SUB-REGION SCALE HINDCASTING OF CONTRAIL OUTBREAKS, UTILIZING THEIR SYNOPTIC CLIMATOLOGY † (original) (raw)

2015, Journal of Applied Meteorology and Climatology

1 Contrail statistical prediction methods are often location specific. To take advantage of 2 the fact that the upper-troposphere (UT) meteorological conditions favoring "clear-sky 3 outbreaks" of persisting contrails, or Contrail Favored Areas (CFAs), tend to be synoptic 4 in scale, we develop and test a visual UT map technique to hindcast CFAs for sub-regions 5 of the contiguous United States (CONUS) having high outbreak frequencies in mid-6 season months (January, April, July, October) of 2000-02. The method compares daily 7 maps with the composite fields for outbreak (CON) versus non-outbreak (NON) days, 8 and those assessments are evaluated using standard skill measures. Binary logistic 9 regression determines which UT variables are significant predictors, individually and in 10 combination. We test reproducibility of the outbreak hindcast results on the same sub-11 regions for corresponding months of 2008-09. The results confirm the importance of UT 12 relative humidity and vertical motion (omega) map patterns in regional clear-sky 13 outbreaks. Although the hindcast skill is modest, sensitivity tests suggest the method 14 would be substantially improved when a longer-term outbreaks climatology becomes 15 available (to increase sample sizes), and with explicit consideration of the synoptic types 16 on CON days. The latter is demonstrated specifically for the South CONUS in January, 17 where improving hindcast success should also consider the vertical wind shear in the UT, 18 given the importance of the subtropical jet stream in contrail outbreaks there. Further 19 development of the method to improve its skill ultimately should permit its use in 20 combination with existing objective (statistical, physical model) methods of contrail 21 prediction. 22

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