Fig. 6. Part (a): Time (year) diagram of occurrences of warm (W) and cold episodes, defined by straddling "mature" event boreal winter. Entries in small font represent episodes of standard strength, in larger bold font moderately strong episodes and strong episodes (see the classification system described in the appendix). Entries in brackets (1954-55) denote episodes at the beginning or end of the study period that are not included in the composite analyses shown in Fig. 5 (except as adjacent periods with respect to the episode years that are included) but are used to form the frequencies shown in part (b). Among the 41 boreal winters from the 1955-56 winter to the 1995-96 winter, 12 warm episodes, 8 cold episodes, and 21 neutral years are identified. Part (b): Frequencies of warm, neutral and cold episode years immediately preceding or following warm episodes (top) and cold episodes (bottom). Frequencies of preceding or following warm (cold) years with a noteworthy imbalance with respect to frequencies of cold (warm) years are shown in bold. This information is provided to aid interpretation of the composites shown in Fig. 5 . ---------------------------------------------------------------------------

Part a

============================================================================
          W                 w     W        w  w        W              w 
  55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 
[c] c                          c                 C        C     
============================================================================
	  W           W  W           W        w
  80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 
		c           C                    c
============================================================================

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 Part b
    

Year                               Year
Preceding                          Following


warm    2     ==================   warm     2
neutral 9        WARM EPISODE      neutral  5
cold    1     ==================   cold     5

    

warm    5     ==================   warm     1
neutral 2        COLD EPISODE      neutral  7
cold    1     ==================   cold     0