Characterization of Western US Hydrologic Processes Linked to Atmospheric Rivers in Two Sets of Seasonal Global Retrospective Forecasts

Characterization of Western US Hydrologic Processes Linked to Atmospheric Rivers in Two Sets of Seasonal Global Retrospective Forecasts | 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 Characterization of Western US Hydrologic Processes Linked to Atmospheric Rivers in Two Sets of Seasonal Global Retrospective Forecasts Breanna Zavadoff, Ben Kirtman This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4953246/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 18 Jun, 2025 Read the published version in Climate Dynamics → Version 1 posted 5 You are reading this latest preprint version Abstract Atmospheric rivers (ARs) are narrow filaments of high water vapor content that have considerable influence on the western United States (US) hydroclimate. ARs provide significant amounts of annual precipitation and snowfall and affect mountain snowpack via snow water equivalent (SWE) accumulation and ablation. With ARs projected to become increasingly key players in western US hydrology, water resource managers will rely progressively more on AR seasonal forecasts to infer flood/drought risks and make informed decisions about water supply allocation. However, precisely how well current seasonal climate prediction systems capture ARs and their associated hydrologic variables is still an open question. Here, we evaluate the ability of high (HR) and low resolution (LR) CCSM4 and CESM1 seasonal global retrospective forecasts to characterize precipitation, snowfall, and SWE changes associated with western US landfalling ARs. HR forecasts more accurately represent hydrologic variables than LR forecasts, however, CCSM4-HR underestimates AR-related snowfall, causing enhanced AR-related SWE ablation. Further investigation reveals amplified onshore positive temperature advection by south-southwesterly biased AR winds causes ARs in CCSM4-HR to be embedded within thicker air columns, yielding increased freezing level heights, reduced snowfall, and increased SWE loss. Results suggest both HR and LR global seasonal forecast models are capable of characterizing AR distribution and frequency, but HR models are needed for proper precipitation, snowfall, and SWE representation. Furthermore, models used to assess AR-related hydrological processes must contain accurate wind fields, as even minor biases can have a profound effect on a model's ability to simulate AR precipitation and SWE accumulation/ablation rates. Atmospheric Rivers Global Climate Model CCSM4 CESM1 Snow Water Equivalent Seasonal Forecast Full Text Supplementary Files ZavadoffKirtmanSI.docx Cite Share Download PDF Status: Published Journal Publication published 18 Jun, 2025 Read the published version in Climate Dynamics → Version 1 posted Editorial decision: Accept 29 May, 2025 Reviewers agreed at journal 18 Mar, 2025 Reviewers invited by journal 18 Mar, 2025 Editor assigned by journal 18 Mar, 2025 First submitted to journal 14 Mar, 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-4953246","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":430467223,"identity":"5c349a6a-c81f-4c26-947f-ce6081139870","order_by":0,"name":"Breanna Zavadoff","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABBUlEQVRIiWNgGAWjYBACAzDJxsDP3t4AYh1gYGAGUgkMDIwNBLRI9pw5AFJKkpYbCVAtUIBTizn/4WcSP8psJHgkHx/8XPnjDoNuO/PTDQ8YbGQ3HMCuxbLhmJlkz7k0CR7ptGTJMwnPGMwOs5kBbUwzxqXF4GCDsQFv2+E6e+kcA8mGhMNALQwgLYcTcWo5zP7Z8G/bYaDDzn/+CdHC/g2o5T9uLcd4DB/zgrRI8LBBbeEB2XIApxbLHp7CxzIgv/CkmVk2pAHVH+Ypu5FgkGw8E4cWc/7jGw6+AYUY++HHNxtsDsuZnT++7eaPCjvZPhxaMAAP1MFEKh8Fo2AUjIJRgBUAACkzYvU1riWOAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0003-4367-3662","institution":"University of Miami","correspondingAuthor":true,"prefix":"","firstName":"Breanna","middleName":"","lastName":"Zavadoff","suffix":""},{"id":430467224,"identity":"51669b25-2741-4170-846f-0056c7d0b4be","order_by":1,"name":"Ben Kirtman","email":"","orcid":"","institution":"University of Miami Rosenstiel School of Marine Atmospheric and Earth Science","correspondingAuthor":false,"prefix":"","firstName":"Ben","middleName":"","lastName":"Kirtman","suffix":""}],"badges":[],"createdAt":"2024-08-21 17:27:56","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4953246/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4953246/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s00382-025-07740-6","type":"published","date":"2025-06-18T15:57:00+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":85231275,"identity":"4557b5e9-4189-4fa0-aa8d-ee3eef027e36","added_by":"auto","created_at":"2025-06-23 16:04:00","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4739954,"visible":true,"origin":"","legend":"","description":"","filename":"CLDYD2400712R1reviewer.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4953246/v1_covered_e733877e-0f83-4b95-ba06-e685989bc61b.pdf"},{"id":79402526,"identity":"14f66994-e0f0-49e8-a2db-5fad14353b11","added_by":"auto","created_at":"2025-03-28 03:05:57","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":2811181,"visible":true,"origin":"","legend":"","description":"","filename":"ZavadoffKirtmanSI.docx","url":"https://assets-eu.researchsquare.com/files/rs-4953246/v1/d78c828602ed4c22ed8d6c70.docx"}],"financialInterests":"","formattedTitle":"Characterization of Western US Hydrologic Processes Linked to Atmospheric Rivers in Two Sets of Seasonal Global Retrospective Forecasts","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"climate-dynamics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"cldy","sideBox":"Learn more about [Climate Dynamics](https://www.springer.com/journal/382)","snPcode":"382","submissionUrl":"https://submission.nature.com/new-submission/382/3","title":"Climate Dynamics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Atmospheric Rivers, Global Climate Model, CCSM4, CESM1, Snow Water Equivalent, Seasonal Forecast","lastPublishedDoi":"10.21203/rs.3.rs-4953246/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4953246/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eAtmospheric rivers (ARs) are narrow filaments of high water vapor content that have considerable influence on the western United States (US) hydroclimate. 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