Frost-Free Season

The number of frost-free days in a year reflects the overall warming trend in the climate system.

The bars on the graph show the difference between the number of frost-free days in each year and the average number of frost-free days from 1979 to 2020.

Frost-Free Season

Caption: Key Points: Over the past 40 years, there has been an increase in the length of the frost-free season over the contiguous United States and Alaska, relative to the 1979–2020 average. About the Indicator: Global daily freeze-thaw data are provided by the National Aeronautics and Space Administration (NASA) Freeze-Thaw Earth Systems Data Record, which represents one of the longest continuous global records from satellite-based observations. Satellite microwave sensors are used to determine the frozen or thawed status of water on the land surface at a given time. Measurements are taken over the contiguous United States and Alaska and include all vegetated land areas where seasonal frozen temperatures are a major constraint to plant growth. Collecting these data over time provides information on the number of frost-free days in a given year. Why It's Important: - Observed changes in the length of the frost-free season reflect the overall warming trend in the climate system. - The frost-free season can be an important factor in determining the potential growing season for vegetation. For instance, some pests and pathogens affecting forests and crops are projected to benefit from warmer temperatures and longer frost-free seasons. - This indicator can help decision-makers understand and anticipate climate impacts on: - Agriculture, including crop planning - Natural resource management - Wildfire risk management

This figure, "Frost-Free Season", was provided by Mike Kolian, with contributions from John Kimball. Please contact Mike Kolian for any questions or additional information regarding this figure.

Panels

This figure, “Frost-Free Season” , is a single panel figure, was created on 01/24/2018 , was last updated on 11/02/2021 , and analyzed 1 dataset .

Please access the “Panel Details” tab for more information on this panel.

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This panel, "Frost-Free Season" is an original panel provided by Mike Kolian, with contributions from John Kimball. Please contact Mike Kolian for any questions or additional information regarding this figure.

Analysis Methods and Tools

This figure panel was created using the following analysis methods:

The average number of frost-free days for the baseline period of 1979-2020 was calculated.
The difference between the annual number of frost-free days and the baseline average number of frost-free days over the long-term (1979-2020) record was calculated for each year to produce an anomaly time series. The period of 1979-2020 was chosen because it is the full period of record and fixed in time. It should be noted that the choice of baseline period will not affect the shape or the statistical significance of the overall trend in anomalies, it only moves the trend up or down on the graph in relation to the point defined as “zero.”

They used Microsoft Excel to analyze the data. The operating system Mac OS Version 11.6 was used to perform the analysis.

The data was visualized using the following methods:

Values were plotted as bars for each year, colored green for above average number of days and blue for below average number of days.
The baseline was labeled as "1979-2020 average" and labels indicating more or fewer number of days were added to the y-axis.

and with the following software:

SigmaPlot , Adobe Photoshop

These methods are not published. For more information please contact the analysis methods authoritative source(s) John Kimball, The University of Montana.

For full details, please download the full metadata record available on the “Full Record” tab.

Dataset1

Dataset: MEaSUREs Global Record of Daily Landscape Freeze/Thaw Status, Version 4

This dataset was published in 2017 by NASA National Snow and Ice Data Center.

The dataset contains Observations over a domain bounded by
Latitude (min/max): -86.7167°/86.7167°
Longitude (min/max): -179.9999°/179.9999°

The dataset includes Freeze/thaw status variable(s) and is hosted at NASA National Snow and Ice Data Center Distributed Active Archive Center, Boulder, CO.

You can access the dataset at http://nsidc.org/data/NSIDC-0477.

Please reference this dataset as:

Kim, Y., J. S. Kimball, J. Glassy, and K. C. McDonald. 2017. MEaSUREs Global Record of Daily Landscape Freeze/Thaw Status, Version 4. [Indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: http://dx.doi.org/10.5067/MEASURES/CRYOSPHERE/nsidc-0477.004.

For full dataset details, please download the full metadata record available from the “Full Record” tab.

