The role of synoptic cloud in orographic rainfall in the Southern Alps of New Zealand

Purdy, J. C.; Austin, G. L.

doi:10.1017/s1350482703001087

Cited by 13 publications

(11 citation statements)

References 11 publications

(12 reference statements)

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“…For the South Island of the country, orographic precipitation is the major precipitation mechanism 27 . The highest annual precipitation totals in New Zealand (over 10,000 mm) occur in the Southern Alps 28 as this extended mountain range provides a significant barrier to the prevailing airflows 29 , 30 all year round. For the North Island, frontal systems and extratropical cyclones are the dominant precipitation mechanisms 19 , 31 , 32 , yet mountain ranges and volcanic mountain peaks in the North Island also provide obstacles to the prevailing airflows 19 .…”

Section: Introductionmentioning

confidence: 99%

The impact of atmospheric rivers on rainfall in New Zealand

Shu

Shamseldin

Weller

2021

Sci Rep

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This study quantifies the impact of atmospheric rivers (ARs) on rainfall in New Zealand. Using an automated AR detection algorithm, daily rainfall records from 654 rain gauges, and various atmospheric reanalysis datasets, we investigate the climatology of ARs, the characteristics of landfalling ARs, the contribution of ARs to annual and seasonal rainfall totals, and extreme rainfall events between 1979 and 2018 across the country. Results indicate that these filamentary synoptic features play an essential role in regional water resources and are responsible for many extreme rainfall events on the western side of mountainous areas and northern New Zealand. In these regions, depending on the season, 40–86% of the rainfall totals and 50–98% of extreme rainfall events are shown to be associated with ARs, with the largest contributions predominantly occurring during the austral summer. Furthermore, the median daily rainfall associated with ARs is 2–3 times than that associated with other storms. The results of this study extend the knowledge on the critical roles of ARs on hydrology and highlight the need for further investigation on the landfalling AR physical processes in relation to global circulation features and AR sources, and hydrological hazards caused by ARs in New Zealand.

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Section: Introductionmentioning

confidence: 99%

The impact of atmospheric rivers on rainfall in New Zealand

Shu

Shamseldin

Weller

2021

Sci Rep

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“…Precipitation associated with these fronts is enhanced typically by the orography of the Southern Alps, which rise from sea level to >3000 m within approximately 40 km of the west coast. The combination of frontal precipitation and orographic uplift can result in a ‘seeder–feeder’ situation, whereby the synoptic‐origin precipitation scavenges moisture that has condensed at a lower level as a result of forced uplift to create extreme heavy precipitation events (Purdy and Austin, ; Purdy et al ., ).…”

Section: Introductionmentioning

confidence: 99%

Floods in the Southern Alps of New Zealand: the importance of atmospheric rivers

Kingston

Lavers

Hannah

2016

Hydrological Processes

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Extremely high precipitation occurs in the Southern Alps of New Zealand, associated with both orographic enhancement and synoptic‐scale weather processes. In this study, we test the hypothesis that atmospheric rivers (ARs) are a key driver of floods in the Southern Alps of New Zealand. Vertically integrated water vapour and horizontal water vapour transport, and atmospheric circulation, are investigated concurrently with major floods on the Waitaki River (a major South Island river). Analysis of the largest eight winter maximum floods between 1979 and 2012 indicates that all are associated with ARs. Geopotential height fields reveal that these ARs are located in slow eastward moving extratropical cyclones, with high pressure to the northeast of New Zealand. The confirmation of ARs as a contributor to Waitaki flooding indicates the need for their further exploration to better understand South Island hydrometeorological extremes. Copyright © 2016 John Wiley & Sons, Ltd.

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“…This enhancement is generally around a factor of four for individual storms and may be as high as a factor of eight, with much of the increase occurring in approximately 30 km between the coastal plains and windward slopes of the Alps (Henderson 1993). A physical mechanism for the observed enhancement is studied in Purdy & Austin (2003), and involves advection of cloud droplets due to synoptic scale lifting into the area of orographic lifting. The Southern Alps run almost the full 800 km length of South Island and regularly reach over 2000 m in altitude.…”

Section: Introductionmentioning

confidence: 99%