CFSR: plant hardiness zones
The Climate Forecast System Reanalysis (CFSR) creates analyses of many
fields including the 2 meter temperature. The CFSR analyses were
used to create a plant hardiness zone map using the same formula
as used by the USDA. See
For practical use, you should use the USDA product. The CFSR based product is for
reasearch on performance of the reanalysis.
For the plots,
a value between 7,0 and 7.5 corresponds to zone 7a and value between 7.5 and 8.0
corresponds to a zone 7b.
- Find the minimum 2m temperature (6 hour forecast) for 1979 from the CFSR.
- Repeat the above for the years 1980 to 2008 (30 years in total).
- Average the 30 years to produce a 30-year average annual minimum temperature
- Convert the data from Kelvin to Fahrenheit.
- To the temperature data, add 70, divide by 10 and set the negative values to zero.
Details and Caveats
The CFSR uses a system very similar to those run by the National Weather Service to
produce the 1-6 day weather forecasts that you see on TV. (Other countries run
similar systems for their 1-6 day forecasts.) As part of producing a weather forecast,
an analysis of the current atmospheric state is created. This analysis is made
using data from satellites, aircraft, weather ballons and other sources but surprising no
2-meter temperature observations. The 2-m temperature is model derived product which
depends on the land-surface model, the model physics, the model parameterizations and the
analyses of the winds, temperatures and humidity at the model levels. There
are many reasons why the analyses will differ from observations. For example,
you make your temperature observation on a patch of grass and the model is using
a forest. (The land surface is suppose to be representative of the average conditions
in a 35x35 km grid box.) Yes, grass vs. forest can be a big difference. Another
problem is model uses the average height of the grid box. Your measurement will
be at a different elevation. An other problem is the model doesn't know the
local orography. You could be on an exposed peak or in a sheltered valley.
These features are not resolved within a 35-km grid used by the CFSR model.
One way to view the CFSR temperature is they are a model estimate of average
temperature of a 35km x 35km grid box. It will not give you the same
number as an observation.
CFSR based plots
Please send comments to: Wesley.Ebisuzaki@noaa.gov