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Because we strive to make our products as widely available and useful as possible, all SNAP products have a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License applied to them. If you’d like to download our products, please read the license link above and click the "Agree" button.

If you are part of a for-profit organization, and are interested in commercialization opportunities and/or collaborative R&D activities please contact us.

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Data

SNAP data includes downscaled historically observed, modeled historical, as well as modeled projected data out to 2100 across several top ranked GCM's and scenarios (SRES or RCPs). Data is produced on a project specific basis, but when time and feasibility allows, we try and extend analyses to the greatest spatial and temporal extent possible to allow the greatest applicability to other projects as well. In the broadest sense, our data extends from the mid–1800s to 2100, across multiple spatial extents including: Alaska, Alaska-Western Canada, Polar, and worldwide.

The list of variables is always expanding, so please explore below to see what we currently have available.

All of our downloadable data is provided in GeoTIFF format. We've standardized on geotiff thus far because it is a stable and compressed format that can be easily read by many open source and commercial GIS and data manipulation programs including ArcGIS, QGIS, R (raster package recommended), GDAL, GRASS, and many others.

While it’s hard to have a completely static file naming scheme, we make every attempt to keep some consistency across our various datasets. This naming scheme outlined below is our general guide, although it does vary depending upon each dataset. Please refer to the full metadata for details on specific datasets.

[variable][metric][units][format][assessmentReport][group][model][scenario][timeFrame].[fileFormat]

Creative Commons License All information produced by the Scenarios Network for Alaska and Arctic Planning is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Attribution text provided on our FAQ page. If you are interested in commercialization opportunities and/or collaborative R&D activities please contact us.

Modeled Historical and Projected Data

Historical Estimates and Projections of Sea Ice Concentration – 0.4 degrees CMIP5/AR5

This set of files includes modeled historical estimates and future projections of monthly sea ice concentration (in percent cover, 0–100) for each month of every year from January 1860–December 2100* at 0.4 x 0.4 degrees spatial resolution from 5 top ranking CMIP5 global climate models (GCMs). Each file represents a single month in a given year.

Baseline Reference ClimateNA
Spatial Resolution0.4 degrees
Temporal ResolutionMonthly
Spatial ExtentPolar

Metadata:

Historical Estimates and Projections of Sea Ice Concentration AR5

Products:

Historical Daily Mean Quantile Mapped Temperatures – 2.5 degrees CMIP5/AR5

This data includes quantile–mapped historical model runs of AR5 daily mean temperature (tas, degrees C) for each day of every year from 1958–2005 at 2.5 x 2.5 degree spatial resolution across 3 AR5 models utilizing the “historical” GCM model run. They are 365 multi–band geotiff files, one file per year, each band representing one day of the year, with no leap years.

Baseline Reference Climate1958–2001 ERA–40
Spatial Resolution2.5 degrees
Temporal ResolutionMonthly
Spatial ExtentWorldwide

Metadata:

Historical Daily Mean Quantile Mapped Temperatures – 2.5 degrees AR5

Products:

tas_mean_C_AR5_3-Models_historical_365_1958-2005.zip (840 MB)

Projected Daily Mean Quantile Mapped Temperatures – 2.5 degrees CMIP5/AR5

This data includes quantile–mapped historical model runs of AR5 daily mean temperature (tas, degrees C) for each day of every year from 2006–2100 at 2.5 x 2.5 degree spatial resolution across 3 AR5 models and 2 RCPs. They are 365 multi–band geotiff files, one file per year, each band representing one day of the year, with no leap years.

Baseline Reference Climate1958–2001 ERA–40
Spatial Resolution2.5 degrees
Temporal ResolutionMonthly
Spatial ExtentWorldwide

Metadata:

Projected Daily Mean Quantile Mapped Temperatures – 2.5 degrees AR5

Products:

Historical Daily Quantile Mapped Near Surface Wind Velocity – 2.5 degrees CMIP5/AR5

This data includes quantile–mapped historical model runs of AR5 daily near surface wind velocity (uas: West/East component of wind, vas: North/South component, m/s) for each day of every year from 1958–2100 at 2.5 x 2.5 degree spatial resolution across 3 AR5 models utilizing the “historical” GCM model run. They are 365 multi–band geotiff files, one file per year, each band representing one day of the year, with no leap years.

Baseline Reference Climate1958–2001 ERA–40
Spatial Resolution2.5 degrees
Temporal ResolutionMonthly
Spatial ExtentWorldwide

Metadata:

Historical Daily Quantile Mapped Near Surface Wind Velocity – 2.5 degrees AR5

Products:

Projected Daily Quantile Mapped Near Surface Wind Velocity – 2.5 degrees CMIP5/AR5

This data includes quantile–mapped projections of AR5 daily near surface wind velocity (uas: West/East component of wind, vas: North/South component, m/s) for each day of every year from 1958–2100 at 2.5 x 2.5 degree spatial resolution across 3 AR5 models and 2 RCPs. They are 365 multi–band geotiff files, one file per year, each band representing one day of the year, with no leap years.

Baseline Reference Climate1958–2001 ERA–40
Spatial Resolution2.5 degrees
Temporal ResolutionMonthly
Spatial ExtentWorldwide

Metadata:

Projected Daily Quantile Mapped Near Surface Wind Velocity – 2.5 degrees AR5

Products:


Projected Monthly Temperature and Precipitation - 2km CMIP5/AR5

Projected (2006–2100: RCP 4.5, 6.0. 8.5 scenarios) monthly average temperature and total precipitation from 5 AR5 GCMs that perform best across Alaska and the Arctic, downscaled to 2km via the delta method. A 5–Model Average is also included.

Baseline Reference Climate1961–1990 PRISM
Spatial Resolution2km
Temporal ResolutionMonthly
Spatial ExtentAlaska and Western Canada (YT, BC, AB, SK, MB)

Temperature

Metadata: Projected Monthly Average Temperature 2km AR5

  Scenario
Model RCP 4.5 RCP 6.0 RCP 8.5
5–model Average 2006–2100 (2.5 GB) 2006–2100 (2.5 GB) 2006–2100 (2.5 GB)
CCSM4 2006–2100 (2.5 GB) 2006–2100 (2.5 GB) 2006–2100 (2.5 GB)
GFDL-CM3 2006–2100 (2.5 GB) 2006–2100 (2.5 GB) 2006–2100 (2.5 GB)
GISS-E2-R 2006–2100 (2.5 GB) 2006–2100 (2.5 GB) 2006–2100 (2.5 GB)
IPSL-CM5A-LR 2006–2100 (2.5 GB) 2006–2100 (2.5 GB) 2006–2100 (2.5 GB)
MRI-CGCM3 2006–2100 (2.5 GB) 2006–2100 (2.5 GB) 2006–2100 (2.5 GB)

Precipitation

Metadata: Projected Monthly Total Precipitation 2km AR5

  Scenario
Model RCP 4.5 RCP 6.0 RCP 8.5
5–model Average 2006–2100 (2.2 GB) 2006–2100 (2.2 GB) 2006–2100 (2.2 GB)
CCSM4 2006–2100 (2.2 GB) 2006–2100 (2.2 GB) 2006–2100 (2.2 GB)
GFDL-CM3 2006–2100 (2.2 GB) 2006–2100 (2.2 GB) 2006–2100 (2.3 GB)
GISS-E2-R 2006–2100 (2.2 GB) 2006–2100 (2.2 GB) 2006–2100 (2.2 GB)
IPSL-CM5A-LR 2006–2100 (2.2 GB) 2006–2100 (2.2 GB) 2006–2100 (2.2 GB)
MRI-CGCM3 2006–2100 (2.2 GB) 2006–2100 (2.2 GB) 2006–2100 (2.3 GB)

Projected Derived Temperature Products - 2km CMIP5/AR5

Projected (2010–2100: RCP 4.5, 6.0. 8.5 scenarios) derived temperature products from 5 AR5 GCMs that perform best across Alaska and the Arctic, downscaled to 2km via the delta method. A 5–Model Average is also included.

