Type TIF
The Total Annual Precipitation raster dataset represents the sum of the twelve monthly precipitation layers derived from the CHELSA Climatologies v2.1 dataset (1981–2010). The dataset was processed and harmonized to ensure consistency in projection, spatial resolution, and grid alignment for seamless integration with the map layers of the CEC North American Environmental Atlas.
This layer, prepared by the Commission for Environmental Cooperation (CEC), shows total annual precipitation across North America for the 1981–2010 climatological reference period, in millimeters. The dataset represents the sum of the twelve monthly precipitation layers derived from the CHELSA Climatologies v2.1 dataset.
The North American climate data were derived from the CHELSA Climatologies v2.1 dataset, which is produced using a mechanistic, terrain-informed climate downscaling framework that generates high-resolution gridded temperature, precipitation, and related climate variables.
Additional technical details on the downscaling methods and derived climate predictors are provided in: Karger, D. N., Conrad, O., Böhner, J., Kawohl, T., Kreft, H., Soria-Auza, R. W., Zimmermann, N. E., Linder, H. P., & Kessler, M. (2017). Climatologies at high resolution for the Earth's land surface areas. Scientific Data, 4, 170122. https://doi.org/10.1038/sdata.2017.122
Geographic Coverage
The coverage spans North America, including Canada, Mexico, and the United States.
Data Sources and Licensing
Commission for Environmental Cooperation (CEC). Swiss Federal Institute for Forest, Snow and Landscape Research (WSL). Karger et al. (2017). The data is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0), allowing redistribution and adaptation with appropriate attribution.
Update frequency: Irregular
Limitations of use: None. Acknowledgment of the Commission for Environmental Cooperation and the (CHELSA) initiative at the Swiss Federal Research Institute WSL (Land Change Science group) would be appreciated in products derived from these data.
Vintage: 1981-2010
Applications (Intended Use)
* Analyzing spatial patterns of long-term average annual precipitation across North America.
* Supporting climate, hydrological, and water-resource research and planning.
* Informing agricultural and ecological modeling and land-use planning.
* Integration with other thematic layers in the North American Environmental Atlas for continental-scale analysis.
* Supporting environmental cooperation and policy-making among Canada, Mexico, and the United States.
Commission for Environmental Cooperation (CEC). 2026. “North American Environmental Atlas - Total Annual Precipitation, 1981-2010”. Swiss Federal Institute for Forest, Snow and Landscape Research (WSL). Ed. 2.0, Raster digital data [1-km].
None. Acknowledgment of the Commission for Environmental Cooperation and the (CHELSA) initiative at the Swiss Federal Research Institute WSL (Land Change Science group) would be appreciated in products derived from these data.
| West | -180 | East | -50 |
| North | 85 | South | 14 |
| Maximum (zoomed in) | 1:5,000 |
| Minimum (zoomed out) | 1:150,000,000 |
Contact Person: Dirk Nikolaus Karger
The Commission for Environmental Cooperation (CEC) is an international organization created by Canada, Mexico, and the United States of America under the North American Agreement on Environmental Cooperation (NAAEC), which came into force at the same time as the North American Free Trade Agreement (NAFTA). The CEC was established to address regional environmental concerns, help prevent potential trade and environmental conflicts, and to promote the effective enforcement of environmental law. As of 2020, the CEC operates in accordance with the Environmental Cooperation Agreement, which entered into force at the same time as the CUSMA/T-MEC/USMCA trade agreement. Additional information on the CHELSA Climatologies v2.1 dataset used to produce the CEC North American climatological map layers is available in: Karger, D. N., Conrad, O., Böhner, J., Kawohl, T., Kreft, H., Soria-Auza, R. W., Zimmermann, N. E., Linder, H. P., & Kessler, M. (2017). Climatologies at high resolution for the Earth’s land surface areas. Scientific Data, 4, 170122. https://doi.org/10.1038/sdata.2017.122 This data set is available in several formats, including TIF, Map package, and a PDF Map, along with other files appropriate to particular formats, such as .lyrx and .qlr files.
Commission for Environmental Cooperation (CEC). 2026. “North American Environmental Atlas - Total Annual Precipitation, 1981-2010”. Swiss Federal Institute for Forest, Snow and Landscape Research (WSL). Ed. 2.0, Raster digital data [1-km].
North America
None. Acknowledgment of the Commission for Environmental Cooperation and the (CHELSA) initiative at the Swiss Federal Research Institute WSL (Land Change Science group) would be appreciated in products derived from these data.
This material is licensed under CC BY 4.0, allowing non-exclusive rights to distribute, remix, adapt, and build upon the material in any medium or format, including for commercial purposes, so long as attribution is given to the creator.
