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Joris Timmermans

Joris Timmermans
LifeWatch ERIC - VLIC

Master of Science

About

57
Publications
9,146
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Citations
Introduction
One of the major drivers behind EO systems has been land surface monitoring , leading to a various land products, such as LAI and SM. A data assimilation system such as the EO-LDAS, provides a generalized environment to retrieve these land surface parameters consistantly, using synergistic combinations of different datasets. My current research investigates the synergies between microwave and optical observations to retrieve simultaneously SM, Tsoil and LAI.
Additional affiliations
March 2009 - present
University of Twente
Position
  • PostDoc Position

Publications

Publications (57)
Article
Full-text available
Global sustainable agricultural systems are under threat, due to increasing and co-occurring drought and salinity stresses. Combined effects of these stresses on agricultural crops have traditionally been evaluated in small-scale experimental studies. Consequently, large-scale studies need to be performed to increase our understanding and assessmen...
Article
The cover image is based on the Research Article Notebook‐as‐a‐VRE (NaaVRE): From private notebooks to a collaborative cloud virtual research environment by Zhiming Zhao et al., https://doi.org/10.1002/spe.3098.
Article
Virtual research environments (VREs) provide user‐centric support in the lifecycle of research activities, for example, discovering and accessing research assets or composing and executing application workflows. A typical VRE is often implemented as an integrated environment, including a catalog of research assets, a workflow management system, a d...
Preprint
Full-text available
In this manuscript (currently undergoing review), we have investigated the opportunities for remote sensing to be developed into essential biodiversity variables to aid in the tracking of international biodiversity policies. For this we investigated (using a integrated user-requirement analysis) the goals and targets of the post-2020 global biodive...
Article
Full-text available
Global biodiversity losses erode the functioning of our vital ecosystems. Functional diversity is increasingly recognized as a critical link between biodiversity and ecosystem functioning. Satellite earth observation was proposed to address the current absence of information on large-scale continuous patterns of plant functional diversity. This stu...
Article
Full-text available
Drought impact monitoring is of crucial importance in light of climate change. However, we lack an understanding of the concomitant responses of ecosystems to a variety of drought characteristics and the links between drought and ecosystem anomaly characteristics for a comprehensive set of vegetation types to provide needed information for water ma...
Preprint
Global sustainable agricultural systems are under threat, due to projected increases of co-occurring drought and salinity with climate change. Combined effects of drought and salinity on agricultural crops have traditionally been evaluated in small-scale experimental studies. As such the need exists for large scale studies that increase our underst...
Preprint
Full-text available
Virtual Research Environments (VREs) provide user-centric support in the lifecycle of research activities, e.g., discovering and accessing research assets, or composing and executing application workflows. A typical VRE is often implemented as an integrated environment, which includes a catalog of research assets, a workflow management system, a da...
Article
Full-text available
In light of the ongoing global biodiversity crisis, the urge to monitor and map terrestrial plant biodiversity at large spatial extents has spurred research on adequate quantitative methods. The use of spectral diversity metrics from different remote sensing platforms has emerged as a promising tool for such biodiversity assessments. Satellite remo...
Article
Full-text available
Large-scale high-resolution satellite observations of plant functional diversity patterns will greatly benefit our ability to study ecosystem functioning. Here, we demonstrate a potentially scalable approach that uses aggregate plant traits estimated from radiative transfer model (RTM) inversion of Sentinel-2 satellite images to calculate community...
Article
Full-text available
Citation: Wen, W.; Timmermans, J.; Chen, Q.; van Bodegom, P.M. A Review of Remote Sensing Challenges for Food Security with Respect to Salin-ity and Drought Threats. Remote Sens. 2021, 13, 6. https://dx.
Article
Full-text available
Ecosystem services offered by mangrove forests are facing severe risks, particularly through land use change driven by human development. Remote sensing has become a primary instrument to monitor the land use dynamics surrounding mangrove ecosystems. Where studies formerly relied on bi-temporal assessments of change, the practical limitations conce...
Method
Full-text available
Early December, lecturer Joris Timmermans gave the first virtual reality lecture at the Institute of Environmental Sciences. Together with the Centre for Innovation, he developed an innovative teaching method for the master's course Methods in Biodiversity Analysis. The first results look promising. ‘I was impressed by the positive reactions of the...
Article
Full-text available
Correct estimation of soil and vegetation thermal emissivities is of huge importance in remote sensing studies. It has been shown that the emissivity of leaves retrieved from field observations show subtle spectral features that are related to leaf water content. However, such field measurements provide additional challenges before leaf water conte...
Article
Full-text available