Baseline Reference Climate1961–1990 PRISM
Spatial Resolution2km
Temporal ResolutionMonthly
Spatial ExtentAlaska and Western Canada (YT, BC, AB, SK, MB)

Temperature

Metadata: Projected Derived Temperature Products - 2km CMIP5/AR5 Decadal Summaries by Month, Year

  Scenario
Model RCP 4.5 RCP 6.0 RCP 8.5
5–model Average 2010–2100 (328 MB) 2010–2100 (327 MB) 2010–2100 (328 MB)
CCSM4 2010–2100 (329 MB) 2010–2100 (328 MB) 2010–2100 (330 MB)
GFDL-CM3 2010–2100 (326 MB) 2010–2100 (327 MB) 2010–2100 (327 MB)
GISS-E2-R 2010–2100 (330 MB) 2010–2100 (329 MB) 2010–2100 (330 MB)
IPSL-CM5A-LR 2010–2100 (328 MB) 2010–2100 (327 MB) 2010–2100 (328 MB)
MRI-CGCM3 2010–2100 (329 MB) 2010–2100 (328 MB) 2010–2100 (329 MB)

Season Day of Freeze, Thaw, Length of Growing Season

Metadata: Projected Derived Temperature Products - 2km CMIP5/AR5 Decadal Summaries by Season Day of Freeze, Thaw, Length of Growing Season

  Scenario
Model RCP 4.5 RCP 6.0 RCP 8.5
5–model Average 2010–2100 (43 MB) 2010–2100 (43 MB) 2010–2100 (43 MB)
CCSM4 2010–2100 (43 MB) 2010–2100 (42 MB) 2010–2100 (42 MB)
GFDL-CM3 2010–2100 (41 MB) 2010–2100 (41 MB) 2010–2100 (41 MB)
GISS-E2-R 2010–2100 (43 MB) 2010–2100 (43 MB) 2010–2100 (43 MB)
IPSL-CM5A-LR 2010–2100 (43 MB) 2010–2100 (42 MB) 2010–2100 (42 MB)
MRI-CGCM3 2010–2100 (42 MB) 2010–2100 (42 MB) 2010–2100 (42 MB)

Projected Derived Precipitation Products - 2km CMIP5/AR5

Projected (2010–2100: historical run and RCP 4.5, 6.0. 8.5 scenarios) derived precipitation products from 5 AR5 GCMs that perform best across Alaska and the Arctic, downscaled to 2km via the delta method. A 5–Model Average is also included.

Baseline Reference Climate1961–1990 PRISM
Spatial Resolution2km
Temporal ResolutionMonthly
Spatial ExtentAlaska and Western Canada (YT, BC, AB, SK, MB)

Precipitation

Metadata: Projected Derived Precipitation Products - 2km CMIP5/AR5 Decadal Summaries by Month, Year, or Season

  Scenario
Model RCP 4.5 RCP 6.0 RCP 8.5
5–model Average 2010–2100 (314 MB) 2010–2100 (314 MB) 2010–2100 (316 MB)
CCSM4 2010–2100 (315 MB) 2010–2100 (315 MB) 2010–2100 (318 MB)
GFDL-CM3 2010–2100 (321 MB) 2010–2100 (322 MB) 2010–2100 (325 MB)
GISS-E2-R 2010–2100 (316 MB) 2010–2100 (315 MB) 2010–2100 (317 MB)
IPSL-CM5A-LR 2010–2100 (314 MB) 2010–2100 (314 MB) 2010–2100 (317 MB)
MRI-CGCM3 2010–2100 (317 MB) 2010–2100 (318 MB) 2010–2100 (319 MB)

Projected Monthly Temperature and Precipitation – 771m CMIP5/AR5

Projected (2006–2100: RCP 4.5, 6.0. 8.5 scenarios) monthly average temperature and total precipitation from 5 AR5 GCMs that perform best across Alaska and the Arctic, downscaled to 771m via the delta method. A 5–Model Average is also included.

Baseline Reference Climate1971–2000 PRISM
Spatial Resolution771m
Temporal ResolutionMonthly
Spatial ExtentAlaska

Temperature

Metadata: Projected Monthly Average Temperature 771m AR5

  Scenario
Model RCP 4.5 RCP 6.0 RCP 8.5
5–model Average 2006–2100 (4.7 GB) 2006–2100 (4.7 GB) 2006–2100 (4.8 GB)
CCSM4 2006–2100 (4.8 GB) 2006–2100 (4.8 GB) 2006–2100 (4.8 GB)
GFDL-CM3 2006–2100 (4.8 GB) 2006–2100 (4.8 GB) 2006–2100 (4.8 GB)
GISS-E2-R 2006–2100 (4.8 GB) 2006–2100 (4.8 GB) 2006–2100 (4.8 GB)
IPSL-CM5A-LR 2006–2100 (4.8 GB) 2006–2100 (4.8 GB) 2006–2100 (4.8 GB)
MRI-CGCM3 2006–2100 (4.8 GB) 2006–2100 (4.8 GB) 2006–2100 (4.8 GB)

Precipitation

Metadata: Projected Monthly Total Precipitation 771m AR5

  Scenario
Model RCP 4.5 RCP 6.0 RCP 8.5
5–model Average 2006–2100 (4.1 GB) 2006–2100 (4.1 GB) 2006–2100 (4.2 GB)
CCSM4 2006–2100 (4.1 GB) 2006–2100 (4.1 GB) 2006–2100 (4.1 GB)
GFDL-CM3 2006–2100 (4.2 GB) 2006–2100 (4.2 GB) 2006–2100 (4.3 GB)
GISS-E2-R 2006–2100 (4.1 GB) 2006–2100 (4.1 GB) 2006–2100 (4.2 GB)
IPSL-CM5A-LR 2006–2100 (4.1 GB) 2006–2100 (4.1 GB) 2006–2100 (4.2 GB)
MRI-CGCM3 2006–2100 (4.1 GB) 2006–2100 (4.2 GB) 2006–2100 (4.2 GB)

Projected Derived Temperature Products – 771m CMIP5/AR5

Projected (2010–2100: historical run and RCP 4.5, 6.0. 8.5 scenarios) derived temperature products from 5 AR5 GCMs that perform best across Alaska and the Arctic, downscaled to 771m via the delta method. A 5–Model Average is also included.