A spatial completeness assessment was conducted after extracting the North American extent and reprojecting the CHELSA Climatologies v2.1 monthly precipitation (pr) raster layers to the standard Lambert Azimuthal Equal Area projection used by the Atlas. The dataset was inspected for NoData values, edge artifacts, and potential cell misalignment introduced during reprojection. Cell counts and value ranges were verified to ensure that no unintended data loss or omissions occurred. The final raster exhibits continuous coverage across the defined terrestrial extent, with NoData values restricted to areas outside the land mask.
The raster maintains consistent cell size, alignment, and spatial continuity following clipping and reprojection. No unintended gaps, overlaps, or resampling artifacts were introduced during processing.
The North American climate data were derived from the CHELSA Climatologies v2.1 dataset, which is produced using a mechanistic, terrain-informed climate downscaling framework that generates high-resolution gridded temperature, precipitation, and related climate variables. The original global dataset was developed by the Climatologies at High Resolution for the Earth’s Land Surface Areas (CHELSA) initiative at the Swiss Federal Research Institute WSL (Land Change Science group). The global CHELSA bioclimatic dataset was created by downscaling global reanalysis and climate model data to a spatial resolution of approximately 30 arcseconds (~1 km). The approach applies physically based, terrain-aware algorithms that explicitly account for orographic effects, atmospheric lapse rates, and wind-driven processes. Monthly temperature and precipitation layers are first generated from bias-corrected reanalysis inputs and then aggregated into bioclimatic variables that summarize annual means, seasonality, and climatic extremes for ecological and environmental applications. For the North American Environmental Atlas, the continental subset was extracted from the global dataset and reprojected to the standard Lambert Azimuthal Equal Area projection used by the Atlas. Additional technical details on the downscaling methods and derived climate predictors are provided in: Karger, D. N., Conrad, O., Böhner, J., Kawohl, T., Kreft, H., Soria-Auza, R. W., Zimmermann, N. E., Linder, H. P., & Kessler, M. (2017). Climatologies at high resolution for the Earth’s land surface areas. Scientific Data, 4, 170122. https://doi.org/10.1038/sdata.2017.122
Each CHELSA Climatologies v2.1 monthly precipitation (pr) raster layer for the 1981–2010 reference period was clipped to the North American region using the CEC North American Political Boundaries vector dataset. The clipping process was performed using the Extract by Mask tool in ArcGIS Pro. During this process, the raster was reprojected to the Lambert Azimuthal Equal Area projection, the standard coordinate reference system used by the CEC North American Environmental Atlas. The data were resampled from the original ~30 arc-second (~1 km) spatial resolution to a 1 km cell size and aligned with Version 1.0 of the CEC North American Total Annual Precipitation raster layer to ensure consistency in grid structure, spatial resolution, and cell alignment.
In each monthly raster layer, pixel values were rescaled using the scale factor specified in the CHELSA Climatologies technical documentation. The transformation was performed by multiplying the raster values by 0.1 (scale factor), resulting in final values expressed in millimeters (mm). This conversion was implemented using the Raster Calculator tool in ArcGIS Pro.
A new raster file was created to sum the twelve monthly precipitation layers and generate the Total Annual Precipitation value for each pixel. The calculation was performed using the Mosaic to New Raster tool in ArcGIS Pro, with Sum selected as the mosaic operator.
The resulting annual raster layer was exported in GeoTIFF format using a 16-bit unsigned pixel type. Converting the data from the previous 32-bit floating-point format to a 16-bit unsigned integer format rounded the values to whole numbers, ensuring that precipitation values are stored as integers in millimeters.
A final adjustment was applied to remove implausible extreme high values. As a rule, the minimum precipitation value among those occurring in at least five pixels within the raster layer was identified and defined as the upper threshold. All values exceeding this threshold were subsequently reclassified to the same upper threshold value. The threshold determined through this procedure was 6,112 mm.
CHELSA-climatologies is a global, kilometer-scale climate dataset generated with the CHELSA downscaling model. It consists of long term climatological means.
~30 arcsecond resolution
Contact Person: Dirk Nikolaus Karger
The Political Boundaries dataset of the North American Environmental Atlas represents political entities in North America as polygons.
The Precipitation dataset is a raster file representing total annual precipitation values. The source data cover the period 1950–2000; however, individual weather stations used to generate the source dataset may not have complete records for all years within this time span.
1000 meters resolution
Sum of monthly precipitation values in millimeters
Commission for Environmental Cooperation
Internal feature number.
Esri
Sequential unique whole numbers that are automatically generated.
Total Annual Precipitation values in millimeters.
Commission for Environmental Cooperation
Number of pixels by value of total annual precipitation.
Commission for Environmental Cooperation
None. Acknowledgment of the Commission for Environmental Cooperation and the (CHELSA) initiative at the Swiss Federal Research Institute WSL (Land Change Science group) would be appreciated in products derived from these data.
This material is licensed under CC BY 4.0, allowing non-exclusive rights to distribute, remix, adapt, and build upon the material in any medium or format, including for commercial purposes, so long as attribution is given to the creator.