@article{HeinemannSiegmannThonfeldetal.2020,
  author    = {Heinemann, Sascha and Siegmann, Bastian and Thonfeld, Frank and Muro, Javier and Jedmowski, Christoph and Kemna, Andreas and Kraska, Thorsten and Muller, Onno and Schultz, Johannes and Udelhoven, Thomas and Wilke, Norman and Rascher, Uwe},
  title     = {Land surface temperature retrieval for agricultural areas using a novel UAV platform equipped with a thermal infrared and multispectral sensor},
  series = {Remote Sensing},
  volume    = {12},
  journal   = {Remote Sensing},
  number    = {7},
  issn      = {2072-4292},
  doi       = {10.3390/rs12071075},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-203557},
  year      = {2020},
  abstract  = {Land surface temperature (LST) is a fundamental parameter within the system of the Earth's surface and atmosphere, which can be used to describe the inherent physical processes of energy and water exchange. The need for LST has been increasingly recognised in agriculture, as it affects the growth phases of crops and crop yields. However, challenges in overcoming the large discrepancies between the retrieved LST and ground truth data still exist. Precise LST measurement depends mainly on accurately deriving the surface emissivity, which is very dynamic due to changing states of land cover and plant development. In this study, we present an LST retrieval algorithm for the combined use of multispectral optical and thermal UAV images, which has been optimised for operational applications in agriculture to map the heterogeneous and diverse agricultural crop systems of a research campus in Germany (April 2018). We constrain the emissivity using certain NDVI thresholds to distinguish different land surface types. The algorithm includes atmospheric corrections and environmental thermal emissions to minimise the uncertainties. In the analysis, we emphasise that the omission of crucial meteorological parameters and inaccurately determined emissivities can lead to a considerably underestimated LST; however, if the emissivity is underestimated, the LST can be overestimated. The retrieved LST is validated by reference temperatures from nearby ponds and weather stations. The validation of the thermal measurements indicates a mean absolute error of about 0.5 K. The novelty of the dual sensor system is that it simultaneously captures highly spatially resolved optical and thermal images, in order to construct the precise LST ortho-mosaics required to monitor plant diseases and drought stress and validate airborne and satellite data.},
  language  = {en}
}
@article{TimmermansvanderTolTimmermansetal.2015,
  author    = {Timmermans, Wim J. and van der Tol, Christiaan and Timmermans, Joris and Ucer, Murat and Chen, Xuelong and Alonso, Luis and Moreno, Jose and Carrara, Arnaud and Lopez, Ramon and Fernando de la Cruz, Tercero and Corcoles, Horacio L. and de Miguel, Eduardo and Sanchez, Jose A. G. and Perez, Irene and Belen, Perez and Munoz, Juan-Carlos J. and Skokovic, Drazen and Sobrino, Jose and Soria, Guillem and MacArthur, Alasdair and Vescovo, Loris and Reusen, Ils and Andreu, Ana and Burkart, Andreas and Cilia, Chiara and Contreras, Sergio and Corbari, Chiara and Calleja, Javier F. and Guzinski, Radoslaw and Hellmann, Christine and Herrmann, Ittai and Kerr, Gregoire and Lazar, Adina-Laura and Leutner, Benjamin and Mendiguren, Gorka and Nasilowska, Sylwia and Nieto, Hector and Pachego-Labrador, Javier and Pulanekar, Survana and Raj, Rahul and Schikling, Anke and Siegmann, Bastian and von Bueren, Stefanie and Su, Zhongbo (Bob)},
  title     = {An Overview of the Regional Experiments for Land-atmosphere Exchanges 2012 (REFLEX 2012) Campaign},
  series = {Acta Geophysica},
  volume    = {63},
  journal   = {Acta Geophysica},
  number    = {6},
  doi       = {10.2478/s11600-014-0254-1},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-136491},
  pages     = {1465-1484},
  year      = {2015},
  abstract  = {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 Tiesas farm in an agricultural area in the south of Spain. During the period of ten days, measurements were made to capture the main processes controlling the local and regional land-atmosphere exchanges. Apart from multi-temporal, multi-directional and multi-spatial space-borne and airborne observations, measurements of the local meteorology, energy fluxes, soil temperature profiles, soil moisture profiles, surface temperature, canopy structure as well as leaf-level measurements were carried out. Additional thermo-dynamical monitoring took place at selected sites. After presenting the different types of measurements, some examples are given to illustrate the potential of the observations made.},
  language  = {en}
}