|
Introduction
Sea Ice Index
Monthly Sea Ice Images
Daily Sea Ice Images
Browse & Compare Images
Archived
Data & Images
Image
Derivation
Interpretation
Resources
Soil Temperature
Alaska
Russia
Snow Cover
Snow Off Day
Greenness
SINDVI
Nascence
Peak
|
Snow Cover: Snow
Off Day
Snow Off Day (SOD) gives the day of the year (to within about five to ten days) when snow last covers a location. The data are derived from satellite passive microwave data. See the documentation for more information.
|
Average SOD The mean SOD value obtained over the period 1979 - 2000. From the Pathfinder data set.
|
|
Current SOD Last day of snow for the most recent season.
|
SOD Anomalies (Relative to 1979-2000 Mean)
SOD Anomaly, First Five Years Passive Microwave Data Minus Mean
|
SOD Anomaly, Last Five Years Passive Microwave Data Minus Mean
|
Notes: The images show that while SOD has, on average, been coming earlier (note that the image on the right has more blue than orange grid cells), there is a considerable amount of regional variability. The North Slope of Alaska, for example, is less blue than is the Russian coast.
Time Series of Average Regional Values for SOD
Notes: Time series of SOD values (left) and anomalies from the 1979-2000 mean (right) for 250 square km areas of Russia, Canada, and Alaska show a general trend toward earlier snow melt, but with large temporal variability. When linear regression is used to find the trends, all three areas have a negative trend in SOD. However the trend is only significant (at a 95% confidence level) for the Canadian site, where it is minus 3.7 days per decade. (For a quick overview of linear regression see Linear Regression for Trend Analysis: Assumptions and Limitations in the Sea Ice Index indicator documentation.)
|