Baseline Reference Climate1971–2000 PRISM
Spatial Resolution771m
Temporal ResolutionMonthly
Spatial ExtentAlaska

Temperature

Metadata: Projected Derived Temperature Products – 771m CMIP5/AR5 Decadal Summaries by Month, Year

  Scenario
Model RCP 4.5 RCP 6.0 RCP 8.5
5–model Average 2010–2100 (633 MB) 2010–2100 (633 MB) 2010–2100 (633 MB)
CCSM4 2010–2100 (635 MB) 2010–2100 (634 MB) 2010–2100 (634 MB)
GFDL-CM3 2010–2100 (638 MB) 2010–2100 (637 MB) 2010–2100 (638 MB)
GISS-E2-R 2010–2100 (634 MB) 2010–2100 (634 MB) 2010–2100 (634 MB)
IPSL-CM5A-LR 2010–2100 (635 MB) 2010–2100 (636 MB) 2010–2100 (636 MB)
MRI-CGCM3 2010–2100 (634 MB) 2010–2100 (634 MB) 2010–2100 (634 MB)

Season Day of Freeze, Thaw, Length of Growing Season

Metadata: Projected Derived Temperature Products – 771m CMIP5/AR5 Decadal Summaries by Season Day of Freeze, Thaw, Length of Growing Season

  Scenario
Model RCP 4.5 RCP 6.0 RCP 8.5
5–model Average 2010–2100 (84 MB) 2010–2100 (83 MB) 2010–2100 (79 MB)
CCSM4 2010–2100 (82 MB) 2010–2100 (82 MB) 2010–2100 (79 MB)
GFDL-CM3 2010–2100 (81 MB) 2010–2100 (80 MB) 2010–2100 (79 MB)
GISS-E2-R 2010–2100 (83 MB) 2010–2100 (82 MB) 2010–2100 (80 MB)
IPSL-CM5A-LR 2010–2100 (81 MB) 2010–2100 (80 MB) 2010–2100 (79 MB)
MRI-CGCM3 2010–2100 (81 MB) 2010–2100 (81 MB) 2010–2100 (79 MB)

Projected Derived Precipitation Products – 771m CMIP5/AR5

Projected (2010–2100: historical run and RCP 4.5, 6.0. 8.5 scenarios) derived precipitation products from 5 AR5 GCMs that perform best across Alaska and the Arctic, downscaled to 771m via the delta method. A 5–Model Average is also included.

Baseline Reference Climate1971–2000 PRISM
Spatial Resolution771m
Temporal ResolutionMonthly
Spatial ExtentAlaska

Precipitation

Metadata: Projected Derived Precipitation Products – 771m CMIP5/AR5 Decadal Summaries by Month, Year, or Season

  Scenario
Model RCP 4.5 RCP 6.0 RCP 8.5
5–model Average 2010–2100 (613 MB) 2010–2100 (613 MB) 2010–2100 (621 MB)
CCSM4 2010–2100 (609 MB) 2010–2100 (609 MB) 2010–2100 (617 MB)
GFDL-CM3 2010–2100 (625 MB) 2010–2100 (628 MB) 2010–2100 (636 MB)
GISS-E2-R 2010–2100 (611 MB) 2010–2100 (610 MB) 2010–2100 (618 MB)
IPSL-CM5A-LR 2010–2100 (616 MB) 2010–2100 (612 MB) 2010–2100 (622 MB)
MRI-CGCM3 2010–2100 (613 MB) 2010–2100 (615 MB) 2010–2100 (619 MB)

Projected Monthly Temperature and Precipitation - 771m CMIP3/AR4

Projected (2001-2100: B1, A1B, and A2 scenarios) monthly average temperature and total precipitation from 5 AR4 GCMs that perform best across Alaska and the Arctic, downscaled to 771m via the delta method. A 5-Model Average is also included.

Baseline Reference Climate1971–2000 PRISM
Spatial Resolution771m
Temporal ResolutionMonthly
Spatial ExtentAlaska

Temperature

Metadata: Projected Monthly Average Temperature 771m AR4

  Scenario
Model B1 A1B A2
5–model Average 2001–2049 (2.5 GB)
2050–2100 (2.6 GB)
2001–2049 (2.5 GB)
2050–2100 (2.6 GB)
2001–2049 (2.5 GB)
2050–2099 (2.5 GB)
cccma_cgcm31 2001–2049 (2.5 GB)
2050–2100 (2.6 GB)
2001–2049 (2.5 GB)
2050–2100 (2.6 GB)
2001–2049 (2.5 GB)
2050–2100 (2.6 GB)
gfdl_cm2_1 2001–2049 (2.5 GB)
2050–2100 (2.6 GB)
2001–2049 (2.5 GB)
2050–2100 (2.6 GB)
2001–2049 (2.5 GB)
2050–2100 (2.6 GB)
miroc3_2_medres 2001–2049 (2.5 GB)
2050–2100 (2.6 GB)
2001–2049 (2.5 GB)
2050–2100 (2.6 GB)
2001–2049 (2.5 GB)
2050–2100 (2.6 GB)
mpi_echam5 2001–2049 (2.5 GB)
2050–2100 (2.6 GB)
2001–2049 (2.5 GB)
2050–2100 (2.6 GB)
2001–2049 (2.5 GB)
2050–2100 (2.6 GB)
ukmo_hadcm3 2001–2049 (2.5 GB)
2050–2100 (2.6 GB)
2001–2049 (2.5 GB)
2050–2100 (2.6 GB)
2001–2049 (2.5 GB)
2050–2099 (2.6 GB)

Precipitation

Metadata: Projected Monthly Total Precipitation 771m AR4

  Scenario
Model B1 A1B A2
5–model Average 2001–2049 (2.1 GB)
2050–2100 (2.2 GB)
2001–2049 (2.1 GB)
2050–2100 (2.3 GB)
2001–2049 (2.1 GB)
2050–2099 (2.2 GB)
cccma_cgcm31 2001–2049 (2.1 GB)
2050–2100 (2.2 GB)
2001–2049 (2.1 GB)
2050–2100 (2.3 GB)
2001–2049 (2.1 GB)
2050–2100 (2.3 GB)
gfdl_cm2_1 2001–2049 (2.1 GB)
2050–2100 (2.3 GB)
2001–2049 (2.1 GB)
2050–2100 (2.3 GB)
2001–2049 (2.1 GB)
2050–2100 (2.3 GB)
miroc3_2_medres 2001–2049 (2.1 GB)
2050–2100 (2.3 GB)
2001–2049 (2.1 GB)
2050–2100 (2.3 GB)
2001–2049 (2.1 GB)
2050–2100 (2.3 GB)
mpi_echam5 2001–2049 (2.1 GB)
2050–2100 (2.2 GB)
2001–2049 (2.1 GB)
2050–2100 (2.3 GB)
2001–2049 (2.1 GB)
2050–2100 (2.3 GB)
ukmo_hadcm3 2001–2049 (2.1 GB)
2050–2100 (2.2 GB)
2001–2049 (2.1 GB)
2050–2100 (2.3 GB)
2001–2049 (2.1 GB)
2050–2099 (2.3 GB)

Projected Derived Temperature Products - 771m CMIP3/AR4

Projected (2010–2100: B1, A1B, and A2 scenarios) derived temperature products from 5 AR4 GCMs that perform best across Alaska and the Arctic, downscaled to 771m via the delta method. A 5-Model Average is also included.

