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Terrestrial Condition Assessment (TCA) Alaska Drought (Map Service)

Published by U.S. Forest Service | Department of Agriculture | Metadata Last Checked: October 02, 2025 | Last Modified: 2025-09-23
<div style='text-align:Left;'><div><div><p style='font-weight:bold;'><a href='https://data.fs.usda.gov/geodata/rastergateway/TCA/Alaska/04_Climate/TCA_AK_Drought_Impacts.zip' style='text-decoration:underline;'><span style='text-decoration:underline;'><span>Direct Download (Raster Data Gateway)</span></span></a></p><p><span style='font-weight:bold;'><span>Objective:</span></span><span><span> Characterize recent drought severity in Alaska. </span></span></p><p><span style='font-weight:bold;'><span>Data:</span></span><span><span> </span></span><span><span>The indicator represents drought severity as a weighted sum of the number of droughts in each category over the most recent 3-year period using data from the U.S. Drought Monitor. A 30km grid was overlaid on Alaska and the number of droughts in each category we calculated over the time period. The weighted sum of droughts (</span></span><span style='font-style:italic;'><span>DwSum</span></span><span><span>) was calculated using the equation:</span></span></p><p style='font-style:italic;'><span> </span><span><span>(D0 [abnormally dry] * 1) + (D1 [moderate drought] *2) + (D2 [severe drought] * 3) + (D3 [extreme drought] * 4) + (D4 [exceptional drought] * 5)</span></span></p><p><span><span>There is a lag between the assessment year and the most recent drought data, for example, the 2024 TCA Assessment used drought data from 2021-2023. Data were summarized at the Subsection scale of the USFS National Hierarchy of Ecological Units and applied to the corresponding landscape (LTA).</span></span></p><p><span style='font-weight:bold;'><span>Data Format:</span></span><span><span> Raster data are continuous</span></span></p><p><span style='font-weight:bold;'><span>Units: </span></span><span><span>Number of droughts (weighted sum)</span></span></p><p><span style='font-weight:bold;'><span>Spatial Resolution:</span></span><span><span> 30000m (30km)</span></span></p><p><span style='font-weight:bold;'><span>Source data:</span></span><span><span> </span></span><a href='https://droughtmonitor.unl.edu/CurrentMap.aspx' style='text-decoration:underline;'><span style='text-decoration:underline;'><span>US Drought Monitor</span></span></a></p><p style='font-weight:bold;'><span><span>Additional Resources:</span></span></p><p><span><span>Details on </span></span><a href='https://usfs.box.com/s/79vx1b42xg8u6ivjombxjes36nzfhgml' style='text-decoration:underline;'><span style='text-decoration:underline;'><span>Method Changes and Source Data Versions</span></span></a></p><p><span><span>Overview of the Terrestrial Condition Assessment: </span></span><a href='https://terrestrial-condition-assessment-usfs.hub.arcgis.com/' style='text-decoration:underline;'><span style='text-decoration:underline;'><span>TCA Hubsite</span></span></a><span><span> or </span></span><a href='https://www.youtube.com/watch?v=Kf0P3cAq1rs&amp;list=PLwRbAc4x5n94rLca1CXXuugtRDt_G666M&amp;index=19' style='text-decoration:underline;'><span style='text-decoration:underline;'><span>Landfire Office Hour Presentation</span></span></a></p><p><span><span>Explore the results of the most recent assessment: </span></span><a href='https://apps.fs.usda.gov/gtac-toolsms/tca/' style='text-decoration:underline;'><span style='text-decoration:underline;'><span>TCA Interactive Data Viewer</span></span></a></p><p><span><span>Learn more about the TCA KPI: </span></span><a href='https://cxodashboard.dl.usda.gov/t/NRE/views/EcologicalConditionOutcomes_17531128629260/EcologicalOutcomes' style='text-decoration:underline;'><span style='text-decoration:underline;'><span>TCA Dashboard</span></span></a></p><p><span><span>*if you have trouble viewing the Dashboard, please submit a </span></span><a href='https://usdagcc.sharepoint.com/sites/fs-wo-cdoc/SitePages/Dashboards.aspx' style='text-decoration:underline;'><span style='text-decoration:underline;'><span>Tableau Viewer Access Request</span></span></a></p></div></div></div>

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