsson, Lukas – Inst for Atm and Clim Sc, ETH, Switzerland;
Zeng, Yijian – University of Twente, the Netherlands;
Bergner, Hannah – Johannes Gutenberg-University, Germany;
Patrick, C. – Johannes Gutenberg-University, Germany;
McGuire – University of Reading, United Kingdom;
Verhoef, Anne – University of Reading, United Kingdom;
The response of land surface models to changing soil parameters is dominated by the description of soil infiltration

Land surface models (LSMs) are tools for assessing the responses and feedbacks of the land surface to current and future climatic conditions. Current LSMs show distinct regional differences for water fluxes. Here we challenged state-of-the-art LSMs by changing soil parameters between two extreme cases to understand the intricate responses of the different water fluxes on the land surface. Controlled multi-model experiments were conducted as part of the Soil Parameter Model Intercomparison Project (SP-MIP), that was originally proposed at the GEWEX-ISMC workshop held in Leipzig (June 2016).
The model experiments closely followed the LS3MIP protocol (van den Hurk et al. 2016). We used results of seven land models (CLM5, ISBA, JSBACH, MATSIRO, MATSIRO-GW, NOAH-MP and ORCHIDEE) that were run globally on =0.5° with GSWP3 forcing, from 1980-2010, for vertically homogeneous soil columns. We focussed on Experiment 4: here the LSM teams were provided, by SP-MIP, with spatially uniform soil hydraulic parameters for the whole globe (loamy sand, loam, clay and silt).
All models showed an in increase in soil moisture when changing from the silt soil to the loamy sand soil, leading to enhanced subsurface runoff. Plant-available soil moisture did, however, decrease in many regions of the world in most models, which led to less plant transpiration for the blanket silty soil scenario compared to the loamy sand one. Notwithstanding, total evapotranspiration increased paradoxically at the same time due to very large increases in soil evaporation, which is hence still a very large portion of total evapotranspiration in current LSMs. We identified the description of water infiltration into soil as the most sensitive and diverse parameterization between LSMs, which consequently led to large and very different surface runoff fluxes and hence to different soil moisture availability and related partitioning over the other hydrologic fluxes. This issue needs to be addressed urgently, especially over irrigated areas.
0 0 0 1 0 0 1 0 0 1
  Poster Presentations                     Study Study Study
No. Name Affiliation Co-authors Abstract L-WG1 L-WG2 L-WG3 OBS RS MOD PROCESS Meso-scale LSM
P16 Garcia-Santos, Vicente University of Valencia –
Estrela, Maria José, University of Valencia, Spain;
Valor, Enric, University of Valencia, Spain;
Caselles, Vicente, University of Valencia, Spain;
Coll, César, University of Valencia, Spain;
Gómez, Igor, University of Alicante, Spain;
Miró J., University of Valencia, Spain;
Puchades, Jesús, University of Valencia, Spain;
Perelló, Martí, University of Valencia, Spain;
García-Ten, Alejandro, University of Valencia, Spain;
Corell, D., University of Valencia, Spain;
Remote Sensing and Modeling Tools to Study Trends and Extreme Events Associated with Climate Change in the Iberian Mediterranean Basin

Extreme weather events are being accentuated over the last years, and warming trends and rainfall pattern changes have been revealed on the Iberian Mediterranean Basin (IMB), with an increase of the torrential rainfalls and tropical nights. The Thermal Remote Sensing Group (as experts on ground data and remote sensing techniques) and the Research Group of climate change, weather risks and inputs to the hydrological system in the Mediterranean (as experts on weather data series, modeling, and forecast) are working together on new techniques to study climate trends and extreme weather events in the IMB. The multidisciplinary research is being mainly carried out in the framework of two research projects. The first project is entitled “New Remote Sensing and Modeling Tools to Improve the Forecast of Extreme Events Associated with Climate Change in the Iberian Mediterranean Basin (Tool4Extreme)”, PID2020-118797RBI00, funded by the national administration through MCIN/AEI/10.13039/501100011033, and the second one is entitled “Analysis and modeling of trends in the Valencian Region in the context of Climate Change”, PROMETEO/2021/016, funded by the regional administration, Generalitat Valenciana. These projects involve the following objectives: a) the evaluation of climate change trends, mainly in two Essential Climate Variables (ECV) defined by the WMO Global Climate Observing System (GCOS), i.e., temperature and precipitation. This evaluation will include the analyses of significant spatial and temporal patterns; b) the monitoring of temperatures and precipitations to generate long time series, and their forecast; and c) the study of the extreme events and the impacts of the change trends, for which the main tasks are: 1) develop a new reconstruction-homogenization of observed temperatures but also precipitation data-series and statistical downscaling techniques; 2) develop new techniques to generate and validate remote sensing products of land, sea, and air surface temperatures and precipitations, and complementary products, such as vegetation indexes, and water in soil and in canopy, using the last advances in Earth Observation Satellites; 3) monitor all these variables for extensive time periods and extreme events; 4) analyze spatial-temporal trends associated to the climate change; 5) forecast these variables; and 6) evaluate impacts in the region of study. This contribution shows the first results obtained in the framework of these current research projects. Another secondary lines of research, carried out by the Thermal Remote Sensing Group are the downscaling of the land surface temperature through the synergy of high/low spatial/temporal resolution sensors, and the influence of surface energy flows such as advection, in the “unclosed” Surface Energy Budget problem.
0.25 0 1 0.75 0.25 0.75 0.75 0.75 0.5 0
P12 Jimenez, Maria A. Universitat de les Illes Balears –
Cuxart, J – Universitat de les Illes Balears, Spain;
Boone, A, CNRM-Meteo France;
Le Moigne, P, CNRM-Meteo France;
Lunel, T, CNRM-Meteo France;
Miró, JR, Servei Meteorològic de Catalunya;
Moré, J, Servei Meteorològic de Catalunya;
Tiesi, A, CNR-ISAC;
Drofa, O, CNR-ISAC;
Brooke, J, Metoffice;
Best, M, Metoffice
LIAISE-1st mesoscale model intercomparison: what have we learned?

