Precipitation Climate Projections from LOCA2 Downscaling - SSP2-4.5

The Climate Resilience Information System (CRIS) provides data and tools for developers of climate services. This image service provides access to downscaled climate projections for 19 threshold values of precipitation for the contiguous United States for 3 SSP climate scenarios from 1950-2100. These services are intended to support analysis of climate exposure for custom geographies and time horizons. Nineteen downscaled global circulation models (GCMs) were chosen to be included in a weighted ensemble, optimized for the contiguous United States. More details on the models included in the ensemble and the weighting methodologies can be found in Understanding CRIS Data. The LOCA2 precipitation data were reprocessed by UC San Diego into version 2 to more accurately estimate extreme precipitation values. Time Ranges Pixel values for each variable were calculated for each year from 2005 to 2100. Additionally, a modeled history runs from 1950 - 2005. The modeled history and future projections have been merged into a single time series. These annual increments support deriving a temporal average, such as a decadal or thirty-year period centered on a specific year. These time steps should not be used to make predictions about conditions for a specific year, especially at a pixel-level. Climate Scenarios Climate models use estimates of future greenhouse gas concentrations and human activities to predict overall change. These different scenarios are called the Shared Socioeconomic Pathways (SSPs). Three different SSPs are presented here: 2-4.5, 3-7.0, and 5-8.5. The 2-, 3-, or 5- represents the socioeconomic growth model. The 4.5, 7.0, or 8.5 number indicates the amount of radiative forcing (watts per meter square) associated with the greenhouse gas concentration scenario in the year 2100 (higher forcing = greater warming). It is unclear which scenario will be the most likely, but SSP2-4.5 aligns closest with the international targets of the COP-26 agreement for no greater than 2oC average global warming. SSP3-7.0 may be the most likely scenario based on current emission trends. SSP5-8.5 acts as a cautionary tale, depicting a worst-case scenario if reductions in greenhouse gasses are not undertaken. Variable Definitions See the variable list and definitions here. All units of measure are Imperial. Additional Services Three versions of the gridded climate projections are available from CRIS: LOCA2 Ensemble: a statistically downscaled 6-km resolution model. LOCA2 has SSP2-4.5, 3-7.0 and 5-8.5 STAR-ESDM Ensemble: a statistically downscaled 4-km resolution model. STAR-ESDM has SSP2-4.5 and 5-8.5 NCA5 Blended Ensemble: a merging of LOCA2 and STAR-ESDM ensembles at a 6-km resolution, as was done for the 5th National Climate Assessment (2023). NCA Blended Ensemble has SSP2-4.5 and 5-8.5 Using the Imagery Layer The ArcGIS Tiled Imagery Service has a multidimensional structure -- a data cube with variable, SSP, and time dimensions. Methods for accessing the different dimensions will depend on the software/client being used. For more details, please see the CRIS Developer’s Hub along with this instructional StoryMap. To run analysis, first use the multidimensional tools Aggregate or Subset in ArcGIS Pro to copy the necessary data locally. Data Export Data export is enabled on the services if using an ArcGIS client. NetCDF or Zarr files are also available from the NOAA Open Data Distribution system on Amazon Web Services.气候韧性信息系统（Climate Resilience Information System，CRIS）为气候服务开发者提供数据与工具。本影像服务可获取美国本土连续区域19个降水阈值的降尺度气候预估数据，涵盖3种共享社会经济路径（Shared Socioeconomic Pathways，SSPs）气候情景，时间跨度为1950年至2100年。此类服务旨在支持针对自定义地理区域与时间跨度的气候暴露分析。 研究团队选取19个降尺度全球环流模式（Global Circulation Models，GCMs）构建针对美国本土优化的加权集合模型。有关集合模式选取与加权方法的更多细节，可参阅《Understanding CRIS Data》。加州大学圣迭戈分校已将LOCA2降水数据重新处理至版本2，以更精准地估算极端降水数值。 时间范围 各变量的像素值以2005年至2100年为逐年计算周期。此外，1950年至2005年设有模拟历史序列。模拟历史数据与未来预估数据已合并为单一时间序列。此类年度增量可用于推导时间平均值，例如以特定年份为中心的十年期或三十年周期平均值。需注意，此类时间步长不可用于针对特定年份（尤其是像素级）的气候状况预测。 气候情景 气候模式基于未来温室气体浓度与人类活动的预估来预测整体气候变化，这类不同的情景即称为共享社会经济路径（SSPs）。本次提供三种SSP情景：2-4.5、3-7.0与5-8.5。其中的2、3、5代表社会经济增长模型，4.5、7.0、8.5则代表2100年时该温室气体浓度情景对应的辐射强迫数值（单位：瓦每平方米），辐射强迫越高，全球变暖幅度越大。目前无法确定哪种情景最有可能发生，但SSP2-4.5最接近《联合国气候变化框架公约》第26次缔约方大会（COP26）设定的全球平均升温不超过2摄氏度的国际目标。基于当前排放趋势，SSP3-7.0或为最贴合实际的情景。SSP5-8.5则作为警示场景，描绘了若不采取温室气体减排措施的最坏情形。 变量定义 详见此处的变量列表与定义。所有度量单位均为英制单位。 附加服务 CRIS提供三种版本的网格化气候预估数据： 1. LOCA2集合模型：经统计降尺度的6千米分辨率模型，支持SSP2-4.5、3-7.0与5-8.5三种情景； 2. STAR-ESDM集合模型：经统计降尺度的4千米分辨率模型，支持SSP2-4.5与5-8.5两种情景； 3. NCA5混合集合模型：以第五次全国气候评估（2023）的整合方式，将LOCA2与STAR-ESDM集合模型合并为6千米分辨率数据集，支持SSP2-4.5与5-8.5两种情景。 使用影像图层 本ArcGIS切片影像服务采用多维结构——即包含变量、SSP与时间维度的数据立方体。访问不同维度的方法取决于所使用的软件/客户端。更多详情可参阅CRIS开发者中心（CRIS Developer’s Hub）与本教程StoryMap。如需开展分析，请首先使用ArcGIS Pro中的多维工具「聚合（Aggregate）」或「子集（Subset）」将所需数据本地复制。 数据导出 使用ArcGIS客户端时，服务支持数据导出。网络通用数据格式（NetCDF）或Zarr格式（Zarr）文件也可通过亚马逊云服务（Amazon Web Services）上的美国国家海洋和大气管理局（National Oceanic and Atmospheric Administration，NOAA）开放数据分发系统获取。