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Projected Derived DOF/DOT/LOGS - 2km CMIP5/AR5

This set of files includes downscaled projections of decadal means of annual day of freeze or thaw (ordinal day of the year), and length of growing season (numbers of days, 0-365) for each decade from 2010 - 2100 at 2km x 2km meter spatial resolution. Each file represents a decadal mean of an annual mean calculated from mean monthly data.

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The spatial extent includes Alaska, the Yukon Territory, British Columbia, Alberta, Saskatchewan, and Manitoba.

Each set of files originates from one of five top ranked global circulation models from the CMIP5/AR5 models and RPCs, or is calculated as a 5 Model Average.

Day of Freeze, Day of Thaw, Length of Growing Season calculations:

Estimated ordinal days of freeze and thaw 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 refers to the number of days between the days of thaw and freeze.

This amounts to connecting temperature values (y-axis) for each month (x-axis) by line segments and solving for the x-intercepts. Calculating a day of freeze or thaw is simple. However, transitions may occur several times in a year, or not at all. The choice of transition points to use as the thaw and freeze dates which best represent realistic bounds on a growing season is more complex. Rather than iteratively looping over months one at a time, searching from January forward to determine thaw day and from December backward to determine freeze day, stopping as soon as a sign change between two months is identified, the algorithm looks at a snapshot of the signs of all twelve mean monthly temperatures at once, which enables identification of multiple discrete periods of positive and negative temperatures. As a result more realistic days of freeze and thaw and length of growing season can be calculated when there are idiosyncrasies in the data.

Please note that these maps represent climatic estimates only. While we have based our work on scientifically accepted data and methods, uncertainty is always present . Uncertainty in model outputs tends to increase for more distant climatic estimates from present day for both historical summaries and future projections.

Simple

Date (Revision)
2019-08-12
Edition
1.0.1
Credit
Michael Lindgren
Credit
Matthew Leonawicz
Credit
Tom Kurkowski
Credit
John Walsh
Credit
Scott Rupp
Status
Completed
Point of contact
  Scenarios Network for Alaska and Arctic Planning
Maintenance and update frequency
As needed
Theme
  • projected
  • modeled
  • freeze
  • thaw
  • growing season
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Use constraints
License
Other constraints
https://creativecommons.org/licenses/by/4.0/
Spatial representation type
Grid
Distance
2  km
Metadata language
eng
Character set
UTF8
Topic category
  • Climatology, meteorology, atmosphere
Begin date
2010-01-15
End date
2100-12-15
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Supplemental Information

Day of freeze or thaw units are ordinal day 15-350 with the below special cases.

Day of Freeze (DOF)

0 = Primarily Frozen

365 = Rarely Freezes

Day of Thaw (DOT)

0 = Rarely Freezes

365 = Primarily Frozen

Length of Growing Season (LOGS) is simply the number of days between the DOT and DOF.

Unique resource identifier
EPSG:3338
Number of dimensions
2
Dimension name
Row
Dimension size
1186
Resolution
2  km
Dimension name
Column
Dimension size
3218
Resolution
2  km
Cell geometry
Area
Distribution format
  • geotiff ( gdal Float32, LZW compression )

OnLine resource
Projected Derived DOF/DOT/LOGS - 2km CMIP5/AR5 ( WWW:LINK-1.0-http--link )

URL to web-accessible folder containing downloads for this data set

Hierarchy level
Dataset
File identifier
fd2580ef-e164-410f-8bdb-1b1a5e901fae XML
Metadata language
English
Character set
UTF8
Date stamp
2022-08-18T10:08:58
Metadata standard name
ISO 19115:2003/19139
Metadata standard version
1.0
Point of contact
  Scenarios Network for Alaska and Arctic Planning
 
 

Overviews

overview

Spatial extent

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Keywords

freeze growing season modeled projected thaw

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