In order to prepare the LIAISE experimental field campaign and future numerical simulations,
a first mesoscale modelling inter-comparison for a summer event in the LIAISE area is intended to evaluate the performance of the MesoNH, Moloch, UM and WRF models compared to the observations and explore the differences between them.
Participant models are run at their standard configurations to evaluate the representation of the surface features in the numerical models and its impact in the organisation of the flow at lower levels. Nevertheless, they are run with similar grid meshes in the horizontal (2km x 2km and 400m x 400m for the outer and inner domains) and the vertical (4m at lower levels and stretched above). A 48-h integration is made between 16 and 18 July 2016 for a case with well-developed thermally-driven circulations in the Ebro Basin. Furthermore, some sensitivity tests are made (initial and lateral boundary conditions, resolution or representation of the surface features, among others) to identify the importance of some model parameters in the model results.
Model results are validated using data from the surface stations of the Servei Meteorològic de Catalunya network and satellite-derived land-surface temperature fields. It is found that each model has a different representation of the surface heterogeneities affecting the grid values of the surface fluxes. Nevertheless, the mesoscale circulations generated by the models are very close being the differences lying mostly at the small scales, namely the values of the exchange fluxes at the surface or the state of the surface and the soil. Model biases are related to the particularities of the parameterisations, specially those related to the surface model, and of the physiographic data bases used by each model. From this exercise we have learned which is the best configuration of each model setup to best reproduce the observations. These configurations will be used to perform simulations of cases corresponding to the LIAISE experimental field campaign, for which there is a larger amount of available observations.
1 0 1 0 0.25 0 1 0 1 0
P15 Martí, Belén CNRM – Météo-France, CNRS, GMME –
Boone, Aaron – CNRM Météo-France/CNRS GMME Toulouse, France; Simulation of surface processes at LIAISE sites using a Land Surface Modelling approach

The processes that govern the conditions of the atmosphere near the ground are strongly influenced by the vegetation and soil dynamics. Land Surface Models (LSM) such as ISBA (interaction soil-biosphere-atmosphere) coded within the SURFEX modelling platform are developed to simulate the exchanges of energy and water between the land surface and the atmosphere. The LIAISE campaign provides measurements for a contrasting land-atmosphere interactions at multiple sites in a semi-arid environment: in this study the focus is on both rain-fed sites (natural grass or low vegetation and bare soil) and for those with irrigation from flooding (mainly corn and alfalfa). Processes at sites, such as la Cendrosa, are modelled taking into account the growth of the crops, the soil characteristics and the exchanges of matter and energy with the vegetation that influence the turbulent fluxes. These make the prediction of the evapotranspiration a construction of many processes, further complicated through the heterogeneity of the terrain.
1 0 0 1 0 0 1 0 0 1
P13 Mercader Carbó, Jordi Servei Meteorològic de Catalunya –
Vicent Altava-Ortiz – Servei Meteorològic de Catalunya, Spain;
Jordi Cristóbal – IRTA, Spain;
Mahsa Bozorgi – IRTA, Spain;
Joaquim Bellvert – IRTA, Spain;
Jaume Casadesús – IRTA, Spain;
Diagnosing the reference evapotranspiration for prediction purposes using the operational version of the WRF-ARW model in the Meteorological Service of Catalonia 

