Theory 29/Earth, Climate & Energy /Energy meteorology
Wind Droughts Follow Blocking
Wind resource is summarised by mean speed. The risk comes from how long the weather stops moving.
Wind droughts are set by the persistence of atmospheric blocking rather than by mean wind speed, so the risk to a wind fleet should be predicted from blocking statistics rather than from average resource.
01The evidence
Wind droughts coincide with blocking episodes, and the duration of the drought tracks the persistence of the block.
02The tension
Resource assessment uses mean wind speed and variability, which predict energy from the average and miss the multi-day still periods that drive storage needs.
03The mechanism
A blocking high stalls the jet stream, removing the pressure gradients that drive wind. The duration of the drought is the duration of the block, which has a characteristic but heavy-tailed distribution.
That makes blocking persistence the risk variable, and predicts drought risk from blocking statistics rather than from mean wind.
04What this is not
Those assessments use averages. This uses blocking persistence, which sets the extremes.
05Predictions
- P1Drought duration should track blocking persistence.
- P2Risk should follow blocking statistics.
- P3Mean wind should predict poorly.
06Refutation
Droughts uncorrelated with blocking would leave mean-wind assessment adequate.
07What it changes
It would change storage planning for wind.