Current earth observation models do not take into account the influence of water salinity on the evaporation rate, even though the salinity influences the evaporation rate by affecting the density and latent heat of vaporization. In this paper, we adapt the SEBS (Surface Energy Balance System) model for large water bodies and add the effect of wate...
Presentation
Full-text available
An example of DA techniques using SPOT data over an agricultural region.
Article
Three eddy covariance stations were installed at the Barrax experimental farm during the Land-Atmosphere Exchanges (REFLEX) airborne training and measurement campaign to provide ground truth data of energy balance fluxes and vertical temperature and wind profiles. The energy balance closure ratio (EBR) was 105% for a homogeneous camelina site, 86%...
Article
Full-text available
The REFLEX 2012 campaign was initiated as part of a training course on the organization of an airborne campaign to support advancement of the understanding of land-atmosphere interaction processes. This article describes the campaign, its objectives and observations, remote as well as in situ. The observations took place at the experimental Las Tie...
Conference Paper
Full-text available
Evaporation over large water bodies has a crucial role in the global hydrological cycle. Evaporation occurs whenever there is a vapor pressure deficit between a water surface and the atmosphere, and the available energy is sufficient. Salinity affects the density and latent heat of vaporization of the water body, which reflects on the evaporation r...
Article
Full-text available
Evaporation over large water bodies has a crucial role in the global hydrological cycle. Evaporation occurs whenever there is a vapor pressure deficit between a water surface and the atmosphere, and the available energy is sufficient. Salinity affects the density and latent heat of vaporization of the water body, which reflects on the evaporation r...
Article
Full-text available
Accurate irrigation and water management is of vital importance in semi-arid regions for improving crop production. Management practices can be improved by precisely assessing the spatial and temporal distribution of evapotranspiration. Accurate estimates of evapotranspiration (ET) contribute towards efficient crop management tasks from local to re...
Article
Soil moisture is a key state variable in hydrology. It plays an important role in distributing precipitation into evapotranspiration, run off and percolation. Understanding the dynamics and variability is therefore of crucial importance for characterizing the influence of the land surface on the atmosphere and climate change. In that context soil m...
Article
This paper introduces a new implementation of the Surface Energy Balance System (SEBS) algorithm harnessing the many cores available on Graphics Processing Units (GPUs). This new implementation uses Compute Unified Device Architecture C (CUDA-C) programming model and is designed to be executed on a system equipped with NVIDIA®'s graphic cards. The...
Article
Full-text available
Accurate estimation of global evapotranspiration is considered to be of great importance due to its key role in the terrestrial and atmospheric water budget. Global estimation of evapotranspiration on the basis of observational data can only be achieved by using remote sensing. Several algorithms have been developed that are capable of estimating t...
Article
Full-text available
Aerodynamic roughness height (Zom) is a key parameter required in several land surface hydrological models, since errors in heat flux estimation are largely dependent on optimization of this input. Despite its significance, it remains an uncertain parameter which is not readily determined. This is mostly because of non-linear relationship in Monin-...
Article
Full-text available
No abstract available.
Article
This study investigated two aerodynamic methods to estimate the momentum roughness length and displacement height (z0 and d0 respectively) of a 32 m-tall Douglas fir forest using simultaneous micrometeorological and flux measurements. When the flux–gradient method was used to objectively determine z0 and d0, corrections for roughness sub-layer effe...
Article
Drought is a reoccurring worldwide problem with impacts ranging from food production to infrastructure. Droughts are different from other natural hazards (floods, hurricanes, and earthquakes) because the effects can only be witnessed slowly and with a time delay. Effects of droughts are diverse, like famine and migration of people. Droughts are cau...
Article
Full-text available
The need to good drought monitoring and management for the Horn of Africa has never been greater. This ongoing drought is the largest in the past sixty years and is effecting the life of around 10 million people, according to the United Nations. The impact of drought is most apparent in food security and health. In addition secondary problems arise...
Article
Full-text available
Aerodynamic roughness height (Zom) is a key parameter required in land surface hydrological model, since errors in heat flux estimations are largely dependent on accurate optimization of this parameter. Despite its significance, it remains an uncertain parameter that is not easily determined. This is mostly because of non-linear relationship in Mon...
Article
Full-text available
Accurate estimation of global evapotranspiration is considered of great importance due to its key role in the terrestrial and atmospheric water budget. Global estimation of evapotranspiration on the basis of observational data can only be achieved by using remote sensing. Several algorithms have been developed that are capable of estimating the dai...
Article
Full-text available
Observing and monitoring the different components of the global water cycle and their dynamics are essential steps to understand the climate of the Earth, forecast the weather, predict natural disasters like floods and droughts, and improve water resources management. Earth observation technology is a unique tool to provide a global understanding o...
