Historical and future precipitation trends (Map Service)

The National Forest Climate Change Maps project was developed by the Rocky Mountain Research Station (RMRS) and the Office of Sustainability and Climate to meet the needs of national forest managers for information on projected climate changes at a scale relevant to decision making processes, including forest plans. The maps use state-of-the-art science and are available for every national forest in the contiguous United States with relevant data coverage. Currently, the map sets include variables related to precipitation, air temperature, snow (including snow residence time and April 1 snow water equivalent), and stream flow.\Historical (1975-2005) and future (2071-2090) precipitation and temperature data for the contiguous United States are ensemble mean values across 20 global climate models from the CMIP5 experiment (https://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-11-00094.1), downscaled to a 4 km grid. For more information on the downscaling method and to access the data, please see Abatzoglou and Brown, 2012 (https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/joc.2312) and the Northwest Knowledge Network (https://climate.northwestknowledge.net/MACA/). We used the MACAv2- Metdata monthly dataset; monthly precipitation values (mm) were summed over the season of interest (annual, winter, or summer). Absolute and percent change were then calculated between the historical and future time periods.Historical (1975-2005) and future (2071-2090) precipitation and temperature data for the state of Alaska were developed by the Scenarios Network for Alaska and Arctic Planning (SNAP) (https://snap.uaf.edu). These datasets have several important differences from the MACAv2-Metdata (https://climate.northwestknowledge.net/MACA/) products, used in the contiguous U.S. They were developed using different global circulation models and different downscaling methods, and were downscaled to a different scale (771 m instead of 4 km). While these cover the same time periods and use broadly similar approaches, caution should be used when directly comparing values between Alaska and the contiguous United States.Raster data are also available for download from RMRS site (https://www.fs.usda.gov/rm/boise/AWAE/projects/NFS-regional-climate-change-maps/categories/us-raster-layers.html), along with pdf maps and detailed metadata (https://www.fs.usda.gov/rm/boise/AWAE/projects/NFS-regional-climate-change-maps/downloads/NationalForestClimateChangeMapsMetadata.pdf).This record was taken from the USDA Enterprise Data Inventory that feeds into the https://data.gov catalog. Data for this record includes the following resources: ISO-19139 metadata ArcGIS Hub Dataset ArcGIS GeoService For complete information, please visit https://data.gov.

国家森林气候变化地图项目由落基山脉研究站（RMRS）和可持续性与气候变化办公室共同开发，旨在满足国家森林管理者对决策过程中相关气候变化的预测信息的需求，包括森林规划。该地图集采用了最先进的科学方法，并覆盖了美国所有连续国家森林的相关数据范围。目前，地图集包括与降水、空气温度、积雪（包括积雪停留时间和4月1日的积雪水当量）以及溪流流量相关的变量。对于美国连续地区的历史（1975-2005）和未来（2071-2090）的降水和温度数据，是通过CMIP5实验（https://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-11-00094.1）的20个全球气候模型的集合平均值，并将其降尺度到4公里网格得到的。有关降尺度方法的信息和数据访问，请参阅Abatzoglou和Brown，2012年发表的论文（https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/joc.2312）以及西北知识网络（https://climate.northwestknowledge.net/MACA/）。我们使用了MACAv2-气象数据月度数据集；将感兴趣的季节（年度、冬季或夏季）的月降水值（毫米）进行了汇总。然后计算了历史时期和未来时期之间的绝对变化和百分比变化。阿拉斯加州的历史（1975-2005）和未来（2071-2090）的降水和温度数据由阿拉斯加和北极规划情景网络（SNAP）开发（https://snap.uaf.edu）。与在美国使用的MACAv2-气象数据（https://climate.northwestknowledge.net/MACA/）产品相比，这些数据集存在几个重要差异。它们采用了不同的全球环流模型和不同的降尺度方法，并且降尺度到不同的比例尺（771米而不是4公里）。尽管它们覆盖了相同的时间段并采用了广泛相似的方法，但在直接比较阿拉斯加和美国的数值时仍需谨慎。栅格数据也可供从RMRS网站下载（https://www.fs.usda.gov/rm/boise/AWAE/projects/NFS-regional-climate-change-maps/categories/us-raster-layers.html），包括PDF地图和详细的元数据（https://www.fs.usda.gov/rm/boise/AWAE/projects/NFS-regional-climate-change-maps/downloads/NationalForestClimateChangeMapsMetadata.pdf）。本记录来自为https://data.gov目录提供数据的美国农业部企业数据目录。本记录的数据包括以下资源：ISO-19139元数据、ArcGIS Hub数据集、ArcGIS地理服务。有关完整信息，请访问https://data.gov。