Baseline Reference Climate1971–2000 PRISM
Spatial Resolution771m
Temporal ResolutionDecadal
Spatial ExtentAlaska

Decadal Summaries by Month, Year, or Season

Metadata by product
All products by model and scenario
  Scenario
Model B1 A1B A2
5–model Average 2001–2100 (638 MB) 2001–2100 (637 MB) 2001–2100 (637 MB)
cccma_cgcm31 2001–2100 (639 MB) 2001–2100 (639 MB) 2001–2100 (638 MB)
gfdl_cm2_1 2001–2100 (637 MB) 2001–2100 (637 MB) 2001–2100 (637 MB)
miroc3_2_medres 2001–2100 (641 MB) 2001–2100 (640 MB) 2001–2100 (640 MB)
mpi_echam5 2001–2100 (639 MB) 2001–2100 (640 MB) 2001–2100 (640 MB)
ukmo_hadcm3 2001–2100 (642 MB) 2001–2100 (642 MB) 2001–2100 (642 MB)

Day of Freeze, Thaw, Length of Growing Season

Estimated Julian days of freeze and thaw (dof, dot) are calculated by assuming a linear change in temperature between consecutive months. Mean monthly temperatures are used to represent daily temperature on the 15th day of each month. When consecutive monthly midpoints have opposite sign temperatures, the day of transition (freeze or thaw) is the day between them on which temperature crosses zero degrees C. The length of growing season (logs) refers to the number of days between the days of freeze and thaw. More detailed explanations are discussed in the metadata.

Date of Freeze, Thaw

Metadata: Projected Day of Freeze or Thaw 771 AR4

  Scenario
Model B1 A1B A2
5–model Average 2001–2100 (51 MB) 2001–2100 (51 MB) 2001–2100 (52 MB)
cccma_cgcm31 2001–2100 (52 MB) 2001–2100 (52 MB) 2001–2100 (52 MB)
gfdl_cm2_1 2001–2100 (52 MB) 2001–2100 (51 MB) 2001–2100 (52 MB)
miroc3_2_medres 2001–2100 (51 MB) 2001–2100 (51 MB) 2001–2100 (51 MB)
mpi_echam5 2001–2100 (51 MB) 2001–2100 (51 MB) 2001–2100 (52 MB)
ukmo_hadcm3 2001–2100 (52 MB) 2001–2100 (51 MB) 2001–2100 (52 MB)
Length of Growing Season

Metadata: Projected Length of Growing Season 771 AR4

  Scenario
Model B1 A1B A2
5–model Average 2001–2100 (31 MB) 2001–2100 (31 MB) 2001–2100 (31 MB)
cccma_cgcm31 2001–2100 (31 MB) 2001–2100 (31 MB) 2001–2100 (32 MB)
gfdl_cm2_1 2001–2100 (31 MB) 2001–2100 (31 MB) 2001–2100 (31 MB)
miroc3_2_medres 2001–2100 (31 MB) 2001–2100 (30 MB) 2001–2100 (31 MB)
mpi_echam5 2001–2100 (31 MB) 2001–2100 (30 MB) 2001–2100 (31 MB)
ukmo_hadcm3 2001–2100 (32 MB) 2001–2100 (31 MB) 2001–2100 (32 MB)

Projected Derived Precipitation Products - 771m CMIP3/AR4

Projected (2010-2100: B1, A1B, and A2 scenarios) derived precipitation products from 5 AR4 GCMs that perform best across Alaska and the Arctic, downscaled to 771m via the delta method. A 5-Model Average is also included.

Baseline Reference Climate1971–2000 PRISM
Spatial Resolution771m
Temporal ResolutionDecadal
Spatial ExtentAlaska

Decadal Summaries by month, year, or season

Metadata by product
All products by model and scenario
  Scenario
Model B1 A1B A2
5–model Average 2001–2100 (612 MB) 2001–2100 (619 MB) 2001–2100 (619 MB)
cccma_cgcm31 2001–2100 (612 MB) 2001–2100 (618 MB) 2001–2100 (621 MB)
gfdl_cm2_1 2001–2100 (618 MB) 2001–2100 (626 MB) 2001–2100 (623 MB)
miroc3_2_medres 2001–2100 (613 MB) 2001–2100 (618 MB) 2001–2100 (618 MB)
mpi_echam5 2001–2100 (609 MB) 2001–2100 (617 MB) 2001–2100 (614 MB)
ukmo_hadcm3 2001–2100 (610 MB) 2001–2100 (621 MB) 2001–2100 (620 MB)

Projected Monthly Temperature and Precipitation - 2 km CMIP3/AR4

Projected (2001–2100: B1, A1B, and A2 scenarios) monthly temperature and precipitation from 5 AR4 GCMs that perform best across Alaska and the Arctic, downscaled to 2 km via the delta method. A 5-Model Average is also included.

Baseline Reference Climate1961–1990 PRISM
Spatial Resolution2 km
Temporal ResolutionMonthly
Spatial ExtentAlaska and Western Canada (YT, BC, AB, SK, MB)

Temperature

Metadata: Projected Monthly Average Temperature 2 km AR4

  Scenario
Model B1 A1B A2
5–model Average 2001–2100 (2.6 GB) 2001–2100 (2.6 GB) 2001–2100 (2.6 GB)
cccma_cgcm31 2001–2100 (2.6 GB) 2001–2100 (2.6 GB) 2001–2100 (2.6 GB)
gfdl_cm2_1 2001–2100 (2.6 GB) 2001–2100 (2.6 GB) 2001–2100 (2.6 GB)
miroc3_2_medres 2001–2100 (2.6 GB) 2001–2100 (2.6 GB) 2001–2100 (2.6 GB)
mpi_echam5 2001–2100 (2.6 GB) 2001–2100 (2.6 GB) 2001–2100 (2.6 GB)
ukmo_hadcm3 2001–2100 (2.7 GB) 2001–2100 (2.6 GB) 2001–2100 (2.7 GB)

Precipitation

Metadata: Projected Monthly Total Precipitation 2 km AR4

  Scenario
Model B1 A1B A2
5–model Average 2001–2100 (2.3 GB) 2001–2100 (2.3 GB) 2001–2100 (2.3 GB)
cccma_cgcm31 2001–2100 (2.4 GB) 2001–2100 (2.3 GB) 2001–2100 (2.3 GB)
gfdl_cm2_1 2001–2100 (2.3 GB) 2001–2100 (2.3 GB) 2001–2100 (2.4 GB)
miroc3_2_medres 2001–2100 (2.3 GB) 2001–2100 (2.3 GB) 2001–2100 (2.3 GB)
mpi_echam5 2001–2100 (2.4 GB) 2001–2100 (2.4 GB) 2001–2100 (2.4 GB)
ukmo_hadcm3 2001–2100 (2.3 GB) 2001–2100 (2.3 GB) 2001–2100 (2.3 GB)

Projected Derived Temperature Products - 2 km CMIP3/AR4

Projected (2010–2100: B1, A1B, and A2 scenarios) derived temperature products from 5 AR4 GCMs that perform best across Alaska and the Arctic, downscaled to 2km via the delta method. A 5-Model Average is also included.