Article
Availability of fresh water supply is an essential important to humans and all forms of life. Precipitation, being the source of most of fresh water plays an important role in the socio-economic activities as human settlement is often found in regions abundant with this precious commodity in its various forms either sourced directly from rainfall o...
Article
Variation of effective roughness and validity of existing canopy flow models; an analysis of Monin-Obukhov Similarity Theory in Surface Energy Balance System (SEBS)
Article
Daily Evapotranspiration estimates are important in many applications. Evapotranspiration plays a significant role in the water, energy and carbon cycles. Through these cycles evapotranspiration is important for monitoring droughts, managing agricultural irrigation, and weather forecast modeling. Drought levels and irrigation needs can be calculate...
Article
Full-text available
This paper presents the model SCOPE (Soil Canopy Observation, Photochemistry and Energy fluxes), which is a vertical (1-D) integrated radiative transfer and energy balance model. The model links visible to thermal infrared radiance spectra (0.4 to 50 μm) as observed above the canopy to the fluxes of water, heat and carbon dioxide, as a function of...
Article
Full-text available
Evapotranspiration is usually estimated in remote sensing from single temperature value representing both soil and vegetation. This surface temperature is an aggregate over multiple canopy components. The temperature of the individual components can differ significantly, introducing errors in the evapotranspiration estimations. The temperature aggr...
Article
Full-text available
EAGLE2006 – an intensive field campaign for the advances in land surface hydrometeorological processes – was carried out in the Netherlands from 8th to 18th June 2006, involving 16 institutions with in total 67 people from 16 different countries. In addition to the acquisition of multiangle and multi-sensor satellite data, several airborne instrume...
Article
Full-text available
Sensible and latent heat fluxes are often calculated from bulk transfer equations combined with the energy balance. For spatial estimates of these fluxes, a combination of remotely sensed and standard meteorological data from weather stations is used. The success of this approach depends on the accuracy of the input data and on the accuracy of two...
Article
Full-text available
This paper presents the model SCOPE (Soil Canopy Observation, Photochemistry and Energy fluxes), which is a vertical (1-D) integrated radiative transfer and energy balance model. It calculates the radiation and the energy balance of a vegetated land surface at the level of single leaves as well as at canopy level, and the spectrum of the outgoing r...
Article
In this paper, we used the available algorithm for soil moisture estimation over LOPEX05 (the Loess Plateau land surface process Experiment (2005)) area. The available algorithm used ENVISAT/ASAR AP mode VV polarization observational data at a low incidence angle and ground measured soil moistures. The ground measurements were performed in the summ...
Article
Full-text available
The potential for directional optical and thermal imagery is very large. Field measurements have been performed with a goniometer on which thermal instruments were attached. In order to reduce dynamical effects the goniometer was adjusted to run in automated mode, for zenith and azimuthal direction. Directional measurements were performed over vari...
Article
Full-text available
Sensible and latent heat fluxes are often calculated from bulk transfer equations combined with the energy balance. For spatial estimates of these fluxes, a combination of remotely sensed and standard meteorological data from weather stations on the ground is used. The success of this approach depends on the accuracy of the input data and on the ac...
Article
In the calculation of Evapotranspiration the kinematic temperature of the individual canopy components plays a crucial role. Most remote sensing algorithms, like SEBAL and SEBS, use a single surface temperature to calculate the evapotranspiration. These algorithms break down when used for canopies with a heterogeneous kinematic temperature profile....
Article
Evapotranspiration models require thermodynamic temperatures as a state variable characterizing the surface energy balance. The thermodynamic temperature is calculated using the brightness temperature and the emissivity because no effective method exists to measure thermodynamic temperatures in space and time. A method was therefore developed to me...
Article
Full-text available
To advance our understanding of land-atmosphere exchanges of water, energy and carbon dioxide (CO2) in space and time over heterogeneous land surfaces, two intensive field campaigns were carried out at the Barrax agricultural test site in Spain during 12-21 July 2004 (SPARC 2004) and 8-14 July 2005 (SEN2FLEX 2005) involving multiple field, satellit...
Conference Paper
Radiation is the driving force for all processes and interactions between earth surface and atmosphere. The amount of measured radiation reflected by vegetation depends on its structure, the viewing angle and the solar angle. This angular dependence is usually expressed in the Bi-directional Reflectance Distribution Function (BRDF). This BRDF is no...
Article
Models that describe the exchange of CO2 and H2O between the surface and atmosphere use bulk-parametrization of the within-canopy aerodynamic resistance and leaf area density (eq. LAI). This bulk parametrization is based on the Monin-Obukhov Similarity (MOS) theory. The MOS theory however breaks down for sparse canopies and it cannot couple profile...

