Influence of almond's canopy-induced shadows on actual evapotranspiration estimation by the TSEB model using sUAS multispectral and thermal imagery

Influence of almond's canopy-induced shadows on actual evapotranspiration estimation by the TSEB model using sUAS multispectral and thermal imagery | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Influence of almond's canopy-induced shadows on actual evapotranspiration estimation by the TSEB model using sUAS multispectral and thermal imagery Moises Rodrigo Duran-Gomez, Alfonso Torres-Rua, Lawrence Hipps, and 14 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7306171/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 28 Feb, 2026 Read the published version in Irrigation Science → Version 1 posted 9 You are reading this latest preprint version Abstract Over the past decade, the estimation of water requirements in almond orchards has improved through the application of remote sensing models like the Two-Source Energy Balance (TSEB) model using various remote sensing platforms. However, there is limited understanding of how canopy-induced shadows influence surface reflectance and thermal infrared (TIR) signals particularly from small Unmanned Aircraft System (sUAS) imagery in energy balance models, and the effect on Latent Heat Flux (LE) estimations. This study evaluates LE estimates from the Priestley-Taylor TSEB model (TSEB-PT) with and without shadow filtering using sUAS-based multispectral and TIR imagery. It establishes a baseline for the impact of shadow exclusion on model inputs and performance. Datasets were collected in 2021 and 2022, as part of the USDA led Tree-crop Remote sensing of Evapotranspiration eXperiment (T-REX) in almonds orchards across California. LAI-2200C Plant Canopy Analyzer measurements facilitated the calibration of an empirical Leaf Area Index (LAI) model based on canopy fractional cover (FC) and NDVI (R 2 = 0.68). Shadow filtering caused land surface temperature (LST) differences up to 5°C in young to semi-mature orchards (FC 0.40–0.80). In contrast, mature orchards (FC > 0.80) showed minimal influence due to the limited shadow occurrence on the imagery. Shadows appeared to reduce surface albedo (α alb ), mainly in interrow areas, thereby affecting the absorption of radiation and the partitioning of energy balance components. Their presence in sUAS imagery also hindered canopy delineation, impacting the accuracy of key TSEB inputs derived from canopy physical characteristics. Thus, the influence of shadow on TSEB estimated LE was more significant in lower fractional tree covers. While LE estimated by TSEB-PT without shadow filtering showed better agreement with observations, combining instantaneous TIR imagery with solar-noon shortwave data is recommended for accurate ETa assessment using sUAS datasets. These baseline results can be improved with more advanced formulations, supporting continued research on E/T partitioning and water stress in almond orchards under varying environmental conditions, particularly when there is advection of hot dry air. TSEB almonds sUAS canopy-induced shadows LAI Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 28 Feb, 2026 Read the published version in Irrigation Science → Version 1 posted Editorial decision: Revision requested 09 Nov, 2025 Reviews received at journal 09 Nov, 2025 Reviewers agreed at journal 10 Oct, 2025 Reviews received at journal 16 Sep, 2025 Reviewers agreed at journal 10 Sep, 2025 Reviewers invited by journal 08 Aug, 2025 Editor assigned by journal 06 Aug, 2025 Submission checks completed at journal 06 Aug, 2025 First submitted to journal 06 Aug, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7306171","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":497498027,"identity":"f870c910-9afe-46d4-b582-661df4eb026b","order_by":0,"name":"Moises Rodrigo Duran-Gomez","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA3UlEQVRIiWNgGAWjYHACAyR2BYSSIEHLGZK1MLYRoUW3gXmbdEXNHQZ59+7Ehz/nHbY3OMB88DYPHi1mB9jKJM8ce8ZgeObsZgPJbYcTNxxgS7bGr4XHTLKB7XD9xhm52yQMtx1OMACKSBPW8u8wg+GM3O0/EueAHMb/jbCWxrbDDPISudsYDjYcZtxwgIcNv5bDbMWWjX2HGQx4zm6WbDiWnjjzMJux5Rx8Wo43b7zZ8A1oS3vvxo8/aqzt+Y43P7zxBo8WBmYobXAAXYQgkG8gVuUoGAWjYBSMOAAArwRNNvSF54UAAAAASUVORK5CYII=","orcid":"","institution":"Utah State University","correspondingAuthor":true,"prefix":"","firstName":"Moises","middleName":"Rodrigo","lastName":"Duran-Gomez","suffix":""},{"id":497498030,"identity":"285cc7ca-591d-4356-a73d-f7a43e28ebf0","order_by":1,"name":"Alfonso Torres-Rua","email":"","orcid":"","institution":"Utah State University","correspondingAuthor":false,"prefix":"","firstName":"Alfonso","middleName":"","lastName":"Torres-Rua","suffix":""},{"id":497498032,"identity":"2fe835b8-c7fc-4da8-ac1f-9aca32bf6112","order_by":2,"name":"Lawrence Hipps","email":"","orcid":"","institution":"Utah State University","correspondingAuthor":false,"prefix":"","firstName":"Lawrence","middleName":"","lastName":"Hipps","suffix":""},{"id":497498034,"identity":"fa46f110-58e5-456b-a3c2-26c9d0e6599c","order_by":3,"name":"William Kustas","email":"","orcid":"","institution":"Agricultural Research Service","correspondingAuthor":false,"prefix":"","firstName":"William","middleName":"","lastName":"Kustas","suffix":""},{"id":497498037,"identity":"ddca4f58-4b74-4a83-9e3e-01f49d6d907b","order_by":4,"name":"Nicolas E. 