Baseline Reference Climate1961–1990 PRISM
Spatial Resolution2 km
Temporal ResolutionDecadal
Spatial ExtentAlaska and Western Canada (YT, BC, AB, SK, MB)

Decadal Summaries by month, year, or season

Metadata by product
All products by model and scenario
  Scenario
Model B1 A1B A2
5–model Average 2001–2100 (375 MB) 2001–2100 (375 MB) 2001–2100 (376 MB)
cccma_cgcm31 2001–2100 (333 MB) 2001–2100 (333 MB) 2001–2100 (333 MB)
gfdl_cm2_1 2001–2100 (332 MB) 2001–2100 (332 MB) 2001–2100 (332 MB)
miroc3_2_medres 2001–2100 (332 MB) 2001–2100 (334 MB) 2001–2100 (336 MB)
mpi_echam5 2001–2100 (332 MB) 2001–2100 (333 MB) 2001–2100 (332 MB)
ukmo_hadcm3 2001–2100 (334 MB) 2001–2100 (336 MB) 2001–2100 (336 MB)

Day of Freeze, Thaw, Length of Growing Season

Estimated Julian days of freeze and thaw (dof, dot) are calculated by assuming a linear change in temperature between consecutive months. Mean monthly temperatures are used to represent daily temperature on the 15th day of each month. When consecutive monthly midpoints have opposite sign temperatures, the day of transition (freeze or thaw) is the day between them on which temperature crosses zero degrees C. The length of growing season (logs) refers to the number of days between the days of freeze and thaw. More detailed explanations are discussed in the metadata.

Day of Freeze, Thaw

Metadata: Projected Day of Freeze or Thaw 2km AR4

  Scenario
Model B1 A1B A2
5–model Average 2001–2100 (27 MB) 2001–2100 (27 MB) 2001–2100 (27 MB)
cccma_cgcm31 2001–2100 (27 MB) 2001–2100 (27 MB) 2001–2100 (27 MB)
gfdl_cm2_1 2001–2100 (27 MB) 2001–2100 (27 MB) 2001–2100 (27 MB)
miroc3_2_medres 2001–2100 (27 MB) 2001–2100 (27 MB) 2001–2100 (27 MB)
mpi_echam5 2001–2100 (27 MB) 2001–2100 (27 MB) 2001–2100 (27 MB)
ukmo_hadcm3 2001–2100 (27 MB) 2001–2100 (27 MB) 2001–2100 (27 MB)
Length of Growing Season

Metadata: Projected Length of Growing Season 2km AR4

  Scenario
Model B1 A1B A2
5–model Average 2001–2100 (17 MB) 2001–2100 (17 MB) 2001–2100 (17 MB)
cccma_cgcm31 2001–2100 (17 MB) 2001–2100 (17 MB) 2001–2100 (17 MB)
gfdl_cm2_1 2001–2100 (17 MB) 2001–2100 (17 MB) 2001–2100 (17 MB)
miroc3_2_medres 2001–2100 (17 MB) 2001–2100 (17 MB) 2001–2100 (17 MB)
mpi_echam5 2001–2100 (17 MB) 2001–2100 (17 MB) 2001–2100 (17 MB)
ukmo_hadcm3 2001–2100 (17 MB) 2001–2100 (17 MB) 2001–2100 (17 MB)

Projected Derived Precipitation Products - 2 km CMIP3/AR4

Projected (2010-2100: B1, A1B, and A2 scenarios) derived precipitation products from 5 AR4 GCMs that perform best across Alaska and the Arctic, downscaled to 2km via the delta method. A 5-Model Average is also included.

Baseline Reference Climate1961–1990 PRISM
Spatial Resolution771m
Temporal ResolutionDecadal
Spatial ExtentAlaska and Western Canada (YT, BC, AB, SK, MB)

Decadal Summaries by month, year, and season

Metadata by product
All products by model and scenario
  Scenario
Model B1 A1B A2
5–model Average 2001–2100 (351 MB) 2001–2100 (353 MB) 2001–2100 (353 MB)
cccma_cgcm31 2001–2100 (318 MB) 2001–2100 (320 MB) 2001–2100 (321 MB)
gfdl_cm2_1 2001–2100 (319 MB) 2001–2100 (321 MB) 2001–2100 (320 MB)
miroc3_2_medres 2001–2100 (317 MB) 2001–2100 (319 MB) 2001–2100 (319 MB)
mpi_echam5 2001–2100 (318 MB) 2001–2100 (320 MB) 2001–2100 (320 MB)
ukmo_hadcm3 2001–2100 (318 MB) 2001–2100 (320 MB) 2001–2100 (320 MB)

Projected Monthly Potential Evapotranspiration - 2km CMIP3/AR4

Projected (2001-2099: A1B scenario) monthly total potential evapotranspiration from 5 AR4 GCMs that perform best across Alaska and the Arctic, utilizing 2km downscaled temperature as model inputs.

These potential evapotranspiration (PET) estimates were produced using the Hamon equation, which calculates PET as a function of temperature and day length. Potential evapotranspiration may also be influenced by cloud cover, humidity, and wind speed. The Hamon equation can not explicitly account for variability in these aspects of weather and climate, so it may over or underestimate changes in PET if humidity, cloud cover, or wind speeds change substantially. In addition, the Hamon equation was developed to calculate daily potential evapotranspiration, and so these estimates, based on monthly data, may differ from those calculated from daily data. We can also provide PET estimated by the Priestley-Taylor equation and standard equations for estimating the surface radiation budget from temperature. Priestley-Taylor data come with a much longer list of assumptions, including those that apply to the Hamon equation. Scripts used to produce both the Harmon and Priestley-Taylor versions are available online.

Baseline Reference Climate 1961–1990 PRISM
Spatial Resolution 2km
Temporal Resolution Monthly
Spatial Extent Alaska

Metadata by product

Metadata: Projected Monthly Total Potential Evapotranspiration 2km AR4

Equations used to derive data: Hamon PET equations (PDF, 597KB)

Data

  Scenario
Model A1B
cccma_cgcm31 2001–2099 (757 MB)
gfdl_cm2_1 2001–2099 (759MB)
miroc3_2_medres 2001–2099 (770MB)
mpi_echam5 2001–2099 (769MB)
ukmo_hadcm3 2001–2099 (762MB)

Projected Derived Potential Evapotranspiration - 2km CMIP3/AR4

Projected (2001-2099: A1B scenario) monthly total potential evapotranspiration from 5 AR4 GCMs that perform best across Alaska and the Arctic, utilizing 2km downscaled temperature as model inputs.

These potential evapotranspiration (PET) estimates were produced using the Hamon equation, which calculates PET as a function of temperature and day length. Potential evapotranspiration may also be influenced by cloud cover, humidity, and wind speed. The Hamon equation can not explicitly account for variability in these aspects of weather and climate, so it may over or underestimate changes in PET if humidity, cloud cover, or wind speeds change substantially. In addition, the Hamon equation was developed to calculate daily potential evapotranspiration, and so these estimates, based on monthly data, may differ from those calculated from daily data. We can also provide PET estimated by the Priestley-Taylor equation and standard equations for estimating the surface radiation budget from temperature. Priestley-Taylor data come with a much longer list of assumptions, including those that apply to the Hamon equation. Scripts used to produce both the Harmon and Priestley-Taylor versions are available online.

