Abstract
Atmospheric rivers (ARs) are an important component of the global water
cycle, and AR-related hydrological hazards are across the midlatitudes,
including New Zealand. The ability to classify the strength and
potential impact of ARs has shown benefits to water resource management
in western U.S. regions. In New Zealand, the topography means that the
impact of ARs may vary significantly on either side of mountainous
areas. In this study, we evaluate whether ARs dominate monthly heavy
rainfall events and investigate characteristics of AR events that
contribute to heavy rainfall as well as the performance of an AR impact
ranking scale concerning orientations for these AR events. We found that
different geographical regions favour ARs with different orientations
for heavy rainfall generation, and northwesterly ARs are more likely to
deliver higher rainfall at certain classification levels. Furthermore,
we showed cases where ARs classified at the level could result in
different benefits and hazards in different locations. Future research
should focus on a more descriptive AR ranking scale regarding
hydrometeorological benefits and hazards, considering factors such as
the correspondence cyclones and topography.