In the atmospheric boundary layer, phenomena exist with challenging properties such as spatial heterogeneity, particularly during stable weak wind situations. Studying spatially heterogeneous features requires spatially distributed measurements on fine spatial and temporal scales. Fiber-Optic Distributed Sensing (FODS) can provide spatially distributed measurements, simultaneously offering a spatial resolution on the order of decimeters and a temporal resolution on the order of seconds. While FODS has already been deployed to study various variables, FODS wind direction sensing has only been demonstrated in idealized wind tunnel experiments. We present the first distributed observations of FODS wind directions from field data. The wind direction sensing is accomplished by using pairs of actively heated fiber optic cables with cone-shaped microstructures attached to them. Here we present three different methods of calculating wind directions from the FODS measurements, two based on using combined wind speed and direction information and one deriving wind direction independently from FODS wind speed. For each approach, the effective temporal and spatial resolution is quantified using spectral coherence. With each method of calculating wind directions, temporal resolutions on the order of tens of seconds can be achieved. The accuracy of FODS wind directions was evaluated against a sonic anemometer, showing deviations of less than 15\uffc2\uffb0 most of the time. The applicability of FODS for wind direction measurements in different environmental conditions is tested by analysing the dependence of FODS wind direction accuracy and observable scales on environmental factors. Finally, we demonstrate the potential of this technique by presenting a period that displays spatial and temporal structures in the wind direction.
", "keywords": ["Spectral analysis/models/distribution", "550", "Atmosphere", "0207 environmental engineering", "Distributed Temperature Sensing", "02 engineering and technology", "Field experiments", "Wind effects", "530", "01 natural sciences", "Turbulence", "13. Climate action", "Atmosphere-land interaction", "0105 earth and related environmental sciences"], "contacts": [{"organization": "Freundorfer, Anita, Lapo, Karl, Schneider, Johann, Thomas, Christoph K.,", "roles": ["creator"]}]}, "links": [{"href": "https://journals.ametsoc.org/downloadpdf/journals/atot/aop/JTECH-D-21-0019.1/JTECH-D-21-0019.1.xml"}, {"href": "https://doi.org/10.1175/jtech-d-21-0019.1"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Journal%20of%20Atmospheric%20and%20Oceanic%20Technology", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1175/jtech-d-21-0019.1", "name": "item", "description": "10.1175/jtech-d-21-0019.1", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1175/jtech-d-21-0019.1"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2021-09-13T00:00:00Z"}}, {"id": "10.1016/j.optmat.2025.117551", "type": "Feature", "geometry": null, "properties": {"updated": "2026-09-22T16:16:17Z", "type": "Journal Article", "created": "2025-09-24", "title": "Er3+/Yb3+ co-activated YNbO4 nanocrystalline phosphors: Up-conversion luminescence under the 980\u00a0nm excitation and integrated lifetime thermometry", "description": "This paper presents the structure, morphology, optical and photoluminescent properties of erbium (1 at %) and ytterbium (2 at %) doped yttrium niobium oxide (YNbOIn the morning, the nocturnal stable boundary layer, SBL, transitions into its daytime convective counterpart substantially impacting the distribution of temperature, humidity, and pollutants. Applying distributed temperature sensing (DTS) below a tethered balloon (2\uffe2\uff80\uff93200\uffc2\uffa0m) and along a tower (0\uffe2\uff80\uff9311\uffc2\uffa0m), for the first time we observed three morning transitions (MTs) in a mountain boundary layer with high temporal (<10\uffc2\uffa0s) and spatial (<0.25\uffc2\uffa0m) resolutions. We show that MTs are best derived from a change in static stability from synchronous DTS observations. Our findings confirm that the MT occurs at the SBL top and bottom simultaneously, and identify horizontal heat advection as a main driver aiding solar surface heating in this midrange mountain valley. We conclude that heterogenous land use and mountainous topography cause complex interactions between valley\uffe2\uff80\uff90scale and local airflows leading to thermal signatures characterized by strong, small\uffe2\uff80\uff90scale variability. Our study highlights DTS as a crucial tool for investigating complex thermodynamic processes.