Baseline Reference Climate 1961–1990 PRISM
Spatial Resolution 2km
Temporal Resolution Decadal
Spatial Extent Alaska

Decadal Summaries by Month, Year, or Season

Metadata by product

Equations used to derive data: Hamon PET equations (PDF, 597KB)

Data

  Scenario
Model A1B
cccma_cgcm31 2001–2099 (188MB)
gfdl_cm2_1 2001–2099 (187MB)
miroc3_2_medres 2001–2099 (188MB)
mpi_echam5 2001–2099 (189MB)
ukmo_hadcm3 2001–2099 (189MB)

Projected Decadal Averages Of Monthly Snow-day Fraction 771m CMIP3/AR4

These snow-day fraction estimates were produced by applying equations relating decadal average monthly temperature to snow-day fraction to downscaled decadal average monthly temperature. Separate equations were used to model the relationship between decadal monthly average temperature and the fraction of wet days with snow for seven geographic regions in the state: Arctic, western Alaska, Interior, Cook Inlet, SW Islands, SW Interior, and the Gulf of Alaska coast.

Although the equations developed here provide a reasonable fit to the data, model evaluation demonstrated that some stations are consistently less well described by regional models than others. It is unclear why this occurs, but it is like related to localized climate conditions. Very few weather stations with long records are located above 500m elevation in Alaska, so the equations used here were developed primarily from low-elevation weather stations. It is not clear whether the equations will be completely appropriate in the mountains. Finally, these equations summarize a long-term monthly relationship between temperature and precipitation type that is the result of short-term weather variability. In using these equations to make projections of future snow, as assume that these relationships remain stable over time, and we do not know how accurate that assumption is.

Detailed information on the construction of this data and its implications is available in this paper. (PDF, 3.27MB)

Baseline Reference Climate 1971–2000 PRISM
Spatial Resolution 771m
Temporal Resolution Monthly
Spatial Extent Alaska

Metadata by product

Metadata: Projected Decadal Averages Of Monthly Snow-day Fraction 771m AR4

Data

Model Data
cccma_cgcm31 2010–2099 (479 MB)
gfdl_cm2_1 2010–2099 (491MB)
miroc3_2_medres 2010–2099 (461MB)
mpi_echam5 2010–2099 (476MB)
ukmo_hadcm3 2010–2099 (470MB)

Historically Observed Data

Historical Sea Ice Atlas: Observed Estimates of Sea Ice Concentration in Alaska Waters

These data were compiled from several historical sea ice data sources into spatially and temporally standardized data sets that include sea ice concentrations (0–100%) for the seas surrounding the state of Alaska, USA.

Spatial Resolution¼×¼ degree
Temporal Resolutionweekly and monthly
Spatial ExtentAlaska marine waters
Temporal ExtentWeekly, 1953–2013; Monthly, 1850–2013

Downloads

Metadata Data
Monthly Observed Estimates of Sea Ice Concentration in Alaska Waters 1850–2013 (5.6 MB)

Historical Monthly Temperature and Precipitation - 771m CRU TS 3.0

Historical (1901–2006) monthly average temperature and total precipitation from CRU TS 3.0 climate data, downscaled to 771m via the delta method.

Baseline Reference Climate1971–2000 PRISM
Spatial Resolution771m
Temporal ResolutionMonthly
Spatial ExtentAlaska

Downloads

Metadata Data
Historical Monthly Average Temperature 771m CRUTS3.0/3.1 1901–1949 (2.5 GB) 1950–2006 (2.9 GB)
Historical Monthly Total Precipitation 771m CRUTS3.0/3.1.01 1901–1949 (2.1 GB) 1950–2006 (2.4 GB)

Historical Monthly Temperature and Precipitation - 771m CRU TS 3.1/3.1.01

Historical (1901–2009) monthly average temperature and total precipitation from CRU TS 3.1.01 climate data, downscaled to 771m via the delta method.

Baseline Reference Climate1971–2000 PRISM
Spatial Resolution771m
Temporal ResolutionMonthly
Spatial ExtentAlaska

Downloads

The Climatic Research Unit (CRU) discovered a systematic error in their CRUTS v3.1 precipitation data, and have addressed those errors with a new update (v3.1.01). All previous SNAP products based upon CRUTS v3.1 precipitation have been updated to reflect this update to 3.1.01. SNAP encourages users to download this new update and discard the previous CRU TS v3.1 precipitation data.

Metadata Data
Historical Monthly Average Temperature 771m CRUTS3.1 1901–1949 (2.5 GB) 1950–2009 (3.0 GB)
Historical Monthly Total Precipitation 771m CRUTS3.1.01 1901–1949 (2.1 GB) 1950–2009 (2.5 GB)

Historical Derived Temperature Products - 771m CRU TS 3.0

Historical (1910–1999) derived temperature products from CRU TS 3.0 climate data, downscaled to 771m via the delta method.

Baseline Reference Climate1971–2000 PRISM
Spatial Resolution771m
Temporal ResolutionDecadal
Spatial ExtentAlaska

Decadal summaries by month, year, and season

Metadata by product
All products
tas_decadal_summaries_AK_771m_CRU_TS30_historical.zip (593 MB)

Day of freeze, thaw, length of growing season

Estimated Julian days of freeze and thaw (dof, dot) are calculated by assuming a linear change in temperature between consecutive months. Mean monthly temperatures are used to represent daily temperature on the 15th day of each month. When consecutive monthly midpoints have opposite sign temperatures, the day of transition (freeze or thaw) is the day between them on which temperature crosses zero degrees C. The length of growing season (logs) refers to the number of days between the days of freeze and thaw. More detailed explanations are discussed in the metadata.

Metadata Data
Historical Day of Freeze or Thaw 771m CRUTS3.0 dof_dot_AK_771m_CRU_TS30_historical.zip (52 MB)
Historical Length of Growing Season 771m CRUTS3.0 logs_AK_771m_CRU_TS30_historical.zip (32 MB)

Historical Derived Temperature Products - 771m CRU TS 3.1

Historical (1910–2009) derived temperature products from CRU TS 3.1 climate data, downscaled to 2 km via the delta method.

Baseline Reference Climate1971–2000 PRISM
Spatial Resolution771m
Temporal ResolutionDecadal
Spatial ExtentAlaska

Decadal summaries by month, year, and season

Metadata by product
All products
tas_decadal_summaries_AK_771m_CRU_TS31_historical.zip (707 MB)

Day of freeze, thaw, length of growing season

Estimated Julian days of freeze and thaw (dof, dot) are calculated by assuming a linear change in temperature between consecutive months. Mean monthly temperatures are used to represent daily temperature on the 15th day of each month. When consecutive monthly midpoints have opposite sign temperatures, the day of transition (freeze or thaw) is the day between them on which temperature crosses zero degrees C. The length of growing season (logs) refers to the number of days between the days of freeze and thaw. More detailed explanations are discussed in the metadata.

