¥Time series of annual counts or exceedences
–E.g., number of exceedence
above 90th percentile
¥Some studies use thresholds as high
as 99.7th percentile
¥Coupled with simple trend analysis techniques or
standard detection and attribution methods
–Detected anthropogenic influence in observed
surface temperature indices
–Perfect and imperfect model
studies of potential to detect anthropogenic influence in temperature
and precipitation extremes
¥Statistical issues include
–̉resolutionÓ of
observational data
–adaptation of threshold to
base period
–use of simple analysis
techniques that implicitly assume data are Gaussian