| Abstrakt: |
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 toward 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. Plain Language Summary: We analyze here how atmospheric rivers (ARs) relate to weather types (WTs), using the case study of Aotearoa New Zealand (ANZ). We show that, for each region of ANZ, ARs tend to occur during different WTs. Generally, for a given region, most ARs form during 3 or 4 main WTs, and these dominant WTs differ from one region to another. These WTs also show different patterns when they are associated with ARs, compared to other days. AR days have atmospheric configurations that are more efficient to direct moisture fluxes toward the coasts of ANZ. Combining both view of regional climate variability is important to understand the drivers of extreme precipitation events. Key Points: Weather types (WTs) are major drivers of atmospheric rivers (ARs) (frequency, angle, moisture transport direction, and landfalling region)ARs explain part of within‐type diversity (circulation and rainfall anomalies)Combined or separate effects of WTs and ARs strongly vary from one region of Aotearoa New Zealand to another [ABSTRACT FROM AUTHOR] |
Plný text