Metadata Data
Historical Day of Freeze or Thaw 771m CRUTS3.1 dof_dot_AK_771m_CRU_TS31_historical.zip (58 MB)
Historical Length of Growing Season 771m CRUTS3.1 logs_AK_771m_CRU_TS31_historical.zip (35 MB)

Historical Derived Precipitation Products - 771m CRU TS 3.0

Historical (1910–1999) derived precipitation products from CRUTS 3.0 climate data, downscaled to 771m via the delta method.

Baseline Reference Climate1971–2000 PRISM
Spatial Resolution771m
Temporal ResolutionDecadal
Spatial ExtentAlaska

Decadal summaries by month, year, and season

Metadata by product
All products
pr_decadal_summaries_AK_771m_CRU_TS30_historical.zip (593 MB)

Historical Derived Precipitation Products - 771m CRU TS 3.1.01

Historical (1910-2009) derived precipitation products from CRU TS 3.1.01 climate data, downscaled to 2 km via the delta method.

Baseline Reference Climate1971–2000 PRISM
Spatial Resolution771m
Temporal ResolutionDecadal
Spatial ExtentAlaska

Decadal summaries by month, year, and season

The Climatic Research Unit (CRU) discovered a systematic error in their CRUTS v3.1 precipitation data, and have addressed those errors with a new update (v3.1.01). All previous SNAP products based upon CRUTS v3.1 precipitation have been updated to reflect this update to 3.1.01. SNAP encourages users to download this new update and discard the previous CRU TS v3.1 precipitation data.

Metadata by product
All products
pr_decadal_summaries_AK_771m_CRU_TS31_historical.zip (655 MB)

Historical Monthly Temperature and Precipitation - 2 km CRU TS 3.0

Historical (1901-2009) monthly average temperature and total precipitation from CRU TS 3.0 climate data, downscaled to 2 km via the delta method.

Baseline Reference Climate1961–1990 PRISM
Spatial Resolution2 km
Temporal ResolutionMonthly
Spatial ExtentAlaska and Western Canada (YT, BC, AB, SK, MB)
Metadata Data
Historical Monthly Average Temperature 2km CRUTS3.0 tas_AK_CAN_2km_CRU_TS30_historical.zip (2.6 GB)
Historical Monthly Total Precipitation 2km CRUTS3.0 pr_AK_CAN_2km_CRU_TS30_historical.zip (2.2 GB)

Historical Monthly Temperature and Precipitation - 2 km CRU TS 3.1/3.1.01

Historical (1901-2009) monthly average temperature and total precipitation from CRU TS 3.1/3.1.01 climate data, downscaled to 2 km via the delta method.

Baseline Reference Climate1961–1990 PRISM
Spatial Resolution2 km
Temporal ResolutionMonthly
Spatial ExtentAlaska and Western Canada (YT, BC, AB, SK, MB)

The Climatic Research Unit (CRU) discovered a systematic error in their CRUTS v3.1 precipitation data, and have addressed those errors with a new update (v3.1.01). All previous SNAP products based upon CRUTS v3.1 precipitation have been updated to reflect this update to 3.1.01. SNAP encourages users to download this new update and discard the previous CRU TS v3.1 precipitation data.

Metadata Data
Historical Monthly Average Temperature 2km CRUTS 3.1 tas_AK_CAN_2km_CRU_TS31_historical.zip (2.9 GB)
Historical Monthly Total Precipitation 2km CRUTS 3.1.01 pr_AK_CAN_2km_CRU_TS31_historical.zip (2.5 GB)

Historical Derived Temperature Products - 2 km CRU TS 3.0

Historical (1910-2009) derived temperature products from CRU TS 3.0 climate data, downscaled to 2 km via the delta method.

Baseline Reference Climate1961–1990 PRISM
Spatial Resolution2 km
Temporal ResolutionDecadal
Spatial ExtentAlaska and Western Canada (YT, BC, AB, SK, MB)

Decadal summaries by month, year, and season

Metadata by product
All products
tas_decadal_summaries_AK_CAN_2km_CRU_TS30_historical.zip (331 MB)

Day of freeze, thaw, length of growing season

Estimated Julian days of freeze and thaw (dof, dot) are calculated by assuming a linear change in temperature between consecutive months. Mean monthly temperatures are used to represent daily temperature on the 15th day of each month. When consecutive monthly midpoints have opposite sign temperatures, the day of transition (freeze or thaw) is the day between them on which temperature crosses zero degrees C. The length of growing season (logs) refers to the number of days between the days of freeze and thaw. More detailed explanations are discussed in the metadata.

Metadata Data
Historical Day of Freeze or Thaw 2km CRUTS3.0 dof_dot_AK_CAN_2km_CRU_TS30_historical.zip (27 MB)
Historical Length of Growing Season 2km CRUTS3.0 logs_AK_CAN_2km_CRU_TS30_historical.zip (17 MB)

Historical Derived Temperature Products - 2 km CRU TS 3.1

Historical (1910-2009) derived temperature products from CRU TS 3.1 climate data, downscaled to 2 km via the delta method.

Baseline Reference Climate1961–1990 PRISM
Spatial Resolution2 km
Temporal ResolutionDecadal
Spatial ExtentAlaska and Western Canada (YT, BC, AB, SK, MB)

Decadal summaries by month, year, and season

Metadata by product
All products
tas_decadal_summaries_AK_CAN_2km_CRU_TS31_historical.zip (368 MB)

Day of freeze, thaw, length of growing season

Estimated Julian days of freeze and thaw (dof, dot) are calculated by assuming a linear change in temperature between consecutive months. Mean monthly temperatures are used to represent daily temperature on the 15th day of each month. When consecutive monthly midpoints have opposite sign temperatures, the day of transition (freeze or thaw) is the day between them on which temperature crosses zero degrees C. The length of growing season (logs) refers to the number of days between the days of freeze and thaw. More detailed explanations are discussed in the metadata.

Metadata Data
Historical Day of Freeze or Thaw 2km CRUTS3.1 dof_dot_AK_CAN_2km_CRU_TS31_historical.zip (30 MB)
Historical Length of Growing Season 2km CRUTS3.1 logs_AK_CAN_2km_CRU_TS31_historical.zip (19 MB)

Historical Derived Precipitation Products - 2 km CRU TS 3.0

Historical (1910–2009) derived precipitation products from CRUTS 3.0 climate data, downscaled to 2 km via the delta method.

Baseline Reference Climate1961–1990 PRISM
Spatial Resolution2 km
Temporal ResolutionDecadal
Spatial ExtentAlaska and Western Canada (YT, BC, AB, SK, MB)

Decadal summaries by month, year, and season

Metadata by product
All products
pr_decadal_summaries_AK_CAN_2km_CRU_TS30_historical.zip (312 MB)

Historical Derived Precipitation Products - 2 km CRU TS 3.1.01

Historical (1910–2009) derived precipitation products from CRUTS 3.1.01 climate data, downscaled to 2 km via the delta method.