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Projects

Projects (6)
Archived project
Sir, Madam We would hereby like to invite you to participate in the ‘Remote Sensing in Ecology’ symposium, which will be held on the 4th October 2018 at Leiden University. Please visit http://remotesensinginecology.nl/ for the agenda and registering. In this Remote Sensing in Ecology Symposium, leading scientific experts as well as institutional policy makers from some of the Netherlands most foremost university’s and institutes will present and discuss the recent developments in ecology that are achieved through the application of remote sensing. The symposium aims to • Present current state-of-art developments in remote sensing ecology • Promote collaboration and the exchange of ideas between different disciplines • Provide input to the national agenda on remote sensing applications in ecology. For this purpose the day consists of a series of inspiring talks led by renowned scientists and public officials. These are each followed up with an interactive question and discussion session. The following intermittent breaks, as well as eventual lunch break, will offer opportunity to continue conversation in a more casual environment. At the end of the program, there will be an opportunity for a final, interactive roundtable discussion on paving the future course of remote sensing in ecology. We hope to celebrate the end of a fruitful day with drinks afterwards. With a diversity of speakers and participants - each with their own unique background but all sharing mutual acknowledgement of the power of remote sensing - the day is promised to be one full of new insights and inspiration for all that attend. Hoping to see you then! With kind regards On behalf of the organizing committee Dr. Ir. Joris Timmermans Research associate at the Institute of Environmental Sciences (CML) j.timmermans@cml.leidenuniv.nl
Archived project