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However, there is limited understanding of how canopy-induced shadows influence surface reflectance and thermal infrared (TIR) signals particularly from small Unmanned Aircraft System (sUAS) imagery in energy balance models, and the effect on Latent Heat Flux (LE) estimations. This study evaluates LE estimates from the Priestley-Taylor TSEB model (TSEB-PT) with and without shadow filtering using sUAS-based multispectral and TIR imagery. It establishes a baseline for the impact of shadow exclusion on model inputs and performance. Datasets were collected in 2021 and 2022, as part of the USDA led Tree-crop Remote sensing of Evapotranspiration eXperiment (T-REX) in almonds orchards across California. LAI-2200C Plant Canopy Analyzer measurements facilitated the calibration of an empirical Leaf Area Index (LAI) model based on canopy fractional cover (FC) and NDVI (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.68). Shadow filtering caused land surface temperature (LST) differences up to 5\u0026deg;C in young to semi-mature orchards (FC 0.40\u0026ndash;0.80). In contrast, mature orchards (FC\u0026thinsp;\u0026gt;\u0026thinsp;0.80) showed minimal influence due to the limited shadow occurrence on the imagery. Shadows appeared to reduce surface albedo (α\u003csub\u003ealb\u003c/sub\u003e), mainly in interrow areas, thereby affecting the absorption of radiation and the partitioning of energy balance components. Their presence in sUAS imagery also hindered canopy delineation, impacting the accuracy of key TSEB inputs derived from canopy physical characteristics. Thus, the influence of shadow on TSEB estimated LE was more significant in lower fractional tree covers. While LE estimated by TSEB-PT without shadow filtering showed better agreement with observations, combining instantaneous TIR imagery with solar-noon shortwave data is recommended for accurate ETa assessment using sUAS datasets. These baseline results can be improved with more advanced formulations, supporting continued research on E/T partitioning and water stress in almond orchards under varying environmental conditions, particularly when there is advection of hot dry air.\u003c/p\u003e","manuscriptTitle":"Influence of almond's canopy-induced shadows on actual evapotranspiration estimation by the TSEB model using sUAS multispectral and thermal imagery","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-13 05:46:47","doi":"10.21203/rs.3.rs-7306171/v1","editorialEvents":[{"type":"communityComments","content":2},{"type":"decision","content":"Revision requested","date":"2025-11-09T21:34:56+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-09T13:48:08+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"262320942689859987361214994166820978155","date":"2025-10-10T11:50:51+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-16T08:55:48+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"150639724083697640986465750499355625882","date":"2025-09-10T12:33:39+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-08-08T06:04:29+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-08-06T06:44:55+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-08-06T06:42:49+00:00","index":"","fulltext":""},{"type":"submitted","content":"Irrigation Science","date":"2025-08-06T06:03:34+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"irrigation-science","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"irsc","sideBox":"Learn more about [Irrigation Science](http://link.springer.com/journal/271)","snPcode":"271","submissionUrl":"https://submission.nature.com/new-submission/271/3","title":"Irrigation Science","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"f6ea7833-4989-4148-bcc3-03c3475092eb","owner":[],"postedDate":"August 13th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-03-02T16:02:26+00:00","versionOfRecord":{"articleIdentity":"rs-7306171","link":"https://doi.org/10.1007/s00271-026-01092-7","journal":{"identity":"irrigation-science","isVorOnly":false,"title":"Irrigation Science"},"publishedOn":"2026-02-28 15:59:01","publishedOnDateReadable":"February 28th, 2026"},"versionCreatedAt":"2025-08-13 05:46:47","video":"","vorDoi":"10.1007/s00271-026-01092-7","vorDoiUrl":"https://doi.org/10.1007/s00271-026-01092-7","workflowStages":[]},"version":"v1","identity":"rs-7306171","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7306171","identity":"rs-7306171","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}