Climatic extremes

Three major teleconnections, Atlantic Multidecadal Oscillation (AMO), North Atlantic
Oscillation (NAO), and the Pacific Decadal Oscillation (PDO), in warm and cool phases,
effect precipitation in Florida. The effects of the oscillation phases on the precipitation
characteristics are analyzed by using long-term daily precipitation data, on different
temporal (annual, monthly, and daily) and spatial scales, utilizing numerous indices, and
techniques. Long-term extreme precipitation data for 9 different durations is used to
examine the effects of the oscillation phases on the rainfall extremes, by employing
different parametric and non-parametric statistical tests, along with Depth-Duration-
Frequency analysis. Results show that Florida will experience higher rainfall when AMO
is in the warm phase, except in the panhandle and south Florida, while PDO cool phase is
positively correlated with precipitation, except for the southern part of the peninsula.

Climate models are common tools for developing design standards in the hydrologic field; however,
these models contain uncertainties in multi-model and scenario selections. Along with these uncertainties,
biases can be attached to the models. Such biases and uncertainties can present difficulties in predicting
future extremes. These hydrologic extremes are believed to be non-stationary in character. Only in the
recent past have model users come to terms that the current hydrologic designs are no longer relevant due
to their assumption of stationarity. This study describes a systematic method of selecting a best fit model in
relationship to location and time, along with the use of that best fit model for evaluation of future extremes.
Rain gage stations throughout Florida are used to collect daily precipitation data used in extreme precipitation and quantitative indices. Through these indices conclusions are made on model selection and
future extremes, as they relate to hydrologic designs.