", "keywords": ["550", "13. Climate action", "0207 environmental engineering", "500", "boundary layer", " cold-air pool", " distributed temperature sensing", " morning transition", " mountainous terrain", " weak wind", "02 engineering and technology", "15. Life on land", "01 natural sciences", "0105 earth and related environmental sciences"]}, "links": [{"href": "https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2020GL092238"}, {"href": "https://doi.org/10.1029/2020gl092238"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Geophysical%20Research%20Letters", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1029/2020gl092238", "name": "item", "description": "10.1029/2020gl092238", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1029/2020gl092238"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2021-05-10T00:00:00Z"}}, {"id": "10.1117/12.2624501", "type": "Feature", "geometry": null, "properties": {"updated": "2026-09-22T16:18:07Z", "type": "Journal Article", "created": "2022-05-19", "title": "Pre-strain effects on CYTOP fibre Bragg grating temperature sensors", "description": "Cyclic transparent optical polymer (CYTOP) based fibre Bragg grating (FBG) sensors are of high interest recently due to their lower optical loss compared with the sensors fabricated in other polymeric materials, such as poly(methyl methacrylate). Numerous scientific reports have shown that polymer based FBGs are usually preferred over their silica counterparts due to their enhanced sensitivity to stress and pressure, and their affinity to humidity. Temperature monitoring with polymer FBGs is also extensively demonstrated, but with inconsistent results and non-linear responses, since most of the polymer optical fibres have a negative thermo-optic coefficient and positive thermal expansion coefficient that work to cancel out each other to some extent, resulting in mixed temperature sensitivities. In this work, an optical fibre with a CYTOP core and a Xylex cladding is used to investigate fibre pre-strain effects on the temperature sensitivity of FBG sensors. The sensors were placed in an environmental chamber with controlled temperature and relative humidity, and their response to temperature was evaluated under various fibre pre-strain values. Without any applied fibre strain, the thermal expansion coefficient slightly prevails over the thermo-optic effect, as a result the Bragg wavelength shifts in longer wavelengths. Under sufficient fibre strain, the thermal expansion coefficient is eliminated, and the temperature sensitivity is greatly enhanced, shifting the Bragg wavelength to shorter wavelengths. This paper demonstrates the possibility to have an array of Bragg grating sensors, some being temperature insensitive and some highly temperature sensitive along the same fibre.", "keywords": ["polymer optical fibre", "optical polymer", "fibre Bragg grating sensors", "0103 physical sciences", "Bragg gratings", "Engineering and Technology", "Electrical Engineering - Electronic Engineering - Information Engineering", "01 natural sciences", "temperature sensing"], "contacts": [{"organization": "Pospori, Andreas, Ioannou, Andreas, Kalli, Kyriacos,", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.1117/12.2624501"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Micro-Structured%20and%20Specialty%20Optical%20Fibres%20VII", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1117/12.2624501", "name": "item", "description": "10.1117/12.2624501", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1117/12.2624501"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2022-05-19T00:00:00Z"}}], "links": [{"rel": "self", "type": "application/geo+json", "title": "This document as GeoJSON", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=temperature+sensing&f=json", "hreflang": "en-US"}, {"rel": "alternate", "type": "text/html", "title": "This document as HTML", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=temperature+sensing&f=html", "hreflang": "en-US"}, {"rel": "collection", "type": "application/json", "title": "Collection URL", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main", "hreflang": "en-US"}, {"type": "application/geo+json", "rel": "first", "title": "items (first)", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=temperature+sensing&", "hreflang": "en-US"}, {"rel": "last", "type": "application/geo+json", "title": "items (last)", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=temperature+sensing&offset=4", "hreflang": "en-US"}], "numberMatched": 4, "numberReturned": 4, "distributedFeatures": [], "timeStamp": "2026-09-22T22:51:19.178980Z"}