Precipitation and temperature anomalies over Aotearoa New Zealand analysed by weather types and descriptors of atmospheric centres of action

Pohl, Benjamin; Sturman, Andrew; Renwick, James; Quénol, Hervé; Fauchereau, Nicolas; Lorrey, Andrew; Pergaud, Julien

doi:10.1002/joc.7762

Cited by 8 publications

(30 citation statements)

References 64 publications

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“…These results (Figure 11a) generally confirm previous work concluding that southerly anomalies advect dry air toward ANZ, northerly fluxes having an opposite effect (e.g., Pohl et al., 2021c, 2023). Furthermore, they point out that the air mass contains significantly more humidity during AR days (Figure 11b).…”

Section: Ar and Wt Inter‐relationshipssupporting

confidence: 90%

“…The effects of landfalling ARs on precipitation in ANZ has already been assessed before (Reid et al., 2021; Shu et al., 2021), as have been those of WTs (K2K; Pohl et al., 2023; Renwick, 2011). Here, we attempt to consider how their respective influences combine, that is, we analyze precipitation anomalies by WT and depending whether or not these WT days also correspond to AR occurrences.…”

Section: Ar and Wt Combined And Separate Influences On Precipitationmentioning

confidence: 99%

“…Both definitions of the WTs are used in both figures, because they lead to slightly different results (both in terms of preferential associations between WTs and ARs, Figure 5, and within‐type differences): please refer to Pohl et al. (2021b, 2023) for more details. Figures S10 and S11 in Supporting Information generalizes the results of Figure 10 results for the South Coast and Northland regions of ANZ, respectively, and Figures S12 and S13 in Supporting Information similarly extend the results of Figure 11.…”

Section: Ar and Wt Inter‐relationshipsmentioning

confidence: 99%

“…Significant relationships have been established between these WTs and the Madden–Julian oscillation (Fauchereau et al., 2016), the interdecadal Pacific oscillation (Lorrey et al., 2007), and the Southern Hemisphere large‐scale background conditions (Renwick, 2011). At the more local and regional scales, these WTs have been shown to drive daily climate anomalies (K2K; Pohl et al., 2023; Renwick, 2011), seasonal rainfall anomalies (Lorrey et al., 2007), and to modulate ocean wave heights (Coggins et al., 2016) and ocean–atmosphere coupled summer heatwaves (Salinger et al., 2020). Recently, they have been shown to conceal strong within‐type variability (Pohl et al., 2021b: P21 hereafter), a given type being associated with atmospheric ridges and troughs highly variable in intensities and locations.…”

Section: Introductionmentioning

confidence: 99%

“…Part of the strong within-type diversity linked to changes in the location and intensities of atmospheric centers of action (ACAs: P21) could partly relate to the development (or lack thereof) of ARs in the ANZ sector. • Although WT influence has been extensively assessed (K2K; Lorrey et al, 2007;Pohl et al, 2023;Renwick, 2011), their separate and combined influence with ARs on daily precipitation amounts, including extremes, remains to be determined. The picture of precipitation changes from one WT to another could be strongly modified depending on their co-occurrence (or lack thereof) with ARs.…”

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confidence: 99%

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Atmospheric Rivers and Weather Types in Aotearoa New Zealand: A Two‐Way Story

et al. 2023

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Here, we analyze the inter‐relationships between weather types (WTs) and atmospheric rivers (ARs) around Aotearoa New Zealand (ANZ), their respective properties, as well as their combined and separate influence on daily precipitation amounts and extremes. Results show that ARs are often associated with 3‐4 WTs, but these WTs change depending on the regions where ARs landfall. The WTs most frequently associated with ARs generally correspond to those favoring anomalously strong westerly wind in the mid‐latitudes, especially for southern regions of ANZ, or northwesterly anomalies favoring moisture export from the lower latitudes, especially for the northern regions.WTs and ARs show strong within‐type and inter‐event diversity. The synoptic patterns of the WTs significantly differ when they are associated with AR occurrences, with atmospheric centers of actions being shifted so that moisture fluxes towards ANZ are enhanced. The location, angle, and persistence of ARs appear strongly driven by the synoptic configurations of the WTs. Although total moisture transport shows weaker WT‐dependency, it appears strongly related to zonal wind speed to the south of ANZ, or the moisture content of the air mass to the north. Finally, WT influence on daily precipitation may completely change depending on their association, or lack thereof, with AR events. WTs traditionally considered as favorable to wet conditions may conceal daily precipitation extremes occurring during AR days, and anomalously dry days or near‐climatological conditions during non‐AR days.

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Section: Ar and Wt Inter‐relationshipssupporting

confidence: 90%

Section: Ar and Wt Combined And Separate Influences On Precipitationmentioning

confidence: 99%

Section: Ar and Wt Inter‐relationshipsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Atmospheric Rivers and Weather Types in Aotearoa New Zealand: A Two‐Way Story

et al. 2023

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Atmospheric Rivers and Weather Types in Aotearoa New Zealand: a two-way story

Pohl

Prince

Wille

et al. 2022

Preprint

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HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

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Increasing temperature extremes in New Zealand and their connection to synoptic circulation features

Thomas

McDonald

Renwick

et al. 2022

Intl Journal of Climatology

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Extreme temperature events (ETEs) have evolved alongside the warming climate over most parts of the world. This study provides a statistical quantification of how human influences have changed the frequencies of extreme temperatures in New Zealand, depending on the synoptic weather types. We use the ensembles under pre‐industrial conditions (natural scenarios with no human‐induced changes) and present‐day conditions (anthropogenic scenarios) from the weather@home regional climate model. The ensemble simulations under these two scenarios are used to identify how human influences have impacted the frequency and intensity of extreme temperatures based on their connection to different large‐scale circulation patterns derived using self‐organizing maps (SOMs). Over New Zealand, an average two to three fold rise in frequencies of extremes occurs irrespective of seasons due to anthropogenic influence with a mean temperature increase close to 1°C. For some synoptic situations, the frequency of extremes are especially enhanced; in particular, for low‐pressure centres to the northeast of New Zealand where the frequency of occurrence of daily temperature extremes has increased by a factor of 7 between anthropogenic and natural ensembles for the winter season, though these synoptic patterns rarely occur. For low‐pressure centres to the northwest of New Zealand, we observe high temperatures frequently in both anthropogenic and natural ensembles which we expect is probably associated with warm air advection from the Tropics. The frequency of occurrence of high temperatures in these synoptic patterns has also increased by a factor of 2 between the natural and anthropogenic ensembles. For these synoptic states, the extremes are observed in the North Island and along the east coast of the country with the highest temperature along the Canterbury coast and Northland. The change between the natural and anthropogenic ensembles is largest on the west coast along the Southern Alps for all the synoptic circulation types.

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Precipitation and temperature anomalies over Aotearoa New Zealand analysed by weather types and descriptors of atmospheric centres of action

Cited by 8 publications

References 64 publications

Atmospheric Rivers and Weather Types in Aotearoa New Zealand: A Two‐Way Story

Atmospheric Rivers and Weather Types in Aotearoa New Zealand: A Two‐Way Story

Atmospheric Rivers and Weather Types in Aotearoa New Zealand: a two-way story

Increasing temperature extremes in New Zealand and their connection to synoptic circulation features

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