Skip Navigation Links 
NOAA logo - Click to go to the NOAA home page National Weather Service   NWS logo - Click to go to the NWS home page
Climate Prediction Center

CPC Search
About Us
   Our Mission
   Who We Are

Contact Us
   CPC Information
   CPC Web Team

HOME > Monitoring and Data > Monitoring Weather & Climate > Blocking > Background > Blocking Stratified By ENSO Cycle
Northern Hemisphere Atmospheric Blocking Stratified By ENSO Cycle
Using the blocking index of Tibaldi and Molteni (1990) we can consider the frequency of DJF "blocked days" for Neutral, Warm and Cold episodes as defined by the magnitude of the SST anomalies in the tropical Pacific. Cold episodes are defined as [C+,C], warm episodes [W+,W], and neutral episodes as [W-,C-,N]. For each panel the number of DJF seasons is shown in square brackets. We have also included in the middle panel on the right-hand side a plot of the neutral episodes defined simply as [N]. This can be compared with the middle left-hand side panel where neutral episodes have been defined as [W-,C-,N]. In each panel the DJF 51 year average has been plotted in red for ease of comparison.
Frequency of December-January-February blocked day for Neutral, Warm and Cold ENSO episodes

NOAA/ National Weather Service
National Centers for Environmental Prediction
Climate Prediction Center
5200 Auth Road
Camp Springs, Maryland 20746
Climate Prediction Center Web Team
Page last modified: October 23, 2002
Disclaimer Privacy Policy