Since 1998, the Meteorological Service of Catalonia (SMC) has computed the reference evapotranspiration (ETo) for automatic weather stations (AWS) belonging to its network. Currently, the SMC uses the FAO Penman-Monteith (PM-FAO98) formulation and computes ETo only for daylight hours (Benaiges, 2019). At the same time, the Institute of Agrifood Research and Technology of Catalonia (IRTA) also provides near-real-time estimations of actual evapotranspiration (ET) and ETo, based on both in-situ and satellite observations using the two-source energy balance (TSEB) modelling approach with Copernicus-based inputs. The aim is to use this data in order to help farmers to improve scheduling irrigation shifts over the following days. 
This, however, is only based on climatological and near-real-time data and lacks any input from numerical weather prediction models. For this reason, to provide a two-dimensional ETo field and its short-term (0-72 h) forecast, the SMC has added the PM-FAO98 formulation to the post-processing software of the WRF-ARW model. Given that the FAO manual (Allen et al., 1998) gives several parameterisations for the variables in the PM-FAO98 formula, various diagnoses of ETo have been coded to analyse its differences.  
In this study, the results of ETo diagnosis from the WRF-ARW model output will be shown for July 2021 (when the LIAISE field campaign took place) and compared to both field data and remote sensing actual ET estimations. For this work, the WRF-ARW model is run as a hindcast, using the ERA5 dataset as initial and boundary conditions. This preliminary task marks the first step within the SMC towards a more complex forecasting system of ETo or even the actual ET to fulfil the farmers' needs. 

Allen, R., Pereira, L., Raes, D., Smith, M., 1998: FAO irrigation and drainage paper no. 56, Rome: Food and Agriculture Organisation of the United Nations, 56, 26-40. 
Benaiges-Lliberia, 2019: Càlcul de l’evapotranspiració de referència a Catalunya utilitzant diferents aproximacions en l’equació de Penman Monteith, Universitat de Barcelona, Treball de Fi de Màster, 12 pp. 
1 0 0.75 0.5 0.25 0 1 0 1 0
P14 Naz, Bibi S. Forschungszentrum Jülich –
Poppe, Christian – Forschungszentrum Jülich, Germany;
Hendricks-Franssen, H-J – Forschungszentrum Jülich, Germany;
Goergen Klaus – Forschungszentrum Jülich, Germany;
Kollet Stefan – Forschungszentrum Jülich, Germany;
Vanderborght Jan – Forschungszentrum Jülich, Germany;
Evaluation of multimodel high-resolution simulations to quantify uncertainties in hydrologic states and fluxes over the Iberian Peninsula.

High-resolution predictions of hydrologic states and fluxes are important for many regional-scale applications and water resource management. However, because of uncertainties related to forcing data, model structural errors arising from simplified representations of hydrological processes or uncertain model parameters, model simulations remain uncertain. To quantify this uncertainty, multi-model simulations were performed at 3km resolution using three models with different complexities in groundwater processes. In this study, we apply the fully-distributed integrated hydrologic ParFlow-CLM model which simulates simultaneously surface and subsurface systems with lateral groundwater flow, land surface community land model v3.5 (CLM3.5) and v5 (CLM5). We evaluate performance of all three models using in-situ and remote sensing observations to explore uncertainties and to investigate whether performance of models with different complexities varies for different variables including soil moisture (SM), evapotranspiration (ET), total water storage (TWS), water table depth (WTD) and groundwater recharge/discharge. Over Iberian Peninsula, all models were driven with the COSMO-REA6 reanalysis dataset for the time period from 1997 to 2006 and used similar datasets for the static input variables (such as topography, vegetation and soil properties). Our results show that all models capture the seasonal and interannual variability well when compared with observational data of WTD, ET, surface SM and TWS. However, ParFlow-CLM model simulates more realistic small-scale spatial variability in these variables where local drainage is better resolved than both CLM3.5 and CLM5 where simulated spatial patterns are more correlated with soil properties and land cover information. Focusing on extreme events, we found an improved performance by ParFlow-CLM during drought condition than in the wetter conditions, but model performance varies for different hydrological variables with best agreement is observed for ET by all models. This study helps to understand and quantify uncertainties in groundwater related processes in hydrologic simulations and resulting implications for water resources assessment at regional scale.
0.25 0 0 1 0.25 0 1 0 0 1
P11 Pedruzo-Bagazgoitia, Xabier ECMWF –
Pedruzo-Bagazgoitia, Xabier – ECMWF, Germany;
Arduini, Gabriele – ECMWF, Germany;
Balsamo, Gianpaolo – ECMWF, Germany;
Boussetta, Souhail – ECMWF, Germany;
Denissen, Jasper – ECMWF, Germany;
Sandu, Irina – ECMWF, Germany;
Exploring the IFS current and future performance at the surface-boundary layer system over a highly heterogenous land-surface

The highly heterogeneous land surface in the North-Eastern Spanish region and its impact on the meteorology poses a challenge to weather and climate models. With irrigated and arid surfaces present within few kilometres distance, it is a great testbed for the current and future capabilities of the Integrated Forecasting System (IFS) developed and maintained at ECMWF. Here, we test the performance of the IFS in its future operational configuration, i.e. cycle 48r1 at an approximate 9km resolution, and perform additional sensitivity experiments testing a) the effect of increasing the spatio-temporal resolution and b) a modified version of the land-surface scheme with an innovative land use/ land cover representation. We compare the results regarding surface and boundary layer properties to ERA5 reanalysis and to the operational analysis produced at ECMWF. This allows us to recognize the current areas for improvement for IFS and the possible shortcomings in the planned transition towards the new land representation.
1 0 1 0 0 0 1 0.5 1 0