Baseline Reference Climate1961–1990 PRISM
Spatial Resolution2 km
Temporal ResolutionDecadal
Spatial ExtentAlaska and Western Canada (YT, BC, AB, SK, MB)

Decadal summaries by month, year, and season

The Climatic Research Unit (CRU) discovered a systematic error in their CRUTS v3.1 precipitation data, and have addressed those errors with a new update (v3.1.01). All previous SNAP products based upon CRUTS v3.1 precipitation have been updated to reflect this update to 3.1.01. SNAP encourages users to download this new update and discard the previous CRU TS v3.1 precipitation data.

Metadata by product
All products
pr_decadal_summaries_AK_CAN_2km_CRU_TS31_historical.zip (345 MB)

Historical Monthly Potential Evapotranspiration - 2km CRUTS3.0

Historical (1901-2006) monthly total potential evapotranspiration utilizing CRU TS 3.0 climate data downscaled to 2 km via the delta method.

These potential evapotranspiration (PET) estimates were produced using the Hamon equation, which calculates PET as a function of temperature and day length. Potential evapotranspiration may also be influenced by cloud cover, humidity, and wind speed. The Hamon equation can not explicitly account for variability in these aspects of weather and climate, so it may over or underestimate changes in PET if humidity, cloud cover, or wind speeds change substantially. In addition, the Hamon equation was developed to calculate daily potential evapotranspiration, and so these estimates, based on monthly data, may differ from those calculated from daily data. We can also provide PET estimated by the Priestley-Taylor equation and standard equations for estimating the surface radiation budget from temperature. Priestley-Taylor data come with a much longer list of assumptions, including those that apply to the Hamon equation. Scripts used to produce both the Harmon and Priestley-Taylor versions are available online.

Baseline Reference Climate 1961–1990 PRISM
Spatial Resolution 2km
Temporal Resolution Monthly
Spatial Extent Alaska

Metadata

Metadata: Historical Monthly Total Potential Evapotranspiration 2km CRUTS3.0

Equations used to derive data: Hamon PET equations (PDF, 597KB)

Data

Historical Derived Potential Evapotranspiration - 2km CRUTS3.0

Historical (1910-1999) monthly total potential evapotranspiration utilizing CRU TS 3.0 climate data downscaled to 2 km via the delta method.

These potential evapotranspiration (PET) estimates were produced using the Hamon equation, which calculates PET as a function of temperature and day length. Potential evapotranspiration may also be influenced by cloud cover, humidity, and wind speed. The Hamon equation can not explicitly account for variability in these aspects of weather and climate, so it may over or underestimate changes in PET if humidity, cloud cover, or wind speeds change substantially. In addition, the Hamon equation was developed to calculate daily potential evapotranspiration, and so these estimates, based on monthly data, may differ from those calculated from daily data. We can also provide PET estimated by the Priestley-Taylor equation and standard equations for estimating the surface radiation budget from temperature. Priestley-Taylor data come with a much longer list of assumptions, including those that apply to the Hamon equation. Scripts used to produce both the Harmon and Priestley-Taylor versions are available online.

Baseline Reference Climate 1961–1990 PRISM
Spatial Resolution 2km
Temporal Resolution Decadal
Spatial Extent Alaska

Metadata by product

Equations used to derive data: Hamon PET equations (PDF, 597KB)

All products by model and scenario


Historical Decadal Averages Of Monthly Snow-day Fraction 771m CRU TS 3.1

These snow-day fraction estimates were produced by applying equations relating decadal average monthly temperature to snow-day fraction to downscaled decadal average monthly temperature. Separate equations were used to model the relationship between decadal monthly average temperature and the fraction of wet days with snow for seven geographic regions in the state: Arctic, western Alaska, Interior, Cook Inlet, SW Islands, SW Interior, and the Gulf of Alaska coast.

Although the equations developed here provide a reasonable fit to the data, model evaluation demonstrated that some stations are consistently less well described by regional models than others. It is unclear why this occurs, but it is like related to localized climate conditions. Very few weather stations with long records are located above 500m elevation in Alaska, so the equations used here were developed primarily from low-elevation weather stations. It is not clear whether the equations will be completely appropriate in the mountains. Finally, these equations summarize a long-term monthly relationship between temperature and precipitation type that is the result of short-term weather variability. In using these equations to make projections of future snow, as assume that these relationships remain stable over time, and we do not know how accurate that assumption is.

Detailed information on the construction of this data and its implications is available in this paper. (PDF, 3.27MB)

Baseline Reference Climate 1971–2000 PRISM
Spatial Resolution 771m
Temporal Resolution Monthly
Spatial Extent Alaska

Metadata by product

Metadata: Historical Decadal Averages Of Monthly Snow-day Fraction 771m CRUTS3.1

Data

1910-2009 (250MB)

Research Data

Data listed in this section are being developed specifically for several broad scale modeling projects. Overviews can be found on their respective project pages including all collaborators and funding sources.

These broad–scale modeling projects have very specific input data requirements. These include a 1×1km pixel resolution, spatial coverage across data poor regions of Alaska, the Yukon Territories, and parts of northern British Columbia, and temporal coverage of monthly data from the early 1900’s to 2100. In addition, because these datasets are being developed as input to specific models, they also require adherence to model specific requirements in order to produce plausible outputs. Because existing input data did not already exist at this level of detail, our approach has been to downscale the variables of interest to an intermediate resolution when available and then to apply common raster resampling methods down to 1×1km pixel sizes. Care has also been taken to keep the range of the data within accepted bounds and consistent across related variables.

This data is preliminary and is constantly being vetted and updated by our research group. Use of these datasets should be limited to these modeling projects only, but are shared here for stakeholder review and general communication of our data efforts.

Ancillary Data: Elevation, Slope, Slope Complexity, Aspect, Land Cover, Fire History (Burned Area)

Data SetOriginal Spatial ResolutionFinal Spatial ResolutionTemporal Resolution
Elevation, Slope, Slope Complexity, Aspect2km1km 
Land Cover500m1km2005, but highly modified classes
Fire History (Burned Area)vector format1km1917—2011

Metadata

Downloads

Ancillary IEM Data, 35MB

Historical Temperature

Baseline Reference Climate1961–1990
Original Spatial Resolution0.5°
Final Spatial Resolution1 km
Temporal Resolution1901 - 2009

Metadata

Historical Temperature

Downloads

Historical Temperature, 6.6 GB

Historical Precipitation

Baseline Reference Climate1961–1990
Original Spatial Resolution0.5°
Final Spatial Resolution1 km
Temporal Resolution1901 - 2009

Metadata

Historical Precipitation

Downloads

Historical Precipitation, 3.0 GB

Historical Surface Downwelling Shortwave Radiation

Baseline Reference Climate1961–1990
Original Spatial Resolution0.5°
Final Spatial Resolution1 km
Temporal Resolution1901 - 2009

Metadata

Historical Surface Downwelling Shortwave Radiation

Downloads

Historical Surface Downwelling Shortwave Radiation, 6.3 GB

Historical Vapor Pressure

Baseline Reference Climate1961–1990
Original Spatial Resolution0.5°
Final Spatial Resolution1 km
Temporal Resolution1901 - 2009

Metadata

Historical Vapor Pressure

Downloads

Historical Vapor Pressure, 2.4 GB