# of panels	1
Panel #1
Graphics Title	Frost-Free Season
Creation Date	01/24/2018
Period of Record	01/01/1979 – 12/31/2020
Spatial Extent	Latitude (min/max): 24.52°/71.83° Longitude (min/max): 172.00°/-66.95°
Point of Contact	Mike Kolian, U.S. Environmental Protection Agency
Contributors	John Kimball, The University of Montana
GCIS URI	/report/indicators-2021/figure/indicator-frost-free-season-2021
Origination	Original
Methods Used	The average number of frost-free days for the baseline period of 1979-2020 was calculated. The difference between the annual number of frost-free days and the baseline average number of frost-free days over the long-term (1979-2020) record was calculated for each year to produce an anomaly time series. The period of 1979-2020 was chosen because it is the full period of record and fixed in time. It should be noted that the choice of baseline period will not affect the shape or the statistical significance of the overall trend in anomalies, it only moves the trend up or down on the graph in relation to the point defined as “zero.”
How Visualized	Values were plotted as bars for each year, colored green for above average number of days and blue for below average number of days. The baseline was labeled as "1979-2020 average" and labels indicating more or fewer number of days were added to the y-axis.
Methods Published?	No
Authoritative Source	John Kimball, The University of Montana
Dataset Modified	Yes
Dataset Modified How	The number of frost-free days for the contiguous U.S. and Alaska was calculated for each year from 1979 to 2020 using the freeze/thaw data for vegetated land areas (defined from a MODIS land cover map).
Software Used	Microsoft Excel
Visualization Software	SigmaPlot , Adobe Photoshop
Operating System Used	Mac OS Version 11.6
Creation Time	02:00
Output File	frost_free_season_2021_v1.png
Files	ESDR_Non_frozen_season_1979_2020_V5_chart.xlsx
Panel #1, Dataset #1: MEaSUREs Global Record of Daily Landscape Freeze/Thaw Status, Version 4
Dataset URL	http://nsidc.org/data/NSIDC-0477
Dataset Archived?	Yes
Dataset Archive Location	NASA National Snow and Ice Data Center Distributed Active Archive Center
Dataset Citation	Kim, Y., J. S. Kimball, J. Glassy, and K. C. McDonald. 2017. MEaSUREs Global Record of Daily Landscape Freeze/Thaw Status, Version 4. [Indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: http://dx.doi.org/10.5067/MEASURES/CRYOSPHERE/nsidc-0477.004.
Dataset Data Type	Observations
Dataset Description	This data set consists of two global records of the daily freeze/thaw (F/T) status of the landscape. The primary record is derived from radiometric brightness temperatures acquired between 1979 and 2016 by three satellite-based passive microwave sensors: the Scanning Multichannel Microwave Radiometer (SMMR), the Special Sensor Microwave/Imager (SSM/I), and the Special Sensor Microwave Imager/Sounder (SSMIS). A second, synergistic record is available for the years 2002 to 2016 derived from observations acquired by the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) and the Advanced Microwave Scanning Radiometer 2 (AMSR2).
Dataset Funding Agency	NASA
Dataset Hosting Location	NASA National Snow and Ice Data Center Distributed Active Archive Center, Boulder, CO
Dataset Publisher	NASA National Snow and Ice Data Center
Dataset Spatial Extent	Latitude (min/max): -86.7167°/86.7167° Longitude (min/max): -179.9999°/179.9999°
Dataset Temporal Extent	12/11/2023 – 12/11/2023
Variables	Freeze/thaw status

Frost-Free Season

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The bars on the graph show the difference between the number of frost-free days in each year and the average number of frost-free days from 1979 to 2020.

Date Range: 1979 - 2020

Contributors:

NASA, National Snow and Ice Data Center

Length of the Frost-free Season in the U.S. is Growing

Over the past 40 years, there has been an increase in the length of the frost-free season over the contiguous United States and Alaska, relative to the 1979–2020 average.

Why It's Important

Observed changes in the length of the frost-free season reflect the overall warming trend in the climate system.
The frost-free season can be an important factor in determining the potential growing season for vegetation. For instance, some pests and pathogens affecting forests and crops are projected to benefit from warmer temperatures and longer frost-free seasons.
This indicator can help decision makers understand and anticipate climate impacts on:
- Agriculture, including crop planning
- Natural resource management
- Wildfire risk management

About Frost-Free Season

Global daily freeze-thaw data are provided by the National Aeronautics and Space Administration (NASA) Freeze-Thaw Earth Systems Data Record, which represents one of the longest continuous global records from satellite-based observations. Satellite microwave sensors are used to determine the frozen or thawed status of water on the land surface at a given time. Measurements are taken over the contiguous United States and Alaska and include all vegetated land areas where seasonal frozen temperatures are a major constraint to plant growth. Collecting these data over time provides information on the number of frost-free days in a given year.

Frost-Free Season